Abstract
The efficient coding hypothesis predicts that disparity preferences in binocular V1 neurons should reflect the distribution of disparities observed during natural viewing. Several investigators have reported that the majority of disparity-selective V1 neurons prefer crossed (or near) disparity and argued that this bias reflects the natural distribution of disparities. To address these issues, we compared empirical measurements of disparity statistics (Cooper et al., 2013) with the preferred disparity of 620 V1 neurons measured in four well-known neurophysiological studies (Cumming, 2002; Durand et al., 2007; Gonzalez et al., 2010; Samonds et al., 2012). We unified the data by projecting into a common coordinate system (Helmholtz coordinates) and examined how horizontal- and vertical-disparity preferences vary with visual-field position. The empirical disparity statistics predicted that neurons in the lower visual field should be more likely to prefer crossed horizontal disparities, while those in the upper field should prefer uncrossed disparities. The distribution of preferences for neurons in the lower field is indeed shifted toward crossed disparities relative to neurons in the upper field. The crossed disparity bias of lower-field neurons may have previously been mistakenly generalized to the whole visual field due to over-sampling of the lower visual field (77% of neurons across these studies). We also predicted that neurons in the upper left or lower right field quadrants are more likely to prefer positive vertical disparities, while neurons in the other quadrants should prefer negative vertical disparities. We observed a small shift towards positive vertical disparities for neurons in the upper left and lower right. Unfortunately, there are not enough neurons in the other quadrants to determine if they have a negative disparity preference. Our analysis of V1 neurons is consistent with the hypothesis that the distribution of preferred disparities reflects the statistics of disparity across the visual field.
Meeting abstract presented at VSS 2014