Rhythmic midbrain-evoked vocalization is inhibited by vasoactive intestinal polypeptide in the teleost Porichthys notatus

Vasoactive intestinal polypeptide (VIP) is distributed in vocal midbrain ar eas of multiple vertebrate tare, suggesting that VIP may modulate midbrain- evoked vocalization. To test this hypothesis, neurophysiological experiment s were conducted in the teleost Porichthys notatus which generates vocaliza tions in mating and agonistic contexts. Electrical stimulation of the paral emniscal midbrain and local delivery of VIP were conducted in conjunction w ith occipital nerve recordings that reflect the patterned output of hindbra in vocal circuitry. Consistent with our hypothesis, VIP significantly reduc ed the duration and number of rhythmic vocal-motor bursts obtained in a dos e-dependent manner; vocalization latency was concomitantly increased. These results provide the first evidence for VIP modulation of midbrain vocal fu nction. (C) 2000 Elsevier Science BN. All rights reserved.