摘要:

AbstractElectrophysiological mapping criteria were employed to identify visual areas 20a, 20b, 21a, 21b, PMLS, AMLS, ALLS, PLLS, DLS, VLS, and PS in the cat, and to guide placement of tracer deposits. Anterograde tracer methods were used to study the corticostriatal projections of these extrastriate visual areas. The experiments demonstrate that all 11 extrastriate areas send projections to two distinct regions within the striatum, an extensive longitudinal zone within the caudate nucleus, and a more compact region within the posterolateral putamen. Cortical visual projections to the putamen terminate in relatively compact sheets or slabs, and appear to overlap extensively, while those to the caudate nucleus are irregularly patchy and more widely dispersed. Retrograde tracer deposits into the visual recipient zone of the caudate nucleus reveal substantial convergence of other cortical inputs to this same domain. Aspects of visuotopic organization are preserved in the visual projections to both the putamen and the caudate nucleus, but unequivocal retinotopic organization could not be inferred from the available material.Ten of the eleven extrastriate visual area also project topographically onto the visual zone of the claustrum. Area PS does not appear to contribute to the corticoclaustral projections. Five of the extrastriate visual areas (ALLS, PLLS, DLS, VLS, PS) also send sparse projections to the amygdaloid complex. c 1993 Wiley‐Liss, In

ISSN:0092-7317    

DOI:10.1002/cne.903270202

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe distribution of muscarinic and nicotinic cholinergic binding sites in the cat nucleus tractus solitarii was studied by the technique of in vitro autoradiography. Using the antagonist [3H]quinuclidinyl benzilate, muscarinic binding sites were differentially located in subdivisions of the nucleus tractus solitarii. The majority of muscarinic binding sites were located predominantly in the caudal half of the nucleus, reaching their greatest amounts at the mid levels of the nucleus tractus solitarii. The medial, dorsolateral, intermediate, and interstitial subdivisions contained the highest densities of quinuclidinyl benzilate binding sites. Nicotinic cholinergic binding sites, using [3H]nicotine and [125I]alpha‐bungarotoxin, had unique patterns of distribution. With [3H]nicotine the majority of binding sites were located in rostral levels of the nucleus with very few binding sites present in the caudal half. In contrast, [125I]alpha‐bungarotoxin binding sites were present mainly in subdivisions located in the caudal half of the nucleus, i.e., commissural, ventrolateral, dorsolateral, medial, and intermediate subdivisions, and dropped off precipitously at more rostral levels. The differential distribution of [3H]nicotine and [125I]alpha‐bungarotoxin suggests the two ligands may be labeling different types of nicotinic binding sites in the nucleus tractus solitarii. The unique distribution of muscarinic and nicotinic cholinergic binding sites in the various subdivisions of the nucleus solitarii suggests that muscarinic and nicotine mechanisms may play an active role in the regulation of the diverse autonomic functions at the level of the nucleus tractus solitarii. © 1993 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903270203

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe retinal projection to the basal telencephalon was studied in eight species of primates from the suborders Strepsirhini and Haplorhini, including one anthropoid primate, the gibbon. Animals received an intraocular injection of tritiated amino acids and the distribution of retinal fibers and terminals was demonstrated by autoradiographic techniques in horizontal and coronal sections. In all species a discrete group of labeled retinal fibers is observed to branch off from the dorsolateral aspect of the optic tract at the level of the suprachiasmatic nucleus. These fibers, destined to the basal telencephalon, are topographically distinct from the retinal fibers which innervate the suprachiasmatic nucleus and medial hypothalamic regions. The fibers of the retinotelencephalic tract course dorsally above the supraoptic nucleus through the lateral hypothalamic area and then proceed further rostrally and laterally below the diagonal band of Broca towards the olfactory tubercle. Within the olfactory tubercle, terminal distribution of label is observed in the mediocaudal region along the granular cell layer II. In the macaque this cellular layer shows a characteristic thickening in the region of retinal terminals which is evident in both coronal and horizontal section. In some species this labeled region is seen within the superficial bulge of the tubercle on the ventral aspect of basal telencephalon. In all Primates the retinal projection to olfactory tubercle is bilateral. In prosimians label is predominantly contralateral to the injected eye, in New World monkeys label is equally distributed on both sides of the brain and in Old World monkeys label is mainly found ipsilaterally. Retinal fibers were also seen in the periamygdaloid region but never extended as far as piriform cortex. These results, in addition to previous studies in other mammalian orders, confirm that the basal telencephalon, and in particular the olfactory tubercle, constitutes a region of visual and olfactory convergence. This sensory integration may be related to photic and chemosensory modulation of reproductive physiology and behavior. © 1993 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903270204

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe efferent connections of the rostral pole of the rat accumbens, where distinct core and shell subterritories can not be identified, were examined with the aid of the anterogradely transported plant lectin,Phaseolus vulgaris‐leucoagglutinin (PHA‐L), for comparison with the previously reported projection patterns of the accumbal core and shell. Injection sites and transported PHA‐L were evaluated with the aid of reference to adjacent sections processed to display substance P or calbindin 28 kD immunoreactivities, i.e., markers that demonstrate the core and shell. Lateral parts of the rostral pole gave rise to a “core‐like” projection system that involved the rostroventral globus pallidus, subcommissural ventral pallidum, entopeduncular nucleus and an adjacent part of the lateral hypothalamus, lateral ventral tegmental area, dorsal pars compacta, and structures in the lateral mesencephalic tegmentum and central grey. The medial part of the rostral pole gave rise to a “shell‐like” innervation of the subcommissural ventral pallidum, lateral preoptic region, lateral hypothalamus, ventral tegmental area, dorsalmost pars compacta, retrorubral field, lateral midbrain tegmentum, and central grey. In contrast to the large numbers of axon varicosities observed through the entire length of lateral hypothalamus following shell injections, dense accumulations of axon collaterals and varicosities in hypothalamus were limited to the levels of origin of the stria medullaris bundle and entopeduncular nucleus and to the posterlateral region following medial injections. The medial part of the rostral pole contributed some projections to preoptic and sublenticular regions, but not to the bed nucleus of the stria terminalis. Noteworthy concentrations of calbindin immunoreactive cells observed in the lateral rostral pole correlate with the origin of the “basal ganglia‐like” projection system, provoking the speculation that ventral striatal calbindin immunoreactive cells contribute principally to basal ganglia‐like projections while cells lacking calbindin immunoreactivity contribute to the innervation of hypothalamus and midbrain tegmentu

ISSN:0092-7317    

DOI:10.1002/cne.903270205

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractWe tested the hypothesis that the rat bowel and pancreas contain 5‐HT1Areceptors.3H‐8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (3H‐8‐OH‐DPAT) was used as a radioligand. Binding of3H‐8‐OH‐DPAT to membranes derived from the myenteric plexus and the pancreas was investigated by rapid filtration. Alternatively, radioautography was employed to locate3H‐8‐OH‐DPAT binding sites in frozen sections of unfixed bowel or pancreas. An excess of 5‐HT (10 μM) was used to define nonspecific binding. Saturable, high affinity binding of3H‐8‐OH‐DPAT to enteric (Kd= 2.8 ± 1.1 nM; Bmax=83.8 ± 4.3 fmol/mgproteim) and pancreatic (Kd= 6.6 ± 1.3 nM; Bmax= 44 ± 2.2 fmol/mg protein) membranes was found. The binding of3H‐8‐OH‐DPAT to enteric and pancreatic membranes was inhibited by 8‐OH‐DPAT, NAN‐190, and spiperone. In contrast, the binding of3H‐8‐OH‐DPAT to enteric and pancreatic membranes was not inhibited by 5‐carboxyamidotryptamine, or by avariety of compounds known to bind to other subtypes of 5‐HT receptor. Digoxigenin‐labeled oligonucleotides were found to detect mRNA encoding the 5‐HT1Areceptor in a subset of neurons in myenteric and submucosal ganglia. In contrast, 5‐HT1AmRNA was not found in the pancreas. Radioautography revealed that the highest density of3H‐8‐OH‐DPAT binding sites was found in the stomach. These sites were especially numerous in the lamina propria adjacent to gastric glands, and in myenteric ganglia. Pancreatic 5‐HT1Areceptors were located on nerves, lymphoid tissue (especially the capsule of nodes), and on cells scattered in the pancreatic parenchyma. The concentration of3H‐8‐OH‐DPAT binding sites in the rat bowel and pancreas was less than that of3H‐5‐HT binding sites; however, the distribution of3H‐8‐OH‐DPAT binding sites was similar to that of sites that bind3H‐5‐HT. It is concluded that the rat gut and its extension in the pancreas contains 5‐HT1Areceptors. Many, if not all, of the nerve cells and processes that express 5‐HT1Areceptors express 5‐HT1preceptors as well. The function of these recepto

