摘要:

AbstractThe distribution of two subunits of nicotinic acetylcholine receptors in the developing and the differentiated central nervous system ofDrosophila melanogasterwas studied. With subunit‐specific antibodies raised against the ligand‐binding α‐like subunit ALS and the putative non‐ligand‐binding subunit ARD, we find both ALS‐like and ARD‐like immunoreactivity widely distributed in most neuropiles of the optic lobes, the protocerebrum, the deutocerebrum and the thoracic ganglion of the adult fly. With a single exception, namely in the lamina of the visual system, the antigens recognized by the two types of antibodies are colocalized. This observation is consistent with previous immunoprecipitation data indicating that the ALS and ARD proteins are integral components of the same hetero‐oligomeric receptor that binds the nicotinic antagonist α‐bungarotoxin with high affinity. During embryonic development ARD‐like immunoreactivity is first detectable in ≈︁ 10 hour old embryos. Both subunits are consistently detected in the central nervous system ofthe late embryo, the three larval stages, and all prepupal and pupal stages. During metamorphosis the optic stalk is transiently immunoreactive with anti‐ARD, but not with anti‐ALS antiserum. Although in larvae and adults, immunoreactivity with both types of antibodies is most abundant in synaptic regions, in embryos and pupae strong staining of cortical cell body layers is observed, in particular with anti‐ARD antisera. As these developmental periods coincide with strong accumulation of ARD transcripts, the cell body staining may reflect newly synthesized and assembled receptors, while the functional ARD‐ and ALS‐containing receptor may be destined f

ISSN:0092-7317    

DOI:10.1002/cne.903350202

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractPrevious neuroanatomic and physiologic studies indicated that afferent fibres from slowly adapting pulmonary stretch receptors (SAR) project to the nuclei of the solitary tract and terminate on inspiratory beta‐neurons. In the present study we combined electrophysiologic and morphologic approaches to verify the presumed monosynaptic connections between SARs and beta‐neurons.Single identified beta‐neurons and single identified SAR afferent fibres were labelled intrasomally and intraaxonally, respectively, with horseradish peroxidase (HRP) in the same anesthetized cats. Under the light microscope, we analyzed the morphology of beta‐neurons and their dendritic fields and of the terminal projection pattern of fibres from SARs and identified potential synaptic connections between boutons of SAR afferent fibres and the soma and dendrites of beta‐neurons. The identified tissue was then processed further for electron microscopic analysis.On average, beta‐neurons had 6 primary dendrites that bifurcated 3–8 times. The dendritic trees extended 1.5 mm both rostrocaudally in the ventrolateral nucleus of the solitary tract and medially into the intermediate subnucleus. Axons of beta‐neurons curved toward the midline and no collateral branches were evident over its stained length (2.5–3.4 mm).Axodendritic synaptic contacts between SAR fibres and beta‐neurons were identified electron microscopically in four of six tissue samples chosen by light microscopy. In addition, we located 2 axodendritic and 2 axosomatic synaptic contacts that were not observed under light microscopic screening. The boutons of SAR fibres contained clear, round vesicles and formed asymmetrical synapses with beta‐neurons. Multiple synaptic connections were found between collaterals of a single SAR and single beta‐neurons, indicating a dense terminal projection of single SAR afferent fibres onto beta‐neurons. These morphologic data prove monosynaptic connections between electrophysiologically identified SAR afferent fibres and beta‐neur

