THE effects of a pharmacological blockade of the periaqueductal grey o
f the midbrain (PAG) on the elicitability of vocal fold movements from
the facial motor cortex on the one hand and the anterior cingulate co
rtex and dorsomedial hypothalamus on the other were studied in the squ
irrel monkey. PAG blockade abolished vocal fold activity induced by th
e cingulate cortex and hypothalamus, but not that induced by the neoco
rtex. These results point to the existence of two separate vocal fold
control pathways at midbrain level: one limbic, responsible for non-ve
rbal emotional vocal utterances, and one neocortical, responsible for
the production of learned vocal patterns. The PAG represents a crucial
relay station of the limbic but not the neocortical vocal control pat
hway.