1
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Yu A, Zhang R, Silva AE, Xing Y, Thompson B, Liu Z. Motion opponency at the middle temporal cortex: Preserved motion information and the effect of perceptual learning. Eur J Neurosci 2022; 56:6215-6226. [PMID: 36266211 DOI: 10.1111/ejn.15850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 12/29/2022]
Abstract
Motion opponency, first observed within the primate middle temporal cortex (MT), refers to the suppressing effect of opposite motion directions on neuronal activity. Namely, when opposing motion directional signals stimulate an MT neuron's receptive field, this neuron's response is comparable with that induced by flicker noise. Under such suppression, it is unknown whether any directional information is still represented at MT. In this study, we applied support vector machine (SVM) learning to human functional magnetic resonance imaging data to investigate if any motion defined orientation information was still available from suppressed MT. We found that, at least at the level of ±45° discrimination, such orientation information was still available. Interestingly, after behavioural perceptual learning that improved human discrimination of fine orientation discrimination (e.g. 42° vs. 48°) using the MT-suppressive motion stimuli, the SVM discrimination of ±45° worsened when functional magnetic resonance imaging (fMRI) signals at post-learning MT were used. This result is consistent with findings in Thompson et al. (2013) that, post-perceptual learning, MT suppression was not released, suggesting that motion opponency was perhaps functionally too important for perceptual learning to overcome.
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Affiliation(s)
- Alexander Yu
- Department of Computer Science, University of California, Los Angeles, Los Angeles, California, USA
| | - Ruizhe Zhang
- Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA
| | - Andrew E Silva
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Yang Xing
- Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA
| | - Benjamin Thompson
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.,Centre for Eye and Vision Research, Hong Kong
| | - Zili Liu
- Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA.,1285 Psychology Building, Box 951563, Los Angeles, California, USA
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2
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Waz S, Liu Z. Evidence for strictly monocular processing in visual motion opponency and Glass pattern perception. Vision Res 2021; 186:103-111. [PMID: 34082396 DOI: 10.1016/j.visres.2021.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/11/2021] [Accepted: 04/27/2021] [Indexed: 10/21/2022]
Abstract
When presented with locally paired dots moving in opposite directions, motion selective neurons in the middle temporal cortex (MT) reduce firing while neurons in V1 are unaffected. This physiological effect is known as motion opponency. The current study used psychophysics to investigate the neural circuit underlying motion opponency. We asked whether opposing motion signals could arrive from different eyes into the receptive field of a binocular neuron while still maintaining motion opponency. We took advantage of prior findings that orientation discrimination of the motion axis (along which paired dots oscillate) is harder when dots move counter-phase than in-phase, an effect associated with motion opponency. We found that such an effect disappeared when paired dots originated from different eyes. This suggests that motion opponency, at some point, involves strictly monocular processing. This does not mean that motion opponency is entirely monocular. Further, we found that the effect of a Glass pattern disappeared under similar viewing conditions, suggesting that Glass pattern perception also involves some strictly monocular processing.
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Affiliation(s)
- Sebastian Waz
- Department of Cognitive Sciences, University of California Irvine, Irvine, CA 92697, USA; Department of Psychology, University of California Los Angeles, Los Angeles, CA 90095, USA.
| | - Zili Liu
- Department of Psychology, University of California Los Angeles, Los Angeles, CA 90095, USA
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3
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Silva AE, Thompson B, Liu Z. Motion opponency examined throughout visual cortex with multivariate pattern analysis of fMRI data. Hum Brain Mapp 2020; 42:5-13. [PMID: 32881175 PMCID: PMC7721233 DOI: 10.1002/hbm.25198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/02/2020] [Accepted: 08/19/2020] [Indexed: 11/08/2022] Open
Abstract
This study explores how the human brain solves the challenge of flicker noise in motion processing. Despite providing no useful directional motion information, flicker is common in the visual environment and exhibits omnidirectional motion energy which is processed by low‐level motion detectors. Models of motion processing propose a mechanism called motion opponency that reduces flicker processing. Motion opponency involves the pooling of local motion signals to calculate an overall motion direction. A neural correlate of motion opponency has been observed in human area MT+/V5, whereby stimuli with perfectly balanced motion energy constructed from dots moving in counter‐phase elicit a weaker response than nonbalanced (in‐phase) motion stimuli. Building on this previous work, we used multivariate pattern analysis to examine whether the activation patterns elicited by motion opponent stimuli resemble that elicited by flicker noise across the human visual cortex. Robust multivariate signatures of opponency were observed in V5 and in V3A. Our results support the notion that V5 is centrally involved in motion opponency and in the reduction of flicker. Furthermore, these results demonstrate the utility of multivariate analysis methods in revealing the role of additional visual areas, such as V3A, in opponency and in motion processing more generally.
