Receptive fields from single-neuron recording and MRI reveal similar information coding for binocular depth

The population receptive field (pRF) approach to functional measurement of the sensory properties of magnetic resonance (MR)-identified locations in the human brain was extended to include the third dimension of binocular depth. In total, pRFs were extracted from nine different visual areas (V1, V2, V3, V3AB, V4, V5, V7, Ventral Occipital Cortex: VOC, Lateral Occipital Cortex: LOC) of the human cortex and, where possible, comparisons were made with electrophysiological recordings from homologous areas in the macaque cortex. Human and macaque V1 showed strikingly similar information profiles for the encoding of binocular depth. Further, both human and macaque V5 showed consistent changes in preferred binocular depth of the stimulus, dependent on whether the stimuli were binocularly correlated or anticorrelated. Across the nine areas of the visual cortex explored, the population profiles of pRFs for binocular depth showed evidence of a greater responsiveness to relative depth in higher visual cortical areas, again consistent with the findings from macaque electrophysiology. Overall, the pRF measures of cortical response were more sensitive to fine-scale differences of binocular depth, compared with many existing electrophysiological measures of tuning for binocular depth. Our results show that the pRF method can be extended beyond the characterization of RFs in retinotopic coordinates to reveal higher-order, derived visual properties. The parallels between noninvasive, MR-based measures of pRFs in humans and the electrophysiological recordings of single neurons in experimental animals make a further step toward validation of the pRF methodology.