摘要:

AbstractAnterior hypothalamic nucleus (AHN) projections were examined with thePhaseolus vulgaris‐leucoagglutinin (PHA‐L) method in adult male rats. Labeled axons from the AHN follow three major routes. 1) A large ascending pathway ends densely in the telencephalon, particularly in the lateral septal nucleus. Axons along this route provide moderate to dense input to the medial and lateral preoptic areas, and a few are also observed in the septofimbrial nucleus and fimbria; the latter end in the temporal hippocampus. A few axons reach the amygdala through the bed nuclei of the stria terminalis, which receive a moderate input, and then the stria terminalis, and others reach it by way of the ansa peduncularis. 2) The second pathway travels dorsal to the AHN, ending densely in rostral perifornical regions of the lateral hypothalamic area, and the rostral ventrolateral tip of the nucleus reuniens. The parataenial and rostral paraventricular thalamic nuclei also receive a significant input. Some fibers and boutons were also observed in the rhomboid, interanterodorsal, and mediodorsal nuclei, and others course through the stria medullaris to the lateral habenula. 3) the largest pathway descends through dorsal and ventral routes in the medial hypothalamic zone before ending massively in the periaqueductal gray. Dorsal route fibers provide inputs to the zona incerta and posterior hypothalamic nucleus, whereas more ventral axons generate dense terminal fields in the ventromedial nucleus capsule and core, and dorsal premammillary nucleus. The retrochiasmatic area, dorsomedial nucleus, and medial supramammillary nucleus also receive significant inputs, and a few axons end in the subparafascicular nucleus, superior colliculus, and mammillary body. The caudalmost axons were seen in the pontine central gray and reticular formation. These pathways are bilateral, usually with a distinct ipsilateral predominance. The overall pattern of efferents from anterior, central, and posterior parts of the AHN is similar, whereas the relative densities of particular terminal fields may vary considerably. Projections from adjacent parts of the retrochiasmatic and perifornical areas are also described. The results are discussed in terms of neural circuitry that may be involved in mediating interactions between animals. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903480102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe organization of projections from the four parts of the ventromedial nucleus (VMH) and a ventrolaterally adjacent region tentatively identified as the tuberal nucleus (TU) have been analyzed with small injections of the anterograde axonal tracerPhaseolus vulgaris‐leucoagglutinin (PHA‐L). Extrinsic and intranuclear projections of each part of the VMH display clear quantitative differences, whereas the overall patterns of outputs are qualitatively similar. Overall, the VMH establishes massive intrahypothalamic terminal fields in other parts of the medial zone, tending to avoid the periventricular and lateral zones. The ventrolateral VMH is more closely related to other parts of the hypothalamus that also express gonadal steroid hormone receptors, including the medial preoptic, tuberal, and ventral premamillary nuclei, whereas other parts of the VMH are more closely related to the anterior hypothalamic and dorsal premammillary nuclei. All parts of the VMH project to the zona incerta (including the A13 region) and parts of the midline thalamus, including the paraventricular and parataenial nuclei and nucleus reuniens. The densest inputs to the septum are to the bed nuclei of the stria terminalis, where the ventrolateral and central VMH innervate the anteroventral and anterodorsal areas and transverse and interfascicular nuclei, whereas the anterior and dorsomedial VMH innervate the latter two. The central, lateral, and medial amygdalar nuclei receive substantial inputs from various parts of the VMH. Other regions of the telencephalon, including the nucleus accurmbens and the piriform‐amygdaloid, infralimbic, prelimbic, anterior cingulate, agranular insular, piriform, perirhinal, entorhinal, and postpiriform transition areas, also receive sparse inputs. All parts of the VMH send a massive, topographically organized projection to the periaqueductal gray. Other brainstem terminal fields include the superior colliculus, peripeduncular area, locus coeruleus, Barrington's nucleus, parabrachial nucleus, nucleus of the solitary tract, and the mesencephalic, pontine, gigantocellular, paragigantocellular, and parvicellular reticular nuclei.The projections of the TU are similar to, and a subset of, those from the VMH and are thus not nearly as widespread as those from adjacent parts of the lateral hypothalamic area. Because of these similarities, the TU may eventually come to be viewed most appropriately as the lateral component of the VMH itself. The functional implications of the present findings are discussed in view of evidence that the VMH plays a role in the expression of ingestive, affective, and copulatory behaviors. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903480103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractCrustacean cardioactive peptide‐immunoreactive neurons have been mapped in wholemount preparations and sections of the ventral nervous system of the crayfishAstacus astacusandOrconectes limosus. Based on their morphology, projection patterns, and staining characteristics, two types of contralaterally projecting neurons are individually identifiable. In both species, these neurons occur in all neuromers as apparent serial homologs. In adult specimens, one type of cell has a small, densely stained dorsal lateral perikaryon, and a descending axon, and appears to be an interneuron. Each neuromer contains a single pair of these cells. Only in maxillary ganglia, these cells may have an additional ascending projection. The other type, a neurosecretory cell, has a larger, weakly stained perikaryon and a projection to the segmental third root of the next anterior neuromer. All neuromers contain a single pair of these neurons adjacent to the interneurons except for the abdominal neuromers, which cotain two pairs of the neurosecretory cells. Central arborizations and varicose processes toward the surface of the third roots and within the perineural sheath of the ventral nerve cord arise from these neurons. Electron microscopy of granule‐ containing terminals substantiated that these newly discovered extensive neurohemal areas are release sites for the peptide. In young immature specimens, the perikarya of both neuron types do not differ in size. Additional weakly stained small perikarya occur in all neuromers ofAstacus astacus. These two types of crayfish neurons and other comparable aminergic and peptidergic neurons of crayfish and lobster are differentially distributed in the ventral cord. Furthermore, comparison of similar neuron types in crab, locust, meal worm, and moth species indicates intra‐ and interphyletic structural homologies. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903480104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe anatomy of the hippocampus, including the organization of its intrinsic neural circuits and afferents, is organized along a rostrocaudal axis. Dopamine D2 receptors are expressed in specific regions of the hippocampal complex (hippocampal subfields, entorhinal cortex, perirhinal cortex) and show differential expression along this axis. The dentate gyrus and CA3/CA4 subfields show higher numbers of D2 receptors in the rostral than in the caudal levels. In contrast, the subiculum shows the reverse gradient. We report here that Alzheimer's disease (AD) is associated with reduced expression of the dopamine D2 receptor, but the effects differ with respect to the rostrocaudal axis and area within the hippocampal complex. The number of D2 receptors is significantly reduced in the molecular layer of the dentate gyrus, CA3 subfield, and subiculum. For the dentate gyrus and subiculum, there were greater losses at more rostral levels. The CA3/CA4 subfields showed the greatest losses caudally. The entorhinal cortex, which shows only modest expression of D2 receptors in controls, does not exhibit reduced numbers in AD. The external laminae of the rostral perirhinal cortex showed more significant losses than more caudally in this cortical field. The regions showing loss of D2 receptors do not typically contain neuritic plaques, neurofibrillary tangles, or significant neuron loss. Thus other mechanisms must account for the unique gradient of D2 receptor loss in the hippocampus. The regions of reduced expression of dopamine D2 receptors do correlate well with the terminal zone of the dentate association pathway, the afferents from the anlygdala and perirhinal cortex, and the sources of those afferents within the amygdala and perirhinal cortex. The specific patterns of reduced D2 receptor expression in AD are likely to contribute significantly to the disrupted information flow into and out of the hippocampus and, thus, of functions subserved by this system. © 1994 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903480105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractActivity‐dependent transneuronal regulation of neuronal soma size has been studied in the medial nucleus of the trapezoid body and ventral cochlear nucleus of adolescent gerbils. Cochlear ablation or tetrodotoxin has been used to eliminate afferent electrical activity in auditory nerve fibers permanently or for 24 or 48 hours. Previous studies have shown that the cross‐sectional area of spherical cell somata in the ipsilateral anteroventral cochlear nucleus decreases within 24 hours of electrical activity blockade with tetrodotoxin, which is fully reversible when activity is restored. The present findings extend this work by directly comparing the results of unilateral blockade of auditory nerve action potentials or unilateral cochlear ablation on the size of spherical and globular cell bodies in the ventral cochlear nucleus with changes produced by the same manipulations in third‐order cells, principal neurons in the medial nucleus of the trapezoid body. Soma size in both ventral cochlear nucleus cell types decreases reliably by 24 hours after cochlear removal or eighth nerve activity blockade by tetrodotoxin. Soma size of neurons in the contralateral medial nucleus of the trapezoid body decreases 48 hours, but not 24 hours, after either manipulation. When activity in auditory nerve fibers is allowed to resume for 7 days following a 48‐hour activity blockade, soma size fully recovers in the medial nucleus of the trapezoid body as well as in ventral cochlear nucleus neurons. We also report that the cross‐sectional area of neuronal soma in the medial nucleus of the trapezoid body is larger in lateral regions of medial nucleus of the trapezoid body (low‐frequency representation) than in the medial regions of the nucleus (high‐frequency representation). We conclude that cell body size changes in brainstem auditory neurons are reversible and that the signals associated with the loss and subsequent recovery of soma size are activity related. However, the delayed effect of activity deprivation in the medial nucleus of the trapezoid body suggests that trophic substances released by afferent axons may contribute to the maintenance of anatomical characteristics. © 1994 W

