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Jiang Z, Shooner C, Mullen KT. Achromatic and chromatic perceived contrast are reduced in the visual periphery. J Vis 2022; 22:3. [DOI: 10.1167/jov.22.12.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Zhuohan Jiang
- McGill Vision Research, Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Quebec, Canada
| | - Christopher Shooner
- McGill Vision Research, Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Quebec, Canada
| | - Kathy T. Mullen
- McGill Vision Research, Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Quebec, Canada
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Goddard E, Shooner C, Mullen KT. Magnetoencephalography contrast adaptation reflects perceptual adaptation. J Vis 2022; 22:16. [PMID: 36121660 PMCID: PMC9503227 DOI: 10.1167/jov.22.10.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Contrast adaptation is a fundamental visual process that has been extensively investigated and used to infer the selectivity of visual cortex. We recently reported an apparent disconnect between the effects of contrast adaptation on perception and functional magnetic resonance imaging BOLD response adaptation, in which adaptation between chromatic and achromatic stimuli measured psychophysically showed greater selectivity than adaptation measured using BOLD signals. Here we used magnetoencephalography (MEG) recordings of neural responses to the same chromatic and achromatic adaptation conditions to characterize the neural effects of contrast adaptation and to determine whether BOLD adaptation or MEG better reflect the measured perceptual effects. Participants viewed achromatic, L-M isolating, or S-cone isolating radial sinusoids before adaptation and after adaptation to each of the three contrast directions. We measured adaptation-related changes in the neural response to a range of stimulus contrast amplitudes using two measures of the MEG response: the overall response amplitude, and a novel time-resolved measure of the contrast response function, derived from a classification analysis combined with multidimensional scaling. Within-stimulus adaptation effects on the contrast response functions in each case showed a pattern of contrast-gain or a combination of contrast-gain and response-gain effects. Cross-stimulus adaptation conditions showed that adaptation effects were highly stimulus selective across early, ventral, and dorsal visual cortical areas, consistent with the perceptual effects.
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Affiliation(s)
- Erin Goddard
- McGill Vision Research, Department of Ophthalmology & Visual Sciences, McGill University Montreal, Quebec, Canada.,Present address: School of Psychology, UNSW, Sydney, Australia.,
| | - Christopher Shooner
- McGill Vision Research, Department of Ophthalmology & Visual Sciences, McGill University Montreal, Quebec, Canada.,
| | - Kathy T Mullen
- McGill Vision Research, Department of Ophthalmology & Visual Sciences, McGill University Montreal, Quebec, Canada.,
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Goddard E, Mullen KT. Attention selectively enhances stimulus information for surround over foveal stimulus representations in occipital cortex. J Vis 2021; 21:20. [PMID: 33749755 PMCID: PMC7991976 DOI: 10.1167/jov.21.3.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
By attending to part of a visual scene, we can prioritize processing of the most relevant visual information and so use our limited resources effectively. Previous functional magnetic resonance imaging (fMRI) work has shown that attention can increase overall blood-oxygen-level-dependent (BOLD) signal responsiveness but also enhances the stimulus information in terms of classifier performance. Here, we investigate how these effects vary across the visual field. We compare attention-enhanced fMRI-BOLD amplitude responses and classifier accuracy in fovea and surrounding stimulus regions using a set of four simple stimuli subdivided into a foveal region (1.4° diameter) and a surround region (15° diameter). We found dissociations between the effects of attention on average response and in enhancing stimulus information. In early visual cortex, we found that attention increased the amplitude of responses to both foveal and surround parts of the stimuli and increased classifier performance only for the surround stimulus. Conversely, ventral visual areas showed less change in average response but greater changes in decoding. Unlike for early visual cortex, in the ventral visual cortex attention produced similar changes in decoding for center and surround stimuli.
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Affiliation(s)
- Erin Goddard
- Department of Ophthalmology & Visual Sciences, McGill Vision Research, McGill University, Montreal, Quebec, Canada.,Present Address: School of Psychology, University of New South Wales, Sydney, New South Wales, Australia.,
| | - Kathy T Mullen
- Department of Ophthalmology & Visual Sciences, McGill Vision Research, McGill University, Montreal, Quebec, Canada.,
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Goddard E, Mullen KT. fMRI representational similarity analysis reveals graded preferences for chromatic and achromatic stimulus contrast across human visual cortex. Neuroimage 2020; 215:116780. [PMID: 32276074 DOI: 10.1016/j.neuroimage.2020.116780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 03/18/2020] [Accepted: 03/24/2020] [Indexed: 01/23/2023] Open
Abstract
Human visual cortex is partitioned into different functional areas that, from lower to higher, become increasingly selective and responsive to complex feature dimensions. Here we use a Representational Similarity Analysis (RSA) of fMRI-BOLD signals to make quantitative comparisons across LGN and multiple visual areas of the low-level stimulus information encoded in the patterns of voxel responses. Our stimulus set was picked to target the four functionally distinct subcortical channels that input visual cortex from the LGN: two achromatic sinewave stimuli that favor the responses of the high-temporal magnocellular and high-spatial parvocellular pathways, respectively, and two chromatic stimuli isolating the L/M-cone opponent and S-cone opponent pathways, respectively. Each stimulus type had three spatial extents to sample both foveal and para-central visual field. With the RSA, we compare quantitatively the response specializations for individual stimuli and combinations of stimuli in each area and how these change across visual cortex. First, our results replicate the known response preferences for motion/flicker in the dorsal visual areas. In addition, we identify two distinct gradients along the ventral visual stream. In the early visual areas (V1-V3), the strongest differential representation is for the achromatic high spatial frequency stimuli, suitable for form vision, and a very weak differentiation of chromatic versus achromatic contrast. Emerging in ventral occipital areas (V4, VO1 and VO2), however, is an increasingly strong separation of the responses to chromatic versus achromatic contrast and a decline in the high spatial frequency representation. These gradients provide new insight into how visual information is transformed across the visual cortex.
