摘要:

AbstractThe distribution of choline acetyltransferase immunoreactivity in the rat thalamus was investigated by using a specific monoclonal antibody and was compared with the pattern of acetylcholinesterase staining. The only choline acetyltransferase‐immunoreactive cell bodies in the thalamus were in the medial habenula. A wide range of densities of immunoreactive fibers and varicosities was found. The highest densities of stained varicosities were in the anteroventral, reticular, lateral mediodorsal, and intralaminar nuclei. At the other extreme, the anterodorsal, ventroposteromedial, and paraventricular nuclei were almost devoid of immunoreactive varicosities. A light density of fibers was observed in several medial nuclei, including parataenial, reuniens, and gelatinosus. Most other nuclei contained moderately dense regions of varicose fibers that were often heterogeneous or patchy. The pattern of choline acetyltransferase immunoreactivity in the thalamus was in general similar to that of acetylcholinesterase. A marked discrepancy, however, was found in the anterodorsal nucleus, which was intensely stained for acetylcholinesterase but contained no apparent choline acetyltransferase immunoreactivity. Numerous physiologic studies have demonstrated striking effects of acetylcholine on thalamic activity. The present study provides a description of choline acetyltransferase‐immunoreactive structures in the thalamic nuclei, providing a first step toward elucidating the anatomical basis for the physiologic and functional importance of cholinergic transmission in the thala

ISSN:0092-7317    

DOI:10.1002/cne.902570302

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution of tyrosine‐hydroxylase (TH)immunoreactive cell bodies and fibers in the diencephalon has been investigated with immunohistological techniques in the pigeon. The results suggest that TH is present in a number of morphologically distinct neuronal systems. Preoptic and hypothalamic TH neurons were subdivided into a medial periventricular and a lateral group. The medial group starts with a rostral collection of small cells in the preoptic region. A significantly larger collection of TH neurons occupies the paraventricular nucleus (PVN)(stratum cellulare internum) and mainly consists of large multipolar cells. Further caudally, the main concentration of cells is in the hypothalamic posteromedial and the periventricular regions of the tuberoinfundibular (arcuate) nucleus. No TH neuron was found in the ventral and lateral parts of the tuberoinfundibular region, suggesting that the prominent tuberoinfundibular dopaminergic system described in mammals is absent in the pigeon. This is further substantiated by the relative scarcity of TH immunoreactive fibers and varicosities in the neurohemal zone of the median eminence (ME). The caudalmost components of the medial group appear to be continuous with the large population of TH neurons distributed in the midline of the mesencephalon. Tyrosine‐hydroxylase‐immunopositive cells have not been found in the paraventricular organ. The lateral group consists of TH neurons loosely arranged in the lateral hypothalamus, including regions of the supraoptic nucleus and hypothalamic posterolateral nucleus. Tyrosine‐hydroxylase containing neurons vary widely in size, shape, and dendritic arborization in each diencephalic region. However, it is possible to distinguish two main cell types. Small bipolar neurons with two simple arborizing dendrites were concentrated in the medial periventricular system. The second type of cell is large, multipolar with four to five branching dendrites. This latter cell type occurs mainly in the lateral system and in the PVN. Major fiber bundles containing TH immunoreactivity were identified in the lateral and periventricular hypothalamus. The paraventricular organ and the organum vasculosum laminae terminalis contained the densest arborization of fibers and varicosities. In the ME, dense innervation was found in the subependymal layer. Dense arborizations of TH positive fibers and varicosities were located in the septal nuclei and the paleostriatum augme

ISSN:0092-7317    

DOI:10.1002/cne.902570303

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

年代:1987

数据来源: WILEY

摘要:

AbstractUnilateral local nonspiking interneurons in the terminal (sixth) abdominal ganglion of crayfish (Procambarus clarkiiGirard) can be classified into two major groups of PL and AL types by their gross morphology and somatic position. These premotor interneurons are the neural components of uropod motor pattern formation. They receive sensory input from the exopodite of the contralateral side as well as that of the ipsilateral side. Small fluctuations in their membrane potentials cause sustained change in activity of the motoneurons innervating the uropod muscles. PL interneurons, which make noninverting connections to an identified closer, the reductor motoneuron No. 1, mainly receive excitatory input from the afferents of the contralateral exopodite, whereas inverting PL interneurons receive inhibitory input. AL interneurons receive distinctly different input from the afferents. Noninverting AL interneurons mainly receive inhibitory input, whereas inverting AL interneurons receive excitatory input. The rate of discharge of the reductor motoneurons is increased by sensory stimulation. The PL interneurons form either excitatory or disinhibitory pathways, which are relevant in function to the observed increase of the motoneuron. Conversely, the AL interneurons form either inhibitory or disfacilitatory pathways. Thus, the PL and the AL interneurons are fractionated in function and distinguishable in terms of their physiology by their input and output correlations. Functional meaning of the presence of these two types of unilateral local nonspiking interneurons of opposing connections in the uropod motor control system is discussed.

