Driving Oscillatory Activity in the Human Cortex Enhances Motor Performance

Summary

Voluntary movement is accompanied by changes in the degree to which neurons in the brain synchronize their activity within discrete frequency ranges. Two patterns of movement-related oscillatory activity stand out in human cortical motor areas. Activity in the beta frequency (15–30 Hz) band is prominent during tonic contractions but is attenuated prior to and during voluntary movement [ 1]. Without such attenuation, movement may be slowed, leading to the suggestion that beta activity promotes postural and tonic contraction, possibly at a cost to the generation of new movements [ 2, 3]. In contrast, activity in the gamma (60–90 Hz) band increases during movement [ 4]. The direction of change suggests that gamma activity might facilitate motor processing. In correspondence with this, increased frontal gamma activity is related with reduced reaction times [ 5]. Yet the possibility remains that these functional correlations reflect an epiphenomenal rather than causal relationship. Here we provide strong evidence that oscillatory activities at the cortical level are mechanistically involved in determining motor behavior and can even improve performance. By driving cortical oscillations using noninvasive electrical stimulation, we show opposing effects at beta and gamma frequencies and interactions with motor task that reveal the potential quantitative importance of oscillations in motor behavior.

Highlights

► Cortical driving at 20 and 70 Hz slows and speeds voluntary force generation ► Performance can be enhanced even during contractions made as fast as possible ► Scale of effects of cortical driving depend on the nature of the cued motor task