Anesthesia Induces Shifts in Spatial Frequency Preference in the Primary Visual Cortex

General anesthesia markedly reduces overall brain responsiveness to external stimuli. Animal studies reveal that in individual neurons of the primary visual cortex (V1), anesthesia modulates the gain of neural responses while leaving orientation and direction tuning unaltered. However, the impact of anesthesia on spatial frequency (SF) tuning is largely unexplored despite it being a fundamental characteristic of visual perception. Furthermore, compared to excitatory neurons, the effects of anesthesia on the visual responsiveness of specific inhibitory neuron subtypes are poorly understood. Here, we directly compared visual responses from the same V1 neurons in mice under both anesthetized and awake states. We found that isoflurane anesthesia significantly shifts the preferred SFs of excitatory neurons to lower values. This downward shift was even more pronounced in inhibitory neurons. These downshifts selectively impaired the neural coding of high-SF information while leaving low-SF coding unaffected. We observed distinct patterns of anesthesia-induced downward shifts of preferred SFs between two major cortical inhibitory neuron subtypes: somatostatin-expressing (SOM) and parvalbumin-expressing (PV) neurons. Furthermore, anesthesia-induced changes in response gain and tuning sharpness were evident in SOM neurons but not in PV neurons. These results highlight the diverse effects of anesthesia on sensory responses, varying significantly based on both the visual feature processed and the specific neuron subtype involved. The consistent decrease in preferred SFs during anesthesia not only suggests a potential mechanism for anesthesia-induced alterations in sensory experience but also emphasizes the critical role of heightened SF preference during wakefulness for fine object perception.