ISSN:0092-7317    

DOI:10.1002/cne.902570304

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe organization of intracortical and callosal projecting cell bodies was examined in somatosensory representation areas I (SI) and II (SII) of the raccoon by use of horseradish peroxidase (HRP) or horseradish peroxidase‐wheat germ agglutin (HRP‐WHA) HRP and HRP‐WHA were injected into commissurally and noncommissurally connected subdivisions of SI and SII. Injection sites in SII were identified electrophysiologically. Results were obtained from transverse sections in which the HRP was visualized with the aid of the substrates dihydrochlorobenzidine or tetramethyl benzidine in the presence of hydrogen peroxidase.The principal findings were the following: (1) there are reciprocal connections between SI and SII; (2) in SI the intracortically projecting cell bodies and terminals are located primarily in sulcal cortex; (3) intracortically projecting neurons in SI are located primarily in layers III whereas in SII they are located principally in layers III and V; (4) there are connections between disparate areas within SI; and (5) there are intracortical connections between callosum‐connected and acallosal regions in SII. These results are discussed with regard to the results of mapping studies of the SI, the significance of intracortical connections to the formation of sulci in SI, and the possible roles of nonhomotopic connections in the intermanual transfer of l

ISSN:0092-7317    

DOI:10.1002/cne.902570305

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution and the time of origin of corticospinal neurons were examined in rats prenatally exposed to ethanol and in control rats. The distribution of corticospinal neurons was determined by tracing the retrograde transport of horseradish peroxidase (HRP) from an injection site in the cervical spinal cord.In control rats, HRP‐positive neurons were distributed in layer Vb throughout motor area 4, rostral motor area 6/8, dorsal somatosensory area 3, caudal somatosensory area 2, and various “association” regions including parietal areas 14, 39, and 40, occipital areas 18a and 18b, cingulate areas 24a and 24b, and prefrontal area 32. In ethanol‐exposed rats, the distribution of retrogradely labeled neurons was similar to control animals with three notable exceptions: (1) HRP‐positive neurons were evident throughout the rostrocaudal extent of area 6/8; (2) occasionally ectopic labeled neurons were identified in the supragranular layers, layers Va and Vc, and superficial layer VI; and (3) the density of HRP‐labeled neurons and the ratio of labeled neurons to the total number of neurons in areas 4, 6/8, 3, and 2 were significantly greater (20–48%) in ethanol‐exposed rats than in controls. There was, however, no intergroup difference in the area of the cell bodies of HRP‐positive neurons. Taken together, these findings indicate that ethanol exposure resulted in an increased number of corticospinal neurons.The time of origin of corticospinal neurons was determined by using a technique that combined tritiated thymidine autoradiography and retrograde transport of HRP. In control animals, HRP‐positive neurons were double labeled by an injection of tritiated thymidine on gestational day (GD) 15, 16, or 17. In ethanol‐exposed rats, corticospinal neurons were generated on GD 16, 17, and 18, the late‐generated ones being distributed in caudal area 6/8.These intergroup differences represent a persisting ethanol‐induced alteration of cortical structure that may underlie motor dysfunction and mental retardation in fetal alcohol‐affected offspring. Moreover, the increase in the number and the delay in the time of origin of corticospinal neurons suggest that the normal process of paring down exuberant orticospinal projections may be affected by p

ISSN:0092-7317    

DOI:10.1002/cne.902570306

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

年代:1987

数据来源: WILEY

摘要:

AbstractNeurotensin‐like immunoreactivity (NT‐LI) was demonstrated in projection neurons of the striatum and nucleus accumbens in the cat by combining immunohistochemistry and the fluorescent retrograde neuronal labeling method. In colchicine‐treated cats, many neurons with NT‐LI were found in the caudate nucleus, nucleus accumbens, and putamen. Most of these neurons were medium‐sized neurons with spiny dendrites. NT‐LI of neuronal elements in the caudate nucleus and nucleus accumbens formed dense aggregates with irregular figures, which appeared to correspond to the striosomes of Graybiel et al. (Proc. Natl. Acad. Sci. USA 75: 5723–5726, '78;Exp. Brain Res. 34: 189–195, '79;Neuroscience 6: 377–397, '81). Fibers with NT‐LI were distributed massively to the globus pallidus and ventral midbrain regions, but not to the entopeduncular nucleus. In the ventral midbrain regions, many fine varicose fibers with NT‐LI were distributed to the pars compacta and pars lateralis of the substantia nigra, ventral tegmental area, and retrorubral area. In the pars reticulata of the substantia nigra, however, fibers with NT‐LI were rather sparse.Examination of consecutive sections immunostained for NT, enkephalin (Enk), GABA, and substance P (SP) revealed that 50% of neurons with NT‐LI in the caudate nucleus and nucleus accumbens exhibited Enk‐LI, 15% showed GABA‐LI, and 5% manifested both Enk‐LI and GABA‐LI; no NT‐positive neurons in the striatum and nucleus accumbens showed SP‐LI. No morphological differences were found between NT‐positive neurons with Enk‐LI and/or GABA‐LI and those without Enk‐LI and GABA‐LI.Most neurons with NT‐LI in the striatum and nucleus accumbens were retrogradely labeled with True Blue injected into the globus pallidus, pars compacta and pars lateralis of the substantia nigra, and ventral tegmental area. After hemitransection severing neuronal connections between the ventral midbrain regions and the forebrain structures, fibers with NT‐LI and those with Enk‐LI in the ventral midbrain regions were markedly reduced in number.On the basis of the present results, combined with those reported previously, it was assumed that most of the NT‐containing neurons in the striatum and nucleus accumbens sent projection fibers massively to the globus pallidus, pars compacta and pars lateralis of the substantia nigra, and retrorubral area, and sparsely to the pars reticulata of the substantia nigra; NT‐containing striatal neurons with Enk‐LI sent projection fibers mainly to the globus pallidu

ISSN:0092-7317    

DOI:10.1002/cne.902570307

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

年代:1987

数据来源: WILEY

摘要:

AbstractResponses of single units in theXenopustectum to stimulation of the contralateral anterior lateral line nerve (cALLN) and optic nerve were studied. Cells responded to cALLN stimulation with a phasic burst of spikes that was repeatable between trials; latencies ranged from 4 to 23 msec. The most excitable cells were located in layer 6 of the ventrolateral tectum. Cells responding to stimulation of the ipsilateral ALLN were far less numerous and robust, and showed latencies 3–10 msec greater than those of contralateral responses. Tectal cell responses to cALLN nerve stimulation grew progressively to saturation with stimulus voltage and paralleled the growth of the ALLN compound action potential; cells responded to stimulation of either supra‐ or infraorbital branches of cALLN. These observations indicate convergence of primary lateral line afferents in the medulla and/or tectum. Lateral line tectal cells showed strong habituation at interstimulus times less than 8–20 seconds. Experiments on bimodal cells revealed facilitatory and inhibitory interactions between optic and lateral line inputs. Some cells responded to stimulation of either lateral line or optic nerves, with combined stimulation producing responses exceeding the sum of responses to separate nerve stimulation. In other cells the response to optic nerve stimulation was markedly increased by lateral line nerve stimulation, despite the absence of response to lateral line nerve stimulation alone. Facilitation was also evident in cells that responded only to combined stimulation of lateral line and optic nerves. Some cells exhibited an early (5–10 msec) and late (20–40 msec) response to optic nerve stimulation; lateral line nerve stimulation, despite eliciting no response itself, produced strong facilitation of the early but almost complete suppression of the late optic nerve

ISSN:0092-7317    

DOI:10.1002/cne.902570308

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

年代:1987

数据来源: WILEY

摘要:

AbstractReeler, an autosomal recessive mutation in mice, causes cytoarchitectonic abnormalities of the cerebral cortex, which are characterized by malposition of neurons. Retrograde and anterograde transport of horseradish peroxidase (HRP) was employed to examine the reciprocal connectivity between the hindlimb area of the primary motor cortex (MI) and thalamus of normal and reeler mutant mice. In the normal mouse, most of the cells labelled after HRP injection into the hindlimb area of MI were located in the ventrolateral nucleus, the lateral division of the ventrobasal nucleus, the central lateral, paracentral and central intralaminar nuclei, and the medial division of the posterior complex. HRP reaction product antero‐gradely transported was also observed in the same nuclei and in the thalamic reticular nucleus. In the reeler mutant mouse, retrogradely labelled neurons and anterogradely labelled terminals were again found in the nuclei referred to above, and the distribution pattern and morphology of HRP‐filled neurons were also similar to those of normal controls. The present results suggest therefore that the normal reciprocal connectivity between MI (hindlimb representation) and thalamus is preserved in the reeler mouse. That is to say, dislocated cortical neurons appropriately project to their target nuclei of the thalamus, and conversely, thalamic neurons send their axons precisely to their target cortical areas of the radially disorganized cor