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Affiliation(s)
- Erin Goddard
- McGill Vision Research, Department of Ophthalmology & Visual Sciences, McGill University, Montreal, QC, H3G1A4, Canada
| | - Kathy T Mullen
- McGill Vision Research, Department of Ophthalmology & Visual Sciences, McGill University, Montreal, QC, H3G1A4, Canada.
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Goddard E, Chang DHF, Hess RF, Mullen KT. Color contrast adaptation: fMRI fails to predict behavioral adaptation. Neuroimage 2019; 201:116032. [PMID: 31326574 DOI: 10.1016/j.neuroimage.2019.116032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/04/2019] [Accepted: 07/17/2019] [Indexed: 11/15/2022] Open
Abstract
fMRI-adaptation is a valuable tool for inferring the selectivity of neural responses. Here we use it in human color vision to test the selectivity of responses to S-cone opponent (blue-yellow), L/M-cone opponent (red-green), and achromatic (Ach) contrast across nine regions of interest in visual cortex. We measure psychophysical adaptation, using comparable stimuli to the fMRI-adaptation, and find significant selective adaptation for all three stimulus types, implying separable visual responses to each. For fMRI-adaptation, we find robust adaptation but, surprisingly, much less selectivity due to high levels of cross-stimulus adaptation in all conditions. For all BY and Ach test/adaptor pairs, selectivity is absent across all ROIs. For RG/Ach stimulus pairs, this paradigm has previously shown selectivity for RG in ventral areas and for Ach in dorsal areas. For chromatic stimulus pairs (RG/BY), we find a trend for selectivity in ventral areas. In conclusion, we find an overall lack of correspondence between BOLD and behavioral adaptation suggesting they reflect different aspects of the underlying neural processes. For example, raised cross-stimulus adaptation in fMRI may reflect adaptation of the broadly-tuned normalization pool. Finally, we also identify a longer-timescale adaptation (1h) in both BOLD and behavioral data. This is greater for chromatic than achromatic contrast. The longer-timescale BOLD effect was more evident in the higher ventral areas than in V1, consistent with increasing windows of temporal integration for higher-order areas.
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Affiliation(s)
- Erin Goddard
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, QC, H3G1A4, Canada
| | - Dorita H F Chang
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, QC, H3G1A4, Canada
| | - Robert F Hess
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, QC, H3G1A4, Canada
| | - Kathy T Mullen
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, QC, H3G1A4, Canada.
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McKeefry DJ, Burton MP, Morland AB. The contribution of human cortical area V3A to the perception of chromatic motion: a transcranial magnetic stimulation study. Eur J Neurosci 2010; 31:575-84. [PMID: 20105228 DOI: 10.1111/j.1460-9568.2010.07095.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Area V3A was identified in five human subjects on both a functional and retinotopic basis using functional magnetic resonance imaging techniques. V3A, along with other visual areas responsive to motion, was then targeted for disruption by repetitive transcranial magnetic stimulation (rTMS) whilst the participants performed a delayed speed matching task. The stimuli used for this task included chromatic, isoluminant motion stimuli that activated either the L-M or S-(L+M) cone-opponent mechanisms, in addition to moving stimuli that contained only luminance contrast (L+M). The speed matching task was performed for chromatic and luminance stimuli that moved at slow (2 degrees/s) or faster (8 degrees/s) speeds. The application of rTMS to area V3A produced a perceived slowing of all chromatic and luminance stimuli at both slow and fast speeds. Similar deficits were found when rTMS was applied to V5/MT+. No deficits in performance were found when areas V3B and V3d were targeted by rTMS. These results provide evidence of a causal link between neural activity in human area V3A and the perception of chromatic isoluminant motion. They establish area V3A, alongside V5/MT+, as a key area in a cortical network that underpins the analysis of not only luminance but also chromatically-defined motion.
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Affiliation(s)
- D J McKeefry
- Bradford School of Optometry and Vision Science, University of Bradford, Bradford, W Yorks, UK.
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The perception of speed based on L-M and S-(L+M) cone opponent processing. Vision Res 2009; 49:870-6. [PMID: 19285523 DOI: 10.1016/j.visres.2009.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 03/04/2009] [Accepted: 03/05/2009] [Indexed: 11/20/2022]
Abstract
We have measured perceived speed and speed discrimination thresholds for stimuli that selectively activate the L-M, S-(L+M) cone opponent and L+M (luminance) post-receptoral pathways. For low speeds and low contrasts speed discrimination thresholds for L-M and S-(L+M) are similar but are higher and have a greater dependency upon contrast than those for luminance motion. These differences between chromatic and luminance speed perception can be eliminated when stimuli are equated with respect to their individual motion detection thresholds (MDTs). For fast moving gratings speed perception based upon L-M, S-(L+M) and L+M signals is similar in terms of threshold performance and contrast dependency. These results are consistent with the view that there are separate mechanisms for the analysis of chromatic and luminance motion, the relative contributions of which may change as a function of stimulus contrast and speed. The similarity in performance for S-(L+M) and L+M chromatic stimuli across a range of stimulus parameters suggests that signals derived from the two cone opponent pathways can be used equally well. Our results argue against the idea that speed perception is compromised when it is based upon information derived from the S-(L+M) cone opponent pathway.
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