Convergence of Afferent Inputs from Tongue, Pharynx, and Larynx in the Insular Cortex of the Rat

Abstract

It has been shown that gustatory afferent input projects to the anterior portion of the insular cortex in rats. Gustatory information from the taste buds distributing the oral and extraoral regions is conveyed by the chorda tympani (CT), greater superficial petrosal (GSP) nerve, the lingual-tonsilar branch of the glossopharyngeal (LT-IXth) nerve, the pharyngeal branch of the glossopharyngeal (PH-IXth) nerve, and the superior laryngeal (SL) nerves. How afferent information from these gustatory nerves is processed in the neurons of the insular cortex is still unknown. On the other hand, it has been demonstrated that visceral afferent information projects to the posterior portion of the insular cortex. There is a possibility that integration of the gustatory and visceral information may occur in the insular cortex. In the present experiment, we investigated the convergence of insular cortex neurons from all taste nerves except the GSP, as well as investigating changes in the spontaneous activity of the insular cortex neurons during chemo- and baroreceptor stimulation.