摘要:

AbstractThe functional role of the ventromedial thalamic nucleus (VM) was investigated by means of the quantitative autoradiographic14C‐deoxyglucose method. Local cerebral glucose utilization (LCGU) was measured bilaterally in 53 discrete brain areas of conscious rats 1 week and 1 month following electrolytic lesion of the VM. There was no difference observed in the LCGU values between the two groups of lesioned animals. In the VM‐lesioned rats glucose consumption was decreased in several ipsilateral (prefrontal, frontal, cingulate, sensorimotor, visual) and in some contralateral (cingulate, sensorimotor, visual) cortical areas. Furthermore, LCGU values were depressed bilaterally in the striatum, hippocampus, dentate gyrus, substantia nigra compacta, superficial layers of the superior colliculus, oculomotor complex, and cerebellar dentate nuclei. Glucose utilization was diminished also in the deep layers of the superior colliculus and in the fastigial nucleus ipsilateral to the lesion. Within the thalamus, glucose metabolism was decreased in several nuclei either bilaterally (reticular, intralaminar, paralamellar mediodorsal) or ipsilaterally (lateroposterior, ventrobasal, ventrolateral, ventroanterior, and medioventral) to the lesion. A significant correlation between the percentage of injured VM and the regional metabolic depression was demonstrated in the areas displaying the most pronounced decrease in LCGU. These results support a widespread influence of the VM on brain function extending beyond the limits of purely motor systems and reveal the consequences of a unilateral lesion of the thalamus on metabolic activity in several contralateral structu

ISSN:0092-7317    

DOI:10.1002/cne.902310202

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

年代:1985

数据来源: WILEY

摘要:

AbstractNon‐pyramidal cells in the rat hippocampus were examined with a combined Golgi‐electron microscopic method.The somata of non‐pyramidal cells were ovoid, about 15 × 30 μm, and several smooth and/or varicose dendrites extended from them. With electron microscopy, Golgi‐impregnated gold‐toned non‐pyramidal cells showed distinctive fine structural features. The somata displayed large nuclei and an extensive perikaryal cytoplasm. The nuclei showed extensive cytoplasmic invaginations, little heterochromatin, conspicuous nucleoli, and intranuclear rods composed of filamentous bundles. The perikaryal cytoplasm was rich in cell organelles such as well‐developed cisternae of rough endoplasmic reticulum and Golgi apparatus, and numerous clusters of free ribosomes and mitochondria. Many synaptic boutons, most of which formed asymmetrical synapses, impinged upon the somata and dendrites. Gap junctions were seen on varicose dendrites of Golgi‐impregnated non‐pyramidal cells. These gap junctions were patch‐like, about 0.1–0.6 μm in diameter, and situated in the stratum radiatum or stratum oriens of the CA1 and CA3 regions 70–230 μm from the soma. They displayed a characteristic cytoplasmic semidense material undercoating the junctional membranes. The gap junctions were usually formed between impregnated and unimpregnated varicose dendrites. Thirteen of a total of 22 gap junctions involving the impregnated dendrites were situated singly, whereas the remaining nine were on four impregnated dendrites in clusters of two or three side by side. In the latter cases, two pairs of junctions were formed between pairs of dendrites running parallel to each other, and each of the other two pairs was formed among three dendrites, appearing to make a dendritic network bridged by gap junctions. One gap junction was seen between two impregnated dendrites originating from two identified Golgi‐impregnated non‐pyramidal cells. These observations revealed unequivocally that non‐pyramidal cells in the hippocampus form gap junctions wi

ISSN:0092-7317    

DOI:10.1002/cne.902310203

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

年代:1985

数据来源: WILEY

摘要:

AbstractNeurons of the dorsal motor nucleus of the vagus nerve were studied following injections of horseradish peroxidase into the vagus nerve in a monkey (Macaca fascicularis). In frozen sections, the dorsal motor nucleus appeared to be completely filled by labeled medium‐sized (20–30 μm in long axis) neurons. Labeled dendrites from these neurons often extended outside the borders of the nucleus into the nucleus of the tractus solitarius. In 1 μm thick plastic sections and ultrathin sections of the dorsal motor nucleus, two distinct types of neurons were observed with the light and electron microscope. Medium‐sized neurons with abundant cytoplasm and an oval nucleus were retrogradely labeled with HRP, while small (10–15 μm in long axis) neurons with a paucity of organelles and an invaginated nucleus remained unlabeled. Medium‐sized neurons outnumbered the small neurons by approximately five to one.The synaptic organization of the dorsal motor nucleus in monkey was studied and compared with that in cat. The porportions of different types of axosomatic synapses were similar in both species. Terminals containing round vesicles and making symmetrical or asymmetrical contact with the postsynaptic structure were more common than synaptic terminals containing pleomorphic vesicles. In both species, there was a slightly greater synaptic density on the medium‐sized neurons than on the small neurons. The synaptic density in the monkey dorsal nucleus was greatest on the smallest dendrites in the neuropil and least

ISSN:0092-7317    

DOI:10.1002/cne.902310204

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

年代:1985

数据来源: WILEY

摘要:

AbstractKnown quantities of test objects approximating the parameters of cortical synapses were embedded in known volumes of a transparent embedding medium. The material was cut in slabs of appropriate thickness. The mean trace length (d) of the profiles of the test objects was measured and the number of profiles per unit area (NA) was calculated. Various stereological formulae were applied to these data to determine the number of test objects per unit volume (NV). For large numbers of those test objects most closely approximating the parameters of cortical synapses, the formula NV= NA/dand the DeHoff and Rhines formula ('61) for polydispersed circular disks NV= 8NAZ/π2(whereZis the mean of the reciprocals of the trace lengths) gave accurate results (error ≤ 5%). Other popular formulae and procedures were not as accurate and underestimated their number by as much as 3

ISSN:0092-7317    

DOI:10.1002/cne.902310205

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe number of synapses per unit volume of tissue (Nv) has been estimated in individual laminae of the binocular and monocular regions of area 17 in six adult cats by using a method of size‐frequency distribution. Separate estimates were obtained for RA synapses (containing round vesicles associated with asymmetric membrane differentiations) and for FS synapses (containing flat vesicles associated with symmetric membrane differentiations). For the total cortical thickness, the Nvof all synapses is not statistically different between binocular (286 million per mml3) and monocular (281 million) regions, nor is it different between the two regions for any of the laminae. Eighty‐four percent of synapses are of the RA type. of those, 79% are found on dendritic spines, 21% on dendritic trunks, 0.1% on somata. FS synapses represent 16% of the total, with 31% of them on spines, 62% on dendritic trunks, and 7% on somata. The ratio of RA to FS synapses is kept relatively constant throughout the layers. A two‐way analysis of variance shows no difference in the Nvof either RA or FS synapses in the two regions nor in the Nvof RA synapses between cats. It does, however, clearly demonstrate (p<0.001) interindividual differences for FS synapses. These variations between individual cats may be due to differences in age, breed, or environmental factors. In contrast to the relative uniformity of the Nvof synapses between regions, the number of each type under 1 mm2of cortical surface is 33% higher in the binocular region. This is due mainly to the greater thickness of the binocular r

ISSN:0092-7317    

DOI:10.1002/cne.902310206

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

年代:1985

数据来源: WILEY

摘要:

AbstractMuch useful information on the localization of alpha1‐adrenergic binding sites has been gained by using tritiated radioligands for in vitro autoradiography. However, the iodinated alpha1‐adrenergic antagonist HEAT (([2‐β (4‐hydroxyphenyl)‐ethylaminomethyl)‐tetralone], BE 2254), a radioligand with high affinity and specificity, provides autoradiographs with a higher signal to noise ratio. This has allowed us to describe the anatomy of these binding sites in much greater detail than previously possible.Regions showing the highest levels of binding include external plexiform layer of the olfactory bulb, layers Va and Vc of frontoparietal cortex, lateral and central amygdaloid nuclei, thalamus, and inferior olive. Other regions were generally less intensely labeled, with the least evidence of labeling in white matter, such as corpus callosum. Some regions (e.g., hippocampus) had only moderate labeling, but the binding appeared in a discrete pattern that reflected the functional organization of the structure.Although the [125I]‐HEAT binding sites were distributed in a pattern similar to that previously reported for [3H]‐WB 4101 and [3H]‐prazosin, the anatomical detail seen with the iodinated ligand is greater. As a result, an association of alpha1‐adrenergic antagonist binding sites with specific layers in the cortex and with some catecholamine‐containing nuclei in the brainstem, such as the locus coeruleus, have been s

ISSN:0092-7317    

DOI:10.1002/cne.902310207

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe spatial‐temporal progress of nerve regeneration was examined in silicone chambers of three different volume capacities: 11, 25, and 75 μl. In all chambers, the stumps of a transected rat sciatic nerve were sutured into the ends of the chamber leaving a 10 mm gap between the stumps. Chambers were implanted empty (E chambers) or prefilled with saline (PF chambers). A coaxial and continuous fibrin matrix had formed in all chambers by 1 week. In E chambers, the matrices had a proximal‐distal taper that was more pronounced in E25 and E75 chambers due to significantly larger matrix diameters in the proximal region. At 3 weeks, vascular and Schwann cell migration and axonal regeneration were less advanced in the E25 and E75 than in the control E11 chambers. The retardation correlated with the presence of an avascular organization of circumferential cells. Saline prefill‐ing affected the caliber and density of fibrin fibers in the 1 week matrices of PF25 and PF75 chambers. The matrices did not have a prominent taper and diameters were progressively larger with increasing chamber volume. Saline prefilling did not affect regeneration progress in 3 week PF11 chambers but did enhance regeneration in the PF25 chambers; a 1.5‐fold larger diameter nerve formed at 3 weeks that contained 2,6‐fold more axons. Progress in the PF75 chamber was retarded. We conclude that the volume, timing, and nature of the fluid filling a silicone chamber have significant influence on the formation of fibrin matrices. Alterations in matrix formation correlate with substantial changes in the subsequent progress of intrachamber regenerat

ISSN:0092-7317    

DOI:10.1002/cne.902310208

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

年代:1985

数据来源: WILEY

摘要:

AbstractLight microscopic studies in our laboratory have indicated that the lateral septum, amygdala, and ventral subiculum project in a perinuclear fashion to the paraventricular (PVN), supraoptic (SON), and suprachiasmatic (SCN) nuclei (Oldfield et al., '82; Silverman and Oldfield, '84). In the present paper a combined anterograde HRP and immunocytochemical procedure has been used to determine the connectivity between these limbic efferents and peptide‐containing processes emanating from the above mentioned hypothalamic nuclei. Synaptic associations were found to exist between efferents from (1) the septum and both vasopressin (VP) and oxytocin (OX)‐positive dendrites derived from cells in the PVN and SON, (2) the septum and VP dendrites dorsal to the SCN, (3) the ventral subiculum and both VP and OX dendrites arising from the PVN and SON, and (iv) the amygdala and VP dendrites from the PVN. These observations help clarify an apparent discrepancy between electrophysiological data, in which limbic efferents have been shown to influence the activity of VP and OX neurons in the PVN ami SON, and anatomical evidence which indicates only a perinuclear innervation from these sites not encroaching on the hypothalamic nuclei themselves. In each case the synaptic connections are made on dendrites external to the nucleus: those lateral and ventrolateral to the PVN, dorsal to the SON, and dorsal or dorsolateral to the

ISSN:0092-7317    

DOI:10.1002/cne.902310209

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

年代:1985

数据来源: WILEY

摘要:

AbstractA class of amacrine cells in the goldfish retina displays substance P‐like immunoreactivity (SPIR). We studied the synaptic organization of SPIR amacrine cells by electron microscopical immunocytochemistry. Amacrine cells showing SPIR have processes which ramify in a very narrow band in layer 3 of the inner plexiform layer. SPIR is restricted to large dense‐cored vesicles (DCVs) which are distributed throughout the dendrites. Processes labeled with SPIR contain a mixture of DCVs and numerous small agranular vesicles. of 88 synaptic contracts analyzed, SPIR processes occurred as the presynaptic element 57 times and as the postsynaptic element 31 times. SPIR processes made synapses upon amacrine and ganglion cell dendrites with equal frequency and received synaptic input from both amacrine and bipolar cells. The stratification of SPIR amacrine cells in proximal sublamina α suggests that their synaptic interactions are restricted to “off” and “on‐off” neurons. However, this is in contrast to published electrophysiological data. Possible explanations for this discrepancy are discu

ISSN:0092-7317    

DOI:10.1002/cne.902310210

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effect of a conditioning lesion on the time‐course of axonal sprout formation after a subsequent testing lesion was evaluated in myelinated axons of the rat sciatic nerve. Transmission electron microscopy of longitudinal nerve sections was used to examine nodes of Ranvier located 200–500 μm proximal to the testing lesion. The conditioning lesion was a cut of the tibial nerve at the ankle; the testing lesion, made 2 weeks later, was a crush of the sciatic nerve at the hip. Sprouts were defined as unmyelinated evaginations of the nodal axolemma that (1) had reached the basement membrane of the Schwann cell, and (2) were located between the myelin sheath of the distal paranode and the basement membrane. Photomicrographs of the nodes at 9, 18, and 27 hours after the testing lesion were assigned to one of seven categories: normal, retracted, myelin degeneration, axonal degeneration, type A sprout formation (cytoskeleton absent), type B sprout formation (cytoskeleton present), and type B sprout degeneration. By 9 hours after the testing lesion, type B sprout formation was found in 9% of the nodes in control nerves (testing lesion alone) and 33% of those in conditioned nerves (P<.01). A 33% incidence of type B sprout formation was not reached in control nerves until 27 hours after the testing lesion. Since the conditioning lesion was located 50 mm distal to the testing lesion and did not induce neuronal death, earlier sprout formation can be attributed to a neuronal response to the conditioning lesion rather than to a putative factor that arises from pre‐degenerated fibers and acts on newly formed s

ISSN:0092-7317    

DOI:10.1002/cne.902310211

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

年代:1985

数据来源: WILEY