ISSN:0092-7317    

DOI:10.1002/cne.903350203

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractArea 3a in the macaque monkey, located in the fundus of the central sulcus, separates motor and somatosensory cortical areas 4 and 3b. The known connections of areas 4 and 3b differ substantially, as does the information which they receive, process, and transfer to other parts of the central nervous system. In this analysis the thalamic projections to each of these three cortical fields were examined and compared by using retrogradely transported fluorescent dyes (Fast Blue, Diamidino Yellow, Rhodamine and Green latex microspheres) as neuron labels. Coincident labeling of projections to 2–3 cortical sites in each monkey allowed the direct comparison of the soma distributions within the thalamic space of the different neuron populations projecting to areas 3a, 3b, and 4, as well as to boundary zones between these cortical fields. The soma distribution ofthalamic neurons projecting to a small circumscribed zone (diameter = 0.5–1.0 mm) strictly within cortical area 3a (in region of hand representation) filled out a “territory” traversing the dorsal half of the cytoarchitectonically defined thalamic nucleus, VPLc (abbreviations as in Olszewski [1952] The Thalamus of theMacaca mulatta. Basel: Karger). This elongate, rather cylindrical, territory extended caudally into the anterior pulvinar nucleus, but not forward into VPLo. The rostrocaudal extent of the thalamic territory defining the soma distribution of neurons projecting to small zones of cortical area 3b was similar, but typically extended into the ventral part of VPLc, filling out a medially concavo‐convex laminar space. Two such territories projecting to adjacent zones of areas 3a and 3b, respectively, overlapped and shared thalamic space, but not thalamic neurons. Contrasting with the 3a and 3b thalamic territories, the soma distribution of thalamic neurons projecting to a circumscribed zone in the nearby motor cortex (area 4) did not penetrate into VPLc, but instead filled out a mediolaterally flattened territory extending from rostral VLo, VLm, VPLo to caudal and dorsal VLc, LP, and Pulo. These territories skirted around VPLc. All three cortical areas (4, 3a, and 3b) also received input from distinctive clusters of cells in the intralaminar Cn.Md. It is inferred that, in combination, the thalamic territories in areas 3a, 3b, and 4 (and also area 1 and 2), which would be coactive during the execution of a manual task, constituted a lamellar space extending from VLo rostrally to Pul.o caudally. How Pul.o neuron populations relate to the more rostral populations within the same thalamic territory projecting to a localized cortical zone remains uncertain. Within the medially located territories the distribution of the neuron population in Pul.o was spatially continuous with the more rostral thalamic cells projecting to the same localized cortex, but in lateral thalamic territories these 2 populations were usually spatially discontinous. In the newborn macaque an orderly change in the territorial projections to localized zones in area 4, 3a, and 3b was also demonstable. However, thalamic nuclear projections were more expansive than in the mature animal. As well as the VPLc input, a third of the thalamic input to area 3a was now from VLo, VPLo, and VLm. Area 4 also had a significant input from VPLc, an input not observed in the mature macaque. © 1993 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903350204

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn the macaque monkey area 3a of the cerebral cortex separates area 4, a primary motor cortical field, from somatosensory area 3b, which has a subcortical input mainly from cutaneous mechanoreceptive neurons. That each of these cortical areas has a unique thalamic input was illustrated in the preceding paper. In the present experiments the cortical afferent projections to these 3 areas of the sensorimotor cortex monkey were visualized and compared, using 4 differentiable fluorescent dyes as axonal retrogradely transported labels. The cortical projection patterns to areas 3a, 3b, and 4 were similar in that they each consisted of (a) a “halo” of input from the immediately surrounding cortex, and (b) discrete projections from one or more remote cortical areas. However, the pattern of remote inputs from precentral, mesial, and posterior parietal cortex was different for each of the 3 cortical target areas. The cortical input configuration was least complex for area 3b, its remote input projecting mainly from insular cortex. The pattern of discrete cortical inputs to the motor area 4, however, was more complex, with projections from the cingulate motor area (24c/d), the supplementary motor area, postarcuate cortex, insular cortex, and postcentral areas 2/5. Area 3a, in addition to the proximal projections from the immediately surrounding cortex, also received input from the supplementary motor area, cingulate motor cortex, insular cortex, and areas 2/5. Thus, this pattern of cortical input to area 3a resembled more closely that of the adjacent motor rather than that of the somatosensory area 3b. Contrasting with this, however, the thalamic input to area 3a was largely from somatosensory VPLc (abbreviations from Olszewski [1952] The Thalamus of theMacaca mulatta. Basel: Karger) and not from VPLo (with input from cerebellum, and projecting to precentral motor areas). © 1993 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903350205

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractExtracellular and intracellular recording, receptive field mapping, and intracellular HRP injection techniques were used to define the morphological classes of cells in the deep laminae of the hamster's superior colliculus and to determine whether there are any correlations between the structural and functional characteristics of these neurons. A total of 110 neurons were characterized and reconstructed. Of these, 23.6% (N = 26) were visual, 60% (N = 66) were somatosensory, 0.9% (N = 1) were bimodal (visual‐somatosensory), and 15.4% (N = 17) were unresponsive. Of the somatosensory neurons, 72.7% (N = 48) were low threshold, 4.5% (N = 3) had a wide dynamic range, 9.1% (N = 6) responded only to noxious stimulation, and 13.6% (N = 9) had complex somatosensory receptive fields.Deep layer cells were divided into eight morphological classes. These classes were multipolar cells (26.4%, N = 29), bipolar cells (9.1%, N = 10), widefield vertical cells (7.3%, N = 8), horizontal cells (13.6%, N = 15), stellate cells (10.9%, N = 12), ventrally directed cells (5.5%, N = 6), sparse radial cells (17.3%, N = 19), and small sparse radial cells (6.4%, N = 7). Four cells (3.6%) did not fit into this classification scheme. Univariate and multivariate analyses of variance of properties such as soma area, number of branch points, total dendritic length, and volume and orientation of dendritic arbor indicated that these classes were significantly different. However, X2analysis and multivariate analysis of variance indicated no significant relationships between morphological class and either laminar location or receptive field type. There was a significant positive relationship between the possession of dendrites that extended into the superficial laminae and visual responsivity. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903350206

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractImmunohistochemical methods were used to study the distribution of substance P in the brain of the small‐spotted dogfish (Scyliorhinus canicula). Substance P‐like immunoreactive (SP‐IR) cell bodies and fibers were widely distributed. In the telencephalon, sparse populations ofSP‐IR neurons are present in the olfactory bulbs, pallium, and subpallium. In the subpallium numerous SP‐IR boutons form unusual coats (“pericellular appositions”) on SP‐immunonegative neurons. In the diencephalon numerous SP‐IR cerebrospinal fluid‐contacting neurons are present in the preoptic recess organ and organon vasculosum hypothalami. Numerous SP‐IR fibers also run in the hypothalamus, although no immunoreactivity was observed in the habenulo‐interpeduncular system. A terminal field of SP‐IR fibers is present in the median eminence. In the mesencephalic tegmentum, SP‐IR neurons were observed in the Edinger‐Westphal nucleus. SP‐IR fibers are present at high density in the basal tegmentum, forming a conspicuous tract. In the hindbrain, numerous SP‐IR fibers were observed in the isthmal region, the trigeminal descending root, the visceral sensory area and commissural nucleus, and the visceromotor column. SP‐IR fibers occur at high density in the substantia gelatinosa of the rostral

ISSN:0092-7317    

DOI:10.1002/cne.903350207

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe dorsal octavolateralis nucleus of lampreys is a primary nucleus for electroreceptive stimuli in the medulla. InLampetra japonica, the rostral and caudal thirds of this nucleus are exclusively occupied by giant terminals, which become evident when the primary fibers of an electrosensory nerve (recurrent branch of the anterior lateral line nerve) are labeled with horseradish peroxidase. We studied the ultrastructure of these terminals. They contain neurofilaments, mitochondria, microtubules, and tubular membranous structures. Many synapses, all of the chemical type, are located around the neck region of the terminal swellings. Many vesicular structures, which are clear, round, and uniform in size, and most of which are probably synaptic vesicles, are densely clustered in a single large mass in the neck region of the terminals. Some of the tubular structures may serve as a membrane reservoir for the large number of synaptic vesicles required in the giant terminals. © 1993 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903350208

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractDistribution of the mRNA for a metabotropic glutamate receptor, mGluR3, which is coupled to the inhibitory cAMP cascade, was examined in the central nervous system of the adult albino rat by in situ hybridization. The hybridization signals of mGluR3 were detected not only on neuronal cells but also on many glial cells throughout the brain and spinal cord. In the neuronal cells, prominent expression of mGluR3 mRNA was seen in the thalamic reticular nucleus. Moderately labeled neurons were seen in the anterior olfactory nucleus, cerebral neo and mesocortical regions, lateral amygdaloid nucleus, ventral part of the basolateral amygdaloid nucleus, dorsal endopiriform nucleus, supraoptic nucleus, superficial layers of the superior colliculus, inferior colliculus, interpeduncular nucleus, superior olivary nuclei, and Golgi cells in the cerebellar cortex. Weakly labeled neurons were observed in the striatum, nucleus accumbens, ventral pallidum, globus pallidus, entopeduncular nucleus, lateral hypothalamic area, hypothalamic paraventricular nucleus, medial habenular nucleus, anterior pretectal nucleus, Barrington's nucleus, Nucleus O, paragenual nucleus, trigeminal sensory complex, cochlear nuclei, dorsal motor nucleus of the trigeminal nerve, dorsal cap of the inferior olive, spinal dorsal horn, and lamina X of the spinal cord. The stellate cells in the cerebellar cortex, and neurons in the deep cerebellar nuclei were also labeled weakly. The granule cell layer of the dentate gyrus, as a whole, appeared to be labeled intensely, but each of the granule cells was labeled only weakly. No significant labeling was detected in the mitral and tufted cells in the olfactory bulb, hippocampal pyramidal cells, Purkinje and granule cells in the cerebellar cortex, or somatic motoneurons. The distribution of mGluR3 mRNA in particular neurons and glial cells indicates specific roles of mGluR3 in the glutamatergic system of the central nervous system. © 1993 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903350209

