Contrasting behavior of beta event-related synchronization and somatosensory evoked potential after median nerve stimulation during finger manipulation in man.

Electrical median nerve stimulation during rest results in two cortical responses: the somatosensory evoked potential (SEP); and the induced beta oscillations (beta event-related synchronization (ERS)). Both types of responses were recorded with electroencephalography and studied during rest and motor behavior in eight normal subjects. During manipulation of a cube with the fingers of the right hand, the beta ERS around 20 Hz, induced by right hand median nerve stimulation, is significantly suppressed, whereas the long-latency SEP components are significantly enhanced. The results suggest that both phenomena can be interpreted as responses of different neuronal structures in sensorimotor areas.