Ascending gustatory pathways to the telencephalon in goldfish

Abstract

Ascending pathways to the telencephalon from the secondary gustatory nucleus (SGN), preglomerular tertiary gustatory nucleus (pTGN), and medial preglomerular nucleus (PGm) were examined by tract-tracing experiments in goldfish Carassius auratus. Tracer injections to the SGN suggest the presence of direct ascending pathways to the supracommissural and the dorsal parts of the ventral telencephalic area, and the medial part of the dorsal telencephalic area (Dm), restricted to its ventral region. The SGN experiments also suggest projections to the pTGN and PGm, and several neuronal types in the primary gustatory centers were newly found to give rise to ascending fibers to the SGN. Injections to the pTGN suggest reciprocal connections of the nucleus with the dorsal region of the Dm (dDm). Injections to the PGm resulted in labeled cells in the dorsal part of the SGN, the secondary general visceral nucleus, and the posterior part of the dorsal telencephalic area, suggesting that this preglomerular nucleus receives gustatory, general visceral, and olfactory inputs. Fibers labeled from the PGm terminated in the central part of the dorsal telencephalic area and the dDm; the latter region contained many labeled somata. The terminal zone of PGm fibers in the dDm is located laterally adjacent to that from the pTGN. Injection experiments to the pTGN and PGm also suggest connections of these nuclei with the inferior lobar nuclei and torus lateralis. Based on the results of the present as well as recent studies, an updated map is provided that shows by and large distinct sensory representation within the goldfish dorsal telencephalic area.

Gustatory and general visceral centers and their connections in the brain of adult zebrafish: a carbocyanine dye tract‐tracing study

“…Understanding of taste nuclei in zebrafish is especially important because this species is a main animal model for neurogenetic studies of vertebrates. The method of DiI tracing in fixed brain used here also produced good results in the gustatory system of trout (Folgueira et al, ) and its performance is comparable with that obtained in studies using in vivo tract‐tracing methods (Finger, ; Morita and Finger, ; Finger and Kanwal, ; Yamamoto and Ito, ; Kato et al, ; Uezono et al, ). Although zebrafish has a small brain, this method allowed, in our hands, precise tracer application and reproducible results, even for minute brain structures, which allows minimizing the number of fish employed.…”

“…This can be considered as quaternary gustatory projections. In the goldfish, tracer application to the tertiary gustatory nucleus labeled both neurons and fiber terminals in a small region of caudal dDm (Kato et al, ). In zebrafish, one Dm cell was retrogradely labeled from the hypothalamic lobe, but our experiments of DiI application to dorsal Dm did not reveal labeled neurons in the diencephalic gustatory nuclei, which might indicate that the taste recipient Dm might be a small region that was not affected in the experiment.…”

Localization of α‐Synuclein in Teleost Central Nervous System: Immunohistochemical and Western Blot Evidence by 3D5 Monoclonal Antibody in the Common Carp,Cyprinus carpio

“…Conversely, nuclear 3D5 labeling was never found in the carp neurons. The nomenclature used for the carp brain was based on previous studies on cyprinids (Clemente et al, ; Mueller et al, ; Yamamoto and Ito, ,b, 2008 in carp; Giraldez‐Perez et al, ; Kato et al, in goldfish; Wulliman et al, 1996 in zebrafish). The distribution of 3D5 positive cells in the carp brain is depicted in the drawings of Figure and summarized in Table .…”

Differential distribution and energy status–dependent regulation of the four CART neuropeptide genes in the zebrafish brain

“…The TS is known to play a role in auditory and lateral line sensory processing in the zebrafish (Sassa et al, ). A cluster of CART 2 mRNA‐expressing cells are seen in the PG, which is known to receive sensory information from the acoustic structures, lateral line, somatosensory, gustatory, visual, and general visceral organs (Yamamoto and Ito, ; Northcutt, ; Yoshimoto and Yamamoto, ; Kato et al, ).…”