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Rostral Portion (rostral + portion)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

Reciprocal connections between olfactory structures and the cortex of the rostral superior temporal sulcus in the Macaca fascicularis monkey

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2005
A. Mohedano-Moriano
Abstract Convergence of sensory modalities in the nonhuman primate cerebral cortex is still poorly understood. We present an anatomical tracing study in which polysensory association cortex located at the fundus and upper bank of the rostral superior temporal sulcus presents reciprocal connections with primary olfactory structures. At the same time, projections from this polysensory area reach multiple primary olfactory centres. Retrograde (Fast Blue) and anterograde (biotinylated dextran,amine and 3H-amino acids) tracers were injected into primary olfactory structures and rostral superior temporal sulcus. Retrograde tracers restricted to the anterior olfactory nucleus resulted in labelled neurons in the rostral portion of the upper bank and fundus of superior temporal sulcus. Injections of biotinylated dextran,amine at the fundus and upper bank of the superior temporal sulcus confirmed this projection by labelling axons in the dorsal and lateral portions of the anterior olfactory nucleus, as well as piriform, periamygdaloid and entorhinal cortices. Retrograde tracer injections at the rostral superior temporal sulcus resulted in neuronal labelling in the anterior olfactory nucleus, piriform, periamygdaloid and entorhinal cortices, thus providing confirmation of the reciprocity between primary olfactory structures and the cortex at the rostral superior temporal sulcus. The reciprocal connections between the rostral part of superior temporal sulcus and primary olfactory structures represent a convergence for olfactory and other sensory modalities at the cortex of the rostral temporal lobe. [source]

Spatial and temporal variation of passer Per2 gene expression in two distinct cell groups of the suprachiasmatic hypothalamus in the house sparrow (Passer domesticus)

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2002
Ute Abraham
Abstract In mammals, the major pacemaker controlling circadian rhythmicity is located in the hypothalamic suprachiasmatic nuclei. Although there is evidence for the presence of a hypothalamic circadian oscillator in birds from lesioning studies, neuroanatomical, neurochemical and functional investigations have failed to identify its exact location. Two cell groups in the avian hypothalamus have been shown to bear characteristics of the mammalian suprachiasmatic nucleus: the suprachiasmatic nucleus and the lateral hypothalamic retinorecipient nucleus. We cloned an avian period homologue (pPer2) and investigated the temporal and spatial expression pattern of this gene in the house sparrow hypothalamus using in situ hybridization. Applying quantitative morphometry, we found rhythmic expression of pPer2 during light,dark as well as in constant conditions in the suprachiasmatic nucleus and in the lateral hypothalamus. The temporal and spatial distribution of pPer2 expression in the suprachiasmatic nucleus suggest a longitudinal compartmentalization of the nucleus with period gene expression being initiated in the most rostral portion of the suprachiasmatic nucleus before lights on. In the lateral hypothalamus, phasing of pPer2 -rhythmicity appeared different from the suprachiasmatic nucleus. The major difference between light,dark and constant conditions was a decrease in the amplitude of pPer2 rhythmicity in the suprachiasmatic nucleus. Our data demonstrate that, unlike in mammals, Per gene expression in the suprachiasmatic hypothalamus of the house sparrow is not confined to a single cell group, indicating a more complex organization of the circadian oscillator in the hypothalamus of birds. [source]

Sex Differences in the Distribution and Abundance of Androgen Receptor mRNA-Containing Cells in the Preoptic Area and Hypothalamus of the Ram and Ewe

JOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2004
C. J. Scott
Abstract Rams and ewes show a negative-feedback response to peripheral treatment with testosterone, with both sexes having a similar degree of suppression in luteinizing hormone (LH) secretion during the breeding season. At least part of the action of testosterone to suppress gonadotropin-releasing hormone/LH secretion is exerted via interaction with an androgen receptor. The distribution of androgen receptor-containing cells in the hypothalamus has been described for the ram, but similar studies have not been performed in the ewe. In the present study, we tested the hypothesis that levels of androgen receptor mRNA expression in the preoptic area and hypothalamus would be similar in rams and ewes. Perfusion-fixed brain tissue was obtained from adult Romney Marsh ewes (luteal phase) and rams during the breeding season (n = 4/sex). Androgen receptor mRNA expression was quantified in hypothalamic sections by in situ hybridization using an 35S-labelled riboprobe and image analysis. Hybridizing cells were found in the medial preoptic area, bed nucleus of the stria terminalis, anterior hypothalamic area, ventromedial nucleus, arcuate nucleus and premamillary nucleus. The level of androgen receptor mRNA expression was higher in rams than ewes in the rostral preoptic area, caudal preoptic area and rostral portion of the bed nucleus of the stria terminalis, with no sex difference in other regions. The preoptic area and bed nucleus of the stria terminalis are important for reproductive behaviour and the sex differences in androgen receptor mRNA expression at these levels may relate to this. The high level of androgen receptor mRNA expression in the basal hypothalamus, with no sex difference, is consistent with the role of this region in the regulation of gonadotropin secretion. [source]

Central projections of the saccular and utricular nerves in macaques

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2003
Shawn D. Newlands
Abstract The central projections of the utricular and saccular nerve in macaques were examined using transganglionic labeling of vestibular afferent neurons. In these experiments, biotinylated dextran amine was injected directly into the saccular or utricular neuroepithelium of fascicularis (Macaca fascicularis) or rhesus (Macaca mulatta) monkeys. Two to 5 weeks later, the animals were killed and the peripheral vestibular sensory organs, brainstem, and cerebellum were collected for analysis. The principal brainstem areas of saccular nerve termination were lateral, particularly the spinal vestibular nucleus, the lateral portion of the superior vestibular nucleus, ventral nucleus y, the external cuneate nucleus, and cell group l. The principal cerebellar projection was to the uvula with a less dense projection to the nodulus. Principle brainstem areas of termination of the utricular nerve were the lateral/dorsal medial vestibular nucleus, ventral and lateral portions of the superior vestibular nucleus, and rostral portion of the spinal vestibular nucleus. In the cerebellum, a strong projection was observed to the nodulus and weak projections were present in the flocculus, ventral paraflocculus, bilateral fastigial nuclei, and uvula. Although there is extensive overlap of saccular and utricular projections, saccular inputs to the lateral portions of the vestibular nuclear complex suggest that saccular afferents contribute to the vestibulospinal system. In contrast, the utricular nerve projects more rostrally into areas of known concentration of vestibulo-ocular related cells. Although sparse, the projections of the utricle to the flocculus/ventral paraflocculus suggest a potential convergence with floccular projection inputs from the vestibular brainstem that have been implicated in vestibulo-ocular motor learning. J. Comp. Neurol. 466:31,47, 2003. © 2003 Wiley-Liss, Inc. [source]

Projections from the hippocampal region to the mammillary bodies in macaque monkeys

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2005
John P. Aggleton
Abstract A combination of anterograde and retrograde tracers mapped the direct hippocampal and parahippocampal inputs to the mammillary bodies in two species of macaque monkey. Dense projections arose from pyramidal cells in layer III of the subiculum and prosubiculum, and terminated in the medial mammillary nucleus. While there was no evidence of an input from the dentate gyrus or fields CA1,3, a small contribution arose from the presubiculum and entorhinal cortices. All of the hippocampal and parahippocampal projections to the mammillary bodies appeared to use the fornix as a route. The caudal portions of the subiculum and prosubiculum contained the greatest numbers of cells projecting to the mammillary bodies. A light contralateral projection to the medial mammillary nucleus was also observed, although this appeared to arise primarily from the more rostral portions of the subiculum and prosubiculum. There was a crude topography within the medial mammillary nucleus, with the caudal subicular projections terminating in the mid and dorsal portions of the nucleus while the rostral subicular and entorhinal projections terminated in the ventral and lateral portions of the medial nucleus. Light ipsilateral projections throughout the lateral mammillary nucleus were sometimes observed. Comparisons with related studies of the macaque brain showed that the dense hippocampal projections to the mammillary bodies arise from a population of subicular cells separate from those that project to the anterior thalamic nuclei, even though the major output from the mammillary bodies is to the anterior thalamic nuclei. Other comparisons revealed underlying similarities with the corresponding projections in the rat brain. [source]