AMYGDALOID MODULATION OF MESOPONTINE PERIBRACHIAL NEURONAL-ACTIVITY -IMPLICATIONS FOR AROUSAL

This research sought to determine if activation of the amygdaloid cent ral nucleus (ACe) modulates the activity of arousal-related neurons wi thin the peribrachial (PB) region. Two categories of neurons were iden tified. Neurons of the Ist category demonstrated low spontaneous rates and responded with a burst of spikes to acoustic stimuli, characteris tics similar to those reported for cholinergic ponto-geniculo-occipita l (PGO) wave generator neurons. Neurons of the 2nd category demonstrat ed significant correlations between their spontaneous activity and the power of delta wave activity in the electroencephalogram (EEG) and re sponded to acoustic stimuli. Electrical stimulation of the ACe activat ed 43% of the PGO-related neurons but only 6% of the EEG-related neuro ns. The results suggest that the ACe modulates the activity of neurons that form the substrate for PGO waves, which are recognized correlate s of arousal.