摘要:

AbstractSpinal neurons with descending axons are important components of spinal sensorimotor networks. We used an anatomical tracing technique to study the distribution of descending propriospinal axons and cell bodies in red‐eared turtles. We injected horseradish peroxidase into a portion of one funiculus in the middle of the hindlimb enlargement and examined six spinal segments rostral to the injection site (dorsal 3 through dorsal 8) for labeled neuronal cell bodies.Injections into each region of the white matter labeled substantial numbers of descending propriospinal neurons. Each injection labeled cell bodies over most of the six spinal segments examined. Each injection also labeled cell bodies in the ipsilateral dorsal horn, intermediate zone, and ventral horn as well as the contralateral intermediate zone and ventral horn. Injections into each of four regions of the white matter, the dorsal funiculus, the medial part of the lateral funiculus, the lateral part of the lateral funiculus, and the ventral funiculus reliably gave rise to a distinct distribution of labeled cell bodies.These experiments establish that descending propriospinal axons in red‐eared turtles are found in all regions of the spinal white matter. This finding contrasts with a popular contempopary view of the organization of descending propriospinal axons in mammals. These experiments also demonstrate that neurons in each region of the gray matter give rise to a different distribution of descending, funicular axons, although these distributions are widely overlapping. Different funicular axon distributions could be associated with different sets of synaptic contacts with the white‐matter dendrites of spinal neurons. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903460302

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe globus pallidus external segment forms a major target center of the mammalian striatum which is characterized by neurochemically distinct compartments. The present study was undertaken to determine if a corresponding compartmentalization exists within the globus pallidus external segment in the rat. Immunocytochemical examination of the calcium‐binding proteins parvalbumin and calbindin D28kDa, which are present in neurons of the striatal matrix compartment, was employed. The results indicate three neurochemically distinct compartments within the globus pallidus external segment: (1) an area in the medial aspect of the entire length of the globus pallidus that contains dense immunoreactivity for calbindin D28kDa; (2) a narrow rim at the striatopallidal junction in the rostral two‐thirds of the globus palidus that contains calbindin D28kDaimmunoreactivity designated as the “border zone” of the globus pallidus; and (3) an area between these two zones showing very poor immunoreactivity for calbindin D28kDabut containing parvalbumin immunoreactive neurons.The calbindin D28kDaimmunoreactive border zone corresponds to the area of the globus pallidus where striatal inputs converge extensively, whereas the rest of the nucleus is involved in segregated, topographically organized pathways. Parvalbumin‐containing neurons are involved in the propagation of striatal output related to striosomal and sensorimotor aspects of basal ganglia function. The present results also indicate that calbindin D28kDaimmunoreactivity is completely absent from striosomal neurons and is therefore a useful marker for striatal compartments. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460303

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

年代:1994

数据来源: WILEY

摘要:

AbstractSingle unit recording studies in anesthetized cats have identified a population of neurons in the brainstem trigeminal complex that can be activated by stimulation of major dural blood vessels. Such dura‐responsive neurons exhibit response properties that are appropriate for a role in the mediation of vascular head pain in that they typically exhibit nociceptive facial receptive fields whose periorbital distribution is similar to the region of referred pain evoked by dural stimulation in humans. In the present study, intracellular labelling with horseradish peroxidase was used to examine the anatomical characteristics of brainstem trigeminal neurons that respond to dural stimulation.A total of 17 neurons was labelled that responded to electrical stimulation of dural sites overlying the superior sagittal sinus or middle meningeal artery. Fourteen of these neurons also responded to electrical stimulation of the cornea. The neurons in this sample were located in the rostral two‐thirds of the trigeminal nucleus caudalis and the caudalmost part of the nucleus interpolaris. Within caudalis, the neurons were located in the deeper part of the nucleus, primarily lamina V, and were concentrated ventrolaterally. The dendritic arborizations of the dura‐responsive neurons typically exhibited a dorsolateral‐to‐ventromedial orientation and did not extend into the superficial laminae of caudalis. Dura‐responsive neurons had axonal collaterals and boutons in the nucleus caudalis, nucleus interpolaris, the infratrigeminal region ventral to nucleus interpolaris, the nucleus of the solitary tract, and the medullary reticular formation. The axonal boutons within the trigeminal complex exhibited a ventrolateral distribution which largely overlapped the distribution of the somata. The results are consistent with previous evidence that dura‐responsive brainstem trigeminal neurons may have a role in the mediation of dural vascular head pain and also indicate that such neurons may contribute to nociceptive processing within the dorsal horn. © 1994 W

ISSN:0092-7317    

DOI:10.1002/cne.903460304

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe orbital and medial prefrontal cortex (OMPFC) of macaque monkeys is a large but little understood region of the cerebral cortex. In this study the architectonic structure of the OMPFC was analyzed with nine histochemical and immunohistochemical stains in 32 individuals of three macaque species. The stains included Nissl, myelin, acetylcholinesterase, Timm, and selenide stains and immunohistochemical stains for parvalbumin, calbindin, a nonphosphorylated neurofilament epitope (with the SMI‐32 antibody), and a membrane‐bound glycoprotein (with the 8b3 antibody). In addition to patterns of cell bodies and myelinated fibers, these techniques allow the visualization of markers related to metabolism, synapses, and neurotransmitters. A cortical area was defined as distinct if it was differentiated in at least three different stains and, as described in later papers, possessed a distinct set of connections. Twenty‐two areas were recognized in the OMPFC. Walker's areas 10, 11, 12, 13, and 14 [J. Comp. Neurol. (1940) 73:59–86] have been subdivided into areas 10m, 10o, 11m, 11l, 12r, 12l, 12m, 12o, 13m, 13l, 13a, 13b, 14r, and 14c. On the medial wall, areas 32, 25, and 24a, b, c have been delineated, in addition to area 10m. The agranular insula also has been recognized to extend onto the posterior orbital surface and has been subdivided into medial, intermediate, lateral, posteromedial, and posterolateral agranular insula areas. The OMPFC, therefore, resembles other areas of primate cortex, such as the posterior parietal and temporal cortices, where a large number of relatively small, structurally and connectionally distinct areas have been recognized. Just as the area‐specific neurophysiological properties of these parietotemporal areas underlie broader regional functions such as visuospatial analysis, it is likely that the many small areas of the OMPFC also make differential contributions to the general mnemonic, sensory, and affective functions of this region. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460305

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe connections between the olfactory bulb, primary olfactory cortex, and olfactory related areas of the orbital cortex were defined in macaque monkeys with a combination of anterograde and retrograde axonal tracers and electrophysiological recording. Anterograde tracers placed into the olfactory bulb labeled axons in eight primary olfactory cortical areas: the anterior olfactory nucleus, piriform cortex, ventral tenia tecta, olfactory tubercle, anterior cortical nucleus of the amygdala, periamygdaloid cortex, and olfactory division of the entorhinal cortex. The bulbar axons terminate in the outer part of layer I throughout these areas and are most dense in areas that are close to the lateral olfactory tract. Labeled axons also were found in the superficial part of nucleus of the horizontal diagonal band. Retrograde tracers injected into the olfactory bulb labeled cells in the nucleus of the diagonal band and in all of the primary olfactory cortical areas except the olfactory tubercle. Electrical stimulation of the olfactory bulb evoked short‐latency unit responses and a characteristic field wave in the primary olfactory cortex. Multiunit activity in layer II tended to be of shorter latency than that in layer III and the endopiriform nucleus.Associational connections within the primary olfactory cortex were demonstrated with anterograde tracer injections into the piriform cortex and the entorhinal cortex. Injections into the piriform cortex near the lateral olfactory tract labeled axons in the deep part of layer I of many primary olfactory areas, but especially in areas near the tract. An injection into the rostral entorhinal cortex, distant to the lateral olfactory tract, labeled a complementary distribution of axons in deep layer I of olfactory areas medial and caudoventral to the tract. This organization resembles that reported in the primary olfactory cortex of the rat [Luskin and Price (1983) J. Comp. Neurol. 216:264–291].The anterograde tracer injections into the piriform cortex and retrograde tracer injections into the orbital and medial prefrontal. Cortex and rostral insula label connections from the primary olfactory cortex to nine areas in the caudal orbital cortex, including the agranular insula areas Iam, lai, Ial, Iapm, and Iapl and areas 14c, 25, 13a, and 13m. The piriform cortex projects most heavily to layer I of these areas. Only Iam, Iapm, and 13a receive a substantial projection to the deeper layers. Areas Iam, Iapm, and 13a were also the only areas that responded with multiunit action potentials to olfactory bulb stimulation in anesthetized animals. Area Iam had predominantly short‐latency units, ranging from 4 to 6 msec after olfactory bulb stimulation: Area Iapm had predominantly longer latency units, with some units faithfully following the stimulus at latencies of 70–90 msec. A small region of area 13a had relatively long‐latency units.These neocortical connections and electrophysiological responses establish the presence of an olfactory representatioin in the posterior orbital cortex of the macaque. Similarities in the structure and connections of the primary olfactory cortex suggest a high degree of homology between the rat and monkey and allow inferences about the process of sequential olfactory activation in the primate. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460306

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

年代:1994

数据来源: WILEY

摘要:

AbstractFollowing optic nerve transection in goldfish, retinal axons regenerate. To determine what the growth cones use as a substrate for their growth, regenerating growth cones were labeled by horseradish peroxidase (HRP) application to the retina 5–6 days after intraorbital optic nerve section (ONS) and identified at 10–11 days after ONS in the brain sided (distal) portion of the optic nerve in thick and serial ultrathin sections. Leading growth cones (n = 5) were found in intimate contact with a variety of elements: with myelin fragments alone, with myelin fragments and glial cells, and with the basal lamina of the glia limitans and the surface of a fibroblast outside the boundary of previous fascicles.In ultrathin sections of conventionally treated regenerating optic nerves, (unlabeled) axon profiles—in addition to myelin fragments—were seen to be in contact with an astrocyte and an oligodendrocyte, suggesting that the growth cones of these axons may have been associated with those cells. The data suggest that leading growth cones of regenerating axons may be capable of growing along myelin fragments and on a wide variety of cellular surfaces in the goldfish optic nerve. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460307

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe spinal trigeminal nucleus is involved in the transmission of orofacial sensory information. Neither the distribution of the neuromessenger, nitric oxide, within the trigeminal system nor the possible relationship of this simple gas with trigeminothalamic neurons has been carefully studied. Using immunocytochemical (against nitric oxide synthase) and histochemical (NADPH‐diaphorase staining) techniques, we have found that nitric oxide neurons and processes are more prominent in the nucleus caudalis and the dorsomedial aspect of the nucleus oralis than in other spinal trigeminal regions. To study the relationship of nitric oxide to trigeminothalamic neurons and intertrigeminal interneurons of the spinal trigeminal nucleus, spinal trigeminal neurons were retrogradely labeled with fluorogold by thalamic injections or by injections into the junction of the nucleus interpolaris and nucleus caudalis. Medullary sections were subsequently processed with NADPH‐diaphorase histochemistry. None of the diaphorase‐stained neurons in the spinal trigeminal nucleus was found to contain fluorogold; however, some diaphorase‐stained processes were found in close proximity to trigeminothalamic neurons. Following spinal trigeminal nucleus injections, many diaphorasestained neurons were found to contain fluorogold, especially in the nucleus caudalis, suggesting that nitric oxide‐containing neurons in the spinal trigeminal nucleus are intertrigeminal interneurons. Collectively, these data indicate that nitric oxide is most prominent in interneurons located in nucleus caudalis and that these interneurons give rise to processes that appose trigeminothalamic neurons, raising the possibility that they may indirectly influence orofacial nociceptive processing at the level of the spinal trigeminal nucleus via nitric oxide production. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460308

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe α‐ketoglutarate dehydrogenase complex (KGDHC) is a key enzyme in mitochondrial oxidation that appears critical to neurodegenerative diseases. Its activity in the brain declines in thiamine‐deficient animals, Alzheimer's disease, and Wernicke‐Korsakoff syndrome. Since selective cell populations are affected in these disorders, understanding the cellular distribution of KGDHC is important in order to define its role in the pathophysiology of these diseases. We used antisera against both bovine KGDHC and its Elk component to determine the immunocytochemical distribution of the enzyme and compare it with that of another mitochondrial enzyme, pyruvate dehydrogenase complex (PDHC) and a cholinergic neuronal marker, choline acetyltransferase (ChAT) in rat brain. Although low levels of immunoreactivity occurred in neurons, glia, and neuropil throughout the brain, some regions displayed relatively high perikaryal KGDHC enrichment. In the cerebral cortex, high immunoreactivity occurred mostly in layers III, V, and VI. The hippocampal pyramidal layer in CAl and CA2 exhibited more intense staining thah CA3. In the mammillary body, intensely labeled cells occurred in the supramammillary and lateral nuclei, while moderately stained cells predominated in the medial nucleus. The basal forebrain, basal ganglia, reticular and midline thalamic nuclei, red nucleus, pons, cranial nerve nuclei, inferior and superior colliculi, and cerebellar nuclei also contained highly immunoreactive neurons. The distribution of KGDHC overlapped with that of PDHC and colocalized to a limited extent with ChAT. These data are the first to demonstrate KGDHC immunoreactivity in discrete areas of rat brain and are vital to our understanding of selective vulnerability to metabolic insults and disease. © 1994 Wiley‐

ISSN:0092-7317    

DOI:10.1002/cne.903460309

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

年代:1994

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903460301

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

年代:1994

数据来源: WILEY