Open Access Publications
From research on the visual systems of turtles, to the perception of faces with or without makeup, to transaccadic perception and perceptual cycles in the brain– VPixx hardware and software solutions have supported research in vision science and beyond for over 20 years. We are immensely proud of the discoveries and accomplishments of our customers across the world.
On this page you will find a non-exhaustive list of peer-reviewed, open access publications citing VPixx tools dating back to 2003. Browse the list or use the tag filter to search for specific products. Note that we report the device used in the paper according to the authors; this may not accurately reflect the specific model of device used (e.g., VIEWPixx vs. VIEWPixx /3D). Nor do we guarantee the accuracy of published content. Please contact our team at [email protected] if you have any questions about a specific paper.
Curious about a specific application of our tools? Can’t find what you are looking for? Our staff scientists are happy to discuss paradigms and protocols using our equipment by email or video chat. Please contact us with your questions.
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Use the search tool below to search for specific terms among the titles, authors and abstracts in our library.
1.
Kumano, Hironori; Uka, Takanori
Employment of time-varying sensory evidence to test the mechanisms underlying flexible decision-making Journal Article
In: NeuroReport, vol. 35, no. 2, pp. 107, 2024, ISSN: 0959-4965.
Abstract | Links | BibTeX | Tags: VIEWPixx3D
@article{kumano_employment_2024,
title = {Employment of time-varying sensory evidence to test the mechanisms underlying flexible decision-making},
author = {Hironori Kumano and Takanori Uka},
url = {https://journals.lww.com/neuroreport/fulltext/2024/02010/employment_of_time_varying_sensory_evidence_to.5.aspx},
doi = {10.1097/WNR.0000000000001980},
issn = {0959-4965},
year = {2024},
date = {2024-02-01},
urldate = {2024-01-09},
journal = {NeuroReport},
volume = {35},
number = {2},
pages = {107},
abstract = {To make flexible decisions in dynamic environments, the brain must integrate behaviorally relevant information while simultaneously discarding irrelevant information. This study aimed to investigate the mechanisms responsible for discarding irrelevant information during context-dependent decision-making. We trained two macaque monkeys to switch between direction and depth discrimination tasks in successive trials. During decision-making, the strength of the motion or depth signal changes transiently at various times, introducing a brief pulse. We assessed the effects of pulse on behavioral choices. Consistent with previous findings, early relevant pulses, such as motion pulses during direction discrimination, had a significantly larger effect compared to late pulses. Critically, the effects of irrelevant pulses, such as motion pulses during depth discrimination, exhibited an initial minimal effect, followed by an increase and subsequent decrease as a function of pulse timing. Gating mechanisms alone, aimed at discarding irrelevant information, did not account for the observed time course of pulse effects. Instead, the observed increase in the effects of irrelevant pulses with time suggested the involvement of a leaky integration mechanism. The results suggested that the brain controls the amount of disposal in accumulating sensory evidence during flexible decision-making.},
keywords = {VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
To make flexible decisions in dynamic environments, the brain must integrate behaviorally relevant information while simultaneously discarding irrelevant information. This study aimed to investigate the mechanisms responsible for discarding irrelevant information during context-dependent decision-making. We trained two macaque monkeys to switch between direction and depth discrimination tasks in successive trials. During decision-making, the strength of the motion or depth signal changes transiently at various times, introducing a brief pulse. We assessed the effects of pulse on behavioral choices. Consistent with previous findings, early relevant pulses, such as motion pulses during direction discrimination, had a significantly larger effect compared to late pulses. Critically, the effects of irrelevant pulses, such as motion pulses during depth discrimination, exhibited an initial minimal effect, followed by an increase and subsequent decrease as a function of pulse timing. Gating mechanisms alone, aimed at discarding irrelevant information, did not account for the observed time course of pulse effects. Instead, the observed increase in the effects of irrelevant pulses with time suggested the involvement of a leaky integration mechanism. The results suggested that the brain controls the amount of disposal in accumulating sensory evidence during flexible decision-making.
2.
Marshall, Tom R.; Ruesseler, Maria; Hunt, Laurence T.; O’Reilly, Jill X.
The representation of priors and decisions in the human parietal cortex Journal Article
In: PLOS Biology, vol. 22, no. 1, pp. e3002383, 2024, ISSN: 1545-7885, (Publisher: Public Library of Science).
Abstract | Links | BibTeX | Tags: PROPixx
@article{marshall_representation_2024,
title = {The representation of priors and decisions in the human parietal cortex},
author = {Tom R. Marshall and Maria Ruesseler and Laurence T. Hunt and Jill X. O’Reilly},
url = {https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002383},
doi = {10.1371/journal.pbio.3002383},
issn = {1545-7885},
year = {2024},
date = {2024-01-01},
urldate = {2024-02-01},
journal = {PLOS Biology},
volume = {22},
number = {1},
pages = {e3002383},
abstract = {Animals actively sample their environment through orienting actions such as saccadic eye movements. Saccadic targets are selected based both on sensory evidence immediately preceding the saccade, and a “salience map” or prior built-up over multiple saccades. In the primate cortex, the selection of each individual saccade depends on competition between target-selective cells that ramp up their firing rate to saccade release. However, it is less clear how a cross-saccade prior might be implemented, either in neural firing or through an activity-silent mechanism such as modification of synaptic weights on sensory inputs. Here, we present evidence from magnetoencephalography for 2 distinct processes underlying the selection of the current saccade, and the representation of the prior, in human parietal cortex. While the classic ramping decision process for each saccade was reflected in neural firing rates (measured in the event-related field), a prior built-up over multiple saccades was implemented via modulation of the gain on sensory inputs from the preferred target, as evidenced by rapid frequency tagging. A cascade of computations over time (initial representation of the prior, followed by evidence accumulation and then an integration of prior and evidence) provides a mechanism by which a salience map may be built up across saccades in parietal cortex. It also provides insight into the apparent contradiction that inactivation of parietal cortex has been shown not to affect performance on single-trials, despite the presence of clear evidence accumulation signals in this region.},
note = {Publisher: Public Library of Science},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
Animals actively sample their environment through orienting actions such as saccadic eye movements. Saccadic targets are selected based both on sensory evidence immediately preceding the saccade, and a “salience map” or prior built-up over multiple saccades. In the primate cortex, the selection of each individual saccade depends on competition between target-selective cells that ramp up their firing rate to saccade release. However, it is less clear how a cross-saccade prior might be implemented, either in neural firing or through an activity-silent mechanism such as modification of synaptic weights on sensory inputs. Here, we present evidence from magnetoencephalography for 2 distinct processes underlying the selection of the current saccade, and the representation of the prior, in human parietal cortex. While the classic ramping decision process for each saccade was reflected in neural firing rates (measured in the event-related field), a prior built-up over multiple saccades was implemented via modulation of the gain on sensory inputs from the preferred target, as evidenced by rapid frequency tagging. A cascade of computations over time (initial representation of the prior, followed by evidence accumulation and then an integration of prior and evidence) provides a mechanism by which a salience map may be built up across saccades in parietal cortex. It also provides insight into the apparent contradiction that inactivation of parietal cortex has been shown not to affect performance on single-trials, despite the presence of clear evidence accumulation signals in this region.
3.
Taubert, Jessica; Japee, Shruti
Real Face Value: The Processing of Naturalistic Facial Expressions in the Macaque Inferior Temporal Cortex Journal Article
In: Journal of Cognitive Neuroscience, pp. 1–17, 2024, ISSN: 0898-929X, 1530-8898.
Abstract | Links | BibTeX | Tags: DATAPixx
@article{taubert_real_2024,
title = {Real Face Value: The Processing of Naturalistic Facial Expressions in the Macaque Inferior Temporal Cortex},
author = {Jessica Taubert and Shruti Japee},
url = {https://direct.mit.edu/jocn/article/doi/10.1162/jocn_a_02108/119171/Real-Face-Value-The-Processing-of-Naturalistic},
doi = {10.1162/jocn_a_02108},
issn = {0898-929X, 1530-8898},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-30},
journal = {Journal of Cognitive Neuroscience},
pages = {1–17},
abstract = {Abstract
For primates, expressions of fear are thought to be powerful social signals. In laboratory settings, faces with fearful expressions have reliably evoked valence effects in inferior temporal cortex. However, because macaques use so called “fear grins” in a variety of different contexts, the deeper question is whether the macaque inferior temporal cortex is tuned to the prototypical fear grin, or to conspecifics signaling fear? In this study, we combined neuroimaging with the results of a behavioral task to investigate how macaques encode a wide variety of fearful facial expressions. In Experiment 1, we identified two sets of macaque face stimuli using different approaches; we selected faces based on the emotional context (i.e., calm vs. fearful), and we selected faces based on the engagement of action units (i.e., neutral vs. fear grins). We also included human faces in Experiment 1. Then, using fMRI, we found that the faces selected based on context elicited a larger valence effect in the inferior temporal cortex than faces selected based on visual appearance. Furthermore, human facial expressions only elicited weak valence effects. These observations were further supported by the results of a two-alternative, forced-choice task (Experiment 2), suggesting that fear grins vary in their perceived pleasantness. Collectively, these findings indicate that the macaque inferior temporal cortex is more involved in social intelligence than commonly assumed, encoding emergent properties in naturalistic face stimuli that transcend basic visual features. These results demand a rethinking of theories surrounding the function and operationalization of primate inferior temporal cortex.},
keywords = {DATAPixx},
pubstate = {published},
tppubtype = {article}
}
Abstract
For primates, expressions of fear are thought to be powerful social signals. In laboratory settings, faces with fearful expressions have reliably evoked valence effects in inferior temporal cortex. However, because macaques use so called “fear grins” in a variety of different contexts, the deeper question is whether the macaque inferior temporal cortex is tuned to the prototypical fear grin, or to conspecifics signaling fear? In this study, we combined neuroimaging with the results of a behavioral task to investigate how macaques encode a wide variety of fearful facial expressions. In Experiment 1, we identified two sets of macaque face stimuli using different approaches; we selected faces based on the emotional context (i.e., calm vs. fearful), and we selected faces based on the engagement of action units (i.e., neutral vs. fear grins). We also included human faces in Experiment 1. Then, using fMRI, we found that the faces selected based on context elicited a larger valence effect in the inferior temporal cortex than faces selected based on visual appearance. Furthermore, human facial expressions only elicited weak valence effects. These observations were further supported by the results of a two-alternative, forced-choice task (Experiment 2), suggesting that fear grins vary in their perceived pleasantness. Collectively, these findings indicate that the macaque inferior temporal cortex is more involved in social intelligence than commonly assumed, encoding emergent properties in naturalistic face stimuli that transcend basic visual features. These results demand a rethinking of theories surrounding the function and operationalization of primate inferior temporal cortex.
