Sound Production and Other Behavioral Effects of Midbrain Stimulation in Free-swimming Toadfish, Opsanus beta

Abstract

The midbrain area of the acoustico-lateral lemniscus, ganglion isthmi and medial torus semicircularis was electrically stimulated in free-swimming toadfish. Grunts (threat sounds) and boatwhistles (probable courtship calls) were evoked in both sexes during stimulation of this region, which has been termed the sonic midbrain area (SMA). Several locomotor and defensive responses were elicited with sound production; however, neither complete reproductive nor aggressive patterns were observed. Several points adjacent to the SMA were negative for sound production. It is postulated that the SMA integrates various sensory and hormonal stimuli and controls sound production through connections to lower sonic motor mechanisms.