ISSN:0092-7317    

DOI:10.1002/cne.903270206

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study was aimed at characterizing the inputs from dorsal roots and dorsal columns to reticulospinal neurons within the posterior rhombencephalic reticular nucleus in the lamprey. The in vitro isolated brainstem and spinal cord preparation was used. Microstimulation of dorsal roots and columns on both sides induced, in identified reticulospinal neurons, synaptic responses which consisted of large IPSPs mixed with excitation, particularly from stimulation on the ipsilateral side. When the spinal cord was selectively exposed to kynurenic acid or to Ca2+, synaptic responses to stimulation of dorsal roots and columns were not modified, whereas the same responses were abolished when the brainstem was exposed selectively to kynurenic acid, thus suggesting that the responses were carried by long fibres ascending directly to the brainstem. The excitatory and inhibitory synaptic responses are relayed by interneurons located in the brainstem. The ascending excitatory inputs to inhibitory interneurons and, most likely, also to excitatory interneurons, use excitatory amino acid transmission. Inhibitory responses were abolished by adding the glycinergic antagonist strychnine (5 μM) to the physiological solution, thus suggesting that inhibitory interneurons use glycine transmission. The synaptic transmission was depressed by (−)‐baclofen, a GABAuagonist, probably acting at a presynaptic site.Taken together, the present results suggest that dorsal root and dorsal column stimulations give rise to disynaptic inhibition and excitation of reticulospinal neurons mediated by excitatory and inhibitory amino acid transmission via brainstem interneurons. © 1993 Wiley‐Li

ISSN:0092-7317    

DOI:10.1002/cne.903270207

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe course and sites of termination of dorsal column fibres in the lamprey brainstem are described along with their brainstem relays projecting to reticulospinal neurons. Dorsal column fibres ascend to the brainstem level where they intermingle with cells located in the alar plate close to the obex, a location that is analogous to that of the dorsal column nucleus in other vertebrates. Some dorsal column fibres continue further rostrally where they reach the octavolateralis and octavomotorii nuclei. Finally, a small contingent of fibres reach the cerebellum. Injections of cobalt‐lysine into the posterior rhombencephalic reticular nucleus retrogradely label neurons within the dorsal column nucleus and within the octavolateralis and octavomotorii nuclei. Microstimulation of the dorsal column nucleus on either side elicits monosynaptic inhibitory responses in reticulospinal neurons while stimulation of octavolateralis and octavomotorius nuclei elicits excitation. By using intracellular recordings, it was shown that neurons within these alar plate nuclei receive monosynaptic inputs from the dorsal columns. It is thus proposed that disynaptic inputs from dorsal columns to reticulospinal neurons are relayed by these alar plate neurons: inhibition is relayed mainly by neurons in dorsal column nuclei and excitation by neurons in the octavolateralis and octavomotorii nuclei. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903270208

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractLabeled or otherwise identified neurons of the crayfish lateral giant escape reaction circuit were examined electron microscopically and the findings compared to expectations from physiology.Terminals of primary afferents contained clear, approximately 45 nm, irregularly round synaptic vesicles, while sensory interneuron terminals had slightly larger, 50 nm, more strictly round vesicles, permitting tentative classification based on anatomical criteria.Excitatory synapses on the lateral giants, believed from physiology to be electrical, generally had some gap junctions, but these were almost invariably paralleled by more prominent chemical junctional regions of unknown function. There may also be a class of interneurons making purely chemical synapses on the lateral giants. Synapses from primary afferents to sensory interneurons, believed from physiology to be cholinergic, had purely chemical morphology.Synapses with narrow elongated vesicles, similar to GABAergic vesicles seen in other neurons, frequently occurred on terminals of primary afferents. These synapses provide a basis for known presynaptic inhibition of afferent input. Consistent with physiology, such inhibitors sometimes also contacted the postsynaptic targets of the primary afferents and sometimes received input from other primary afferents. Afferent terminals also received some input from profiles richin large dense cored vesicles.Presumptive inhibitory input found on proximal dendrites of lateral giants provides a basis for known recurrent inhibition. However, similar inhibitory synapses that sometimes received local input from excitors of the lateral giants were also found distally mixed with excitatory inputs. These provide a basis for recently discovered distal inhibitory input following excitation and for tonic inhibition. © 1993 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903270209

