ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01161.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractIn order to find brain areas involved in the vocal expression of emotion, we comparedc‐fosexpression in three groups of saddle‐back tamarins (Saguinus fuscicollis). One group, consisting of three animals, was made to utter more than 800 mobbing calls by electrical stimulation of the periaqueductal grey of the midbrain (PAG). A second group, consisting of two animals, was stimulated in the PAG with the same intensity and for the same duration as the first group but at sites that did not produce vocalization. These sites lay somewhat medial to the vocalization‐eliciting sites. A third group, consisting of two animals, was stimulated at vocalization‐eliciting sites in the PAG but with an intensity below vocalization threshold. Fos‐like immunoreactivity that was found in the vocalizing but not in the non‐vocalizing animals was located in the dorsomedial and ventrolateral prefrontal cortex, anterior cingulate cortex, ventrolateral premotor cortex, sensorimotor face cortex, insula, inferior parietal cortex, superior temporal cortex, claustrum, entorhinal and parahippocampal cortex, basal amygdaloid nucleus, anterior and dorsomedial hypothalamus, nucleus reuniens, lateral habenula, Edinger‐Westphal nucleus, ventral and dorsolateral midbrain tegmentum, nucleus cuneiformis, sagulum, pedunculopontine and laterodorsal tegmental nuclei, ventral raphe, periambigual reticular formation and solitary tract nucleus. For some of these structures (e.g. anterior cingulate cortex and periambigual reticular formation), there is evidence also from electrical stimulation, lesioning and single‐unit recording studies that they are involved in vocal control. For other structures (e.g. lateral habenula, Edinger‐Westphal nucleus), the available evidence speaks against such a role. Fos activation in these cases is probably related to non‐vocal reactions accompanying the electrically elicited vocalizations. A third group of structures consists of areas for which a role in vocal control cannot be excluded but for which the present study presents the first evidence for such a role (e.g. claustrum and sagulum). These structures deserve further studies using mo

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01162.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractIn each body ganglion of the leechHirudo medicinalisthere is a single S‐cell. After an S‐cell axon is severed, it regenerates along its surviving distal segment and reconnects with its synaptic target, the axon of the neighbouring S‐cell. In approximately half the cases the regenerating axon forms a temporary electrical synapse specifically with the distal segment, which remains active and connected to the target, thereby functioning as a splice until regeneration is complete. To determine whether the distal axon segment is required for successful regeneration, distal segments of severed S‐cell axons were ablated by intracellular injection of bacterial protease. Fifty‐seven preparations were examined from 2 to 212 days after injection of the axon segment. The extent of S‐cell axon regeneration was assessed electrophysiologically by intracellular and extracellular recording, and anatomically by intracellular injection of markers followed by light microscopy and electron microscopy. The S‐cell axons regenerated successfully in almost 90% of animals examined after 2 weeks or more. In a further four animals the target S‐cell was ablated in addition to the distal axon segment, permanently disrupting conduction along the S‐cell pathway. Nevertheless, the regenerating axon grew along its usual pathway and there was no evidence that alternative connections were formed. It is concluded that, although the distal axon segment can provide a means for rapid functional repair, the segment is not required for reliable regeneration of the axon along its usual pathway and accurate formation of an e

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01163.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractOptical signals were recorded in thein vivorat piriform cortex in response to a burst of seven electrical stimulations (100 ms interval) delivered in the olfactory bulb. Based on the recorded responses, three types of signal could be identified according to the relative amplitude of their monosynaptic and disynaptic components. The disynaptic component had a larger (type 1) or an equal amplitude (type 2) compared with the monosynaptic one. Type 3 exhibited only the monosynaptic component. Type 1 represented 96% of the first response. The second response was characterized by an increase in type 3 signals (39%). The remaining type 1 signals were lower in amplitude when compared with the first response. The responses to the last five stimulations did not differ from one another but were different from the first two (type 1, 74%; type 2, 7.8%; type 3, 18.2% on average). The spatial distribution of these three types of signal was analysed by dividing the piriform cortex into several areas. These areas were not homogeneous in the percentage of each signal type: the percentage of type 3 signals was highest (˜30%) in the area near the lateral olfactory tract and<10% in the most posterodorsal area. Thus the level of inhibition remained high in some piriform areas whereas it decreased rapidly in others, suggesting that the inhibitory processes were not homogeneously distributed in the whole piriform cortex. Functional implications are discussed