For primates, expressions of fear are thought to be powerful social signals. In laboratory settings, faces with fearful expressions have reliably evoked valence effects in inferior temporal cortex. However, because macaques use so called “fear grins” in a variety of different contexts, the deeper question is whether the macaque inferior temporal cortex is tuned to the prototypical fear grin, or to conspecifics signaling fear? In this study, we combined neuroimaging with the results of a behavioral task to investigate how macaques encode a wide variety of fearful facial expressions. In Experiment 1, we identified two sets of macaque face stimuli using different approaches; we selected faces based on the emotional context (i.e., calm vs. fearful), and we selected faces based on the engagement of action units (i.e., neutral vs. fear grins). We also included human faces in Experiment 1. Then, using fMRI, we found that the faces selected based on context elicited a larger valence effect in the inferior temporal cortex than faces selected based on visual appearance. Furthermore, human facial expressions only elicited weak valence effects. These observations were further supported by the results of a two-alternative, forced-choice task (Experiment 2), suggesting that fear grins vary in their perceived pleasantness. Collectively, these findings indicate that the macaque inferior temporal cortex is more involved in social intelligence than commonly assumed, encoding emergent properties in naturalistic face stimuli that transcend basic visual features. These results demand a rethinking of theories surrounding the function and operationalization of primate inferior temporal cortex.
4.
Coop, Shanna H.; Yates, Jacob L.; Mitchell, Jude F.
Pre-saccadic Neural Enhancements in Marmoset Area MT Journal Article
In: Journal of Neuroscience, vol. 44, no. 4, 2024, ISSN: 0270-6474, 1529-2401, (Publisher: Society for Neuroscience Section: Research Articles).
Abstract | Links | BibTeX | Tags:
@article{coop_pre-saccadic_2024,
title = {Pre-saccadic Neural Enhancements in Marmoset Area MT},
author = {Shanna H. Coop and Jacob L. Yates and Jude F. Mitchell},
url = {https://www.jneurosci.org/content/44/4/e2034222023},
doi = {10.1523/JNEUROSCI.2034-22.2023},
issn = {0270-6474, 1529-2401},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-30},
journal = {Journal of Neuroscience},
volume = {44},
number = {4},
abstract = {Each time we make an eye movement, attention moves before the eyes, resulting in a perceptual enhancement at the target. Recent psychophysical studies suggest that this pre-saccadic attention enhances the visual features at the saccade target, whereas covert attention causes only spatially selective enhancements. While previous nonhuman primate studies have found that pre-saccadic attention does enhance neural responses spatially, no studies have tested whether changes in neural tuning reflect an automatic feature enhancement. Here we examined pre-saccadic attention using a saccade foraging task developed for marmoset monkeys (one male and one female). We recorded from neurons in the middle temporal area with peripheral receptive fields that contained a motion stimulus, which would either be the target of a saccade or a distracter as a saccade was made to another location. We established that marmosets, like macaques, show enhanced pre-saccadic neural responses for saccades toward the receptive field, including increases in firing rate and motion information. We then examined if the specific changes in neural tuning might support feature enhancements for the target. Neurons exhibited diverse changes in tuning but predominantly showed additive and multiplicative increases that were uniformly applied across motion directions. These findings confirm that marmoset monkeys, like macaques, exhibit pre-saccadic neural enhancements during saccade foraging tasks with minimal training requirements. However, at the level of individual neurons, the lack of feature-tuned enhancements is similar to neural effects reported during covert spatial attention.},
note = {Publisher: Society for Neuroscience
Section: Research Articles},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Each time we make an eye movement, attention moves before the eyes, resulting in a perceptual enhancement at the target. Recent psychophysical studies suggest that this pre-saccadic attention enhances the visual features at the saccade target, whereas covert attention causes only spatially selective enhancements. While previous nonhuman primate studies have found that pre-saccadic attention does enhance neural responses spatially, no studies have tested whether changes in neural tuning reflect an automatic feature enhancement. Here we examined pre-saccadic attention using a saccade foraging task developed for marmoset monkeys (one male and one female). We recorded from neurons in the middle temporal area with peripheral receptive fields that contained a motion stimulus, which would either be the target of a saccade or a distracter as a saccade was made to another location. We established that marmosets, like macaques, show enhanced pre-saccadic neural responses for saccades toward the receptive field, including increases in firing rate and motion information. We then examined if the specific changes in neural tuning might support feature enhancements for the target. Neurons exhibited diverse changes in tuning but predominantly showed additive and multiplicative increases that were uniformly applied across motion directions. These findings confirm that marmoset monkeys, like macaques, exhibit pre-saccadic neural enhancements during saccade foraging tasks with minimal training requirements. However, at the level of individual neurons, the lack of feature-tuned enhancements is similar to neural effects reported during covert spatial attention.
5.
Franken, Tom P.; Reynolds, John H.
Grouping cells in primate visual cortex Miscellaneous
2024, (Pages: 2024.01.16.575953 Section: New Results).
Abstract | Links | BibTeX | Tags: PROPixx
@misc{franken_grouping_2024,
title = {Grouping cells in primate visual cortex},
author = {Tom P. Franken and John H. Reynolds},
url = {https://www.biorxiv.org/content/10.1101/2024.01.16.575953v1},
doi = {10.1101/2024.01.16.575953},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-24},
publisher = {bioRxiv},
abstract = {Our perception of how objects are laid out in visual scenes is remarkably stable, despite rapid shifts in the patterns of light that fall on the retina with each saccade. One mechanism that may help establish perceptual stability is border ownership assignment. Studies in macaque area V2 have identified border ownership neurons that signal which side of a border belongs to a foreground surface. This signal persists for hundreds of milliseconds after border ownership has been rendered ambiguous by deleting the stimulus features that distinguish foreground from background. Remarkably, this signal survives eye movements: border ownership neurons also exhibit border ownership signals de novo when an eye movement places the newly ambiguous border within their receptive field. The grouping cell hypothesis proposes the existence of hypothetical grouping cells in a downstream brain area. These cells would compute persistent proto-object representations and therefore have the properties to endow cells in upstream brain areas with selectivity for border ownership. Such grouping cells have been predicted to show a centripetal and persistent pattern of preferred side of ownership for a border placed parallel to the perimeter of their classical receptive field, and such a centripetal ownership preference pattern should also occur de novo in these same cells if an ambiguous border lands in their receptive field after a saccade. It is unknown if grouping cells exist. Here we used laminar multielectrodes in area V4 – the main source of feedback to V2 – of behaving macaques to determine whether such grouping cells exist. Consistent with the model prediction we find a substantial population of neurons with these properties, in all laminar compartments, and they exhibit a response latency that is short enough to act as the source that endows neurons in V2 with selectivity for border ownership. While grouping cell activity provides information about the location of foreground surfaces, these neurons are, counterintuitively, not as strongly tuned for luminance contrast polarity, a feature of those surfaces, as are border ownership cells. Our data suggest a division of labor in which these newly discovered grouping cells provide spatiotemporal continuity of segmented surfaces whereas border ownership cells link this location information with surface features such as luminance contrast.},
note = {Pages: 2024.01.16.575953
Section: New Results},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {misc}
}
Our perception of how objects are laid out in visual scenes is remarkably stable, despite rapid shifts in the patterns of light that fall on the retina with each saccade. One mechanism that may help establish perceptual stability is border ownership assignment. Studies in macaque area V2 have identified border ownership neurons that signal which side of a border belongs to a foreground surface. This signal persists for hundreds of milliseconds after border ownership has been rendered ambiguous by deleting the stimulus features that distinguish foreground from background. Remarkably, this signal survives eye movements: border ownership neurons also exhibit border ownership signals de novo when an eye movement places the newly ambiguous border within their receptive field. The grouping cell hypothesis proposes the existence of hypothetical grouping cells in a downstream brain area. These cells would compute persistent proto-object representations and therefore have the properties to endow cells in upstream brain areas with selectivity for border ownership. Such grouping cells have been predicted to show a centripetal and persistent pattern of preferred side of ownership for a border placed parallel to the perimeter of their classical receptive field, and such a centripetal ownership preference pattern should also occur de novo in these same cells if an ambiguous border lands in their receptive field after a saccade. It is unknown if grouping cells exist. Here we used laminar multielectrodes in area V4 – the main source of feedback to V2 – of behaving macaques to determine whether such grouping cells exist. Consistent with the model prediction we find a substantial population of neurons with these properties, in all laminar compartments, and they exhibit a response latency that is short enough to act as the source that endows neurons in V2 with selectivity for border ownership. While grouping cell activity provides information about the location of foreground surfaces, these neurons are, counterintuitively, not as strongly tuned for luminance contrast polarity, a feature of those surfaces, as are border ownership cells. Our data suggest a division of labor in which these newly discovered grouping cells provide spatiotemporal continuity of segmented surfaces whereas border ownership cells link this location information with surface features such as luminance contrast.