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Affiliation(s)
- Andrew E Silva
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.,Department of Psychology, University of California at Los Angeles, Los Angeles, California, USA
| | - Benjamin Thompson
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Zili Liu
- Department of Psychology, University of California at Los Angeles, Los Angeles, California, USA
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4
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Jia K, Xue X, Lee JH, Fang F, Zhang J, Li S. Visual perceptual learning modulates decision network in the human brain: The evidence from psychophysics, modeling, and functional magnetic resonance imaging. J Vis 2019; 18:9. [PMID: 30452587 DOI: 10.1167/18.12.9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Perceptual learning refers to improved perceptual performance after intensive training and was initially suggested to reflect long-term plasticity in early visual cortex. Recent behavioral and neurophysiological evidence further suggested that the plasticity in brain regions related to decision making could also contribute to the observed training effects. However, how perceptual learning modulates the responses of decision-related regions in the human brain remains largely unknown. In the present study, we combined psychophysics and functional magnetic resonance imaging (fMRI), and adopted a model-based approach to investigate this issue. We trained participants on a motion direction discrimination task and fitted their behavioral data using the linear ballistic accumulator model. The results from model fitting showed that behavioral improvement could be well explained by a specific improvement in sensory information accumulation. A critical model parameter, the drift rate of the information accumulation, was correlated with the fMRI responses derived from three spatial independent components: ventral premotor cortex (PMv), supplementary eye field (SEF), and the fronto-parietal network, including intraparietal sulcus (IPS) and frontal eye field (FEF). In this decision network, we found that the behavioral training effects were accompanied by signal enhancement specific to trained direction in PMv and FEF. Further, we also found direction-specific signal reduction in sensory areas (V3A and MT+), as well as the strengthened effective connectivity from V3A to PMv and from IPS to FEF. These findings provide evidence for the learning-induced decision refinement after perceptual learning and the brain regions that are involved in this process.
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Affiliation(s)
- Ke Jia
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, China
| | - Xin Xue
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, China.,Department of Health Industry Management, Beijing International Studies University, Beijing, China
| | - Jong-Hwan Lee
- Department of Brain and Cognitive Engineering, Korea University, Seoul, Republic of Korea
| | - Fang Fang
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | | | - Sheng Li
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, China
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5
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Silva AE, Liu Z. Spatial proximity modulates the strength of motion opponent suppression elicited by locally paired dot displays. Vision Res 2018; 144:1-8. [PMID: 29355566 DOI: 10.1016/j.visres.2018.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 01/06/2018] [Accepted: 01/08/2018] [Indexed: 11/30/2022]
Abstract
Locally paired dot stimuli that contain opposing motion signals at roughly the same spatial locations (counter-phase stimuli) have been reported to produce percepts devoid of global motion. Counter-phase stimuli are also thought to elicit a reduced neural response at motion processing brain area MT/V5, an effect known as motion opponency. The current study examines the effect of vertical counter-phase background motion on behavioral discrimination of horizontal target motion. We found that counter-phase backgrounds generally produced lower behavioral thresholds than locally unbalanced backgrounds, an effect consistent with the idea that counter-phase motion elicits opponency. However, this effect was apparent only if the paired dots were close enough in proximity that they crossed one another during their movement. Furthermore, we found that counter-phase stimuli containing within-pair dot crossing elicits similar behavioral thresholds to non-motion flicker stimuli. These results provide insight into the requirements for activating opponency in the brain and suggest that the brain processes counter-phase and flicker stimuli similarly due to opponency.
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Affiliation(s)
- Andrew E Silva
- Department of Psychology, University of California, Los Angeles, United States.
| | - Zili Liu
- Department of Psychology, University of California, Los Angeles, United States
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6
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Connell CJW, Thompson B, Green H, Sullivan RK, Gant N. Effects of regular aerobic exercise on visual perceptual learning. Vision Res 2017; 152:110-117. [PMID: 29183780 DOI: 10.1016/j.visres.2017.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 08/17/2017] [Accepted: 08/23/2017] [Indexed: 12/26/2022]
Abstract
This study investigated the influence of five days of moderate intensity aerobic exercise on the acquisition and consolidation of visual perceptual learning using a motion direction discrimination (MDD) task. The timing of exercise relative to learning was manipulated by administering exercise either before or after perceptual training. Within a matched-subjects design, twenty-seven healthy participants (n = 9 per group) completed five consecutive days of perceptual training on a MDD task under one of three interventions: no exercise, exercise before the MDD task, or exercise after the MDD task. MDD task accuracy improved in all groups over the five-day period, but there was a trend for impaired learning when exercise was performed before visual perceptual training. MDD task accuracy (mean ± SD) increased in exercise before by 4.5 ± 6.5%; exercise after by 11.8 ± 6.4%; and no exercise by 11.3 ± 7.2%. All intervention groups displayed similar MDD threshold reductions for the trained and untrained motion axes after training. These findings suggest that moderate daily exercise does not enhance the rate of visual perceptual learning for an MDD task or the transfer of learning to an untrained motion axis. Furthermore, exercise performed immediately prior to a visual perceptual learning task may impair learning. Further research with larger groups is required in order to better understand these effects.
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Affiliation(s)
- Charlotte J W Connell
- Department of Exercise Sciences, Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
| | - Benjamin Thompson
- School of Optometry and Vision Science, University of Waterloo, Ontario N2L 3G1, Canada; Department of Optometry and Vision Science, University of Auckland, Auckland 1142, New Zealand
| | - Hayden Green
- Department of Exercise Sciences, Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
| | - Rachel K Sullivan
- Department of Exercise Sciences, Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
| | - Nicholas Gant
- Department of Exercise Sciences, Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand.
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7
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Larcombe SJ, Kennard C, Bridge H. Increase in MST activity correlates with visual motion learning: A functional MRI study of perceptual learning. Hum Brain Mapp 2017; 39:145-156. [PMID: 28963815 PMCID: PMC5725689 DOI: 10.1002/hbm.23832] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/17/2017] [Accepted: 09/19/2017] [Indexed: 11/24/2022] Open
Abstract
Repeated practice of a specific task can improve visual performance, but the neural mechanisms underlying this improvement in performance are not yet well understood. Here we trained healthy participants on a visual motion task daily for 5 days in one visual hemifield. Before and after training, we used functional magnetic resonance imaging (fMRI) to measure the change in neural activity. We also imaged a control group of participants on two occasions who did not receive any task training. While in the MRI scanner, all participants completed the motion task in the trained and untrained visual hemifields separately. Following training, participants improved their ability to discriminate motion direction in the trained hemifield and, to a lesser extent, in the untrained hemifield. The amount of task learning correlated positively with the change in activity in the medial superior temporal (MST) area. MST is the anterior portion of the human motion complex (hMT+). MST changes were localized to the hemisphere contralateral to the region of the visual field, where perceptual training was delivered. Visual areas V2 and V3a showed an increase in activity between the first and second scan in the training group, but this was not correlated with performance. The contralateral anterior hippocampus and bilateral dorsolateral prefrontal cortex (DLPFC) and frontal pole showed changes in neural activity that also correlated with the amount of task learning. These findings emphasize the importance of MST in perceptual learning of a visual motion task. Hum Brain Mapp 39:145–156, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Stephanie J Larcombe
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Oxford, United Kingdom.,Nuffield Department of Clinical Neurosciences (NDCN), University of Oxford, Oxford, United Kingdom
| | - Chris Kennard
- Nuffield Department of Clinical Neurosciences (NDCN), University of Oxford, Oxford, United Kingdom
| | - Holly Bridge
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Oxford, United Kingdom.,Nuffield Department of Clinical Neurosciences (NDCN), University of Oxford, Oxford, United Kingdom
