Jessica Randa
Advisor: Catherine McCormick
Honors Project
CONNECTIONS OF A HYPOTHALAMIC NUCLEUS THAT RECEIVES INPUT FROM THE ACOUSTIC AND LATERAL LINE SYSTEMS
Information from the auditory endorgans of the inner ear and from the mechanosensory lateral line organs is conveyed to distinct auditory and lateral line nuclei in the medulla. Each of these nuclei form the initial part of circuits through which information from each of these senses is relayed through the neuraxis: from medulla to midbrain, midbrain to thalamus, and thalamus to telencephalon. An unexpected relay from the midbrain to a hypothalamic nucleus, the anterior tuberal nucleus, is present in certain teleost fish. This connection is particularly prominent in the Otophysii, the taxon to which the goldfish (Carassius auratus) belongs. The significance of this projection to the hypothalamus is unknown. The hypothalamus is strongly influenced by the limbic system (which is involved in emotional behavior) and controls the autonomic nervous system. The hypothalamus also exerts major influence on the endocrine system. Thus, the acoustic and lateral line input to the anterior tuberal nucleus may be relevant to such behaviors as reproduction or fear responses. Knowledge of the connections of the anterior tuberal nucleus may shed insight onto the functional significance of this structure.