AJP - Gastrointestinal and Liver Physiology, Vol 257, Issue 1 24-G29, Copyright © 1989 by American Physiological Society
Brain stem responses to electrical stimulation of ventral vagal gastric fibers
W. D. Barber and C. S. Yuan
Department of Anatomy, University of Arizona Health Sciences Center, Tucson 85724.
The brain stem neuronal responses to electrical stimulation of gastric
branches of the ventral vagal trunk serving the proximal stomach were
localized and evaluated in anesthetized cats. The responses were equally
distributed bilaterally in the region of nucleus solitarius in the caudal
brain stem. The mean latency of the response was 289 +/- 46 (SD) ms, which
translated into a conduction velocity of less than 1 m/s based on the
distance between the stimulating and recording electrodes. The responses
consisted of single and multiple spikes that showed slight variability in
the latency, indicating orthodromic activation via a synapse in
approximately 98% of the responses recorded. Forty two percent of the units
tested showed evidence of convergence of input from vagal afferent fibers
in different branches of the ventral vagal trunk that served the proximal
stomach. The resultant activity pattern of the unitary response appeared to
be the product of 1) the gastric sensory input or modality conveyed by the
afferent source and 2) the time of arrival and diversity of modalities
served by other gastric afferents impinging on the unit. This provides a
mechanism capable of responding on the basis of specific sensory modalities
that dynamically reflect ongoing events monitored and conveyed by other
gastric afferents in the region.
