Abstract
It has been shown that both the amygdala and the insular cortex are important for conditioning taste aversion learning. Anatomically there are reciprocal connections between the insular cortex and the amygdala. However, a few electrophysiological studies on the neuronal networks between of these nuclei have been done. Previously, we reported that spontaneous activity of the insular cortex neuron was depressed after microinjection of glutamate into the amygdala. In the present study, we investigated the changes in neuronal activity in the insular cortex after amygdalar electrical stimulation (train; 100 Hz for 2 sec). At the end of the experiment, the stimulation site was lesioned, electrically. Of the 13 rats, 7 were stimulated within or near the basolateral nucleus of the amygdala. In all cases, spontaneous discharge rate of the insular cortex neurons was depressed after amygdalar train stimulation. In the remaining 6 rats, stimulation sites were located outside of the amygdala. In these cases, spontaneous activity of the insular cortex neurons was unaffected after train stimulation. The data obtained here were similar to those in the chemical stimulation of the amygdala (microinjection of glutamate). These results indicate that excitation of the amygdala depress the activity of the insular cortex neurons. Neural network between the amygdala and the insular cortex may have some roles in the neural mechanisms for the taste aversion learning. [J Physiol Sci. 2008;58 Suppl:S149]
