Top-down modulation of stimulus drive via beta-gamma cross-frequency interaction

SUMMARY Recently, several studies have demonstrated that visual stimulus routing is subserved by inter-areal gamma-band synchronization, whereas top-down influences are mediated by alpha-beta band synchronization. These processes might implement top-down control, if top-down and bottom-up mediating rhythms are coupled through cross-frequency interaction. To test this possibility, we investigated Granger-causal influences among awake macaque primary visual area V1, higher visual area V4 and parietal control area 7a during attentional task performance. Top-down 7a-to-V1 beta-band influences enhanced visually driven V1-to-V4 gamma-band influences. This enhancement was spatially specific and largest for a beta-to-gamma delay of ~100 ms, suggesting a causal relationship. We propose that this cross-frequency interaction mechanistically subserves the attentional control of stimulus selection.