ISSN:0092-7317    

DOI:10.1002/cne.902570309

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe functional organization of geniculocortical afferents and the visual responses of neurons in primary visual cortex (area 17) were studied in barbiturate‐anesthetized, paralyzed minks and cats.Responses of the afferents were studied after silencing intrinsic cortical activity with injections of kainic acid. In both species, afferents were segregated into patches on the basis of eye of origin. In the mink, but not in the cat, there was a further segregation on the basis of center type, with on‐ and off‐center afferents terminating in alternating, partially overlapping patches.The visual responses of cortical neurons in the mink showed many similarities to those in the cat. Nearly all units were orientation‐selective, and there was a columnar organization for preferred orientation. Many units were selective for one direction of movement. Within the binocular segment of cortex, although many units could be driven from either eye, there was a marked bias toward the contralateral eye compared to the cat. There was a columnar system for ocular dominance, but contralateral eye columns were wider than ipsilateral.In both species, a quantitative study was made of the responses of cortical neurons to stationary, flashing slits as a function of position in the receptive field. In the mink, and less clearly in the cat, units could be identified as simple or complex on the basis of the spatial separation or overlap of “on” and “off” discharge zones. In both species, simple cells were found most commonly in layers IV and VI, while layer V contained the greatest proportion of complex cells.The relative strengths of the on and off discharges of single cells were also measured. In the mink, many units gave better overall responses to the on or off phase of the stimulus, and 15% showed a strong (>9:1) preference for one or the other, compared to 4% in the cat.In the mink, units with a common preference for the on or off phase of stationary stimuli were arranged in columnar aggregates, a feature of cortical organization that was not found in the cat. These columns probably result from the partial segregation of on‐center and off‐center geniculate afferents within layers IV and VI of the mink's cortex. On‐dominated columns were, however, wider or more numerous than

ISSN:0092-7317    

DOI:10.1002/cne.902570310

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn the vertebrate olfactory bulb, the primary projection neurons, mitral and tufted cells, have reciprocal dendrodendritic synapses with respective subpopulations of anaxonic interneurons called granule cells. In the neurological murine mutant Purkinje Cell Degeneration (PCD) all mitral cells are lost during early adulthood. As a consequence, a subpopulation of granule cells is deprived of both afferent input and efferent targets. The effect of this event, on the morphology and sublaminar distribution of granule cells was studied with light microscopic Golgi procedures in affected homozygous recessive PCD mutants and normal heterozygous littermate controls. In the control mice, a minimum of three subpopulations were identified predominantly on the basis of the topology of apical dendrites and their spinous processes within the external plexiform layer (EPL) of the olfactory bulb: type I had dentrites extending across the full width of the EPL and a homogeneous distribution of spines; type II had dendritic arbors confined to the deeper EPL; type III had apical dendrites that arborized extensively within the superficial EPL with no arbors or spines present in the deeper EPL. Prior studies suggest that type II cells form connections with mitral cells; type III cells form connections with tufted cells; and type I cells may integrate information from both populations of projection neurons. In the mutant PCD mice, the classification of subpopulations of granule cells proved difficult due to a compression of dendritic arbors within the EPL. Dendritic processes followed a more horizontal tangent relative to the radial orientation seen in control mice. The length of dendritic branches was reduced by approximately 20% with a corresponding decrease in the number of spines. The density of spines ( #/1 m̈m of dendrite) was constant in both controls and mutants at approximately 0.21. Truncation of the dendrites in the PCD mutants appeared to occur at terminal portions because the number of dendritic bifurcations was equal in both groups of mice. The data are discussed in terms of subpopulations of granule cells in the mouse olfactory bulb, the sublaminar organization of olfactory bulb circuits, and the capacity for survival and plasticity in the reciprocal dendrodendritic circuits mediated by the granule cell spines

ISSN:0092-7317    

DOI:10.1002/cne.902570311

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

年代:1987

数据来源: WILEY