Background and Aim : Visuo-motor responses rely on flexible transmission of information between visual and frontoparietal associative areas in the human and non-human primate brain. However, it remains unclear how such transmission is dynamically controlled allowing an efficient guidance of the behavioral report.Methods : We recorded extracellular activities from the medial temporal area (MT) of two macaque monkeys while they performed a visual motion change detection task. The animals were trained to report a brief change in one of two moving random dot patterns presented on a screen, while they fixated their eye gaze on a central fixation point. We divided the hit trials into fast and slow subsets based on the monkeys’ reaction time in each trials. To study how the rhythmic synchronization of MT neurons may modulate behavioral speed, we extracted local field potentials (LFP) and single-unit spiking activities during the period before the direction change and calculated
spike-phase coupling (SPC) as well as the
phase-amplitude coupling (PAC) for different frequency pairs in each trial.Results : Our results demonstrate that the strength of coupling between single-unit activities and the phase of high-gamma LFP oscillations (> 180 Hz) predicts the monkey’s speed in reporting the change in stimuli. This suggests that spikes are more likely evoked at a specific phase of high-gamma oscillations in fast, rather than slow trials. Given that a previous study in the visual area V4 reported a similar observation, but in a different frequency band (gamma frequencies, 40-70Hz), we propose that visual pathways (dorsal vs. ventral) may use distinct frequency bands (high-gamma vs. gamma) for routing information into downstream areas, enabling them to distinguish input sources. Moreover, our results indicate that, power of high-gamma oscillations are more strongly modulated by beta rhythmic activities in fast compared to slow trials. This observation suggests that an increase of beta to high-gamma PAC could facilitate the transmission of sensory information to associative areas facilitating behavioral responses.Conclusion : We concluded that beta coupled high-gamma synchrony could facilitate effective transmission of visuo-motor information in the macaque brain