title: Sensorimotor electroencephalogram rhythmic activity: a functional gate mechanism.
abstract: Neurophysiological evidence for a negative feedback loop in somatosensory thalamic nuclei has provided a basis for understanding the origins of rhythmic activity in the electroencephalogram (EEG) of sensorimotor cortex. Studies reviewed here suggest that state-specific activation of this mechanism is responsible both for a variable pattern of rhythmic frequencies during wakefulness and the spindle burst pattern during sleep. It is proposed further that these rhythms index immobility and a common set of physiological changes in sensorimotor function, including reduced excitability in both afferent and efferent pathways. It is hypothesized, therefore, that the closing of a thalamic "inhibitory gate" is indicated by the occurrence of these rhythms. While a greater resolution of specific relationships is necessary, the study of these EEG patterns clearly provides a measure of complex physiological events in the nervous system, and can be also useful in identifying functional abnormalities.
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology; D002415:Cats; D004569:Electroencephalography / Q000379:methods*; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D007223:Infant; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition; D009434:Neural Pathways / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D013788:Thalamus / Q000502:physiology