MUSCARINIC ELICITATION OF EEG ASYMMETRY IN FREELY MOVING RATS

Averaged frequency spectra (0.5-30 Hz) of electroencephalogram (EEG) w ere studied in six freely moving rats with chronically implanted elect rodes in symmetrical areas of somatosensory cortex. Hemispheric asymme try in spectra of an ongoing EEG was expressed as a power decrease in 15.6-17.2 Hz band on the left hemisphere and as that in 25.2-27.8 Hz b and on the right one. Physostigmine subcutaneous (s.c.) injection (0.2 5 mg/kg) provoked appearance of the significant left brain bias in 4.7 -8.6 Hz range of EEG spectra and the right brain bias in 19.3-21.3 Hz band. These physostigmine effects were counteracted by scopolamine (1. 5 mg/kg, s.c.) injected 30 min before. It is suggested that a muscarin ic component may be involved in the interhemispheric cooperation assoc iated with cortical theta activity in rats. (C) 1998 Elsevier Science B.V. All rights reserved.