摘要:

AbstractTo better understand the input‐output organization of the midline thalamus, we compared the distribution of its peptidergic and monoaminergic afferents, which were visualized by using immunocytochemistry, with the distribution of neurons projecting to different basal forebrain structures, which were mapped using retrograde fluorescent tracers. Serotonin and most of the peptides were found throughout paraventricular thalamic nucleus (PV) and in other midline and intralaminar nuclei (type 1 pattern). Neuropeptide Y, αMSH and the catecholamine synthetic enzymes were largely restricted to dorsolateral PV (type 2 pattern). Vasopressin was found in dorsomedial PV and intermediodorsal nucleus in a pattern complementary to the type 2 distribution (type 3 pattern). Neurons projecting to accumbens core were present in paraventricular, intermediodorsal, and other midline nuclei. Neurons projecting to accumbens shell and to central amygdaloid nucleus were found in dorsal PV. The peptidergic zones were only loosely correlated with the distribution of different classes of projection neurons. The type 2 pattern overlapped best with neurons projecting to accumbens shell, and to a lesser extent to central amygdaloid nucleus, While the type 3 pattern overlapped best with neurons projecting to core of accumbens. This partial overlap suggests that some brainstem and hypothalamic nuclei preferentially affect differentbasal forebrain targets through the midline thalamus, and may allow, for example, information about stress to specifically influence accumbens shell and central amygdaloid nucleus. Nevertheless, most of the peptidergic afferents (type 1 pattern) to midline thalamus cover neurons projecting throughout the basal forebrain, which suggests that all of these neurons receive a variety of brainstem and hypothalamic inputs. © 1994 Wiley‐Liss

ISSN:0092-7317    

DOI:10.1002/cne.903480302

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

年代:1994

数据来源: WILEY

摘要:

AbstractUndernutrition during early life causes deficits and distortions of brain structure. However, whether or not this includes a diminution of the total numbers of neurones remains uncertain. Recent advances in stereological techniques have made it possible to obtain unbiased cells in well‐defined biological structures. Rats were undernourestimates of total number of cells in well‐defined biological structures. Rats were undernourished from conception to 90 postnatal days of age by standardised procedures. Groups of well‐fed control and undernourished rats were anaesthetised and killed by intracardiac perfusion with fixatives at 30 and 90 days of age. Each olfactory bulb was serially sectioned at a nominal thickness of 100 pm on a vibratome. These sections were analysed by the Cavalieri principle to obtain estimates of the total volume of the olfactory bulb as well as the volume of its granule cell layer. The physical “disector” method was later used on serial 1‐μm‐thick toluidine‐blue‐stained sections to estimate the numerical density of granule cell neurones in the olfactory granule cell layer. These values were used to compute estimates of the total number of olfactory granule cell neurones for each animal. Thirty‐day‐old control and undernourished rats had between 2.6 and 3 million granule cell neurones in the olfactory bulb. By 90 days of age the number of granule cells had increased in both groups of animals to between about 4.2 and 5.2 million cells. Analysis of variance tests showed a significant main effect of age but not nutrition in these estimates. Although the interaction term did reach statistical significance, post hoc analysis did not reveal any differential effect of undernutrition between the two age groups examined. Therefore, undernutrition of rats from conception until 90 postnatal days of age does not seem to affect the total numbers of granule cell neurones in the olfactory bulbs.

ISSN:0092-7317    

DOI:10.1002/cne.903480303

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis study was aimed at characterizing the ultrastructural morphology of the normal acetylcholine (ACh) innervation in adult rat parietal cortex. After immunostaining with a monoclonal antibody against purified rat brain choline acetyltransferase (ChAT), more than 100 immunoreactive axonal varicosities (terminals) from each layer of the Par 1 area were photographed and examined in serial thin sections across their entire volume. These varicosities were relatively small, averaging 0.6 μm in diameter, 1.6 μM2in surface, and 0.12 μM3in volume. In every layer, a relatively low proportion exhibited a synaptic membrane differentiation (10% in layer I, 14% in II–III, 11% in IV, 21% in V, 14% in VI), for a I–VI average of 14%. These synaptic junctions were usually single, symmetrical (>99%), and occupied a small portion of the surface of varicosities (85% of its varicosities), and the composition of the microenvironment of its varicosities suggests some randomness in their distribution at the microscopic level. It is unlikely that these ultrastructural characteristics are exclusive to the parietal region. Among other functional implications, they suggest that this system depends predominantly on volume transmission to exert its modulatory effects on cortical activity. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903480304

