摘要:

AbstractTwo physiologically defined classes of pontomedullary raphe neurons were intracellularly labeled in order to determine the target nuclei of their axonal projections. In the lightly anesthetized cat, cells either increased (on‐cells) or decreased (off‐cells) their discharge rate during the paw withdrawal reflex evoked by noxious pinch or heat. On‐ and off‐cells were injected with horseradish peroxidase and the initial course of labeled axons through the lower brainstem was reconstructed.On‐cell projections to the pontomedullary raphe and medial reticular nuclei were sparse. On‐cells projected densely to regions of the lateral reticular formation and the ventrolateral medulla at both rostral and caudal medullary levels. In general, on‐cells had few collaterals and sparse axonal swellings.In contrast to on‐cells, most off‐cells had axons that collateralized densely within the brainstem raphe and adjacent reticular formation. Such collaterals were either local, within the neuron's dendritic field, or distant, involving a projection of 1–8 mm. One off‐cell had a dense terminal field within the sensory trigeminal complex, a projection that may subserve the inhibition of trigeminal sensory neurons produced by raphe magnus stimulation. Well‐labeled off‐cells had numerous collaterals and dense regions of axonal swellings.In summary, off‐cells terminated densely in the raphe magnus and adjacent reticular formation whereas on‐cells projected predominantly to the ventrolateral medulla, a region implicated in autonomic control. Local off‐cell collaterals provide an anatomical substrate that would enable off‐cells to coordinate the activity of on‐ and

ISSN:0092-7317    

DOI:10.1002/cne.902880202

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe lateral geniculate nucleus of the ferret contains not only eye‐specific layers, but a further subdivision of layers A and A1 into inner and outer sublaminae that contain, respectively, ON‐center and OFF‐center cells (Stryker and Zahs, '83). To study how the arbors of single retinal ganglion cell axons correlate with these cellular divisions, we have examined the morphology of physiologically classified retinal axons in the ferret's lateral geniculate nucleus.As in cats, we could classify retinal axons as X or Y on the basis of a number of physiological criteria. X and Y axons have distinct patterns of termination in the lateral geniculate nucleus. Contralateral X axons innervate lamina A and ipsilateral axons lamina A1. X axons are further segregated in these laminae so that ON‐center axons terminate in the inner sublamina, and OFF‐center axons in the outer sublamina. We did not observe any branches of X axons innervating the medial interlaminar nucleus or the midbrain. Y axons have much larger terminal arbors and exhibit greater variation in their terminations. Generally, within layers A and A1, ON‐center Y axons innervate the inner sublamina and OFF‐center Y axons innervate the outer sublamina. However, they often innervate both sublaminae, and occasionally have a few boutons in the inappropriate lamina as well. Y axons also terminate in the dorsal C laminae, the interlaminar zones, and the medial interlaminar nucleus; branches of these axons course toward the midbrain, presumably to innervate the superior colliculus. Thus, whereas the Y pathway in the ferret is one of high divergence, the X pathway appears to be the substrate for segregated ON and OFF channels through the lateral genic

ISSN:0092-7317    

DOI:10.1002/cne.902880203

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the optic lobes (OLs) of the sphinx mothManduca sexta, 300–350 neurons per hemisphere are immunoreactive with an antiserotonin antiserum. Two groups of weakly serotonin‐immunoreactive cells (OL1) appear to be amacrine cells of the medulla, whereas more intensely immunoreactive cells (OL2) are probably centrifugal neurons that innervate the lobula, medulla, and lamina, as well as the superior protocerebrum. At least one other OL2 cell is a local optic‐lobe interneuron with arborizations in the dorsal medulla and lobula. The serotonin‐immunoreactive cells are also immunoreactive with an antiserum againstDrosophila melanogasterDOPA decarboxylase. All OL2 cells, but not the OL1 cells, are furthermore immunoreactive with an anti‐FMRFamide antiserum and an anti‐SCPBantiserum. This suggests that neuropeptides related or identical to FMRFamide and SCPBare colocalized and may serve as cotransmitters with serotonin in OL2 optic‐lobe

ISSN:0092-7317    

DOI:10.1002/cne.902880204

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

年代:1989

数据来源: WILEY

摘要:

AbstractThree functional regions of the inferior olive, the caudal medial accessory olive (cMAO) and the caudal and rostral dorsal accessory olive (DAO) receive input from the spinal cord. The present study determined how spinal inputs to cMAO interact with olivary neurons. These inputs were labeled by injections in cat lumbosacral of wheat germ agglutinin conjugated to horseradish peroxidase. The tracer was visualized with tetramethylbenzidine. The morphology of the labeled spino‐olivary terminals and the relationship between these terminals and postsynaptic elements were determined.Spino‐olivary terminals in cMAO displayed the morphological characteristics classically associated with excitatory synapses. Almost three quarters synapsed on spines, most of which contacted other spines, forming spine clusters. The majority of postsynaptic spines also received convergent input from apparently excitatory, nonlumbosacral afferents. This postsynaptic organization provides several possible benefits for the putative role of cMAO in the control of posture.An earlier study demonstrated that in DAO, almost three quarters of lumbosacral, spino‐olivary terminals synapse on dendrites (Molinari:Neuroscience 27:425–435, 1988). Thus, lumbosacral afferents appear to differ fundamentally in the way in which they interact with neurons in cMAO and DAO. These results suggest that the way information is processed may be as important in determining the functional differences between olivary regions as what information is r

ISSN:0092-7317    

DOI:10.1002/cne.902880205

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

年代:1989

数据来源: WILEY

摘要:

AbstractApplication of horseradish peroxidase to the pudendal nerve in the female cat labelled lumbosacral afferent and efferent neurons and their processes. Afferent axons entered the spinal cord primarily at the S1and S2segments and traveled rostrocaudally in Lissauer's tract and the dorsal columns. A distinctive component of the dorsal column projection was located at the lamina I‐dorsal column border as a densely labelled, compact bundle that distributed fibers to the dorsal horn at spinal levels near the segments of entry of the afferent axons. Afferent terminal labelling was located in the marginal zone, the intermediate gray matter, and the dorsal gray commissure in the lumbosacral and coccygeal spinal cord. A well‐defined terminal field restricted to the S1and rostral S2segments was present in the medial third of the nucleus proprius and substantia gelatinosa. Labelled motoneurons in Onuf's nucleus (S1and S2) exhibited longitudinal dendrites that extended rostrocaudally within the nucleus and three groups of transverse dendrites that emanated periodically from the nucleus and passed to the ventrolateral funiculus, the intermediate gray, and the dorsal gray commissure. Components of the pudendal nerve that innervate the anal and urethral sphincters were also labelled by injecting HRP into the respective sphincter muscles. Motoneurons innervating the anal and urethral sphincters were located in the dorsomedial and ventrolateral divisions, respectively, of Onuf's nucleus. Afferent projections from the two sphincters were similar; the most prominent terminations were present in the marginal zone, intermediate gray, and dorsal gray commissure. These results are discussed with respect to the physiological function of the pudendal nerve and its relationship with sacral autonomic pathw

