摘要:

Injections of the carbocyanine dye, DiI, into the lateral pallium of the silver lamprey reveal that this pallial region receives bilateral inputs from the olfactory bulbs, dorsomedial telencephalic neuropil, and the habenular nuclei, and ipsilateral inputs from the septum, preoptic area, medial pallium, thalamus, and, possibly, the striatum. The efferent projections of the lateral pallium form dorsal (olfacto-habenular tract of Heier) and ventral (olfacto-thalamic and hypothalamic tracts of Heier) bundles. The dorsal bundle terminates ipsilaterally in the dorsal pallium, medial pallium, habenular nuclei, and pretectum and contralaterally in the habenular nuclei and, possibly, the dorsal pallium. The ventral bundle terminates ipsilaterally in the septum, striatum, and preoptic areas and bilaterally within the hypothalamus. Injections of DiI into the medial pallium reveal bilateral inputs to this pallial formation from the olfactory bulbs, the dorsomedial telencephalic neuropil, septum, habenular nuclei, thalamic nuclei, preoptic area and hypothalamus, as well as ipsilateral inputs from the lateral pallium, dorsal isthmal grey and midbrain tegmentum. The efferent projections of the medial pallium form dorsal, ventral and descending bundles. The dorsal bundle terminates ipsilaterally in the dorsal and lateral pallia and in the olfactory bulb. The ventral bundle terminates ipsilaterally in the dorsal pallium and bilaterally within the lateral pallium and in preoptic and hypothalamic areas. The descending bundle terminates bilaterally in thalamic and hypothalamic areas and in the pretectum and optic tectum. These data support a number of earlier hypotheses concerning pallial homologues in lampreys and other vertebrates but suggest that the earlier hypothesis of an olfactory origin of the telencephalon of craniates should be rejected.

ISSN:0006-8977    

DOI:10.1159/000112978

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

This paper presents a survey of the cell groups in the telencephalon of the teleost Astyanax hubbsi, based on series of transverse sections stained with the Nissl-, Klüver-Barrera and Bodian procedures. The work was conducted for two reasons. Firstly, it was intended to determine the contribution of the forebrain of blind cave fish to certain forms of behavior. An understanding of the anatomy of the telencephalic organization is essential for such a neuroethological approach. The second purpose was to provide the cytoarchitectural basis for the experimental analysis of the fiber connectivity of the telencephalon of A. hubbsi. Furthermore, information about the forebrain of characids is widely lacking, and this study may thus provide important knowledge about the cellular organization of characid forebrains for comparative anatomists. The brain of A. hubbsi is slender and elongated. Both optic nerves and optic tectum are reduced. Three longitudinal sulci – s. ypsiliformis, s. externus and s. limitans telencephali – can be distinguished in the telencephalon. A fiber lamina reaching from the s. externus to the s. limitans telencephali separates the area dorsalis (D) from the area ventralis telencephali (V). The two hemispheres are connected by libers decussating in the anterior commissure. Although cross sections revealed no distinct fiber laminae between cytoarchitectonic components, 17 cell masses could be delineated: ten of these belong to D, seven to V. The topological analysis yielded the following results. The dorsal telencephalon D consists of three longitudinal columns, termed pars medialis (Dm), pars dorsalis and centralis (Dd and Dc) considered together, and pars lateralis (Dl), which converge into a uniform posterior part (Dp). The columns can be divided into several subregions: Dm1 and Dm2, as well as Dlv and Dld, precommissurally, Dm3 and Dm4 postcommissurally. At polus posterior levels nucleus tenia can be identified. The ventral telencephalon (V) is arranged precommissurally in a periventricular neuronal column consisting of a dorsal (Vd) and ventral (Vv) part. Additionally, a lateral part (VI) is delineated. More caudally, a supracommissural part (Vs), a commissural part (Vc), a posterior part (Vp), and nucleus entopeduncularis are identified. This topological organization reflects many features characteristic for actinopterygian forebr

ISSN:0006-8977    

DOI:10.1159/000112979

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The primary subdivisions of the telencephalon of a characidian, Astyanax hubbsi, were extensively described and this subsequent study elucidates the organization of the secondary olfactory system based on horseradish peroxidase (HRP) and carbocyanine dye (DiI) tracing techniques. Both methods yielded similar results. Two fiber bundles project from the olfactory bulbs into the ventral rostral telencephalon: the medial olfactory tract (torn), embedded in the white matter of the ventral telencephalon (V), which gives rise to a dorsal (tom-d) and a ventral (tom-v) branch, and the lateral olfactory tract (tol). Running caudally, fibers of the tom-v synapse both ipsi- and contralaterally, after decussation in the ventral part of the anterior commissure, identified as the interbulbar commissure of Goldstein, in the medial terminal field of V, and in the preoptic terminal field. The dorsal branch (tom-d) projects bilaterally to a complex pattern of terminal fields, including the medial terminal field in V, the central terminal field in the dorsomedial forebrain (Dm), the caudal part of the lateral terminal field in the dorsoposterior telencephalon (Dp), and, finally, a hypothalamic terminal field at the lateral edge of the posterior nucleus tuberis. In addition, some fibers of tom-d and tom-v reach into the contralateral olfactory bulb. Here, both nerve terminals and cells were stained in the olfactory nucleus. The lateral olfactory tract (tol) runs along the lateral edge of the external sulcus forming a horizontal band. Extensive terminals were identified bilaterally in the lateral terminal field, which uniformly covers the medial and caudal parts of the dorsal hemispheres (Dc, Dl and Dp). Fibers decussate prominently in the dorsal part of the anterior commissure. A small number of projections, which join the stria medullaris, protrude into the diencephalon, decussate in the habenular commissure, and turn rostrally back into the telencephalon to synapse in the caudal part of the contralateral terminal field. These features resemble a simple bauplan of olfactory fiber connections in actinopterygian brains and further indicate that substantial parts of the telencephalon are not dominated by olfactory inputs.

ISSN:0006-8977    

DOI:10.1159/000112980

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Based largely on results of studies of laboratory rodents, the vomeronasal or accessory olfactory system is believed to function mainly in social communication, mediating the effects of stimuli such as urine or glandular secretions on the behavior or endocrine response of conspecifics. In the domestic pig (Sus scrofa), the steroid androstenone has been identified as a pheromone that facilitates expression of both attraction to the male and a receptive mating stance in estrous females. Though the domestic pig is one of the few vertebrate species in which the identity of a compound that functions as a pheromone is known, the role of the vomeronasal system in domestic pigs has never been investigated. We have examined the role of the vomeronasal organ in mediating the pheromonal effects of androstenone in pigs. In addition, we have examined the structure of the vomeronasal organ at the gross and light-microscopic levels. The vomeronasal organ appears functional, with sensory epithelium lining the medial wall, and has access to stimuli from both the oral and nasal cavities. To determine whether the vomeronasal organ is necessary for androstenone detection or attraction or receptive behavior in female pigs, access to the vomeronasal organ was blocked with surgical cement, and androstenone detection threshold and sexual behavior were measured. Experimental animals did not differ significantly in androstenone sensitivity, measured behaviorally, from untreated controls. Vomeronasal organ-blocked animals also did not differ from untreated controls in either androstenone-mediated receptive standing behavior or attraction to the odor of androstenone. We conclude that in the domestic pig, the vomeronasal organ is not necessary for androstenone detection or androstenone-mediated sexual behavior in estrous females.

ISSN:0006-8977    

DOI:10.1159/000112981

出版商:S. Karger AG    

年代:1997

数据来源: Karger