Fig. 5.

Vocal behavior and central vocal network of fish. (A) Top: Oscillogram trace of hydrophone record of a series (“train”) of agonistic grunts from the nest of a type I male plainfin midshipman fish (Porichthys notatus). Bottom: Single grunt on an expanded time scale. (B) Top: Recording from a type I male of spontaneously generated vocal nerve volley that mimics natural grunt train. Bottom: Single fictive grunt on expanded time scale. Fictive calls are readily evoked using electrical microstimulation from vocally active midbrain sites. (C) Sagittal view of brain of midshipman fish showing the location of regions comprising central vocal motor network. Vocal midbrain regions (VMB) act as a gate for descending forebrain input from the preoptic area (POA) that leads to activation of vocal central pattern generator (CPG). The Vocal CPG includes three distinct cell populations of vocal prepacemaker (VPP), vocal pacemaker (VPN) and vocal motor (VMN) neurons. (D) Schematic sagittal view of hindbrain summarizing the connectivity and neurophysiology of vocal CPG. The vocal CPG generates a vocal nerve motor volley (vocal output) that determines, in turn, natural call properties including duration and pulse repetition rate (PRR, also sets fundamental frequency in fish). Vocalization duration, frequency (PRR) and amplitude are coded by VPP, VPN and VMN neurons, respectively. VPP also transmits a corollary discharge that informs auditory hindbrain populations about the duration of natural vocalizations. Modified from [41; 76].