Visual Contrast Sensitivity Improvement by Right Frontal High-Beta Activity Is Mediated by Contrast Gain Mechanisms and Influenced by Fronto-Parietal White

Behavioral andelectrophysiological studies inhumansandnon-humanprimates have correlated frontal high-beta activitywith the orienting of endogenous attention and shown the ability of the latter function to modulate visual performance. We here combined rhythmic transcranial magnetic stimulation (TMS) and diffusion imaging to study the relation between frontal oscillatory activity and visual performance, andwe associated these phenomena to a specific set of whitematter pathways that in humans subtend attentional processes. High-beta rhythmic activity on the right frontal eye field (FEF) was inducedwith TMS and its causal effects on a contrast sensitivity function were recorded to explore its ability to improve visual detection performance across different stimulus contrast levels. Our results show that frequency-specific activity patterns engaged in the right FEF have the ability to induce a leftward shift of the psychometric function. This increase in visual performance across different levels of stimulus contrast is likelymediated bya contrast gainmechanism. Interestingly,microstructuralmeasures o