摘要:

The ''core'' subnucleus of the mediodorsal thalamic nucleus (MD) receives direct input from olfactory cortex in the rat. This part of MD projects to the frontal neocortex of the rhinal sulcus (RS), while other parts of the MD project to the anterior medial wall of the neocortex (MW). In this study, rats were tested on odor threshold, detection of specific odors, and three odor discriminations both before and after lesions of MD, MW, RS, or sham lesions. Olfactory threshold and detection ability remained unaffected by any of these lesions; however, subjects with MD and RS lesions were markedly impaired on odor discriminations. Furthermore, subjects were more profoundly impaired when the stimuli to be discriminated were novel or difficult to associate. Thus, MD and its ''olfactory'' projection target, RS, seem to mediate cognitive, rather than sensory aspects of odor-guided behavior in the rat.

ISSN:0006-8977    

DOI:10.1159/000121803

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The role of the thalamocortical ''olfactory'' pathway in odor preferences and sexual behavior was examined in the hamster, a species which depends crucially upon olfaction for mating. Before and after ablation of primary or secondary olfactory structures, male hamsters were tested for threshold, interest, and preference for the odor of an estrus female hamster and other odors. Sexual competency was also observed in daily mating sessions. Disruption of the primary olfactory pathway resulted in an absence of interest in odors and mating. Lesions of mediodorsal thalamic nucleus or frontal neocortex of the rhinal sulcus did not result in anosmia, but did eliminate or alter odor preferences and resulted in inappropriate, inefficient, precopulatory and copulatory behavior. It appears that substructures in the thalamofrontal pathway play a role in discriminative or cognitive aspects of processing adaptively significant stimuli.

ISSN:0006-8977    

DOI:10.1159/000121804

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The distribution of dorsal root fibers into the spinal cord as well as to the brainstem have been studied in various types of reptiles. At the site of entrance into the spinal cord no clear segregation of large fibers medially and smaller fibers laterally has been observed. A peculiarity for reptiles seems to be a lateral bundle of primary afferent fibers which traverses the dorsal part of the lateral funiculus. The fibers of this bundle enter the spinal gray at the lateral side of the dorsal horn. Notable variation in the distribution of dorsal root fibers has been observed in the reptiles studied. In the turtle Testudo hermanni and in the snake Python reticulatus almost no fibers were found to extend into the ventral horn. However, in the lizard Tupinambis nigropunctatus a distinct projection into the ventral horn was observed. This closer potential coupling between the primary input and output systems of the spinal cord than in the turtle Testudo hermanni seems to be related to the long multijointed digits in the lizard studied which give its limbs a marked prehensile character.

ISSN:0006-8977    

DOI:10.1159/000121805

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The neuroanatomical pathways of the rat disrupted in aphagia and adipsia were investigated using the Fink-Heimer and autoradiographic anterograde tracing procedures. Following lesions in the lateral hypothalamic complex (LHC) which produce aphagia and adipsia as well as the injection of labeled proline into the LHC, projections were seen in the nucleus accumbens, the preoptic area, the lateral habenular nucleus, the ventromedial hypothalamic nucleus, the nucleus reuniens, the parafascicular nucleus, the posterior hypothalamus, the zona incerta, the central gray matter, the tegmentum, the substantia nigra (pars compacta), the ventral tegmental area of Tsai and the parabrachial area. However, axonal degeneration and not radioactive label were observed in the mediodorsal thalamus, the superior colliculus, the medial pontine gray, the mesencephalic nucleus of the Vth nerve, the motor nucleus of V, the raphe nuclei and the crus cerebri fiber system.The LHC is discussed as a region which connects with other levels of the central nervous system known to be related to the act of ingestion.

ISSN:0006-8977    

DOI:10.1159/000121806

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The neuroanatomical pathways of the rat disrupted in aphagia and adipsia were investigated using the Fink-Heimer and autoradiographic anterograde tracing procedures. Following lesions in the lateral hypothalamic complex (LHC) which produce aphagia and adipsia as well as the injection of labeled proline into the LHC, projections were seen in the nucleus accumbens, the preoptic area, the lateral habenular nucleus, the ventromedial hypothalamic nucleus, the nucleus reuniens, the parafascicular nucleus, the posterior hypothalamus, the zona incerta, the central gray matter, the tegmentum, the substantia nigra (pars compacta), the ventral tegmental area of Tsai and the parabrachial area. However, axonal degeneration and not radioactive label were observed in the mediodorsal thalamus, the superior colliculus, the medial pontine gray, the mesencephalic nucleus of the Vth nerve, the motor nucleus of V, the raphe nuclei and the crus cerebri fiber system.The LHC is discussed as a region which connects with other levels of the central nervous system known to be related to the act of ingestion.

ISSN:0006-8977    

DOI:10.1159/000121807

出版商:S. Karger AG    

年代:1980

数据来源: Karger