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8
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Chen N, Lu J, Shao H, Weng X, Fang F. Neural mechanisms of motion perceptual learning in noise. Hum Brain Mapp 2017; 38:6029-6042. [PMID: 28901676 DOI: 10.1002/hbm.23808] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/31/2017] [Accepted: 09/01/2017] [Indexed: 11/08/2022] Open
Abstract
Practice improves our perceptual ability. However, the neural mechanisms underlying this experience-dependent plasticity in adult brain remain unclear. Here, we studied the long-term neural correlates of motion perceptual learning. Subjects' behavioral performance and BOLD signals were tracked before, immediately after, and 2 weeks after practicing a motion direction discrimination task in noise over six daily sessions. Parallel to the specificity and persistency of the behavioral learning effect, we found that training sharpened the cortical tuning in MT, and enhanced the connectivity strength from MT to the intraparietal sulcus (IPS, a motion decision-making area). In addition, the decoding accuracy for the trained motion direction was improved in IPS 2 weeks after training. The dual changes in the sensory and the high-level cortical areas suggest that learning refines the neural representation of the trained stimulus and facilitates the information transmission in the decision process. Our findings are consistent with the functional specialization in the visual cortex, and provide empirical evidence to the reweighting theory of perceptual learning at a large spatial scale. Hum Brain Mapp 38:6029-6042, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Nihong Chen
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, 100871, People's Republic of China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, 100871, People's Republic of China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, People's Republic of China.,IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, People's Republic of China.,Department of Psychology, University of Southern California, Los Angeles, California 90089-1061
| | - Junshi Lu
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, 100871, People's Republic of China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, 100871, People's Republic of China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, People's Republic of China.,IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, People's Republic of China
| | - Hanyu Shao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xuchu Weng
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, 311121, People's Republic of China
| | - Fang Fang
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, 100871, People's Republic of China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, 100871, People's Republic of China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, People's Republic of China.,IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, People's Republic of China
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9
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Lagas AK, Black JM, Byblow WD, Fleming MK, Goodman LK, Kydd RR, Russell BR, Stinear CM, Thompson B. Fluoxetine Does Not Enhance Visual Perceptual Learning and Triazolam Specifically Impairs Learning Transfer. Front Hum Neurosci 2016; 10:532. [PMID: 27807412 PMCID: PMC5069436 DOI: 10.3389/fnhum.2016.00532] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 10/06/2016] [Indexed: 01/17/2023] Open
Abstract
The selective serotonin reuptake inhibitor fluoxetine significantly enhances adult visual cortex plasticity within the rat. This effect is related to decreased gamma-aminobutyric acid (GABA) mediated inhibition and identifies fluoxetine as a potential agent for enhancing plasticity in the adult human brain. We tested the hypothesis that fluoxetine would enhance visual perceptual learning of a motion direction discrimination (MDD) task in humans. We also investigated (1) the effect of fluoxetine on visual and motor cortex excitability and (2) the impact of increased GABA mediated inhibition following a single dose of triazolam on post-training MDD task performance. Within a double blind, placebo controlled design, 20 healthy adult participants completed a 19-day course of fluoxetine (n = 10, 20 mg per day) or placebo (n = 10). Participants were trained on the MDD task over the final 5 days of fluoxetine administration. Accuracy for the trained MDD stimulus and an untrained MDD stimulus configuration was assessed before and after training, after triazolam and 1 week after triazolam. Motor and visual cortex excitability were measured using transcranial magnetic stimulation. Fluoxetine did not enhance the magnitude or rate of perceptual learning and full transfer of learning to the untrained stimulus was observed for both groups. After training was complete, trazolam had no effect on trained task performance but significantly impaired untrained task performance. No consistent effects of fluoxetine on cortical excitability were observed. The results do not support the hypothesis that fluoxetine can enhance learning in humans. However, the specific effect of triazolam on MDD task performance for the untrained stimulus suggests that learning and learning transfer rely on dissociable neural mechanisms.
