Disentangling sensory-and motor-related EEG activities elicited in the context of rhythmic sensorimotor interactions

Abstract

Disentangle rhythmic sensory-and motor-related brain activity in electroencephalographic signal is rendered difficult by the fact that both processes can be expected to elicit Steady-State Evoked-Potentials (SS-EPs) at the same frequencies. Previous behavioural studies have shown that when participants are asked to tap along a musical beat, their taps precede the actual occurrence of the beat by 30-50 ms. This phenomenon, referred to as mean negative asynchrony is smaller in musicians than non-musicians. Furthermore, in a pilot experiment (6 participants) we observed significant fluctuations in the tapping period, resulting in some amount of desynchronization between auditory input and motor output. Therefore, we investigated whether the fluctuations in motor output can be used as a “temporal signature” to disentangle sensory-and motor-related periodic brain activity. The EEG was recorded in 16 healthy participants while they tapped in synchrony with a periodic auditory beat. The onset of the taps was measured using a touch pad. In the original EEG signals, activity related to sensory processing can be expected to follow the strict periodicity of the auditory beat and, hence, to elicit an SS-EP concentrated at the beat frequency. In contrast, movement-related activity can be expected to exhibit temporal fluctuations following those of the actual tapping movement and, hence, to elicit a relatively attenuated SS-EP spread around the mean tapping frequency. We then applied a linear time warping function to the recorded EEG signals, so as to suppress the fluctuations in tapping onsets. In these time-warped signals, movement-related activity can …

Gan Huang

My research interests include Neural Modulation, Brain Computer Interface and Neural Prosthetics.