Abstract
Visual stimulation produces oscillatory gamma responses in human primary visual cortex (V1) that also relate to visual perception. We have shown previously that peak gamma frequency positively correlates with central V1 cortical surface area. We hypothesized that people with larger V1 would have smaller receptive fields and that receptive field size, not V1 area, might explain this relationship. Here we set out to test this hypothesis directly by investigating the relationship between fMRI estimated population receptive field (pRF) size and gamma frequency in V1. We stimulated both the near-center and periphery of the visual field using both large and small stimuli in each location and replicated our previous finding of a positive correlation between V1 surface area and peak gamma frequency. Counter to our expectation, we found that between participants V1 size (and not PRF size) accounted for most of the variability in gamma frequency. Within-participants we found that gamma frequency increased, rather than decreased, with stimulus eccentricity directly contradicting our initial hypothesis.
Highlights
The primary visual cortex (V1) is composed of columnar aggregations of neurons with similar tuning properties [1,2,3]
As there was no association with volume, we suggested that the higher peak gamma frequency was potentially due to the smaller receptive field sizes that one would expect in individuals with greater V1 surface area
There was, no evidence to support our prediction that higher peak gamma frequencies should be associated with smaller population receptive field (pRF) size; as both within and between participants, the more eccentric stimuli gave rise to increased gamma frequency
Summary
The primary visual cortex (V1) is composed of columnar aggregations of neurons with similar tuning properties [1,2,3]. There is substantial individual variability in V1 surface area which can greatly affect visual perception [5,6,7]. Those people with larger surface area are less susceptible to certain visual illusions as they fail to use broader visual contextual information compared to those with smaller V1 surface areas. Visual stimulation produces oscillatory electrical activity in visually responsive neuronal populations that can be measured using magnetoencephalography (MEG). These neuronal dynamics are most evident in the gamma-band frequency of 30-80Hz and have been linked to perceptual and cognitive function [8]. There is a positive association between higher frequency within the gamma band and neuronal tuning and behavioral discrimination
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