SENSORIMOTOR ENCODING BY SYNCHRONOUS NEURAL ENSEMBLE ACTIVITY AT MULTIPLE LEVELS OF THE SOMATOSENSORY SYSTEM

Neural ensemble processing of sensorimotor information during behavior was investigated by simultaneously recording up to 48 single neurons at multiple relays of the rat trigeminal somatosensory system. Cortica l, thalamic, and brainstem neurons exhibited widespread 7- to 12-hertz synchronous oscillations, which began during attentive immobility and reliably predicted the imminent onset of rhythmic whisker twitching. Each oscillatory cycle began as a traveling wave of neural activity in the cortex that then spread to the thalamus. Just before the onset of rhythmic whisker twitching, the oscillations spread to the spinal tri geminal brainstem complex. Thereafter, the oscillations at all levels were synchronous with whisker protraction. Neural structures manifesti ng these rhythms also exhibited distributed spatiotemporal patterns of neuronal ensemble activity in response to tactile stimulation, thus, multilevel synchronous activity in this system may encode not only sen sory information but also the onset and temporal domain of tactile exp loratory movements.