THE ROLE OF THE BASOLATERAL NUCLEUS OF THE AMYGDALA IN THE PATHWAY BETWEEN THE AMYGDALA AND THE MIDBRAIN PERIAQUEDUCTAL GRAY IN THE RAT

We electrophysiologically examined the connection between the basolate ral nucleus of the amygdala (BLA) and the periaqueductal gray (FAG) an d examined the role of the central nucleus of the amygdala (CNA) in th is pathway. Train electrical stimulation of the BLA excited 21% (7/33) and inhibited 27% (9/33) of the cells recorded in the FAG. Chemical s timulation of the BLA excited 23% (13/56) and inhibited 16% (9/56) of the cells recorded in the FAG. Injection of lidocaine into the CNA by itself had no effect on FAG cells (n=9) or on blood pressure but block ed the effect of BLA stimulation on FAG neurons in 78% of the cells re corded. It was concluded that: (1) PAG cells respond to BLA stimulatio n; (2) the majority of these cells are located in the dorsolateral and lateral columns of the FAG; and (3) the CNA modulates a majority of t he activities of the BLA in the PAG.