摘要:

AbstractImmunocytochemistry with antibodies against the calcium binding proteins parvalbumin (PV) and calbindin (CaBP‐28kD) was used to study horizontal cells in the macaque monkey retina. Both morphological types (H1 and H2) are stained by PV immunocytochemistry. Horizontal cells in the centre of the fovea are described for the first time. From a minimum of 250/mm2at the foveal centre, total horizontal cell density rapidly increases to a peak of 23,000/mm2in an annulus of 0.6 mm radius around the fovea. Horizontal cell density then drops continuously to approximately 800–1000 cells/mm2in peripheral retina. The density ratio of cones to horizontal cells is 1.5 in central and 4 in peripheral retina.The cones were stained with antibodies against CaBP‐28kD. Thus the spatial correlation between the cone inner segments and the cone pedicles could be measured to show that they are in perfect register. There is no reorganization of the spatial array of cone outer segments to produce chromatically specific connections between cone pedicles and horizontal

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00349.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractHorizontal cells of the macaque monkey retina were quantified and the number of cones converging onto an individual horizontal cell as well as the number of horizontal cells contacting a single cone were determined. This was done by combining data from individual horizontal cells stained by the Golgi method with the results of immunocytochemical staining described in the preceding paper (Röhrenbeck et al., 1989).The observation (Boycott et al., 1987) that all horizontal cells contact all cones in their dendritic field irrespective of cone type was confirmed. The particular cones contacted by the terminal aggregates of each horizontal cell were found. The dendritic fields of H1 and H2 cells increase with increasing eccentricity; close to the fovea H1 cells are smaller than H2 cells, at 6 mm eccentricity they are about the same size and in peripheral retina H1 cells are much larger than H2 cells. The density gradients of the two cell types balance their denritic field changes so that throughout the retina each and every cone synapses with 3–5 horizontal cells of each type. Horizontal cells of both cat (Wässle et al., 1978) and monkey retina follow the general rule that all cones in the dendritic fields are contacted, their perikarya form a regular mosaic and the boundaries of their dendritic fields are marked by the perikarya of their homologous neighbo

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00350.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractUsing anin vitroincubation method, we stimulated cGMP production in rat brain slices by rat ANF‐(103–126). The localization of the cells responding to this ANF stimulation with an increase in cGMP production was studied by cGMP immunocytochemistry. ANF‐responding cells were found in specific loci throughout the central nervous system of the rat. Regions containing the highest number of these cells were: the olfactory bulb, the lateral septum, the bed nucleus of the accessory olfactory tract, the mediobasal amygdala, the central grey area, the medial vestibular nucleus, and the nucleus of the solitary tract. Scattered ANF‐responding, cGMP‐immunoreactive cells were found in the hippocampus, the cingulate cortex, the ventral pallidum, the medial preoptic area, and the endopeduncular nucleus. ANF‐responding cells in these areas had the same morphology, that is, multipolar with numerous processes. The nature of these ANF‐responding cells was studied by sequential staining with an antiserum against glial fibrillary acidic protein (GFAP). In the hippocampus it was demonstrated that all ANF‐responding cells are astroglial cells. However, not all astroglial cells in this area showed a cGMP response, demonstrating a regional heterogeneity. ANF‐responding cells, having the appearance of neuronal cell bodies, could be found in the subfornical organ, and the hypothalamic paraventricular nucleus. Fibres producing cGMP immunoreactivity in response to ANF were found in the median preoptic nucleus, the medial preoptic area, and the do

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00351.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractRats with neocortex totally removed (decorticates), rats with hippocampal lesions (hippocampals), and their surgical controls, were trained on a fixed interval (FI) 40 s schedule, where the first bar‐press response made more than 40 s after a previous reinforcement was rewarded. The decorticates and hippocampals adopted similar patterns of behaviour to the control groups though there were between‐group differences in the details of performance. Compared to controls the hippocampals showed shorter post‐reinforcement pauses and faster overall rates of responding, whilst the reverse was true of the decorticates. Some of this performance difference in the decorticates was attributed to difficulty in retrieving and consuming solid food reinforcement. The performance of the decorticates and hippocampals, as reflected by the post‐reinforcement pause, response distribution and running rate as a function of post‐reinforcement pause duration, suggests that timing remains operational in both groups. The differences in response profiles between the two experimental groups, however, indicate that hippocampus and neocortex probably make independent contributions to performance in this situation. The decorticates and their control group were later transferred from the FI to a response‐independent fixed time (FT) 40 s schedule. Both groups then returned to the former FI 40 s schedule. The decorticates adjusted their behaviour to the different schedules in the same way as the control animals. The results overall are consistent with previous findings that decortication does not abolish normal patterns of operant learning and extends them to include tempora

