https://www.pisavisionlab.org Research centre dedicated to frontier, interdisciplinary research of human perception Wed, 08 Jul 2026 11:54:43 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.10 https://www.pisavisionlab.org/2026/07/08/characterizing-human-disparity-tuning-properties-using-population-receptive-field-mapping/ Wed, 08 Jul 2026 11:50:11 +0000 https://www.pisavisionlab.org/?p=5380 The Journal of Neuroscience Our visual percept of small differences in depth is largely informed by binocular stereopsis, the ability to decode depth from the horizontal offset between the retinal images in each eye. While multiple cortical areas are associated with stereoscopic processing, it is unclear how tuning to specific binocular disparities is organized across the human visual cortex. We used 3 T functional magnetic resonance imaging to generate population receptive fields (pRFs) in response to modulation of binocular disparity to characterize the neural tuning to disparity. We also used psychophysics to measure stereoacuity thresholds compared with backgrounds at different depths (pedestal disparity). Ten human participants (seven females) observed correlated or anticorrelated random-dot stereograms with disparity ranging from −0.3 to 0.3°, and responses were modeled as one-dimensional tuning curves along the depth dimension. First, we demonstrate that lateral and dorsal visual areas show the greatest proportion of vertices selective for binocular disparity. Second, with binocularly correlated stimuli, we show a polynomial relationship between preferred disparity and tuning curve width, with sharply tuned disparity responses at near-zero disparities, and broader disparity tuning profiles at near or far disparities. This relationship held across visual areas and was not present for anticorrelated stimuli. Finally, the individual thresholds for psychophysical stereoacuity at the three different pedestal disparities were broadly related to pRF tuning width in area V1, suggesting a possible limit for fine stereopsis at the earliest level of cortical processing. Together, these findings point to heterogeneity of disparity processing across human visual areas, comparable with nonhuman primates. Ivan Alvarez, Alessandro Mancari, I. Betina Ip, Andrew J. Parker and Holly Bridge https://www.pisavisionlab.org/2026/07/08/characterizing-human-disparity-tuning-properties-using-population-receptive-field-mapping/e0795242025-full/https://doi.org/10.1523/JNEUROSCI.0795-24.2025 https://www.pisavisionlab.org/2026/07/08/receptive-fields-from-single-neuron-recording-and-mri-reveal-similar-information-coding-for-binocular-depth/ Wed, 08 Jul 2026 11:54:42 +0000 https://www.pisavisionlab.org/?p=5383 PNAS 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. Andrew J. Parker, Ivan Alvarez, Alessandro Mancari, I. Betina Ip, Kristine Krug, and Holly Bridge https://www.pisavisionlab.org/2026/07/08/receptive-fields-from-single-neuron-recording-and-mri-reveal-similar-information-coding-for-binocular-depth/parker-et-al-2025-receptive-fields-from-single-neuron-recording-and-mri-reveal-similar-information-coding-for-binocular/https://doi.org/10.1073/pnas.2409893122