6.
Doré, Sydney; Coutinho, Jonathan; Brooks, Emma; Khan, Aarlenne Z; Lefèvre, Philippe; Blohm, Gunnar
Timing and Amplitude of Catch-up Saccades to Accelerating Targets Technical Report
Neuroscience 2024.
Abstract | Links | BibTeX | Tags: VIEWPixx
@techreport{dore_timing_2024,
title = {Timing and Amplitude of Catch-up Saccades to Accelerating Targets},
author = {Sydney Doré and Jonathan Coutinho and Emma Brooks and Aarlenne Z Khan and Philippe Lefèvre and Gunnar Blohm},
url = {http://biorxiv.org/lookup/doi/10.1101/2024.01.11.575233},
doi = {10.1101/2024.01.11.575233},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-23},
institution = {Neuroscience},
abstract = {To track moving targets, humans move their eyes using both saccades and smooth pursuit. If pursuit eye movements fail to accurately track the moving target, catch-up saccades are initiated to rectify the tracking error. It is well known that retinal position and velocity errors determine saccade timing and amplitude, but the extent to which retinal acceleration error influences these aspects is not well quantified. To test this, 13 adult human participants performed an experiment where they pursued accelerating / decelerating targets. During ongoing pursuit, we introduced a randomly sized target step to evoke a catch-up saccade and analyzed its timing and amplitude. We observed that retinal acceleration error was a statistically significant predictor of saccade amplitude and timing. A multiple linear regression supported our hypothesis that retinal acceleration errors influence saccade amplitude in addition to the influence of retinal position and velocity errors. We also found that saccade latencies were shorter when retinal acceleration error increased the tracking error and vice versa. In summary, our findings support a model in which retinal acceleration error is used to compute a predicted position error textasciitilde100ms into the future to trigger saccades and determine saccade amplitude.},
keywords = {VIEWPixx},
pubstate = {published},
tppubtype = {techreport}
}
To track moving targets, humans move their eyes using both saccades and smooth pursuit. If pursuit eye movements fail to accurately track the moving target, catch-up saccades are initiated to rectify the tracking error. It is well known that retinal position and velocity errors determine saccade timing and amplitude, but the extent to which retinal acceleration error influences these aspects is not well quantified. To test this, 13 adult human participants performed an experiment where they pursued accelerating / decelerating targets. During ongoing pursuit, we introduced a randomly sized target step to evoke a catch-up saccade and analyzed its timing and amplitude. We observed that retinal acceleration error was a statistically significant predictor of saccade amplitude and timing. A multiple linear regression supported our hypothesis that retinal acceleration errors influence saccade amplitude in addition to the influence of retinal position and velocity errors. We also found that saccade latencies were shorter when retinal acceleration error increased the tracking error and vice versa. In summary, our findings support a model in which retinal acceleration error is used to compute a predicted position error textasciitilde100ms into the future to trigger saccades and determine saccade amplitude.
7.
Blondiaux, Florence; Colmant, Lise; Lebrun, Louisien; Hanseeuw, Bernard; Crevecoeur, Frédéric
Erroneous compensation for long-latency feedback delays as origin of Essential Tremor Technical Report
Neuroscience 2024.
Abstract | Links | BibTeX | Tags: VIEWPixxXL
@techreport{blondiaux_erroneous_2024,
title = {Erroneous compensation for long-latency feedback delays as origin of Essential Tremor},
author = {Florence Blondiaux and Lise Colmant and Louisien Lebrun and Bernard Hanseeuw and Frédéric Crevecoeur},
url = {http://biorxiv.org/lookup/doi/10.1101/2024.01.11.575204},
doi = {10.1101/2024.01.11.575204},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-23},
institution = {Neuroscience},
abstract = {Abstract Essential tremor (ET), a movement disorder characterized by involuntary oscillations of the limbs during movement, remains to date not well understood. It has been recently suggested that the tremor originates from impaired delay compensation, affecting movement representation and online control. Here we tested this hypothesis directly with ET patients (N=24) and neurologically intact (NI) volunteers (N=28) in an upper limb postural perturbation task. After maintaining their hand in a visual target, participants experienced perturbations of unpredictable direction and magnitude, and were instructed to counter the perturbation and steer their hand back to the starting position. In comparison with NI volunteers, ET patients early muscular responses (Short and Long Latency Responses, 20-50 ms and 50-100 ms respectively) were preserved or even slightly increased. However, they exhibited perturbation-dependent deficits when stopping and stabilizing their hand in the final target supporting the hypothesis that the tremor was generated by the feedback controller. We show in a computational model that errors in delay compensation accumulating over time produced the same small increase in initial feedback response followed by oscillations that scaled with the perturbation magnitude as observed in ET population. Our experimental results therefore validate the computational hypothesis that inaccurate delay compensation in long-latency pathways could be the origin of the tremor.
Significance Statement
Essential Tremor origin remains poorly understood. In the present study, we focused on motor impairments associated with feedback control. Following a mechanical perturbation applied to their arm, patients’ short and initial long latency stretch responses were preserved. However, we observed clear impairments during the stabilization phase that scaled with the perturbation magnitude. These results were reproduced in a computational model where delay compensation was inaccurate, suggesting that the origin of the tremor may lie in an underestimation of the delays impacting the internal monitoring of the motor commands.},
keywords = {VIEWPixxXL},
pubstate = {published},
tppubtype = {techreport}
}
Abstract Essential tremor (ET), a movement disorder characterized by involuntary oscillations of the limbs during movement, remains to date not well understood. It has been recently suggested that the tremor originates from impaired delay compensation, affecting movement representation and online control. Here we tested this hypothesis directly with ET patients (N=24) and neurologically intact (NI) volunteers (N=28) in an upper limb postural perturbation task. After maintaining their hand in a visual target, participants experienced perturbations of unpredictable direction and magnitude, and were instructed to counter the perturbation and steer their hand back to the starting position. In comparison with NI volunteers, ET patients early muscular responses (Short and Long Latency Responses, 20-50 ms and 50-100 ms respectively) were preserved or even slightly increased. However, they exhibited perturbation-dependent deficits when stopping and stabilizing their hand in the final target supporting the hypothesis that the tremor was generated by the feedback controller. We show in a computational model that errors in delay compensation accumulating over time produced the same small increase in initial feedback response followed by oscillations that scaled with the perturbation magnitude as observed in ET population. Our experimental results therefore validate the computational hypothesis that inaccurate delay compensation in long-latency pathways could be the origin of the tremor.
Significance Statement
Essential Tremor origin remains poorly understood. In the present study, we focused on motor impairments associated with feedback control. Following a mechanical perturbation applied to their arm, patients’ short and initial long latency stretch responses were preserved. However, we observed clear impairments during the stabilization phase that scaled with the perturbation magnitude. These results were reproduced in a computational model where delay compensation was inaccurate, suggesting that the origin of the tremor may lie in an underestimation of the delays impacting the internal monitoring of the motor commands.
Significance Statement
Essential Tremor origin remains poorly understood. In the present study, we focused on motor impairments associated with feedback control. Following a mechanical perturbation applied to their arm, patients’ short and initial long latency stretch responses were preserved. However, we observed clear impairments during the stabilization phase that scaled with the perturbation magnitude. These results were reproduced in a computational model where delay compensation was inaccurate, suggesting that the origin of the tremor may lie in an underestimation of the delays impacting the internal monitoring of the motor commands.
8.
Mendoza-Halliday, Diego; Major, Alex James; Lee, Noah; Lichtenfeld, Maxwell J.; Carlson, Brock; Mitchell, Blake; Meng, Patrick D.; Xiong, Yihan (Sophy); Westerberg, Jacob A.; Jia, Xiaoxuan; Johnston, Kevin D.; Selvanayagam, Janahan; Everling, Stefan; Maier, Alexander; Desimone, Robert; Miller, Earl K.; Bastos, André M.
A ubiquitous spectrolaminar motif of local field potential power across the primate cortex Journal Article
In: Nature Neuroscience, pp. 1–14, 2024, ISSN: 1546-1726, (Publisher: Nature Publishing Group).
