Aim: To localize and characterize the response of single accumbal neurons to electrical stimulation of the gastric vagal fibers.
Methods: Unitary responses to electrical stimulation of the ventral and dorsal gastric vagal fibers which serve the proximal stomach were recorded extracellularly in the nucleus accumbens in anesthetized cats.
Results: The evoked units recorded in the nucleus accumbens consisted of phasic and tonic responses, with a mean latency of (396+/-43) ms. Convergence of ventral and dorsal gastric vagal inputs onto single phasic and tonic accumbal units was observed. For tonic inhibitory responses, convergence was exhibited when stimulation applied to both the ventral and dorsal gastric vagal branches resulted in a significantly longer inhibitory period than did stimulation of a single gastric vagal branch. Comparing the gastric vagally evoked accumbal unitary responses to the neuronal responses recorded in the nucleus tractus solitarius, parabrachial nucleus and hypothalamus in our previous studies, our data showed a higher percentage of single spike responses and shorter response duration's in the nucleus accumbens than in the other nuclei. This suggests that the synaptic drive from the gastric vagal inputs to the nucleus accumbens is less powerful than in the other structures.
Conclusion: The present study localized and characterized gastric vagally evoked responses in the nucleus accumbens, which suggest that the nucleus accumbens may process gastric signals concerned with the ingestive process.