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01164.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractWe have compared physiological data recorded from three alert macaque monkeys with separate observations of local connectivity, to locate and characterize the functional border between two related but distinct visual areas on the caudal face of the superior parietal gyrus. We refer to these areas as V6 and V6A. They occupy almost the entire extent of the anterior bank of the parieto‐occipital sulcus, V6A being the more dorsal. These two areas are strongly interconnected. Anatomically, we have defined the border as the point at which labelled axon terminals first adopt a recognizably ‘descending’ pattern in their laminar characteristics, after injections of wheatgerm agglutinin‐horseradish peroxidase into the dorsal half of the gyrus (in presumptive V6A). A similar principle was used to recognize the same border by the pattern of input from area V5, except that in this case the relevant transition in laminar characteristics is that between an ‘intermediate’ pattern (in V6) and an ‘ascending’ pattern (in V6A). V6A was found to be distinct from V6 in a number of its physiological properties. Unlike V6, it contains visually unresponsive cells as well as units with craniotopic receptive fields (‘real‐position’ cells), units tuned to very slow stimulus speeds, units with complex visual selectivities and units with activity related to attention. V6A was also found to have a larger mean receptive field size and scatter than V6. By contrast, response properties related to the basic orientation and direction of moving bar stimuli were indistinguishable between V6 and V6A, as was the influence of gaze direction on cell activity in the two areas. Two‐dimensional maps of the recording sites allowed reconstruction of the V6/V6A border. For comparison, the anatomical results were rendered on two‐dimensional maps of identical format to those used to summarize the physiological data. After normalizing for relative size, the physiological and connectional estimates of the border between V6 and V6A were found to coincide, at least within the range of individual variation between hemispheres. An architectonic map in the same format was also made from a hemisphere stained for myelin and Nissl substance. Area PO, defined by its general density of myelination was not distinct in this material, but several architectural features were traceable and one of these was also found to approximate the V6/V6A border. The particular criteria that distinguish V6 from V6A differ from a recent description of areas PO and POd in theCebusmonkey; we believe it most likely that PO and POd toge

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01165.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe pattern of pre‐ and postnatal appearance of 5‐HT1Dreceptors throughout the different areas of the human brain was studied by quantitativein vitroautoradiography, using [125I]GTI (serotoninO‐carboxymethyl‐glycyl‐[125I]tyrosinamide) as a ligand. The anatomical distribution of 5‐HT1Dreceptors in neonatal, infant and children's brain was in good agreement with that observed in the adult, the basal ganglia and substantia nigra being the most intensely labelled areas. The development of these receptors throughout the human brain was mainly postnatal: low densities of [125I]GTI binding sites were observed at the fetal/neonatal stage in most regions analyzed, in contrast with the high levels of labelling found in infant and children's brains. Indeed, in a number of regions, including the globus pallidus, substantia nigra and visual cortex, a peak of overexpression of 5‐HT1Dreceptors was observed in the first decade of life. Such overexpression could support a regulatory role for 5‐HT1Dreceptors in advanced periods of the CNS developmental process. Our results also indicate that the administration of drugs acting on 5‐HT1Dreceptors during the early postnatal period of life could result in modifications of their properties, as these receptors are already function

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01166.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMAP1a is a microtubule‐associated protein with an apparent molecular weight of 360 kDa that is found in the axonal and dendritic processes of neurons. Two monoclonal anti‐MAP1a antibodies, anti‐A and anti‐BW6, revealed different epitope distributions in the adult mouse cerebellum. Anti‐A stained Purkinje and granule cells uniformly throughout the cerebellum. In contrast, anti‐BW6 selectively stained the dendrites of a subset of Purkinje cells, revealing parasagittal bands of immunoreactivity in the molecular layer. The compartmentation of the BW6 epitope was compared to the Purkinje cells as revealed by immunostaining with anti‐zebrin II, a well known antigen expressed selectively by bands of Purkinje cells. The anti‐BW6 staining pattern was complementary to the zebrin II bands, the zebrin II‐Purkinje cells having BW6+dendrites. These results demonstrate that MAP1a is present in two forms in the mouse cerebellum, one of which is segregated into parasagittal bands. This may indicate a unique MAP1a isoform or may reflect differences in the metabolic states of Purkinje cell classes, and regional differences i

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01167.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractRoles and mechanisms ofN‐methyl‐D‐aspartate (NMDA) receptors in glutamate neurotoxicity were investigated in cultures of NMDA receptor‐deficient cortical neuronal cells. Mutant mice lacking a functional NMDA receptor were generated by gene targeting of the NR1 NMDA receptor subunit. Cortical neuronal cells prepared from wild‐typeNR1+/+, heterozygousNR1+/‐and homozygous mutant NR1‐/‐mice at 15–17 days of gestation grew indistinguishably from each other. Brief exposures (5 min) of bothNR1+/+andNR1+/‐neuronal cells to glutamate or NMDA, but not kainate or α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA), resulted in widespread neuronal degeneration by the following day. In contrast, neither glutamate nor NMDA treatment caused neuronal degeneration inNR1‐/‐cells, indicating that NMDA receptors are responsible for rapidly triggered glutamate neurotoxicity. The above four compounds were all effectivein inducing the death ofNR1+/+andNR1+/‐neuronal cells after prolonged exposure (20–24 h). However, NMDA had no neurotoxic effects onNR1‐/‐ cells, although the other three compounds were neurotoxic with potencies comparable to those forNR1+/+andNR1+/‐cells. The AMPA and kainate receptors are thus sufficient for inducing slowly triggered glutamate neurotoxicity. Brief exposure of a mixed population ofNR1+/+andNR1‐/‐neuronal cells to NMDA selectively killed the NMDA receptor‐expressing cells without any appreciable effects on neighbouring NMDA receptor‐deficient cells. This finding further supports a direct and indispensable ro

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01168.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe large so‐called type I afferents of the cochlear nerve carry the majority of the auditory input from the cochlea to the cochlear nuclei in the brainstem. These fibres are excitatory and previous studies have suggested they may use glutamate as their neurotransmitter. In the present investigation therefore, antibodies to glutamate and to the glutamate precursor, glutamine, were applied to resin sections of perfusion‐fixed brains and ofin vitrobrain slices subjected to depolarizing levels of potassium before fixation to study glutamate handling and synaptic release. Ultrathin sections were labelled by the immunogold technique, and the immunoreactivity was quantified by recording the density of gold particles over the various tissue profiles. Non‐primary, presumably inhibitory, terminals and glial processes were used as reference structures. The cochlear primary terminals proved to be strongly immunoreactive for glutamate. The density of glutamate labelling was higher in primary terminals than in non‐primary ones, and lowest in glial processes. The ratio between the mean glutamate and glutamine labelling densities was also higher in primary terminals than in non‐primary ones, and lowest in glial processes in each case. In the primary terminals, the glutamate immunoreactivity was higher over vesicle‐containing regions than over vesicle‐free regions, whilst glutamine was evenly distributed throughout. Thein vitrobrain slices showed a potassium‐induced, partly calcium‐dependent depletion of glutamate from the primary terminals but not from the non‐primary ones. These observations strongly support the conclusion that glutamate is a neurotransmitter of type I

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01169.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe nucleus of the optic tract (NOT) and the dorsal terminal nucleus of the accessory optic tract (DTN) are essential nuclei for the generation of slow‐phase eye movements during horizontal optokinetic nystagmus. We recorded from 101 neurons (all directionally selective) in four NOT/DTN of three trained and behaving rhesus monkeys. Neuronal activity increased when stimuli moved ipsiversively with respect to the recording site and decreased below spontaneous activity when stimuli moved contraversively. While the monkey fixated a small spot, some NOT/DTN neurons did not respond at all to the retinal image slip of a whole‐field random dot pattern; others showed a monotonic increase of activity to increasing velocities of that stimulus. The velocity range tested was up to 100°/s. During the execution of optokinetic nystagmus, 39 of 73 cells tested showed a velocity‐tuned response with an average optimum at 21°/s retinal image slip. Following saccades during optokinetic nystagmus (quick phases), the NOT/DTN neuronal activity briefly attained the level of spontaneous activity, as predicted from the velocity selectivity during optokinetic nystagmus. Immediately upon cessation of optokinetic stimulation in the preferred direction, NOT/DTN activity returned to the spontaneous level and did not reflect the ongoing optokinetic afternystagmus in darkness. Most NOT/DTN neurons displayed direction selectivity also during smooth pursuit. Twenty‐one of 50 cells tested (42%) always responded to the retinal slip of the target (target velocity cells), 16 cells (32%) responded to the retinal slip of the background (background velocity cells), and 13 cells (26%) did not respond at all during smooth pursuit. We conclude from our results that the NOT/DTN is an essential structure for the processing of the direction and speed of retinal image slip. This information is then used for the generation and maintenance of slow eye movements, preferentially during horizontal optokinetic nystagmus but also during pursuit eye

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1996.tb01170.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY