Zhaoping, L. | bioRxiv Science

bioRxiv2025

V1 superficial layers create a saliency map that feeds forward to the parietal cortex for attentional guidance

A salient visual object with a distinct feature from the surrounding environment automatically captures attention. While the saliency signals have been found in many brain regions, their source remains highly controversial. Here, we investigated the neural origin of visual saliency using cortical layer-dependent functional magnetic resonance imaging (fMRI) of cerebral blood volume (CBV) at 7 Tesla. Behaviorally, human observers were better at detecting foreground bars with a larger orientation contrast from uniformly oriented background bars. Saliency-sensitive signals were strongest in the superficial layers of the primary visual cortex (V1), and in the middle layers of the intraparietal sulcus (IPS) of the parietal cortex. Layer-dependent effective connectivity revealed the transmission of saliency signals along the feedforward pathway from V1 to IPS. Furthermore, behavioral sensitivity to the foreground stimulus correlated significantly with the fMRI response in the superficial layers of V1. Our findings provide mesoscale evidence that a visual saliency map is created by iso-feature suppression through lateral inhibition in the superficial layers of V1, and then feeds forward to attentional control brain regions to guide attention and eye movements.

neuroscience↗

bioRxiv2017

Reversed depth in anti-correlated random dot stereograms and central-peripheral difference in visual inference

1Two images of random black and white dots, one for each eye, can represent object surfaces in a threedimensional scene when the dots correspond interocularly in a random dot stereogram (RDS). The spatial disparities between the corresponding dots represent depths of object surfaces. If the dots become anti-correlated such that a black dot in one monocular image corresponds to a white dot in the other, disparity-tuned neurons in the primary visual cortex (V1) respond as if their preferred disparities become non-preferred and vice versa, thereby reversing the disparity signs reported to higher visual areas. Humans have great difficulty perceiving the reversed depth, or any depth at all, in anti-correlated RDSs. We report that the reversed depth is more easily perceived when the RDSs are viewed in peripheral visual field, supporting a recently proposed central-peripheral dichotomy in mechanisms of feedback from higher to lower visual cortical areas for visual inference.

neuroscience↗