Sonic/vocal motor pathways in squirrelfish (Teleostei, Holocentridae)

Area of Science:

• Neurobiology
• Comparative Anatomy
• Ichthyology

Background:

• Teleost fish, including squirrelfish (family Holocentridae), utilize swimbladder vibrations for sound production.
• Understanding the neural control of vocalizations is crucial for studying fish communication and evolution.

Purpose of the Study:

• To anatomically characterize the vocal motor nucleus (SMN) in squirrelfish.
• To compare the SMN of squirrelfish with other motor neuron groups and related fish species.

Main Methods:

• Biotinylated compounds and transneuronal transport of biocytin were used to trace neuronal pathways.
• Identification and mapping of vocal motor neurons, premotor neurons, and other motor neuron groups (dorsal epaxial muscle, opercular muscle).

Main Results:

• The SMN was located in the caudal medulla and rostral spinal cord, with specific dendritic and axonal projections.
• Premotor neurons within the SMN and reticular formation showed projections to contralateral SMN and other brain nuclei.
• Motor neurons for dorsal muscle and opercular muscle were identified in distinct locations.

Conclusions:

• Squirrelfish SMN anatomy is similar to Scorpaeniformes but differs from more distantly related teleosts.
• The findings suggest potential homology of SMNs among acanthopterygian fishes.
• Interactions between vocal and octavolateralis systems are indicated, consistent with other teleosts.