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn order to determine whether somatostatin coexists with GABA or glycine in neurones in rat spinal dorsal horn, a combined pre‐ and post‐embedding immunocytochemical study was carried out. One hundred six somatostatin‐immunoreactive neurones located in lamina II and the dorsal half of lamina III were tested with antiserum or monoclonal antibody to GABA and none of these cells showed GABA‐like immunoreactivity. However, 8 out of 13 somatostatin immunoreactive neurones located deeper in the dorsal horn (ventral lamina III and lamina IV) showed glycine‐like immunoreactivity, and 6 of these were also GABA‐immunoreactive. We have previously shown that neurotensin‐immunoreactive neurones in laminae II and III are also not immunoreactive when tested with GABA antiserum (Todd et al.:Neuroscience 47: 685–691, 1992), and a double‐labelling fluorescence method was therefore used to compare the distribution of somatostatin and neurotensin within the superficial dorsal horn. The two types of peptide‐immunoreactivity were never found in the same profile.These results suggest that somatostatin and neurotensin are present in different populations of non‐GABAergic neurones in rat superficial dorsal horn, but that some somatostatin containing neurones in the deeper part of the dorsal horn contain glycine, with or without GABA.

ISSN:0092-7317    

DOI:10.1002/cne.903270210

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractFive green monkeys were examined with light and electron microscopic preparations to explore the regional differences in the distribution of parvalbumin (PV)‐positive neurons and axon terminals in the primate hippocampus. PV‐positive neurons were mainly found in the hilus of the dentate gyrus and the strata oriens and pyramidale of Ammon's horn. In electron microscopic preparations, the PV‐positive cells displayed nuclear infoldings, intranuclear rods, a large rim of perikaryal cytoplasm with numerous organelles and both asymmetric and symmetric axosomatic synapses. One prominent PV‐positive cell type in CA1 was a large multipolar neuron that resembled the large basket cells of the neocortex. Although most PV‐positive dendrites were aspiny and postsynaptic to numerous axon terminals, some PV‐positive dendrites in the molecular layer of the dentate gyrus displayed filipodia‐like appendages with no synapses or spines that were postsynaptic to multiple axon terminals. The PV‐positive dendrites in the hilus and stratum oriens were apposed at specialized junctions that resembled gap junctions. PV‐positive axons were concentrated in the principal cell layers, and formed axosomatic, axodendritic, and axon initial segment synapses. In cases where these axons were observed to appose the surface of granule cells for a long length, only one axosomatic symmetric synapse per cell was found. In the hilus, PV‐positive axon terminals formed synapses onto thorny excrescences of spiny cells. Both semithin sections and electron microscopic preparations indicated that more PV‐positive axon terminals formed symmetric axosomatic synapses with pyramidal cells in CA2 than in CA1 and CA3. Also, CA2 displayed a unique plexus of PV‐positive axon terminals in stratum lacunosum moleculare.These results indicate that the PV‐positive hippocampal cells form a subset of GABAergic local circuit neurons, including the basket and chandelier cells. The ubiquitous finding of PV‐positive dendrites linked by gap junctions throughout the dentate gyrus and Ammon's horn adds further data to indicate that this subset of GABAergic neurons is linked electrotonically. The synaptic organization of PV‐positive neurons in the hippocampus suggests their participation in both feedback and feedforward inhibition. The PV‐positive neurons in the hippocampus are only a proportion of the basket and chandelier cells, whereas virtually all of these cells in neocortex are PV

ISSN:0092-7317    

DOI:10.1002/cne.903270211

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY