Comparing pRF Mapping Estimates for Words and Checker Patterns

Functional MRI responses from voxels in the visual cortex are driven by stimuli within restricted regions of the visual field, their so-called population receptive fields (pRF). The central position and size of every voxel’s receptive field can be quantified using pRF mapping. In a previous report, we measured the pRF centers of individual voxels using words and contrast-reversing checker patterns shown within the stimulation area. The pRF centers measured with words differed from those measured with checkers. Voxels with a pRF center in the near periphery (5-10 degrees visual angle from the fixation) are more eccentric (1-3 degrees) when measured with checkers compared to words. To gain a deeper understanding of these effects, we acquired new datasets that differed significantly from the previous data. These variations included using different MRI scanners, fields of view, and acquisition sequences with either high-temporal or high-spatial resolution. Additionally, we adapted the used stimuli (such as variations in bar width and speed, flickering frequency) and participant populations, including individuals with both uncorrected and corrected visual acuity. Data were analyzed using a highly reproducible containerized public analysis platform (prfprepare and prfanalyze-vista). Results confirm the main effect in higher visual areas (hV4, VO1, IPS0-1). Further, initial measurements suggest specific stimulus manipulations (including defocus) impact the size of the change in eccentricity. Moreover, these manipulations may have different impacts on the eccentricity shift measured in different visual field maps. These findings offer a compelling starting point to further investigate stimuli induced pRF differences.