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn 1–week‐old domestic chicks, the connectivity of the lobus parolfactorius (LPO), part of the avian basal ganglia, was investigated usingPhaseolus vulgarisleucoagglutinin and horseradish peroxidase for anterograde and retrograde pathway tracing, respectively. Tyrosine hydroxylase immunocytochemistry was applied in combination withPhaseoluslectin to assess the overlap between LPO efferents and diencephalic and meseticephalic catecholamine centres. Anterograde projections from LPO were detected in the hyperstriatum, neostriatum, and paleostriatum. Intranuclear connections were also apparent within the LPO. Descending LPO efferents innervated the lateral mammillary and intramedial nuclei and the dorsomedial thalamic complex. Fibres from LPO were observed in the tectal gray, substantia nigra, area ventralis tegmentalis of Tsai, and the adjacent nucleus mesencephalicus profundus. Further caudally, projections from LPO reached the nucleus papillioformis, locus coeruleus, and subcoeruleus ventralis. LPO efferents were coextensive with tyrosine hydroxylase‐positive cells in the nuclei mamillaris lateralis and intramedialis of the hypothalamus, area ventralis tegmentalis, substantia nigra, locus coeruleus, and subcoeruleus ventralis of mesencephalic and pontine tegmentum. Close contacts between LPO fibres and catecholamine cells were visible in the nigra and the area ventralis tegmentalis. Retrograde labelling from LPO was found in the archistriatum, dorsomedial thalamic complex, nuclei lateralis anterior and superficialis parvicellularis thalami, substantia nigra, central gray, area ventralis tegmentalis of Tsai, and locus coeruleus and in cells dorsal to the decussation of brachium conjunctivum. Reciprocal connections were verified between the LPO and the following areas: dorsomedial thalamic complex, central gray, substantia nigra, area ventralis of Tsai, and locus coeruleus. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903480305

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe chick archistriatum receives afferents from the intermediate part of the medial hyperstriatum ventrale (IMHV) and projects to the lobus parolfactorius (LPO). There is functional evidence to suggest that the IMHV and the LPO are connected, but there is no anatomical evidence for a direct connection between the two structures. The aim of the current study was to characterize the termination pattern of medial hyperstriatal afferents within the archistriatum to determine whether the archistriatum may act as a relay between the IMHV and LPO. Following iontophoresis ofPhaseolus vulgarisleucoagglutinin into the medial hyperstriatum ventrale (including the IMHV) of 1‐week‐old domestic chicks, anterogradely labelled fibers were observed to descend through the medial neostriatum and paleostriatum to enter the archistriatum. These medial hyperstriatum ventrale afferents arborised profusely to give varicose axon branches within all except the anterior part of the archistriatum. However, the greatest density was present in the ventral part of the intermediate archistriatum. Electron microscope examinationPhaseoluslectin immunocytochemistry and Golgi impregnation revealed that medial hyperstriatum ventrale axons formed multiple asymmetric synapses with dendritic spines (head and neck regions) on the terminal and preterminal dendritic segments of densely spiny archistriatal projection neurons. Medial hyperstriatum ventrale afferents were not observed to contact calbindin immunoreactive, presumptive “local circuit” neurons, within the archistriatum, despite a spatial overlap in their distribution. These results suggest that the archistriatum may be capable of mediating the transfer of information from the IMHV to the LPO. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903480306

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe auditory brainstem nuclei, angularis (NA), magnocellularis (NM), and laminaris (NL) of the chicken,Gallus, contain terminals that stain for antibodies against the inhibitory neurotransmitter, gamma‐aminobutyric acid (GABA). Some of these terminals originate from cells surrounding nucleus Magnocellularis. Results from this study indicate that themajorityof the GABAergic terminals found in NA, NM and NL originate from the superior olivary nucleus (SON). Injections of cholera toxin and horseradish peroxidase show that superior olivary nucleus (SON) neurons, which respond to pure tones, project bilaterally to NA, NM and NL. NA and NL are reciprocally connected with the SON. More NA cells project to the SON than NL cells. While SON neurons project to NM, NM neurons do not project axons back to the SON. The configuration of SON terminals in NA, NM and NL matches the pattern of GABAimmunoreactive puncta seen in these three nuclei: they surround individual NM cells, congregate in the dendritcneuropil of NL, and blanket the NA. The data indicate that NA, NM and NL may be affected by two different inhibitory cell types: local interneurons and SON neurons. Patterns of connectivity described in this report suggest that the activity of NA cells could influence NM and NL cell physiology, Specifically, increases in NA cell activity could augment the effects of GABAergic SON neurons on NM and NL. Hence, binaural perception in the chicken may be more dependent upon changes in intensity cues than previously believed. © 1994 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903480307

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

年代:1994

数据来源: WILEY

摘要:

AbstractBioassay and immunological studies have detected the presence of opioid peptides in the nervous system of representatives of all classes of vertebrates. The present study evaluates the expression and localization of preproenkephalin (PPE) mRNA to determine the sites of synthesis of the enkephalin peptides in the adult chicken and pigeon telencephalon using in situ hybridization histochemistry. We used a 500‐base‐pair chicken RNA probe corresponding to chicken PPE cDNA. In both the chicken and the pigeon telencephalon, the highest concentration of PPE mRNA‐containing cells was observed in the lobus parolfactorius, paleostriatum augmentatum, nucleus accumbens, and septum. Distinct populations of labeled cells were also detected in the hyperstriatum accessorium, hippocampus, area parahippocampalis, nucleus of the diagonal band, cortex dorsolateralis, and cortex piriformis. Differences in PPE mRNA expression between chicken and pigeon were observed in several telencephalic regions. For instance, the bulbus olfactorius was heavily labeled in the pigeon, but was not labeled in the chicken, and numerous PPE mRNA‐containing cells were present in the area parahippocampalis of pigeons but not of chickens. In contrast, in the hyperstriatum dorsale and hyperstriatum ventrale, numerous PPE mRNA‐expressing cells were detected in the chicken but not in the pigeon. Overall, PPE mRNA‐expressing cells were more numerous than enkephalinimmunoreactive cells described in previous studies. In addition, our results suggest that the general pattern of enkephalin expression in the avian telencephalon is similar to that found in other vertebrates. Finally, the results of the present study illustrate some differences in the pattern of PPE mRNA distribution between closely related species, indicating the existence of species‐specific neurochemical pathways, which may influence and perhaps mediate different behaviors characteristics of these species. © 1994 W

ISSN:0092-7317    

DOI:10.1002/cne.903480308

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

年代:1994

数据来源: WILEY

摘要:

AbstractBrainstem catecholaminergic neurons have been implicated as mediating adaptive autonomic and neuroendocrine responses to cardiovascular challenges. To clarify the nature of this involvement, immuno‐ and hybridization histochemical methods were used to followc‐fosexpression in these neurons in response to acute stimuli that differentially affect blood pressure and volume. From low basal levels, hypotensive hemorrhage (15%) provoked a progressive increase in the number and distribution of Fos‐immunoreactive (ir) nuclei in the nucleus of the solitary tract (NTS), the Al and C1 cell groups of the ventrolateral medulla, and in the pontine A5, locus coeruleus, and lateral parabrachial cell groups peaking at 2.0–2.5 hours after the challenge. Fos‐ir ventrolateral medullary neurons, subsets of which were identified as projecting to the paraventricular hypothalamic nucleus or spinal cord, were predominantly aminergic, whereas most of those in the NTS were not. Infusion of an angiotensin II antagonist blunted hemorrhage‐induced Fos expression in the area postrema, and attenuated that seen elsewhere in the medulla and pons. Nitroprusside‐induced isovolemic hypotension yielded a pattern of c‐fos induction similar to that seen following hemorrhage, except in the area postrema and the Al cell group, where the response was muted or lacking. Phenylephrineinduced hypertension stimulated a restricted pattern ofc‐fosexpression, largely limited to non‐aminergic neurons, whose distribution in the NTS conformed to the termination patterns of primary baroreceptor afferents, and in the ventrolateral medulla overlapped in part with those of vagal cardiomotor and depressor neurons. These findings underscore the importance of brainstem catecholaminergic neurons in effecting integrated homeostatic responses to cardiovascular challenges and their ability to responding strategically to specific modalities of cardiovascular information. They also foster testable predictions as to effector neuron populations that might be recruited to respond to perturbations in individual circulatory parameters. ©

ISSN:0092-7317    

DOI:10.1002/cne.903480309

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

年代:1994

数据来源: WILEY

摘要:

AbstractQuantitative stereological methods were used to determine if the number, density, and types of synaptic connections formed during development are regulated by presynaptic input or by postsynaptic target cells in the optic tectum of normal and 3‐eyedRana pipienstadpoles and frogs. Our analysis indicates that the number and size of synapses is approximately the same in both tecta of 3‐eyed tadpoles and frogs, even though one tectal lobe is receiving input from twice the normal complement of retinal ganglion cells. Moreover, the number and size of synapses in the tectal lobes of 3‐eyed animals did not differ significantly from values determined for normal tadpoles and frogs of the same developmental stage. These data suggest strongly that developing tectal cells regulate the number of synaptic contacts they will form. Differences in several morphological features between singly and doubly innervated tecta, however, including synapse density, distribution and complexity, amount of extracellular space, and number of myelin figures, suggest that the presence of supernumerary input retards tectal maturation. We propose that the noncorrelated activity of retinal ganglion cell terminals in the doubly innervated tectum results in fewer stabilized synapses per unit volume of neuropil and in the delayed maturation of the tectal neuropil. Taken together, our data suggest a complex dynamic interaction between retina and tectum during development. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903480310

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.903480301

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

年代:1994

数据来源: WILEY