EEG beta power increase indicates inhibition in motor memory.

Beta power increase has been suggested to be an electrophysiological marker of response inhibition during voluntary action stopping. We examined whether beta power increase accompanies inhibition in human motor memory, focusing the phenomenon of retrieval-induced forgetting that has been assumed to be the consequence of inhibition in memory. Whereas most studies on this effect comprise word materials, a variant of the retrieval-induced-forgetting paradigm exists for examining motor memory. In the present study, we recorded scalp EEG during this motor-specific variant and examined EEG oscillatory correlates of retrieval-induced slowing of motor actions. Here, forgetting occurred in the form of significant slowing when executing motor sequences in a final recall test. Participants first learned to associate memory cues to sequential finger movements, half of which were performed with the left hand and half with the right hand. They then selectively retrieval-practiced half of the items of one hand before finally memory for all items was tested. On a behavioral level, selective retrieval practice induced slower execution of the non-retrieved items of the retrieval-practiced hand in a final memory test. On a physiological level, this retrieval-induced-slowing effect was predicted by an increase of EEG beta power during retrieval practice. The results suggest that motor retrieval-induced forgetting is a consequence of inhibition in human memory.