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00352.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe importance of trophic agents for the development and maintenance of neurons and their presence in mesenchyme‐derived neuronal target organs such as muscle is well exemplified by the protein nerve growth factor (NGF) and its synthesis in target areas of sympathetic and sensory nerves. Stringent conceptualization of target organ‐regulated neuronal maintenance would imply that neurons were able to provide trophic support to their presynaptic counterparts. We present data suggesting that basic fibroblast growth factor (bFGF), a mitogen and trophic factor for several neuron populationsin vitro, may be such a protein involved in retrograde trophic neuron‐neuron interaction. Basic FGF or a closely related protein is present in the adrenal medulla and its sympathetic neuron‐like chromaffin cells. A polyclonal antibody specific for bFGF recognizes an 18 kD band in Western blots of bFGF‐enriched bovine adrenal medulla extracts and immunostains isolated bovine chromaffin cells. This antibody also blocks the bFGF‐like activity present in adrenal medullary extracts and chromaffin granule extracts that both promotein vitrosurvival of embryonic chick ciliary ganglionic neurons. Furthermore, like bFGF, the soluble proteins of bovine chromaffin granules are mitogenic for cultured bovine aorta endothelial cells. Electrothermal unilateral destruction of the adrenal medulla causes the disappearance of 25% of Nissl‐stained neurons in the ipsilateral intermediolateral column (IML) of the spinal cord between levels Th7 and L1, which contains the preganglionic neurons projecting to the adrenal medulla. Substitution of the adrenal medulla by gel foams soaked with bFGF prevents neuron losses in the IML. The effects are specific in that NGF and cytochrome C are ineffective. Our results suggest that bFGF is located in chromaffin cells and maintains target‐deprived autonomic spinal cord neurons, thus possibly acting as an interneuronal trophic m

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00353.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractIntracellular recordings have been made from neurons of the superficial dorsal horn in slices of the lumbar and thoracic spinal cord of young adult rats. Three broad categories of neurons could be distinguished on the basis of their firing patterns to intracellular current pulses and their afterhyperpolarizations (AHP); there was no detectable difference in the regional distribution of the three types. Category 1 cells were characterized by maintained firing to intracellular depolarizing current pulses, brief action potential durations and polyphasic AHPs. Category 2 cells showed spike adaptation, without spike attenuation, during intracellular current pulses, and had monophasic AHPs. Category 3 cells fired only 1 or 2 spikes to maintained depolarizing pulses and had smaller monophasic AHPs than category 2 neurons. Spontaneous excitatory and inhibitory postsynaptic potential (epsp and ipsp) activity was seen with psp durations varying widely. Low intensity electrical stimulation of afferent fibres, or of superficial white matter, resulted in polyphasic epsps and/or ipsps. The spike discharge in response to such afferent inputs correlated with the membrane properties of the cells, such that the synaptic responses of category 1 neurons were usually bursts of spikes, whereas category 2 and 3 neurons either failed to fire or fired only a single spike. These results in adult rat spinal cord suggest that the discharge pattern within synaptic sensory responses of superficial dorsal horn neurons is determined by postsynaptic membrane properties as well as by the pattern of the afferent input.

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00354.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of somatostatin (SS14) on neocortical neurons of the rat were investigated in anin vitroslice preparation. Intracellular recordings were performed in neurons (n=30) in layers 2 and 3 of the frontal cortex.Iontophoretically applied SS14 reduced the responses evoked by iontophoretically applied L‐glutamate (GLU) and γ‐aminobutyric acid (GABA). The blocking effect of SS14 was apparent 1–2 min after onset of SS14 application and recovery required 2–3 min. The conductance increase evoked by GLU or GABA was reduced by SS14. In the majority of neurons, SS14 did not produce any measurable changes in passive membrane properties, spike threshold or on orthodromically evoked synaptic potentials. In 5 cells, SS14 induced a slight hyperpolarization (<3 mV).These results lend further support to claims that SS14 plays a neuromodulatory role in the n

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00355.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have studied the connections between two visual areas of macaque monkey cortex, V2 and V4, by injecting wheat‐germ agglutinin horseradish peroxidase (HRP‐WGA) into V4 and examining the distribution of labelled cells and terminals in V2, in relation to its characteristically striped cytochrome oxidase architecture. The cells projecting from V2 to V4 are arranged in bands and the number of bands per cycle of cytochrome oxidase stripes varies (one cycle consists of a thin stripe, a thick stripe and two interstripes). In the Type 1 connectivity pattern, there is just one band per cycle, centred over the thin stripes but normally spreading into the neighbouring interstripes. In the Type 2 connectivity pattern there are two bands per cycle, generally rather narrower and centred over the interstripes. Thick stripes are mostly free of labelled cells. The return projection from V4 to V2, whilst being concentrated in the vicinity of the labelled cells, is more diffusely distributed and invades the territory of all the stri

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00356.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractXenopusembryos immobilized in tubocurarine respond to natural skin stimulation with fictive swimming. This can also occur in saline without Mg2+and is blocked by NMDA antagonists. Ventral spinal cord neurons which are rhythmically active during swimming are depolarized by bath applied N‐methyl‐D‐aspartate (NMDA) (in 1 μM tetrodotoxin (TTX) to block indirect effects). By using current clamp techniques this depolarization is shown to be partially blocked by 0.5 and 1 mM Mg2+in a voltage‐dependent manner similar to that described in cultured neurons.Mg2+partially and reversibly reduces the slow NMDA‐mediated component of excitatory post‐synaptic potentials (EPSPs) in ventral neurons. However, in 1 mM Mg2+fictive swimming can still be evoked by natural stimulation. The frequency of swimming is slightly lower than in nominally 0 mM Mg2+, but the pattern of ventral root activity and synaptic drive to ventral neurons seems little affected. Fictive swimming can also be induced by applying NMDA to spinal preparations. In 0 mM Mg2+, such rhythmic activity is unstable and transient over a narrow NMDA concentration range. In 0.5 mM Mg2+, continuous rhythmic activity is induced over a wide range of NMDA concentrations. Lower spinal preparations need higher NMDA concentrations to induce activity.We conclude that the neurons rhythmically active in swimming have NMDA receptor channels which show a voltage dependent block in the presence of Mg2+. However, while Mg2+exerts a powerful stabilizing influence on rhythmic activity induced in spinal embryos by exogenous NMDA, its influence on ‘naturally’ evoked fictive swimming is less clear. The fictive swimming machinery in the brain and spinal cord can produce stable swimming with or without Mg2+induced voltage dependency of t

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00357.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe anatomical localization of glutamate receptor subtype‐selective ligand binding sites was investigated in 1‐day‐old chick brain using quantitative autoradiography. Under the conditions used, the regional distributions of [3H]glutamate, [3H]AMPA (a selective quisqualate receptor ligand) and [3H]kainate binding sites are manifestly different. [3H]L‐glutamate binding is densely localized in the telencephalon, particularly in the neostriatum (2.8 pmol/mg protein). In addition, [3H]L‐glutamate labels the thalamus, the nucleus mesencephalicus lateralis pars dorsalis, the superficial layers of the optic tectum and the molecular layer of the cerebellum. [3H]AMPA binding sites are most densely localized in the hippocampus (0.90 pmol/mg protein), with an otherwise relatively uniform distribution of binding within the telencephalon. [3H]AMPA also labels the striatum griseum et fibrosum superficiale of the optic tectum and the molecular layer of the cerebellum. [3H]Kainate binding sites are extremely densely packed in the molecular layer of the cerebellum (10 pmol/mg protein). Other regions of [3H]kainate binding include the hyperstriatum and the thalamus. The binding of the NMDA receptor channel blocker [3H]MK‐801 is increased in the presence of 1 mM L‐glutamate. [3H]MK‐801 binding is generally widespread in the telencephalon but is notably absent from the ectostriatum. No evidence of [3H]MK‐801 binding sites was detected in the cerebellum, even in the presence of 1 mM L‐glutamate. The relatively high densities and the well‐defined localizations of the glutamate receptor subtype binding sites suggest that chick brain provides a useful system for the further study of excitatory

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1989.tb00358.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY