Electrically and chemically induced spindling and slow waves in the encéphale isolé rat: a possible role for dopamine in the regulation of electrocortical activity.

The effects of electrical and chemical stimulation of brain areas known to contain dopaminergic cell bodies or terminals on electrocortical activity have been studied in the encéphale isolé rat. Electrical stimulation of medial basal midbrain areas with single stimuli resulted in a single evoked spindle but stimulation of more lateral areas resulted in the appearance of slow waves and spindling. These effects were blocked or reduced by prior treatment with 6-hydroxydopamine. Electrical stimulation of the caudate nucleus also produced a single evoked spindle. Local injection of dopamine into the caudate nucleus induced spindling, with higher doses also resulting in slow waves. Electrical stimulation of the basal forebrain brought about slow waves, an effect which was also seen following injection of dopamine into this area. It appears that electrical stimulation of certain brain areas produces similar effects to those produced by the injection of dopamine. This suggests the involvement of dopaminergic pathways in the production of cortical spindling and slow waves and also the involvement of neurones of both limbic and striatal systems.