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe term “Bötzinger Complex” (BOT) refers to a distinct group of neurons, located near the rostral portion of the nucleus ambiguus, which are known to play an important role in the control of respiratory movements. Previous studies conducted in cats have demonstrated that most of these neurons are active during expiration, exerting a monosynaptic inhibitory action on several subpopulations of inspiratory neurons in the medulla and spinal cord. The aim of this study was to examine morphological properties and possible synaptic targets of BOT neurons in the rat. Forty‐one expiratory neurons were labeled intracellularly with biocytin; 12 were interneurons (BOT neurons) and 29 were motoneurons. The latter could not be antidromically activated following stimulation of the superior laryngeal or vagal nerves. BOT neurons showed extensive axonal arborisations in the ipsilateral medulla, with some projections to the contralateral side. Bouton‐like axon varicosities mainly clustered in two areas: near the parent cell bodies, and in the area corresponding to the rostral part of the ventral respiratory group (VRG). In five pairs of labeled neurons, each consisting of one BOT neuron and one inspiratory neuron in the rostral VRG, no appositions were identified at the light microscopic level between axons of BOT neurons and dendrites or cell bodies of inspiratory neurons. These results demonstrate that some features of BOT expiratory neurons in the rat are similar to those previously described in cats. The differences include their more ventral location in relation to the compact formation of nucleus ambiguus (retrofacial nucleus), and the relative paucity in the rat of neurons displaying an augmenting pattern of activity and of neurons with spinally projecting axons. In addition, we were unable to find morphological evidence for contacts between labeled BOT neurons and ipsilateral inspiratory neurons near the obex level, a finding not consistent with previous electrophysiological studies in the cat in which such synaptic connections have been identified. © 1993 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903350210

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of gestational ethanol exposure on stimulus‐induced sensory activity in the trigeminal/somatosensory System was determined. The mature offspring of mothers fed an ethanol‐containing diet (Et) or pair‐fed a nutritionally matched control diet (Ct) were examined. The C‐row mystacial whiskers were stimulated. Glucose utilization in the principal sensory nucleus of the trigeminal nerve (PSN), ventrobasal thalamus, and somatosensory cortex was determined with [14C]2‐deoxyglucose autoradiography.In Ct‐ and Et‐treated rats, whisker stimulation increased glucose utilization in C‐row barrel(oid)s in the left PSN, the right ventrobasal thalamus, and the right somatosensory cortex. The rate of glucose utilization in the C‐row barrel(oid)s and in nonstimulated regions was lower in the Et‐treated rats than in controls. In the cortices of Ct‐treated rats, the activity in the C‐row barrels on the right side was greater than in the right nonbarrel somatosensory cortex. Et‐treated rats also exhibited an increase in glucose utilization, albeit smaller than that in the Ct‐treated rats. In contrast, the glucose utilization in the left B‐ and C‐row barrels of Ct‐treated rats was decreased. No such decrease was evident in the left cortices of Et‐treated rats.Thus, stroking whiskers stimulates the activity of sites in the trigeminal/somatosensory system. In cortex, the definition of these sites is emphasized by depressed activity, i.e., “surround” inhibition, in sites connected via callosal or corticocortical projections. Prenatal exposure to ethanol depresses the metabolic activity regardless of the physiological state; however, the “surround” inhibition of cortical activity is eliminated by prenatal exposure to ethanol through an e

ISSN:0092-7317    

DOI:10.1002/cne.903350211

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY