摘要:

AbstractWe used an antibody raised against the inhibitory transmitter gamma‐aminobutyric acid (GABA) in the basilar pontine gray (bpg) of the monkey. Somata, dendrites, and a plexus of probably axonal fibers exhibited GABA‐like immunoreactivity. Labeled neurons were small with oval, triangular, or circular soma shape. They gave rise to 2 to 4 dendrites with little branching. No axons were seen issuing from the soma. Occasionally, appendages consisting of spheroidal bodies positioned at the distal end of tenuous stalks and (in 1 cell) axonlike processes were observed to originate from dendrites. According to their morphology, we suggest that these putative GABA‐ergic neurons may correspond to the type II neurons observed in Golgi material.The average number of putative GABA‐ergic cells in 40–μm sections was about 30/mm2. When compared with Nissl‐stained sections, these amounted to about 5% of all cells. There was no substantial variation in average density in different parts of the bpg. However, labeled cells tended to lie in clusters, perhaps related to the well‐established input‐output compartments of the bpg.The demonstration of a significant population of putative inhibitory neurons challenges the traditional view of the bpg, which suggests that this brainstem cell group functions as a simple relay exchanging signals between corte

ISSN:0092-7317    

DOI:10.1002/cne.902650302

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe synaptic organization of the feline globus pallidus (GP) was studied electron microscopically. The axon terminals were classified into five types on the basis of the size and shape of synaptic vesicles and the type of postsynaptic differentiations. Type I and II axon terminals were characterized by large, pleomorphic vesicles and by a symmetric and an asymmetric synaptic contact, respectively. Type III and IV axon terminals were characterized by small, pleomorphic vesicles and by a symmetric and an asymmetric synaptic contact, respectively. Type V axon terminals were characterized by elongated and large round vesicles and by a symmetric synaptic contact.The origins of these terminals were determined by a combined degeneration and HRP tracing technique. Following injections of HRP into the caudate nucleus or electrolytic lesions in this nucleus, type I terminals were anterogradely labeled with HRP or degenerated, respectively. Although type III, IV, and V terminals were labeled with HRP after HRP injections into the subthalamic nuclear region, only type IV and V terminals degenerated after lesions in that area. Type II terminals did not show any alterations following such treatment. These results suggest that type I terminals originate from the caudate nucleus, that type IV and V terminals come from the subthalamic nucleus or caudal to it, and that type III terminals are the terminals of intrinsic axon collaterals of GP neurons which send axons to the subthalamic nucleus.Occasionally convergence of different kinds of axon terminals on the same GP neuron was also observed. These terminals originated from the caudate nucleus and the subthalamic nucleus or caudal to it. The similarity between the synaptic organization of the GP and the entopeduncular nucleus is briefly discussed.

ISSN:0092-7317    

DOI:10.1002/cne.902650303

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

年代:1987

数据来源: WILEY

摘要:

AbstractPhysiological (intracortical microstimulation) and anatomical (transport of horseradish peroxidase conjugated to wheat germ agglutinin as shown by tetramethyl benzidine) approaches were combined in the same animals to reveal the locations, extents, and cortical connections of the frontal eye fields (FEF) in squirrel, owl, and macaque monkeys. In some of the same owl and macaque monkeys, intracortical microstimulation was also used to evoke eye movements from dorsomedial frontal cortex (the supplementary motor area). In addition, in all of the owl and squirrel monkeys, intracortical microstimulation was also used to evoke body movements from the premotor and motor cortex situated between the central dimple and the FEF. These microstimulation data were directly compared to the distribution of anterogradely and retrogradely transported label resulting from injections of tracer into the FEF in each monkey. Since the injection sites were limited to the physiologically defined FEF, the demonstrated connections were solely those of the FEF. To aid in the interpretation of areal patterns of connections, the relatively smooth cortex of owl and squirrel monkeys was unfolded, flattened, and cut parallel to the flattened surface. Cortex of macaque monkeys, which has numerous deep sulci, was cut coronally.Reciprocal connections with the ipsilateral frontal lobe were similar in all three species: dorsomedial cortex (supplementary motor area), cortex just rostral (periprincipal prefrontal cortex) to the FEF, and cortex just caudal (premotor cortex) to the FEF. In squirrel and owl monkeys, extensive reciprocal connections were made with cortex throughout the caudal half of the lateral fissure and, to a much lesser extent, cortex around the superior temporal sulcus. In macaque monkeys, only sparse connections were present with cortex of the lateral fissure, but extensive and dense connections were made with cortex throughout the caudal one‐third to one‐half of the superior temporal sulcus. In addition, very dense reciprocal connections were made with the cortex of the lateral, or inferior, bank of the intraparietal sulcus. Contralateral reciprocal connections in all three species were virtually limited to regions that correspond in location to the FEF and the supplementary motor area.The results of this study reveal connections between the physiologically defined frontal eye field and cortical regions known to participate in higher order visual processing, short‐term memory, multimodal, visuomotor, and skeletomotor functions. Some of the demonstrated pathways may contribute to functional interactions between oculomotor and skeletomotor systems, perhaps facilitating the planning and coordination of related eye, head, and hand move

ISSN:0092-7317    

DOI:10.1002/cne.902650304

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

年代:1987

数据来源: WILEY

摘要:

AbstractExplants of the metencephalic basal plate from stage 11 (40–hour) chick embryos containing the trigeminal (V) motor nucleus were cultured in standard control medium, in medium supplemented with nerve growth factor (NGF), in medium supplemented with NGF and specific antibodies to NGF (anti‐NGF), and in medium supplemented with anti‐NGF alone. The explants grown in the presence of NGF displayed an enhanced density and complexity of neuritic outgrowth, with this growth significantly surpassing that seen in the control group (p≥.001). The explants grown in NGF plus anti‐NGF and those grown in anti‐NGF alone did not differ from controls. The results indicate that this early cholinergic population is specifically responsive to NGF. This finding is consistent with recent studies in which NGF receptor binding has been found in this and other early brainstem and spinal cord motor neuron populations. The possible relevance of these observations to the normal sequence involved in the development of the V motor nucleus is discussed, particularly as they may relate to the relationship between the V ganglion and the developing V motor

ISSN:0092-7317    

DOI:10.1002/cne.902650305

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

年代:1987

数据来源: WILEY

摘要:

AbstractClassical studies of the cat rubrospinal tract describe dense terminations in spinal laminae V–VII and an absence of any significant projection to lamina IX. In contrast, our recent studies, utilizing the anterograde transport of wheat germ agglutinin conjugated with horseradish peroxidase, have demonstrated a consistent and circumscribed area of label in lamina IX at caudal cervical segments.The present study was undertaken to determine the distribution of rubrospinal terminals among motor neurons in lamina IX as well as to identify the likely target muscles of those motor neurons located near rubrospinal terminals. We injected wheat germ agglutinin‐horseradish peroxidase into the red nucleus and unconjugated horseradish peroxidase into selected forearm muscles of the same side of the body. The locations of rubrospinal terminals showing anterograde label on one side of the spinal cord could then be compared with the locations motor neurons showing retrograde label on the opposite side of the cord.The results demonstrated a clear focus of rubrospinal terminals in the lateral and dorsal portions of the ventral horn beginning at C8 and extending through rostral T1. No other segments of the spinal cord showed a focus of rubrospinal terminations in lamina IX. Retrogradely labeled motor neurons from the muscle injections showed that the rubrospinal terminals overlap extensively with motor neuronal pools supplying distal forearm muscles. Several lines of evidence indicate that the terminals are from rubrospinal fibers and are not due to transneuronal transp

ISSN:0092-7317    

DOI:10.1002/cne.902650306

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

年代:1987

数据来源: WILEY

摘要:

AbstractLayer V pyramidal neurons in the cat parietal cortex (areas 5 and 7) were investigated with intracellular HRP staining. Antidromic responses were recorded intracellularly as well as extracellularly with pontine stimulation under Nembutal anesthesia. The relationship between the latency of antidromic responses and the morphology of HRP‐stained neurons was analyzed. A total of 65 neurons were stained with HRP, and sixteen of these neurons were activated antidromically with pontine stimulation.Two distinct groups of layer V pyramidal neurons were detected morphologically by intracellular HRP staining; i.e., one (F type) consisted of neurons with relatively large somata (58.4±8.1 μm × 24.5±5.1 μm, N = 11) and aspiny or sparsely spinous apical dendrites, and the other (S type) consisted of neurons with smaller somata (44.6±7.6 μm × 19.3±3.9 μm, N = 22) and richly spinous apical dendrites. These two groups showed different electrophysiological properties; i.e., the former responded antidromically to pontine stimulation at a latency shorter than 1.5 ms (namely, with a conduction velocity faster than 18 m/second) and the latter responded at a latency longer than 1.5 ms.The two neuronal types in the parietal cortex corresponded respectively to fast and slow pyramidal tract neurons (PTNs) investigated in the sensorimotor cortex. Although their morphological features were almost similar to those of PTNs, the branching pattern of apical dendrites of the F‐type pyramidal neuron seemed to be different from that of fast PTNs. In the parietal cortex, apical dendrites of F‐type neurons showed rather frequent branching in layer I. This was simialr to the pattern of branching in slow PTNs. Such a characteristic branching pattern suggested that, in the cat parietal cortex, layer V pyramidal neurons of both types are adapted to receive cerebellar inputs through the ventroanterior (VA) thalamic nucleus to the superficial

ISSN:0092-7317    

DOI:10.1002/cne.902650307

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

年代:1987

数据来源: WILEY

摘要:

AbstractFollowing transection of the optic nerve, ganglion cells in the cat retina undergo retrograde degeneration. However, many small profiles (≤ 10 μm) survive in the ganglion cell layer. Previously considered to be neuroglia, there is now substantial evidence that they are displaced amacrine cells. Their density increases from approximately 1,000 cells/mm2in peripheral retina to 7,000 cells/mm2in the central area. Their total number was found to be 850,000, which is five times the number of ganglion cells and also five times the number of astrocytes.Uptake of3H‐muscimol followed by autoradiography labelled 75% of the displaced amacrine cells; hence, the majority seem to be GABAergic. Immunocytochemistry with an antibody directed against choline‐acetyltransferase labelled approximately 10% of the displaced amacrines in the peripheral retina and 17% in the central area. Uptake of serotonin (5–HT) followed by immunocytochemistry was found in 25–30% of displaced amacrines. NADPH diaphorase histochemistry labelled approximately 5% of displaced amacrine cells. The sum of the various percentages makes colocalization likely. Intracellular injection of Lucifer Yellow under microscopic control revealed that displaced amacrine cells constitute several morpholog

ISSN:0092-7317    

DOI:10.1002/cne.902650308

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

年代:1987

数据来源: WILEY

摘要:

AbstractThalamic and corticocortical connections of the second somatic sensory area (SII) in the mouse cerebral cortex were investigated by means of the retrograde transport of horseradish peroxidase. Focal injections of the enzyme were made in physiologically determined locations within the parietal cortex. Results show that SII receives substantial inputs from topographically appropriate regions within the ipsilateral ventrobasal nucleus and from the ipsilateral posterior group. The limb representation, which was previously found to be responsive to auditory stimulation, received inputs also from the medial division of the medial geniculate body. The SII face representation, which is largely unresponsive to auditory stimuli, received little or no input from the medial geniculate body. SII injections yielded retrograde labeling in the topographically appropriate region in the first somatic sensory area (SI), and SI injections retrogradely labeled cells in SII in a pattern consistent with previous electrophysiological maps. Homotypical regions within SI and SII therefore appear to be reciprocally interconnected. SII also receives inputs from the ipsilateral motor cortex and from contralateral SI and SII. Finally, injections into the SI paw but not face regions yielded retrograde labeling in the thalamic ventrolateral nucleus. Thus, the distal limb representations in SI and SII each receive inputs from a third major relay nucleus (i.e., medial geniculate to SII, ventrolateral nucleus to SI) whereas the face representations do not. These results indicate a close functional interrelationship between homotypical areas in SI and SII, though the two areas differ in several important respects. It is proposed that SII in mice may complement the function of SI by helping to define the overall sensory context in which detailed tactile discriminations are made.

ISSN:0092-7317    

DOI:10.1002/cne.902650309

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

年代:1987

数据来源: WILEY

摘要:

AbstractLight‐ or dark‐adapted goldfish (Carassius auratus) retinas were treated with dopamine, which is believed to uncouple horizontal cells via D1receptors, or with the dopamine antagonist haloperidol. Aldehyde‐fixed retinas were freeze‐fractured and the replicas examined by electron microscopy to identify horizontal gap junctions. The density (number per μm2) of intra‐membrane particles of horizontal ceil soma gap junctions was significantly lower in light‐adapted and dopamine‐treated retinas than in dark‐adapted and haloperidol‐treated retinas. There was no statistically significant difference between gap junction particles densities in (I) light‐adapted (untreated) and in dopamine‐treated (light‐ or dark‐adapted) retinas, or between (II) dark‐adapted (untreated) and haloperidol‐treated (light‐ or dark‐adapted). These results suggest that the uncoupling of horizontal cell somas by dopamine is accompanied by a decrease in gap junction particle density and that there is a greater release of dopamine during light‐adaptation than dark‐adaptation. Unlike horizontal cell somas, horizontal cell axon terminals did not show consistent changes in gap junction particle density with light‐ or dark‐adaptation. Although the data suggests that there may be a reduction in axon terminal gap junction particle density with dopamine treatment, this effect is not reversible with haloperidol treatment. Our results suggest that the regulation of gap junctions ma

ISSN:0092-7317    

DOI:10.1002/cne.902650310

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe pentapeptide proctolin (H‐Arg‐Tyr‐Leu‐Pro‐Thr‐OH) is a well‐studied bioactive substance in insects. With an antiserum against proctolin we have mapped proctolinlike‐immunoreactive (PLI) neurons in the nervous system of the blowflyCalliphora erythrocephala.In the brain, including the suboesophageal ganglia, 80–90 neurons were found to be PLI. A further 200–250 PLI neurons innervate the lobula of the optic lobe. The thoracic ganglia contain 100–130, and the abdominal ca. 60 PLI neurons. In the brain and ventral ganglia the immunoreactive neurons are of different types: interneurons, efferents (possibly some motorneurons), and neurosecretory cells. Some of these neurons are individually identifiable; others can be identified collectively as clusters. Identifiable neurons innervate protocerebral neuropil associated with thepars intercerebralisand the β‐lobes of the mushroom bodies as well as tritocerebral neuropil. Some of the prominent clusters innervate the central body of the protocerebrum, tritocerebrum, and possibly leg motor neurons. One abdominal cluster is of special interest because it consists of efferent neurons with processes in the lateral abdominal nerves. Some of these processes are located in the neural sheath in neurohaemal regions, and electron microscopy demonstrates that their terminals are outside the blood‐brain barrier. The PLI processes in the proto‐cerebrum contain large granular vesicles and form chemical synapses with different kinds of nonimmunoreactive neural elements. Thus, inCalliphorathe proctolinlike substance may be used as a central transmitter/modulator, a neuromuscular transmitter, and a neurohormone r

ISSN:0092-7317    

DOI:10.1002/cne.902650311

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

年代:1987

数据来源: WILEY