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Affiliation(s)
- Alice K Lagas
- School of Optometry and Vision Science, University of AucklandAuckland, New Zealand; Centre for Brain Research, University of AucklandAuckland, New Zealand
| | - Joanna M Black
- School of Optometry and Vision Science, University of AucklandAuckland, New Zealand; Centre for Brain Research, University of AucklandAuckland, New Zealand
| | - Winston D Byblow
- Centre for Brain Research, University of AucklandAuckland, New Zealand; Department of Exercise Sciences, University of AucklandAuckland, New Zealand
| | - Melanie K Fleming
- Department of Exercise Sciences, University of AucklandAuckland, New Zealand; Centre of Human and Aerospace Physiological Sciences, King's College LondonLondon, UK
| | - Lucy K Goodman
- School of Optometry and Vision Science, University of AucklandAuckland, New Zealand; Centre for Brain Research, University of AucklandAuckland, New Zealand
| | - Robert R Kydd
- Centre for Brain Research, University of AucklandAuckland, New Zealand; Department of Psychological Medicine, University of AucklandAuckland, New Zealand
| | - Bruce R Russell
- School of Pharmacy, University of AucklandAuckland, New Zealand; National School of Pharmacy, University of OtagoDunedin, New Zealand
| | - Cathy M Stinear
- Centre for Brain Research, University of AucklandAuckland, New Zealand; Department of Medicine, University of AucklandAuckland, New Zealand
| | - Benjamin Thompson
- School of Optometry and Vision Science, University of AucklandAuckland, New Zealand; Centre for Brain Research, University of AucklandAuckland, New Zealand; School of Optometry and Vision Science, University of Waterloo, WaterlooON, Canada
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10
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Thompson B, Deblieck C, Wu A, Iacoboni M, Liu Z. Psychophysical and rTMS Evidence for the Presence of Motion Opponency in Human V5. Brain Stimul 2016; 9:876-881. [PMID: 27342938 DOI: 10.1016/j.brs.2016.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 04/22/2016] [Accepted: 05/30/2016] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND Motion sensitive cells within macaque V5, but not V1, exhibit motion opponency whereby their firing is suppressed by motion in their anti-preferred direction. fMRI studies indicate the presence of motion opponent mechanisms in human V5. OBJECTIVE/HYPOTHESIS We tested two hypotheses. 1) Performance of a motion discrimination task would be poorer when stimuli were constructed from pairs of dots that moved in counter-phase vs. in-phase, because counter-phase dots would activate motion opponent mechanisms in V5. 2) Offline 1 Hz rTMS of V5 would impair discrimination performance for in-phase stimuli but not counter-phase stimuli, and the opposite effect would be found for rTMS of V1. METHODS Stimuli were constructed from 100 dot pairs. Paired dots moved along a fixed motion axis either in counter-phase (motion opponent stimulus) or in-phase (non-opponent motion stimulus). Motion axis orientation discrimination thresholds were measured for each stimulus. Blocks of 300 trials were then presented at 85% correct threshold and discrimination accuracy was measured before and after 1 Hz offline rTMS of either V1 or V5. Subjects were 8 healthy adults. RESULTS Discrimination thresholds were significantly larger (worse) for counter-phase than in-phase stimuli (p = 0.02). V5 rTMS mildly impaired discrimination accuracy for the in-phase dot stimuli (p = 0.02) but not the counter-phase dot stimuli. The opposite effect occurred for V1 rTMS (p = 0.05). CONCLUSIONS Opponent motion mechanisms are present within human V5 and activation of these mechanisms impairs motion discrimination. In addition, perception of the motion axis within opponent motion stimuli involves processing within V1.
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Affiliation(s)
- Benjamin Thompson
- School of Optometry and Vision Science, University of Waterloo, Canada; School of Optometry and Vision Science, University of Auckland, New Zealand.
| | - Choi Deblieck
- AcCENT (Academic Center for ECT and Neuromodulation), University Psychiatric Center - KU Leuven (University of Leuven) - Campus Kortenberg, Kortenberg, Belgium
| | - Allan Wu
- Ahmanson-Lovelace Brain Mapping Center, UCLA, Los Angeles, CA, USA; Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Marco Iacoboni
- Ahmanson-Lovelace Brain Mapping Center, UCLA, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Zili Liu
- Department of Psychology, UCLA, Los Angeles, CA, USA
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11
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Shibata K, Sasaki Y, Kawato M, Watanabe T. Neuroimaging Evidence for 2 Types of Plasticity in Association with Visual Perceptual Learning. Cereb Cortex 2016; 26:3681-9. [PMID: 27298301 PMCID: PMC5004756 DOI: 10.1093/cercor/bhw176] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Visual perceptual learning (VPL) is long-term performance improvement as a result of perceptual experience. It is unclear whether VPL is associated with refinement in representations of the trained feature (feature-based plasticity), improvement in processing of the trained task (task-based plasticity), or both. Here, we provide empirical evidence that VPL of motion detection is associated with both types of plasticity which occur predominantly in different brain areas. Before and after training on a motion detection task, subjects' neural responses to the trained motion stimuli were measured using functional magnetic resonance imaging. In V3A, significant response changes after training were observed specifically to the trained motion stimulus but independently of whether subjects performed the trained task. This suggests that the response changes in V3A represent feature-based plasticity in VPL of motion detection. In V1 and the intraparietal sulcus, significant response changes were found only when subjects performed the trained task on the trained motion stimulus. This suggests that the response changes in these areas reflect task-based plasticity. These results collectively suggest that VPL of motion detection is associated with the 2 types of plasticity, which occur in different areas and therefore have separate mechanisms at least to some degree.
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Affiliation(s)
- Kazuhisa Shibata
- Department of Cognitive, Linguistic & Psychological Sciences, Brown University, 190 Thayer Street, Providence, RI 02912, USA Department of Decoded Neurofeedback, Brain Information Communication Research Laboratory Group, Advanced Telecommunications Research Institutes International, 2-2-2 Hikaridai, Keihanna Science City, Kyoto 619-0288, Japan Current address: Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yuka Sasaki
- Department of Cognitive, Linguistic & Psychological Sciences, Brown University, 190 Thayer Street, Providence, RI 02912, USA Department of Decoded Neurofeedback, Brain Information Communication Research Laboratory Group, Advanced Telecommunications Research Institutes International, 2-2-2 Hikaridai, Keihanna Science City, Kyoto 619-0288, Japan
| | - Mitsuo Kawato
- Department of Decoded Neurofeedback, Brain Information Communication Research Laboratory Group, Advanced Telecommunications Research Institutes International, 2-2-2 Hikaridai, Keihanna Science City, Kyoto 619-0288, Japan
| | - Takeo Watanabe
- Department of Cognitive, Linguistic & Psychological Sciences, Brown University, 190 Thayer Street, Providence, RI 02912, USA Department of Decoded Neurofeedback, Brain Information Communication Research Laboratory Group, Advanced Telecommunications Research Institutes International, 2-2-2 Hikaridai, Keihanna Science City, Kyoto 619-0288, Japan
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12
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Chen N, Bi T, Zhou T, Li S, Liu Z, Fang F. Sharpened cortical tuning and enhanced cortico-cortical communication contribute to the long-term neural mechanisms of visual motion perceptual learning. Neuroimage 2015; 115:17-29. [DOI: 10.1016/j.neuroimage.2015.04.041] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 04/12/2015] [Accepted: 04/20/2015] [Indexed: 11/30/2022] Open
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13
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Silva AE, Liu Z. Opponent backgrounds reduce discrimination sensitivity to competing motions: effects of different vertical motions on horizontal motion perception. Vision Res 2015; 113:55-64. [PMID: 26049036 DOI: 10.1016/j.visres.2015.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 04/05/2015] [Accepted: 05/06/2015] [Indexed: 11/28/2022]
Abstract
We examined the relationship between two distinct motion phenomena. First, locally balanced stimuli in which opposing motion signals are presented spatially near one another fail to cause a robust firing pattern in brain area MT. The brain's response to this motion is effectively suppressed, a phenomenon known as opponency. Second, past research has found that discrimination sensitivity to a target motion is negatively affected by a superimposed irrelevant motion signal - a process we call "perceptual suppression." In the current study, we examined how opponency affects the strength of perceptual suppression. We found unexpected results: a target motion embedded within an opponent background was harder to discriminate than a target motion embedded within a non-opponent background. We argue that this pattern of results runs contrary to the clear prediction stemming from the current understanding of the role of opponency in motion processing and tentatively offer an explanation based on recent MT physiology.
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Affiliation(s)
- Andrew E Silva
- Department of Psychology, University of California, Los Angeles, United States.
| | - Zili Liu
- Department of Psychology, University of California, Los Angeles, United States
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