ISSN:0092-7317    

DOI:10.1002/cne.903480106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractPrevious studies suggest that sensory information from primary afferent fibers is processed in a distinct manner in the individual subnuclei of trigeminal sensory nuclear complex. The present study has addressed this issue by using intra‐axonal labeling with horseradish peroxidase to examine the ultrastructure and synaptic organization of axon terminals from slowly adapting (SA) periodontal afferents in the ventral subdivision (Vpv) of principalis and the rostro‐dorsomedial part (Vo. r) of oralis. Our observations are based on complete or near‐complete reconstructions of 139 synaptic boutons in Vpv and 105 in Vo. r.All the labeled boutons contained clear, spherical, synaptic vesicles and were presynaptic to unlabeled dendrites, and they were frequently postsynaptic to unlabeled axon terminals containing pleomorphic synaptic vesicles (P‐endings). The P‐endings frequently formed axodendritic synapses on dendrites which received axodendritic synapses from labeled boutons (synaptic triads). On the basis of the number of contacts, synaptic arrangements associated with the labeled boutons could be subgrouped into simple (one or two contacts), intermediate (three or four contacts), and complex (five or more contacts) types. The labeled boutons varied from round to elongated forms with smooth to more irregular or scalloped contours. The boutons with scalloped contour were much more frequent in the complex type. The boutons of the intermediate type were significantly smaller than the complex type and larger than the simple type.The SA periodontal afferent terminals participated in each type of synaptic arrangements in Vpv, but were mostly of the simple type in Vo. r. The size of labeled boutons was significantly larger in Vpv than in Vo. r. The total number of axodendritic and axoaxonic contacts per labeled bouton was significantly higher in Vpv than in Vo. r. Another difference was the more frequent occurrence of synaptic triads in Vpv than in Vo. r.These observations provide evidence that sensory information from primary afferent fibers is processed in a different manner in the two subnuclei. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903480107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractParvalbumin immunoreactivity in the developing neocortex of the cat progresses following specific laminar, areal, and, in a particular area, roughly anteroposterior gradients. Parvalbumin immunoreactivity first occurs in basket cells and later in chandelier neurons. Pyramid‐like immunoreactive neurons are also transitorily observed from the second to the third week in layer V of the auditory association‐related areas. Parvalbumin‐immunoreactive neurons first appear in the primary somatosensory cortex and primary auditory and visual areas, followed by the primary motor and polysensory association areas and, finally, the auditory association areas and cortical areas related to the limbic system.In addition to cortical neurons, three fiber systems are immunolabeled with antiparvalbumin antibodies: thalamocortical, callosal, and ipsilateral corticocortical. Parvalbumin‐immunoreactive thalamocortical fibers appear during the first month of postnatal life. Parvalbumin‐immunoreactive callosal and ipsilateral corticocortical fibers are seen from the fourth postnatal week onward. Because all parvalbumin‐immunoreactive cortical neurons in adulthood are nonpyramidal inhibitory cells, the present findings suggest that a number of ipsilateral corticocortical and callosal connections may be inhibitory. © 1994 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903480108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractAs part of a study of turnover of rat olfactory receptor neurons we have been examining immunohistochemical expression of members of the 70 kD heat shock protein (HSP70) family in the olfactory epithelium. Expression of HSP70 family members is up‐regulated in many cells following exposure to physiologically stressing conditions. Because dying neurons are likely to undergo some sort of physiological stress before the onset of frank degeneration, we hoped that anti‐HSP70 monoclonal antibodies would prove to be useful markers for early stages of olfactory neuron cell death. Two anti‐human HSP70 monoclonal antibodies were used, Mabs 2A4 and 3a3. Two‐dimensional gel electrophoresis /western blot analysis indicates that these Mabs are reactive with the HSC70 and HSP70 members of the rat HSP70 family. Immunohis‐ tological observations Show that both Mabs are strongly reactive with a widely dispersed subpopulation of olfactory receptor neurons. Morphological, immunohistological, and autoradiographic birthdating analyses demonstrate that reactive cells are fully mature receptor neurons. Their reactivity, however, doesnotappear to be stress‐related. More significantly, axon of reactive neurons show intense anti‐2A4 reactivity. This has allowed us to trace these axons to their target glomeruli in the olfactory bulb, demonstrating that the reactive neurons project to just one to two glomeruli on either side of each bulb via consistent and predictable pathways. This is the first subpopulation of olfactory receptor neurons to be traced to such a small number of glomeruli. Given this extremely small number, it seems likely that the reactive receptor cell subpopulation serves some specific olfactory function. In addition, axonal 2A4 reactivity should also prove useful in deffining the relative roles of receptor neurons and glomeruli in the establishment of epithelial‐glomerular connections. © 1994

ISSN:0092-7317    

DOI:10.1002/cne.903480109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903480101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY