Wakefulness-sleep modulation of thalamic multiple unit activity and EEG in man

Quantitative changes in the number of EEG waves and MUA neuronal spikes of various thalamic nuclear groups were studied during steady and transitional wakefulness-sleep states in a group of patients with implanted electrodes, used as an electrophysiological procedure for the surgical treatment of unilateral tremor and rigidity. Thalamic nuclei included ventroposterolateral (VPL), ventrolateral (VL) and centromedian (CM). Steady states included initial wakefulness (W1), slow wave sleep (SWS) I, II, IV and IIL, paradoxical sleep phasic (PSP) and tonic (PST) and final wakefulness (W2). Transitional states included transition from SWS to PSP (transition) and from sleep to W2 (arousal). (1) There was a significant correlation in EEG and MUA between different thalamic nuclei simultaneously recorded in the same patient during different steady-states. (2) Thalamic MUA significantly decreased from W to SWS, increased from SWS to PS and SWS to W2, while thalamic EEG significantly decreased from W to SWS, increased from SWS to W2 but was not significantly modified from SWS to PS, consecutive steady-state shifts. (3) Thalamic MUA significantly decreased while EEG remained unchanged from PSP to PST consecutive steady-state shifts. (4) Both thalamic MUA and EEG significantly decreased from SWS II to IIL while they were not systematically modified from W1 to W2 indirect steady-state shifts. (5) Thalamic MUA significantly increased 1 sec before transition and arousal while EEG increased 5 sec after arousal and did not change during transition.