Project: Research project

Project Details


Energy, water and electrolyte balance are among the most closely regulated
parameters found in complex organisms. Even a minor, uncorrected defect in
the control of any one system could be life-threatening. Most of the
processes involved in these systems regulate internal use and
conservation. Only one process, ingestion of foods or fluids, can
replenish exhausted supplies. The ultimate goal of the research outlined
in this proposal is to understand the neural mechanisms that govern the
decision to ingest or reject the contents of the oral cavity. Recent
evidence from this and other laboratories indicates that the basis for
these neuronal mechanisms in complete in the caudal brainstem -- the
midbrain, pons and medulla. Sensory information from the oral cavity --
tactile, temperature, and gustatory afferent activity -- first reaches the
brain in the pons and medulla. The motor neurons that produce ingestive
behavior are located in the pons and medulla. Visceral afferent activity
that can alter the response elicited by an oral stimulus from one of
ingestion to one of rejection also reaches the brain via axons that first
synapse in the caudal brainstem. Using neuroanatomical,
electrophysiological, and behavioral analysis, this project will examine
the function of oral sensory activity in eliciting and guiding the motor
apparatus responsible for ingestion and rejection, the nature of the
visceral events that control these responses, and the neural integration of
oral and visceral afferent activity that supports switching from one
behavior to the other. Specific experiments will examine (1) the
convergence of oral tactile, thermal, and gustatory afferent activity onto
single neurons in the nucleus of the solitary tract, (2) the effects on
ingestive behavior of disconnecting the afferent input or efferent output
of the solitary nucleus, (3) the importance of visceral afferent or
efferent activity immediating hormonal initiation or satiation of
ingestion, and (4) the interaction of oral and visceral afferent activity
at the neuronal level in the medulla and pons. In addition to contributing
toward a basic understanding of how the nervous system coordinates diverse
sensory information into precise physiological and behavioral controls,
this research has direct relevance to sensory mechanisms involved in the
etiology of a variety of morbid conditions. Specifically, excess ingestion
of carbohydrates (sugars) and salt (sodium) is highly correlated with, and
may be causally related to, obesity, diabetes, and hypertension.
Effective start/end date1/1/901/1/90


  • National Institute of Neurological Disorders and Stroke
  • National Institute of Neurological Disorders and Stroke
  • National Institute of Neurological Disorders and Stroke
  • National Institute of Neurological Disorders and Stroke


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