Distinct patterns of surround modulation in V1 and hMT+

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buir.contributor.authorEr, Görkem
buir.contributor.authorPamir, Zahide
buir.contributor.authorBoyacı, Hüseyin
dc.citation.epage117084-10en_US
dc.citation.spage117084-1en_US
dc.citation.volumeNumber220en_US
dc.contributor.authorEr, Görkem
dc.contributor.authorPamir, Zahide
dc.contributor.authorBoyacı, Hüseyin
dc.date.accessioned2021-03-04T14:13:23Z
dc.date.available2021-03-04T14:13:23Z
dc.date.issued2020
dc.departmentDepartment of Psychologyen_US
dc.departmentNational Magnetic Resonance Research Center (UMRAM)en_US
dc.description.abstractModulation of a neuron’s responses by the stimuli presented outside of its classical receptive field is ubiquitous in the visual system. This “surround modulation” mechanism is believed to be critical for efficient processing and leads to many well-known perceptual effects. The details of surround modulation, however, are still not fully understood. One of the open questions is related to the differences in surround modulation mechanisms in different cortical areas, and their interactions. Here we study patterns of surround modulation in primary visual cortex (V1) and middle temporal complex (hMT+) utilizing a well-studied effect in motion perception, where human observers’ ability to discriminate the drift direction of a grating improves as its size gets bigger if the grating has a low contrast, and deteriorates if it has a high contrast. We first replicated the findings in the literature with a behavioral experiment using small and large (1.67 and 8.05 degrees of visual angle) drifting gratings with either low (2%) or high (99%) contrast presented at the periphery. Next, using functional MRI, we found that in V1 with increasing size cortical responses increased at both contrast levels. Whereas in hMT+ with increasing size cortical responses remained unchanged or decreased at high contrast, and increased at low contrast, reflecting the perceptual effect. We also show that the divisive normalization model successfully predicts these activity patterns, and establishes a link between the behavioral results and hMT+ activity. We conclude that surround modulation patterns in V1 and hMT+ are different, and that the size-contrast interaction in motion perception is likely to originate in hMT+.en_US
dc.description.provenanceSubmitted by Zeynep Aykut (zeynepay@bilkent.edu.tr) on 2021-03-04T14:13:23Z No. of bitstreams: 1 Distinct_patterns_of_surround_modulation_in_V1_and_hMT+.pdf: 1108661 bytes, checksum: 2aaeae9e64fd3c2d9d7be67fab29120e (MD5)en
dc.description.provenanceMade available in DSpace on 2021-03-04T14:13:23Z (GMT). No. of bitstreams: 1 Distinct_patterns_of_surround_modulation_in_V1_and_hMT+.pdf: 1108661 bytes, checksum: 2aaeae9e64fd3c2d9d7be67fab29120e (MD5) Previous issue date: 2020en
dc.identifier.doi10.1016/j.neuroimage.2020.117084en_US
dc.identifier.issn1053-8119
dc.identifier.urihttp://hdl.handle.net/11693/75790
dc.language.isoEnglishen_US
dc.publisherAcademic Press Inc.en_US
dc.relation.isversionofhttps://dx.doi.org/10.1016/j.neuroimage.2020.117084en_US
dc.source.titleNeuroImageen_US
dc.subjectMiddle temporal complexen_US
dc.subjectMotion perceptionen_US
dc.subjectPrimary visual cortexen_US
dc.subjectSurround facilitationen_US
dc.subjectSurround modulationen_US
dc.subjectSurround suppressionen_US
dc.titleDistinct patterns of surround modulation in V1 and hMT+en_US
dc.typeArticleen_US

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