Visual Perception and Gamma Oscillations in Cat V1 are Dynamically Correlated in Contrast Sensitivity Functions.

Local field potentials (LFPs) encode visual information through power variations across multiple frequencies. However, the mechanism through which LFPs encode visual contrast sensitivity during visual perception remains unclear. Herein, we developed a method to decode visual perception levels using LFPs and found that gamma oscillations exhibited the best performance in the detection of visual contrast. Furthermore, gamma power and theta-gamma phase amplitude coupling employed different strategies to code contrast sensitivity. Subsequently, suppressing the top-down influence from area 21a lowered both behavioral and gamma power-measured contrast sensitivity across the same spatial frequencies. Model analysis revealed that gamma oscillations modulated contrast-tuning responses via a contrast gain mechanism and were involved in the external noise exclusion mechanism through a top-down influence. Our findings reveal a link between gamma oscillations and visual contrast sensitivity and demonstrate that a reduction in gamma oscillation power through the suppression of top-down influences impairs perception of visual contrast.