Telencephalon of the teleost Macropodus: experimental localization of secondary olfactory areas and of components of the lateral forebrain bundle

Abstract

Connections of the telencephalic hemisphere were experimentally examined to facilitate investigations of the functions of this major brain area in teleosts. The distribution of afferent olfactory tract fibers was traced using a degeneration method and autoradiographic localization of axonally transported protein. Afferents terminate predominantly ipsilaterally in the medial, lateral, and posterior zones of the hemisphere and in the nucleus posterior tuberis of the diencephalon. Afferents also project to the contralateral olfactory bulb through the commissure of Goldstein. The results of similar experiments in five other teleosts are briefly reviewed. Evidence of retrograde transport of tritiated proline or metabolite is also discussed. Components of the lateral forebrain bundle originating in the extreme rostral end of the dorsal zone of the hemisphere were traced to: (1) the corresponding zone of the contralateral hemisphere; (2) nucleus entopenduncularis; and (3) the extreme ventral part of the posterior zone of the diencephalon. The anatomical findings are discussed in relation to previous experiments in Macropodus dealing with the location of brain areas which concentrate sex steroids and with the effects of brain lesions on reproductive behavior in the male. We thank R. Glenn Northcutt and Catherine McCormick for assistance in the degeneration staining procedure. Requests for reprints should be sent to R. E. Davis.

An experimental study of the connections of the telencephalon in the rainbow trout (Oncorhynchus mykiss). I: Olfactory bulb and ventral area

“…Dl-v is also traversed by the lateral olfactory tract. These telencephalic projections roughly correspond to those found in other teleosts with either the Fink-Heimer method or with application of different neuronal tracers (Finger, 1975;Bass, 1981a;Davis et al, 1981;Ebbesson et al, 1981;Murakami et al, 1983;Northcutt and Davis, 1983;Prasada Rao and Finger, 1984;von Bartheld et al, 1984;Levine and Dethier, 1985;Rooney et al, 1992;Sas et al, 1993;Riedel and Krug, 1997). In the bichir (Cladistia), the olfactory bulb projects to the medial division of the pallium (P1; Northcutt and Braford, 1980;von Bartheld and Meyer, 1986), whereas in a sturgeon (Chondrostei) the main targets of axons from the olfactory bulb appear to be the posterior and medial pallium (Huesa et al, 2000).…”

Development of the olfactory system of the white sucker,Catostomus commersoni, in relation to imprinting and homing: a comparison to the salmonid model

“…Wilson et al (1990) demonstrate that as early as one day post fertilization in the cypriniform zebra fish, Bruchydanio rerio, olfactory tract neurons can be traced to the dorsal telencephalon. In adult teleosts, olfactory tract target nuclei within the forebrain nuclei have been extensively documented (Sheldon 1912, Ito 1973, Finger 1975, Bass 1981, Oka 1980, Davis et al 1981, Northcutt & Davis 1983, Levine & Dethier 1985. Targets for the lateral olfactory tract include the dorsal posterior and ventrointermediate nuclei, the nucleus taenia, and the dorsolateral nuclear complex (Finger 1975, Bass 1981, Levine & Dethier 1985.…”

Immunohistochemical localization of thyrotropin‐releasing hormone in the brain of chinook salmon (oncorhynchus tshawytscha)

“…Although individual axons cannot be followed along their entire length, our material raises the possibility that ICL neurons give rise to TRHpositive fibers in Dp. Projections of the bulb to the dorsal posterior region of the telencephalon have been described in studies that have used the standard axonal tracing methods (Scalia and Ebbesson, 1971;Finger, 1975;Davis et al, 1981;Ebbesson et al, 1981;Levine and Dethier, 1985). However, these authors did not determine whether these fibers originate from neurons in the external cellular layer (ECL) or the ICL.…”