Chronic stress impairs multi-scale visual processing in V1.

Visual perceptual deficits are increasingly acknowledged as a core yet underexplored feature of Major Depressive Disorder (MDD), involving impairments in contrast sensitivity, contextual modulation, and social-emotional perception. However, the underlying circuit-, neuron-, and network-level mechanisms through which depressive states influence early visual processing remain poorly understood. In this study, mice subjected to chronic restraint stress (CRS) underwent single-unit recordings in layer 2/3 (L2/3) of the primary visual cortex (V1) under light anesthesia to examine the effects of chronic stress on visually evoked neuronal responses and local network dynamics. V1 neurons in CRS-exposed mice exhibited broadened orientation tuning bandwidths, diminished surround suppression, and impaired center-surround discontinuity discrimination. At the network level, visually evoked oscillatory power in the θ, low γand high γ frequency bands was significantly attenuated in CRS mice, accompanied by a marked reduction in visual evoked potential (VEP) amplitude. These findings show that chronic stress impairs both the tuning of V1 neurons to visual stimuli and the local neural rhythms underlying early visual processing. The results uncover a multi-level physiological basis for depression-related visual deficits and provide a preclinical framework that could help develop objective sensory biomarkers for MDD.