Abstract | Links | BibTeX | Tags: VIEWPixx3D
@article{mendoza-halliday_ubiquitous_2024,
title = {A ubiquitous spectrolaminar motif of local field potential power across the primate cortex},
author = {Diego Mendoza-Halliday and Alex James Major and Noah Lee and Maxwell J. Lichtenfeld and Brock Carlson and Blake Mitchell and Patrick D. Meng and Yihan (Sophy) Xiong and Jacob A. Westerberg and Xiaoxuan Jia and Kevin D. Johnston and Janahan Selvanayagam and Stefan Everling and Alexander Maier and Robert Desimone and Earl K. Miller and André M. Bastos},
url = {https://www.nature.com/articles/s41593-023-01554-7},
doi = {10.1038/s41593-023-01554-7},
issn = {1546-1726},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-18},
journal = {Nature Neuroscience},
pages = {1–14},
abstract = {The mammalian cerebral cortex is anatomically organized into a six-layer motif. It is currently unknown whether a corresponding laminar motif of neuronal activity patterns exists across the cortex. Here we report such a motif in the power of local field potentials (LFPs). Using laminar probes, we recorded LFPs from 14 cortical areas across the cortical hierarchy in five macaque monkeys. The laminar locations of recordings were histologically identified by electrolytic lesions. Across all areas, we found a ubiquitous spectrolaminar pattern characterized by an increasing deep-to-superficial layer gradient of high-frequency power peaking in layers 2/3 and an increasing superficial-to-deep gradient of alpha-beta power peaking in layers 5/6. Laminar recordings from additional species showed that the spectrolaminar pattern is highly preserved among primates—macaque, marmoset and human—but more dissimilar in mouse. Our results suggest the existence of a canonical layer-based and frequency-based mechanism for cortical computation.},
note = {Publisher: Nature Publishing Group},
keywords = {VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
The mammalian cerebral cortex is anatomically organized into a six-layer motif. It is currently unknown whether a corresponding laminar motif of neuronal activity patterns exists across the cortex. Here we report such a motif in the power of local field potentials (LFPs). Using laminar probes, we recorded LFPs from 14 cortical areas across the cortical hierarchy in five macaque monkeys. The laminar locations of recordings were histologically identified by electrolytic lesions. Across all areas, we found a ubiquitous spectrolaminar pattern characterized by an increasing deep-to-superficial layer gradient of high-frequency power peaking in layers 2/3 and an increasing superficial-to-deep gradient of alpha-beta power peaking in layers 5/6. Laminar recordings from additional species showed that the spectrolaminar pattern is highly preserved among primates—macaque, marmoset and human—but more dissimilar in mouse. Our results suggest the existence of a canonical layer-based and frequency-based mechanism for cortical computation.
9.
Fakche, Camille; Dugué, Laura
Perceptual Cycles Travel Across Retinotopic Space Journal Article
In: Journal of Cognitive Neuroscience, vol. 36, no. 1, pp. 200–216, 2024, ISSN: 0898-929X.
Abstract | Links | BibTeX | Tags: PROPixx
@article{fakche_perceptual_2024,
title = {Perceptual Cycles Travel Across Retinotopic Space},
author = {Camille Fakche and Laura Dugué},
url = {https://doi.org/10.1162/jocn_a_02075},
doi = {10.1162/jocn_a_02075},
issn = {0898-929X},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-16},
journal = {Journal of Cognitive Neuroscience},
volume = {36},
number = {1},
pages = {200–216},
abstract = {Visual perception waxes and wanes periodically over time at low frequencies (theta: 4–7 Hz; alpha: 8–13 Hz), creating “perceptual cycles.” These perceptual cycles can be induced when stimulating the brain with a flickering visual stimulus at the theta or alpha frequency. Here, we took advantage of the well-known organization of the visual system into retinotopic maps (topographic correspondence between visual and cortical spaces) to assess the spatial organization of induced perceptual cycles. Specifically, we tested the hypothesis that they can propagate across the retinotopic space. A disk oscillating in luminance (inducer) at 4, 6, 8, or 10 Hz was presented in the periphery of the visual field to induce perceptual cycles at specific frequencies. EEG recordings verified that the brain responded at the corresponding inducer frequencies and their first harmonics. Perceptual cycles were assessed with a concurrent detection task—target stimuli were displayed at threshold contrast (50% detection) at random times during the inducer. Behavioral results confirmed that perceptual performance was modulated periodically by the inducer at each frequency. We additionally manipulated the distance between the target and the inducer (three possible positions) and showed that the optimal phase, that is, moment of highest target detection, shifted across target distance to the inducer, specifically when its flicker frequency was in the alpha range (8 and 10 Hz). These results demonstrate that induced alpha perceptual cycles travel across the retinotopic space in humans at a propagation speed of 0.3–0.5 m/sec, consistent with the speed of unmyelinated horizontal connections in the visual cortex.},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
Visual perception waxes and wanes periodically over time at low frequencies (theta: 4–7 Hz; alpha: 8–13 Hz), creating “perceptual cycles.” These perceptual cycles can be induced when stimulating the brain with a flickering visual stimulus at the theta or alpha frequency. Here, we took advantage of the well-known organization of the visual system into retinotopic maps (topographic correspondence between visual and cortical spaces) to assess the spatial organization of induced perceptual cycles. Specifically, we tested the hypothesis that they can propagate across the retinotopic space. A disk oscillating in luminance (inducer) at 4, 6, 8, or 10 Hz was presented in the periphery of the visual field to induce perceptual cycles at specific frequencies. EEG recordings verified that the brain responded at the corresponding inducer frequencies and their first harmonics. Perceptual cycles were assessed with a concurrent detection task—target stimuli were displayed at threshold contrast (50% detection) at random times during the inducer. Behavioral results confirmed that perceptual performance was modulated periodically by the inducer at each frequency. We additionally manipulated the distance between the target and the inducer (three possible positions) and showed that the optimal phase, that is, moment of highest target detection, shifted across target distance to the inducer, specifically when its flicker frequency was in the alpha range (8 and 10 Hz). These results demonstrate that induced alpha perceptual cycles travel across the retinotopic space in humans at a propagation speed of 0.3–0.5 m/sec, consistent with the speed of unmyelinated horizontal connections in the visual cortex.
10.
Campbell, Maya; Oppenheimer, Nicole; White, Alex L.
Severe processing capacity limits for sub-lexical features of letter strings Journal Article
In: Attention, Perception, & Psychophysics, 2024, ISSN: 1943-393X.
Abstract | Links | BibTeX | Tags: VIEWPixx3D
@article{campbell_severe_2024,
title = {Severe processing capacity limits for sub-lexical features of letter strings},
author = {Maya Campbell and Nicole Oppenheimer and Alex L. White},
url = {https://doi.org/10.3758/s13414-023-02830-1},
doi = {10.3758/s13414-023-02830-1},
issn = {1943-393X},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-08},
journal = {Attention, Perception, & Psychophysics},
abstract = {When reading, the visual system is confronted with many words simultaneously. How much of that information can a reader process at once? Previous studies demonstrated that low-level visual features of multiple words are processed in parallel, but lexical attributes are processed serially, for one word at a time. This implies that an internal bottleneck lies somewhere between early visual and lexical analysis. We used a dual-task behavioral paradigm to investigate whether this bottleneck lies at the stage of letter recognition or phonological decoding. On each trial, two letter strings were flashed briefly, one above and one below fixation, and then masked. In the letter identification experiment, participants indicated whether a vowel was present in a particular letter string. In the phonological decoding experiment, participants indicated whether the letter string was pronounceable. We compared accuracy in a focused attention condition, in which participants judged only one of the two strings, with accuracy in a divided attention condition, in which participants judged both strings independently. In both experiments, the cost of dividing attention was so large that it supported a serial model: participants were able to process only one letter string per trial. Furthermore, we found a stimulus processing trade-off that is characteristic of serial processing: When participants judged one string correctly, they were less likely to judge the other string correctly. Therefore, the bottleneck that constrains word recognition under these conditions arises at a sub-lexical level, perhaps due to a limit on the efficiency of letter recognition.},
keywords = {VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
When reading, the visual system is confronted with many words simultaneously. How much of that information can a reader process at once? Previous studies demonstrated that low-level visual features of multiple words are processed in parallel, but lexical attributes are processed serially, for one word at a time. This implies that an internal bottleneck lies somewhere between early visual and lexical analysis. We used a dual-task behavioral paradigm to investigate whether this bottleneck lies at the stage of letter recognition or phonological decoding. On each trial, two letter strings were flashed briefly, one above and one below fixation, and then masked. In the letter identification experiment, participants indicated whether a vowel was present in a particular letter string. In the phonological decoding experiment, participants indicated whether the letter string was pronounceable. We compared accuracy in a focused attention condition, in which participants judged only one of the two strings, with accuracy in a divided attention condition, in which participants judged both strings independently. In both experiments, the cost of dividing attention was so large that it supported a serial model: participants were able to process only one letter string per trial. Furthermore, we found a stimulus processing trade-off that is characteristic of serial processing: When participants judged one string correctly, they were less likely to judge the other string correctly. Therefore, the bottleneck that constrains word recognition under these conditions arises at a sub-lexical level, perhaps due to a limit on the efficiency of letter recognition.
11.
Doherty, Joanne L.; Cunningham, Adam C.; Chawner, Samuel J. R. A.; Moss, Hayley M.; Dima, Diana C.; Linden, David E. J.; Owen, Michael J.; Bree, Marianne B. M.; Singh, Krish D.
Atypical cortical networks in children at high-genetic risk of psychiatric and neurodevelopmental disorders Journal Article
In: Neuropsychopharmacology, vol. 49, no. 2, pp. 368–376, 2024, ISSN: 1740-634X, (Number: 2 Publisher: Nature Publishing Group).
Abstract | Links | BibTeX | Tags: PROPixx
@article{doherty_atypical_2024,
title = {Atypical cortical networks in children at high-genetic risk of psychiatric and neurodevelopmental disorders},
author = {Joanne L. Doherty and Adam C. Cunningham and Samuel J. R. A. Chawner and Hayley M. Moss and Diana C. Dima and David E. J. Linden and Michael J. Owen and Marianne B. M. Bree and Krish D. Singh},
url = {https://www.nature.com/articles/s41386-023-01628-x},
doi = {10.1038/s41386-023-01628-x},
issn = {1740-634X},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-04},
journal = {Neuropsychopharmacology},
volume = {49},
number = {2},
pages = {368–376},
abstract = {Although many genetic risk factors for psychiatric and neurodevelopmental disorders have been identified, the neurobiological route from genetic risk to neuropsychiatric outcome remains unclear. 22q11.2 deletion syndrome (22q11.2DS) is a copy number variant (CNV) syndrome associated with high rates of neurodevelopmental and psychiatric disorders including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia. Alterations in neural integration and cortical connectivity have been linked to the spectrum of neuropsychiatric disorders seen in 22q11.2DS and may be a mechanism by which the CNV acts to increase risk. In this study, magnetoencephalography (MEG) was used to investigate electrophysiological markers of local and global network function in 34 children with 22q11.2DS and 25 controls aged 10–17 years old. Resting-state oscillatory activity and functional connectivity across six frequency bands were compared between groups. Regression analyses were used to explore the relationships between these measures, neurodevelopmental symptoms and IQ. Children with 22q11.2DS had altered network activity and connectivity in high and low frequency bands, reflecting modified local and long-range cortical circuitry. Alpha and theta band connectivity were negatively associated with ASD symptoms while frontal high frequency (gamma band) activity was positively associated with ASD symptoms. Alpha band activity was positively associated with cognitive ability. These findings suggest that haploinsufficiency at the 22q11.2 locus impacts short and long-range cortical circuits, which could be a mechanism underlying neurodevelopmental and psychiatric vulnerability in this high-risk group.},
note = {Number: 2
Publisher: Nature Publishing Group},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
Although many genetic risk factors for psychiatric and neurodevelopmental disorders have been identified, the neurobiological route from genetic risk to neuropsychiatric outcome remains unclear. 22q11.2 deletion syndrome (22q11.2DS) is a copy number variant (CNV) syndrome associated with high rates of neurodevelopmental and psychiatric disorders including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia. Alterations in neural integration and cortical connectivity have been linked to the spectrum of neuropsychiatric disorders seen in 22q11.2DS and may be a mechanism by which the CNV acts to increase risk. In this study, magnetoencephalography (MEG) was used to investigate electrophysiological markers of local and global network function in 34 children with 22q11.2DS and 25 controls aged 10–17 years old. Resting-state oscillatory activity and functional connectivity across six frequency bands were compared between groups. Regression analyses were used to explore the relationships between these measures, neurodevelopmental symptoms and IQ. Children with 22q11.2DS had altered network activity and connectivity in high and low frequency bands, reflecting modified local and long-range cortical circuitry. Alpha and theta band connectivity were negatively associated with ASD symptoms while frontal high frequency (gamma band) activity was positively associated with ASD symptoms. Alpha band activity was positively associated with cognitive ability. These findings suggest that haploinsufficiency at the 22q11.2 locus impacts short and long-range cortical circuits, which could be a mechanism underlying neurodevelopmental and psychiatric vulnerability in this high-risk group.
12.
Minarik, Tamas; Berger, Barbara; Jensen, Ole
Optimal parameters for rapid (invisible) frequency tagging using MEG Journal Article
In: NeuroImage, vol. 281, pp. 120389, 2023, ISSN: 1053-8119.
Abstract | Links | BibTeX | Tags: PROPixx
@article{minarik_optimal_2023,
title = {Optimal parameters for rapid (invisible) frequency tagging using MEG},
author = {Tamas Minarik and Barbara Berger and Ole Jensen},
url = {https://www.sciencedirect.com/science/article/pii/S1053811923005402},
doi = {10.1016/j.neuroimage.2023.120389},
issn = {1053-8119},
year = {2023},
date = {2023-11-01},
urldate = {2024-01-31},
journal = {NeuroImage},
volume = {281},
pages = {120389},
abstract = {Frequency tagging has been demonstrated to be a useful tool for identifying representational-specific neuronal activity in the auditory and visual domains. However, the slow flicker (<30 Hz) applied in conventional frequency tagging studies is highly visible and might entrain endogenous neuronal oscillations. Hence, stimulation at faster frequencies that is much less visible and does not interfere with endogenous brain oscillatory activity is a promising new tool. In this study, we set out to examine the optimal stimulation parameters of rapid frequency tagging (RFT/RIFT) with magnetoencephalography (MEG) by quantifying the effects of stimulation frequency, size and position of the flickering patch. Rapid frequency tagging using flickers above 50 Hz results in almost invisible stimulation which does not interfere with slower endogenous oscillations; however, the signal is weaker as compared to tagging at slower frequencies so certainty over the optimal parameters of stimulation delivery are crucial. The here presented results examining the frequency range between 60 Hz and 96 Hz suggest that RFT induces brain responses with decreasing strength up to about 84 Hz. In addition, even at the smallest flicker patch (2°) focally presented RFT induces a significant and measurable oscillatory brain signal (steady state visual evoked potential/field, SSVEP/F) at the stimulation frequency (66 Hz); however, the elicited response increases with patch size. While focal RFT presentation elicits the strongest response, off-centre presentations do generally mainly elicit a measureable response if presented below the horizontal midline. Importantly, the results also revealed considerable individual differences in the neuronal responses to RFT stimulation. Finally, we discuss the comparison of oscillatory measures (coherence and power) and sensor types (planar gradiometers and magnetometers) in order to achieve optimal outcomes. Based on our extensive findings we set forward concrete recommendations for using rapid frequency tagging in human cognitive neuroscience investigations.},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
Frequency tagging has been demonstrated to be a useful tool for identifying representational-specific neuronal activity in the auditory and visual domains. However, the slow flicker (<30 Hz) applied in conventional frequency tagging studies is highly visible and might entrain endogenous neuronal oscillations. Hence, stimulation at faster frequencies that is much less visible and does not interfere with endogenous brain oscillatory activity is a promising new tool. In this study, we set out to examine the optimal stimulation parameters of rapid frequency tagging (RFT/RIFT) with magnetoencephalography (MEG) by quantifying the effects of stimulation frequency, size and position of the flickering patch. Rapid frequency tagging using flickers above 50 Hz results in almost invisible stimulation which does not interfere with slower endogenous oscillations; however, the signal is weaker as compared to tagging at slower frequencies so certainty over the optimal parameters of stimulation delivery are crucial. The here presented results examining the frequency range between 60 Hz and 96 Hz suggest that RFT induces brain responses with decreasing strength up to about 84 Hz. In addition, even at the smallest flicker patch (2°) focally presented RFT induces a significant and measurable oscillatory brain signal (steady state visual evoked potential/field, SSVEP/F) at the stimulation frequency (66 Hz); however, the elicited response increases with patch size. While focal RFT presentation elicits the strongest response, off-centre presentations do generally mainly elicit a measureable response if presented below the horizontal midline. Importantly, the results also revealed considerable individual differences in the neuronal responses to RFT stimulation. Finally, we discuss the comparison of oscillatory measures (coherence and power) and sensor types (planar gradiometers and magnetometers) in order to achieve optimal outcomes. Based on our extensive findings we set forward concrete recommendations for using rapid frequency tagging in human cognitive neuroscience investigations.
13.
Huber-Huber, Christoph; Melcher, David
Saccade execution increases the preview effect with faces: An EEG and eye-tracking coregistration study Journal Article
In: Attention, Perception, & Psychophysics, 2023, ISSN: 1943-393X.
Abstract | Links | BibTeX | Tags: VIEWPixxEEG
@article{huber-huber_saccade_2023,
title = {Saccade execution increases the preview effect with faces: An EEG and eye-tracking coregistration study},
author = {Christoph Huber-Huber and David Melcher},
url = {https://doi.org/10.3758/s13414-023-02802-5},
doi = {10.3758/s13414-023-02802-5},
issn = {1943-393X},
year = {2023},
date = {2023-11-01},
urldate = {2023-12-21},
journal = {Attention, Perception, & Psychophysics},
abstract = {Under naturalistic viewing conditions, humans conduct about three to four saccadic eye movements per second. These dynamics imply that in real life, humans rarely see something completely new; there is usually a preview of the upcoming foveal input from extrafoveal regions of the visual field. In line with results from the field of reading research, we have shown with EEG and eye-tracking coregistration that an extrafoveal preview also affects postsaccadic visual object processing and facilitates discrimination. Here, we ask whether this preview effect in the fixation-locked N170, and in manual responses to the postsaccadic target face (tilt discrimination), requires saccade execution. Participants performed a gaze-contingent experiment in which extrafoveal face images could change their orientation during a saccade directed to them. In a control block, participants maintained stable gaze throughout the experiment and the extrafoveal face reappeared foveally after a simulated saccade latency. Compared with this no-saccade condition, the neural and the behavioral preview effects were much larger in the saccade condition. We also found shorter first fixation durations after an invalid preview, which is in contrast to reading studies. We interpret the increased preview effect under saccade execution as the result of the additional sensorimotor processes that come with gaze behavior compared with visual perception under stable fixation. In addition, our findings call into question whether EEG studies with fixed gaze capture key properties and dynamics of active, natural vision.},
keywords = {VIEWPixxEEG},
pubstate = {published},
tppubtype = {article}
}
Under naturalistic viewing conditions, humans conduct about three to four saccadic eye movements per second. These dynamics imply that in real life, humans rarely see something completely new; there is usually a preview of the upcoming foveal input from extrafoveal regions of the visual field. In line with results from the field of reading research, we have shown with EEG and eye-tracking coregistration that an extrafoveal preview also affects postsaccadic visual object processing and facilitates discrimination. Here, we ask whether this preview effect in the fixation-locked N170, and in manual responses to the postsaccadic target face (tilt discrimination), requires saccade execution. Participants performed a gaze-contingent experiment in which extrafoveal face images could change their orientation during a saccade directed to them. In a control block, participants maintained stable gaze throughout the experiment and the extrafoveal face reappeared foveally after a simulated saccade latency. Compared with this no-saccade condition, the neural and the behavioral preview effects were much larger in the saccade condition. We also found shorter first fixation durations after an invalid preview, which is in contrast to reading studies. We interpret the increased preview effect under saccade execution as the result of the additional sensorimotor processes that come with gaze behavior compared with visual perception under stable fixation. In addition, our findings call into question whether EEG studies with fixed gaze capture key properties and dynamics of active, natural vision.
14.
Kim, June Hee; Yin, Christine; Merriam, Elisha P.; Roth, Zvi N.
Pupil Size Is Sensitive to Low-Level Stimulus Features, Independent of Arousal-Related Modulation Journal Article
In: eNeuro, vol. 10, no. 10, 2023, ISSN: 2373-2822, (Publisher: Society for Neuroscience Section: Research Article: New Research).
Abstract | Links | BibTeX | Tags: VIEWPixx3D
@article{kim_pupil_2023,
title = {Pupil Size Is Sensitive to Low-Level Stimulus Features, Independent of Arousal-Related Modulation},
author = {June Hee Kim and Christine Yin and Elisha P. Merriam and Zvi N. Roth},
url = {https://www.eneuro.org/content/10/10/ENEURO.0005-23.2023},
doi = {10.1523/ENEURO.0005-23.2023},
issn = {2373-2822},
year = {2023},
date = {2023-10-01},
urldate = {2024-01-17},
journal = {eNeuro},
volume = {10},
number = {10},
abstract = {Visual Abstract <img class="highwire-fragment fragment-image" alt="Figure" src="https://www.eneuro.org/content/eneuro/10/10/ENEURO.0005-23.2023/F1.medium.gif" width="440" height="243"/>Download figureOpen in new tabDownload powerpoint
Similar to a camera aperture, pupil size adjusts to the surrounding luminance. Unlike a camera, pupil size is additionally modulated both by stimulus properties and by cognitive processes, including attention and arousal, though the interdependence of these factors is unclear. We hypothesized that different stimulus properties interact to jointly modulate pupil size while remaining independent from the impact of arousal. We measured pupil responses from human observers to equiluminant stimuli during a demanding rapid serial visual presentation (RSVP) task at fixation and tested how response amplitude depends on contrast, spatial frequency, and reward level. We found that under constant luminance, unattended stimuli evoke responses that are separable from changes caused by general arousal or attention. We further uncovered a double-dissociation between task-related responses and stimulus-evoked responses, suggesting that different sources of pupil size modulation are independent of one another. Our results shed light on neural pathways underlying pupillary response.},
note = {Publisher: Society for Neuroscience
Section: Research Article: New Research},
keywords = {VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
Visual Abstract <img class="highwire-fragment fragment-image" alt="Figure" src="https://www.eneuro.org/content/eneuro/10/10/ENEURO.0005-23.2023/F1.medium.gif" width="440" height="243"/>Download figureOpen in new tabDownload powerpoint
Similar to a camera aperture, pupil size adjusts to the surrounding luminance. Unlike a camera, pupil size is additionally modulated both by stimulus properties and by cognitive processes, including attention and arousal, though the interdependence of these factors is unclear. We hypothesized that different stimulus properties interact to jointly modulate pupil size while remaining independent from the impact of arousal. We measured pupil responses from human observers to equiluminant stimuli during a demanding rapid serial visual presentation (RSVP) task at fixation and tested how response amplitude depends on contrast, spatial frequency, and reward level. We found that under constant luminance, unattended stimuli evoke responses that are separable from changes caused by general arousal or attention. We further uncovered a double-dissociation between task-related responses and stimulus-evoked responses, suggesting that different sources of pupil size modulation are independent of one another. Our results shed light on neural pathways underlying pupillary response.
Similar to a camera aperture, pupil size adjusts to the surrounding luminance. Unlike a camera, pupil size is additionally modulated both by stimulus properties and by cognitive processes, including attention and arousal, though the interdependence of these factors is unclear. We hypothesized that different stimulus properties interact to jointly modulate pupil size while remaining independent from the impact of arousal. We measured pupil responses from human observers to equiluminant stimuli during a demanding rapid serial visual presentation (RSVP) task at fixation and tested how response amplitude depends on contrast, spatial frequency, and reward level. We found that under constant luminance, unattended stimuli evoke responses that are separable from changes caused by general arousal or attention. We further uncovered a double-dissociation between task-related responses and stimulus-evoked responses, suggesting that different sources of pupil size modulation are independent of one another. Our results shed light on neural pathways underlying pupillary response.
15.
Kryklywy, James H.; Forys, Brandon J.; Vieira, Joana B.; Quinlan, Derek J.; Mitchell, Derek G. V.
Dissociating representations of affect and motion in visual cortices Journal Article
In: Cognitive, Affective, & Behavioral Neuroscience, vol. 23, no. 5, pp. 1322–1345, 2023, ISSN: 1531-135X.
Abstract | Links | BibTeX | Tags: VPixxProgram
@article{kryklywy_dissociating_2023,
title = {Dissociating representations of affect and motion in visual cortices},
author = {James H. Kryklywy and Brandon J. Forys and Joana B. Vieira and Derek J. Quinlan and Derek G. V. Mitchell},
url = {https://doi.org/10.3758/s13415-023-01115-2},
doi = {10.3758/s13415-023-01115-2},
issn = {1531-135X},
year = {2023},
date = {2023-10-01},
urldate = {2024-01-02},
journal = {Cognitive, Affective, & Behavioral Neuroscience},
volume = {23},
number = {5},
pages = {1322–1345},
abstract = {While a delicious dessert being presented to us may elicit strong feelings of happiness and excitement, the same treat falling slowly away can lead to sadness and disappointment. Our emotional response to the item depends on its visual motion direction. Despite this importance, it remains unclear whether (and how) cortical areas devoted to decoding motion direction represents or integrates emotion with perceived motion direction. Motion-selective visual area V5/MT+ sits, both functionally and anatomically, at the nexus of dorsal and ventral visual streams. These pathways, however, differ in how they are modulated by emotional cues. The current study was designed to disentangle how emotion and motion perception interact, as well as use emotion-dependent modulation of visual cortices to understand the relation of V5/MT+ to canonical processing streams. During functional magnetic resonance imaging (fMRI), approaching, receding, or static motion after-effects (MAEs) were induced on stationary positive, negative, and neutral stimuli. An independent localizer scan was conducted to identify the visual-motion area V5/MT+. Through univariate and multivariate analyses, we demonstrated that emotion representations in V5/MT+ share a more similar response profile to that observed in ventral visual than dorsal, visual structures. Specifically, V5/MT+ and ventral structures were sensitive to the emotional content of visual stimuli, whereas dorsal visual structures were not. Overall, this work highlights the critical role of V5/MT+ in the representation and processing of visually acquired emotional content. It further suggests a role for this region in utilizing affectively salient visual information to augment motion perception of biologically relevant stimuli.},
keywords = {VPixxProgram},
pubstate = {published},
tppubtype = {article}
}
While a delicious dessert being presented to us may elicit strong feelings of happiness and excitement, the same treat falling slowly away can lead to sadness and disappointment. Our emotional response to the item depends on its visual motion direction. Despite this importance, it remains unclear whether (and how) cortical areas devoted to decoding motion direction represents or integrates emotion with perceived motion direction. Motion-selective visual area V5/MT+ sits, both functionally and anatomically, at the nexus of dorsal and ventral visual streams. These pathways, however, differ in how they are modulated by emotional cues. The current study was designed to disentangle how emotion and motion perception interact, as well as use emotion-dependent modulation of visual cortices to understand the relation of V5/MT+ to canonical processing streams. During functional magnetic resonance imaging (fMRI), approaching, receding, or static motion after-effects (MAEs) were induced on stationary positive, negative, and neutral stimuli. An independent localizer scan was conducted to identify the visual-motion area V5/MT+. Through univariate and multivariate analyses, we demonstrated that emotion representations in V5/MT+ share a more similar response profile to that observed in ventral visual than dorsal, visual structures. Specifically, V5/MT+ and ventral structures were sensitive to the emotional content of visual stimuli, whereas dorsal visual structures were not. Overall, this work highlights the critical role of V5/MT+ in the representation and processing of visually acquired emotional content. It further suggests a role for this region in utilizing affectively salient visual information to augment motion perception of biologically relevant stimuli.
16.
Hussain, Sana; Menchaca, Isaac; Shalchy, Mahsa Alizadeh; Yaghoubi, Kimia; Langley, Jason; Seitz, Aaron R.; Hu, Xiaoping P.; Peters, Megan A. K.
Locus coeruleus integrity predicts ease of attaining and maintaining neural states of high attentiveness Journal Article
In: Brain Research Bulletin, vol. 202, pp. 110733, 2023, ISSN: 0361-9230.
Abstract | Links | BibTeX | Tags: TRACKPixx3
@article{hussain_locus_2023,
title = {Locus coeruleus integrity predicts ease of attaining and maintaining neural states of high attentiveness},
author = {Sana Hussain and Isaac Menchaca and Mahsa Alizadeh Shalchy and Kimia Yaghoubi and Jason Langley and Aaron R. Seitz and Xiaoping P. Hu and Megan A. K. Peters},
url = {https://www.sciencedirect.com/science/article/pii/S0361923023001582},
doi = {10.1016/j.brainresbull.2023.110733},
issn = {0361-9230},
year = {2023},
date = {2023-10-01},
urldate = {2023-12-21},
journal = {Brain Research Bulletin},
volume = {202},
pages = {110733},
abstract = {The locus coeruleus (LC), a small subcortical structure in the brainstem, is the brain’s principal source of norepinephrine. It plays a primary role in regulating stress, the sleep-wake cycle, and attention, and its degradation is associated with aging and neurodegenerative diseases associated with cognitive deficits (e.g., Parkinson’s, Alzheimer’s). Yet precisely how norepinephrine drives brain networks to support healthy cognitive function remains poorly understood – partly because LC’s small size makes it difficult to study noninvasively in humans. Here, we characterized LC’s influence on brain dynamics using a hidden Markov model fitted to functional neuroimaging data from healthy young adults across four attention-related brain networks and LC. We modulated LC activity using a behavioral paradigm and measured individual differences in LC magnetization transfer contrast. The model revealed five hidden states, including a stable state dominated by salience-network activity that occurred when subjects actively engaged with the task. LC magnetization transfer contrast correlated with this state’s stability across experimental manipulations and with subjects’ propensity to enter into and remain in this state. These results provide new insight into LC’s role in driving spatiotemporal neural patterns associated with attention, and demonstrate that variation in LC integrity can explain individual differences in these patterns even in healthy young adults.},
keywords = {TRACKPixx3},
pubstate = {published},
tppubtype = {article}
}
The locus coeruleus (LC), a small subcortical structure in the brainstem, is the brain’s principal source of norepinephrine. It plays a primary role in regulating stress, the sleep-wake cycle, and attention, and its degradation is associated with aging and neurodegenerative diseases associated with cognitive deficits (e.g., Parkinson’s, Alzheimer’s). Yet precisely how norepinephrine drives brain networks to support healthy cognitive function remains poorly understood – partly because LC’s small size makes it difficult to study noninvasively in humans. Here, we characterized LC’s influence on brain dynamics using a hidden Markov model fitted to functional neuroimaging data from healthy young adults across four attention-related brain networks and LC. We modulated LC activity using a behavioral paradigm and measured individual differences in LC magnetization transfer contrast. The model revealed five hidden states, including a stable state dominated by salience-network activity that occurred when subjects actively engaged with the task. LC magnetization transfer contrast correlated with this state’s stability across experimental manipulations and with subjects’ propensity to enter into and remain in this state. These results provide new insight into LC’s role in driving spatiotemporal neural patterns associated with attention, and demonstrate that variation in LC integrity can explain individual differences in these patterns even in healthy young adults.
17.
Taveras-Cruz, Yesenia; Jr., Rhea T. Eskew
Threshold versus intensity curves measured with a new high-brightness display system Journal Article
In: Journal of Vision, vol. 23, no. 11, pp. 71, 2023, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: PROPixx
@article{taveras-cruz_threshold_2023,
title = {Threshold versus intensity curves measured with a new high-brightness display system},
author = {Yesenia Taveras-Cruz and Rhea T. Eskew Jr.},
url = {https://doi.org/10.1167/jov.23.11.71},
doi = {10.1167/jov.23.11.71},
issn = {1534-7362},
year = {2023},
date = {2023-09-01},
urldate = {2023-12-21},
journal = {Journal of Vision},
volume = {23},
number = {11},
pages = {71},
abstract = {Classical threshold vs. intensity (tvi) curves were measured using optical systems and were generally limited to increment test stimuli and relatively simple spatial patterns. Modern displays provide more flexibility in terms of stimuli spatial profiles but are usually dim enough that there may be rod intrusion when measuring cone responses. Here we describe a high-brightness display system and present tvi’s for increment and decrement achromatic tests. The system consists of a PROPixx three-chip DLP LED color projector (VPixx Technologies, Saint-Bruno, Canada) controlled via a Datapixx display driver, with 12-bit digital to analog conversion per RGB channel. Light from the projector is collected in a large diameter lens and focused on high gain rear projection screen. Retinal illuminance of the background may be varied in three ways: (a) varying the mean current supplied to the LEDs from the controller (adjustable in software); (b) using calibrated neutral density filters mounted near the eye; and (c) changing the midpoint of the RGB channels in software (e.g., making the white background as R=G=B=0.1 instead of 0.5). Method (c) is made easier by the fact that the PROPixx “gamma curve” is linear, which also means that no RGB bits are lost to gamma correction. We will show thresholds for achromatic tests on a white background varying from 0.56 to 4.03 log trolands, with preliminary results suggesting differences in the tvi curves between the increment and decrement tests.},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
Classical threshold vs. intensity (tvi) curves were measured using optical systems and were generally limited to increment test stimuli and relatively simple spatial patterns. Modern displays provide more flexibility in terms of stimuli spatial profiles but are usually dim enough that there may be rod intrusion when measuring cone responses. Here we describe a high-brightness display system and present tvi’s for increment and decrement achromatic tests. The system consists of a PROPixx three-chip DLP LED color projector (VPixx Technologies, Saint-Bruno, Canada) controlled via a Datapixx display driver, with 12-bit digital to analog conversion per RGB channel. Light from the projector is collected in a large diameter lens and focused on high gain rear projection screen. Retinal illuminance of the background may be varied in three ways: (a) varying the mean current supplied to the LEDs from the controller (adjustable in software); (b) using calibrated neutral density filters mounted near the eye; and (c) changing the midpoint of the RGB channels in software (e.g., making the white background as R=G=B=0.1 instead of 0.5). Method (c) is made easier by the fact that the PROPixx “gamma curve” is linear, which also means that no RGB bits are lost to gamma correction. We will show thresholds for achromatic tests on a white background varying from 0.56 to 4.03 log trolands, with preliminary results suggesting differences in the tvi curves between the increment and decrement tests.
18.
Marijan, Aleksandra; Mestre, Clara; Candy, T Rowan; Bonnen, Kathryn
The Role of Prediction During Continuous Visual Tracking in 3D Environments Journal Article
In: Journal of Vision, vol. 23, no. 9, pp. 5601, 2023, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: 3DPolarizer, PROPixx
@article{marijan_role_2023,
title = {The Role of Prediction During Continuous Visual Tracking in 3D Environments},
author = {Aleksandra Marijan and Clara Mestre and T Rowan Candy and Kathryn Bonnen},
url = {https://doi.org/10.1167/jov.23.9.5601},
doi = {10.1167/jov.23.9.5601},
issn = {1534-7362},
year = {2023},
date = {2023-08-01},
urldate = {2023-12-21},
journal = {Journal of Vision},
volume = {23},
number = {9},
pages = {5601},
abstract = {In everyday life, prediction plays a critical role in ocular motor target tracking. The ocular motor system employs a mixture of saccades and smooth pursuit across version and vergence eye movements to successfully follow objects as they move in the world. However, these eye movements are most often studied in isolation, saccades separate from smooth pursuit, version separate from vergence. Here we examined the perception/prediction of motion trajectories and how different types of eye movements are employed to coordinate the ocular motor tracking of those targets. Eye movements were recorded with an Eyelink 1000 (SR Research) at 500 Hz. The stimuli were presented using a PROPixx projector (VPixx Technologies) and an active circular polarizer, with subjects wearing passive circular polarizing glasses. The screen was set at a viewing distance of 70 cm. Cartoon images of angular size 2.2° moved with horizontal trajectories (initiating version eye movements) or motion-in-depth trajectories (initiating convergence and divergence). The motion trajectories in the predictable condition were sinusoids of varying amplitudes (5, 10 and 20 cm) and temporal frequencies (.25, .5, and 1 Hz). The unpredictable trajectories were smoothed Brownian random walks in position (sigma = 0.1 cm, 0.2 cm, and 0.3 cm). We measured the number of saccades across all conditions. In the horizontal motion condition, there were systematic increases in the number of saccades with increasing trajectory amplitudes and temporal frequency. For the motion-in-depth condition, participants made similar numbers of saccades regardless of the trajectory amplitude and frequency. There were no consistent differences between saccade behavior in the predictable vs. unpredictable conditions. A cross-correlogram analysis of the unpredictable trajectory condition revealed a longer latency (µ=77ms},
keywords = {3DPolarizer, PROPixx},
pubstate = {published},
tppubtype = {article}
}
In everyday life, prediction plays a critical role in ocular motor target tracking. The ocular motor system employs a mixture of saccades and smooth pursuit across version and vergence eye movements to successfully follow objects as they move in the world. However, these eye movements are most often studied in isolation, saccades separate from smooth pursuit, version separate from vergence. Here we examined the perception/prediction of motion trajectories and how different types of eye movements are employed to coordinate the ocular motor tracking of those targets. Eye movements were recorded with an Eyelink 1000 (SR Research) at 500 Hz. The stimuli were presented using a PROPixx projector (VPixx Technologies) and an active circular polarizer, with subjects wearing passive circular polarizing glasses. The screen was set at a viewing distance of 70 cm. Cartoon images of angular size 2.2° moved with horizontal trajectories (initiating version eye movements) or motion-in-depth trajectories (initiating convergence and divergence). The motion trajectories in the predictable condition were sinusoids of varying amplitudes (5, 10 and 20 cm) and temporal frequencies (.25, .5, and 1 Hz). The unpredictable trajectories were smoothed Brownian random walks in position (sigma = 0.1 cm, 0.2 cm, and 0.3 cm). We measured the number of saccades across all conditions. In the horizontal motion condition, there were systematic increases in the number of saccades with increasing trajectory amplitudes and temporal frequency. For the motion-in-depth condition, participants made similar numbers of saccades regardless of the trajectory amplitude and frequency. There were no consistent differences between saccade behavior in the predictable vs. unpredictable conditions. A cross-correlogram analysis of the unpredictable trajectory condition revealed a longer latency (µ=77ms
19.
Charbonneau, Isabelle; Ledrou-Paquet, Vicki; Blais, Caroline; Fiset, Daniel
Does Observers’ Ethnicity Influence Visual Strategies for Gender and Expressiveness Judgments ? Journal Article
In: Journal of Vision, vol. 23, no. 9, pp. 4976, 2023, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: Pack&Go
@article{charbonneau_does_2023,
title = {Does Observers’ Ethnicity Influence Visual Strategies for Gender and Expressiveness Judgments ?},
author = {Isabelle Charbonneau and Vicki Ledrou-Paquet and Caroline Blais and Daniel Fiset},
url = {https://doi.org/10.1167/jov.23.9.4976},
doi = {10.1167/jov.23.9.4976},
issn = {1534-7362},
year = {2023},
date = {2023-08-01},
urldate = {2023-12-21},
journal = {Journal of Vision},
volume = {23},
number = {9},
pages = {4976},
abstract = {Recent advances in cross-cultural studies emphasized the importance of including diversified groups of participants to better understand mechanisms underlying various face processing abilities, whether they reveal a difference or not (e.g. Blais et al., 2021). In visual psychophysics, little is known about visual strategies underlying face perception among Black observers. Therefore, we investigated visual strategies in Black and White participants in a Gender and Expressiveness (ExNex) tasks, using a newly validated platform, Pack & Go by VPIXX, which allows high quality psychophysic testing online. Sixty participants (15 Blacks and 45 Whites) completed both experiments (4000 trials per participant) conducted using the Bubble’s technique (Gosselin & Schyns, 2001) which samples visual information on a trial-by-trial basis using small gaussian windows in order to reveal the most useful information in any visual task. Accuracy was maintained at 75% by adjusting online the number of bubbles using QUEST (Watson & Pelli, 1983). Group performance levels were controlled by matching individual Black participants with White participants according to their final average number of bubbles in both tasks. Classification images were produced by calculating a weighted sum of the bubbles mask, using the trial-by-trial accuracy transformed into z-scores as weights. Pixel tests from the Stat4CI (Chauvin et al., 2005) toolbox revealed significant pixels associated with performance (p< .05; Zcrit = 4.05). Mainly, both groups made use of the same visual information for both race stimuli, that is, reliance on the eye in the Gender task and on the mouth in the ExNex task. Interestingly, Black participants also relied significantly more on the left eye for ExNex judgements, but only with Black stimuli. These differences and similarities in visual strategies for Black and White observers, will be discussed regarding cross-cultural differences in face perception in general.},
keywords = {Pack&Go},
pubstate = {published},
tppubtype = {article}
}
Recent advances in cross-cultural studies emphasized the importance of including diversified groups of participants to better understand mechanisms underlying various face processing abilities, whether they reveal a difference or not (e.g. Blais et al., 2021). In visual psychophysics, little is known about visual strategies underlying face perception among Black observers. Therefore, we investigated visual strategies in Black and White participants in a Gender and Expressiveness (ExNex) tasks, using a newly validated platform, Pack & Go by VPIXX, which allows high quality psychophysic testing online. Sixty participants (15 Blacks and 45 Whites) completed both experiments (4000 trials per participant) conducted using the Bubble’s technique (Gosselin & Schyns, 2001) which samples visual information on a trial-by-trial basis using small gaussian windows in order to reveal the most useful information in any visual task. Accuracy was maintained at 75% by adjusting online the number of bubbles using QUEST (Watson & Pelli, 1983). Group performance levels were controlled by matching individual Black participants with White participants according to their final average number of bubbles in both tasks. Classification images were produced by calculating a weighted sum of the bubbles mask, using the trial-by-trial accuracy transformed into z-scores as weights. Pixel tests from the Stat4CI (Chauvin et al., 2005) toolbox revealed significant pixels associated with performance (p< .05; Zcrit = 4.05). Mainly, both groups made use of the same visual information for both race stimuli, that is, reliance on the eye in the Gender task and on the mouth in the ExNex task. Interestingly, Black participants also relied significantly more on the left eye for ExNex judgements, but only with Black stimuli. These differences and similarities in visual strategies for Black and White observers, will be discussed regarding cross-cultural differences in face perception in general.
20.
Taveras-Cruz, Yesenia; Sehgal, Aanya; Eskew, Jr. Rhea T.
Increment and decrement threshold vs. intensity curves for achromatic and L-cone tests. Journal Article
In: Journal of Vision, vol. 23, no. 9, pp. 5729, 2023, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: PROPixx
@article{taveras-cruz_increment_2023,
title = {Increment and decrement threshold vs. intensity curves for achromatic and L-cone tests.},
author = {Yesenia Taveras-Cruz and Aanya Sehgal and Jr. Rhea T. Eskew},
url = {https://doi.org/10.1167/jov.23.9.5729},
doi = {10.1167/jov.23.9.5729},
issn = {1534-7362},
year = {2023},
date = {2023-08-01},
urldate = {2023-12-21},
journal = {Journal of Vision},
volume = {23},
number = {9},
pages = {5729},
abstract = {The desensitization of the visual system as a function of the increasing luminance of a background field yields threshold vs. intensity (tvi) curves, classically measured using increment tests. Here we use a new, high-brightness display system to measure both increment and decrement thresholds. Our display system is based upon a PROPixx three-chip DLP LED color projector (VPixx Technologies, Saint-Bruno, Canada), with light from the projector collected into a field lens and focused onto a high gain rear projection screen. This display combines the brightness of traditional optical systems with the flexibility of control provided by modern displays; in particular, it is simple to use the silent substitution method to isolate single cone types. Here we report tvi curves for achromatic and (L-)ong wavelength sensitive cone isolating tests, measured using method of adjustment. Selected thresholds were verified with a spatial, two-alternative forced-choice procedure. The adapting background was white, with luminances ranging from 0.6 to 4.0 log Trolands (a maximum near 3200 cd/m2, bleaching about 1/3 of the L and M cone pigment). Our observers are slightly more sensitive to decrements than increments (about 0.1 log units), for both achromatic and L-cone tests, and to L-cone tests than to achromatic tests (about 0.6 log cone contrast units), over the entire adapting range. Both increment and decrement thresholds follow the Stiles template, approximating Weber’s law except at the lowest adapting levels. The achromatic tvi’s, for both increment and decrement tests, are, on average, slightly steeper than the L-cone tvi’s. In addition, decrement tvi’s are steeper than the increment tvi’s, indicating greater effects of light adaptation for the decrements, which may be due to differences in the effects of light adaptation in ON and OFF pathways.},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
The desensitization of the visual system as a function of the increasing luminance of a background field yields threshold vs. intensity (tvi) curves, classically measured using increment tests. Here we use a new, high-brightness display system to measure both increment and decrement thresholds. Our display system is based upon a PROPixx three-chip DLP LED color projector (VPixx Technologies, Saint-Bruno, Canada), with light from the projector collected into a field lens and focused onto a high gain rear projection screen. This display combines the brightness of traditional optical systems with the flexibility of control provided by modern displays; in particular, it is simple to use the silent substitution method to isolate single cone types. Here we report tvi curves for achromatic and (L-)ong wavelength sensitive cone isolating tests, measured using method of adjustment. Selected thresholds were verified with a spatial, two-alternative forced-choice procedure. The adapting background was white, with luminances ranging from 0.6 to 4.0 log Trolands (a maximum near 3200 cd/m2, bleaching about 1/3 of the L and M cone pigment). Our observers are slightly more sensitive to decrements than increments (about 0.1 log units), for both achromatic and L-cone tests, and to L-cone tests than to achromatic tests (about 0.6 log cone contrast units), over the entire adapting range. Both increment and decrement thresholds follow the Stiles template, approximating Weber’s law except at the lowest adapting levels. The achromatic tvi’s, for both increment and decrement tests, are, on average, slightly steeper than the L-cone tvi’s. In addition, decrement tvi’s are steeper than the increment tvi’s, indicating greater effects of light adaptation for the decrements, which may be due to differences in the effects of light adaptation in ON and OFF pathways.