General visceral and gustatory connections of the posterior thalamic nucleus of goldfish.

Fiber connections of the posterior thalamic nucleus were studied in goldfish. Tracer injections into the rostral part of posterior thalamic nucleus labeled somata and terminals in the medial subnucleus of commissural nucleus of Cajal, secondary general visceral nucleus, a nucleus tentatively identified as the preglomerular general visceral nucleus, torus lateralis, inferior lobar nuclei, preoptic area, dorsal region of medial part of dorsal telencephalic area, and supracommissural part of ventral telencephalic area. Labeled terminals were observed in the lateral subnucleus of commissural nucleus of Cajal; primary gustatory centers, in particular the vagal lobe; and lateral valvular nucleus. Other occasional connections were also observed in a number of structures. The results of tracer injections to the brainstem general visceral and gustatory structures suggested reciprocal connections with the caudal part of posterior thalamic nucleus. These findings suggest that the posterior thalamic nucleus is primarily a general visceral/gustatory structure, serving as a forebrain integration center of visceral information. Descending fibers to the vagal lobe presumably represent a major channel through which the forebrain regulates pharyngeal feeding behavior. J. Comp. Neurol. 519:3102–3123, 2011. © 2011 Wiley-Liss, Inc.