ISSN:0092-7317    

DOI:10.1002/cne.902880206

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of the monoclonal antibody Cat‐301 was examined in the frontal and parietal cortex of macaque monkeys. In both regions the distribution was uniform within cytoarchitecturally defined areas (or subareas) but varied between them. In all areas, Cat‐301 labeled the soma and proximal dendrites of a restricted population of neurons. In the frontal lobe, Cat‐301‐positive neurons were intensely immunoreactive and present in large numbers in the motor cortex (area 4), premotor cortex (area 6, excluding its lower ventral part), the supplementary motor area (SMA), and the caudal prefrontal cortex (areas 8a, 8b and 45). In the parietal lobe, large numbers of intensely immunoreactive neurons were evident in the post‐central gyrus (areas 1 and 2), the superior parietal lobule (PE/5), and the dorsal bank (PEa), fundus (IPd), and deep half of the ventral bank (POa(i)) of the intraparietal sulcus (IPS).Two major patterns of laminar distribution were evident. In motor, supplementary motor, premotor (excluding the lower part of its ventral division), and the caudal prefrontal cortex (Walker's areas 8a, 8b and 45), and throughout the parietal cortex (with the exception of area 3), Cat‐301‐positive neurons were concentrated in the lower part of layer III and in layer V. The laminar positions of labeled cells in these areas were remarkably constant, as were the proportions of labeled neurons that had pyramidal and nonpyramidal morphologies (means of 30.2% and 69.8%, respectively). In contrast, in prefrontal areas 9, 10, 11, 12, 13, 14, and 46, in the cingulate cortex (areas 23, 24 and 25), and in the lower part of the ventral premotor cortex, Cat‐301‐positive neurons were spread diffusely across layers II to VI and a mean of 3.6% of the labeled neurons were pyramidal while 96.4% were nonpyramidal. Area 3 was unique among frontal and parietal areas, in that the labeled neurons in this area were concentrated in layers IV and VI.The areas in the frontal lobe which were heavily labeled are thought to be involved in the control of somatic (areas 4 and 6) and ocular (areas 8 and 45) movements. Those in parietal cortex may be classified as areas with somatosensory functions (1, 2, PE/5, and PEa) and areas which may participate in the analysis of visual motion (Pandya and Seltzer's IPd and POa(i), which contain Maunsell and Van Essen's VIP). The parietal somatosensory areas are connected to frontal areas with somatic motor functions, while POa(i) is interconnected with the frontal eye fields (8a and 45). Both POa(i) and the frontal eye fields are known to receive inputs from visual areas specialized for motion analysis.Cat‐301 may heavily label neurons in frontal and parietal areas that are broadly concerned with the control of somatic and ocular movements and the processing of the sensory information on which their norma

ISSN:0092-7317    

DOI:10.1002/cne.902880207

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

年代:1989

数据来源: WILEY

摘要:

AbstractAn analysis of the cerebellar nucleocortical projections was made by means of retrograde cellular labeling with wheat germ agglutinin‐horseradish peroxidase conjugate. Each of the main nuclear subregions appears to give rise to nucleocortical projections. The cortical distribution of the projections is referred to here in term of sagittal zones. Zones A, B, and C conform to the recent description in the rat (Buisseret‐Delmas, '88a, (b) on the basis of their olivocortical and corticonuclear projections. A corresponding description of zone D is given here. According to their distribution, three types of nucleocortical projections have been distinguished: (1) ipsilateral, reciprocal; (2) nonreciprocal; and 3) contralateral, symmetrical to the corticonuclear afferent.Reciprocal projectionsare strictly arranged in the sagittal direction, with the following zonal distribution. Zone A is subdivided into two subzones. Medial A zone receives its nuclear afferents from the medial aspect of the nucleus medialis (NM). The lateral A zone of the anterior lobe and lobule VI and that of the posterior lobe receive their reciprocal nuclear afferents from the ventrolateral NM and the dorsolateral protuberance, respectively. Zone B does not seem to receive nucleocortical projections. Zone C has three subzones in the rat. C1 is supplied from the medial third of the anterior and posterior subdivisions of the nucleus interpositus (NIA and NIP, respectively). C2 is supplied from the central third of the NIA and NIP. Rostrocaudally, the anterior lobe and lobule VIII are connected to the NIA, and lobules VI and VII to the NIP. C3 appears to be connected to the lateral third of NIA. Zone D contains three subzones mediolaterally in the rat. D0, not previously described, is defined on the basis of both its olivary afferent from the medial half of the ventral lamella of the principal olive and its corticonuclear projections onto the dorsolateral hump of Goodman et al. ('63). It receives a reciprocal nucleocortical afferent from the dorsolateral hump. D1 receives its olivary afferent from the dorsal lamella of the principal olive. It is reciprocally connected with the lateral, magnocellular part of the nucleus lateralis (NL). D2 is the most lateral subzone of the hemisphere. Its olivary afferent comes from the lateral half of the ventral lamella of the principal olive. D2 is reciprocally connected with the ventral, parvicellular subdivision of NL.The main cortical recipients for thenonreciprocal projectionsare the lateral A zone, the C3, and the D1 subzones. Nonreciprocal fibers to the lateral A zone come from the NIA and NIP, those to the C3 subzone mostly arise in the dorsolateral hump and the lateral NL, and those to the D1 subzone come from the dorsolateral hump as well as the lateral NIP.Symmetrical projectionsare contralateral projections that were found mainly connecting the NM and the lateral A zone, but there were also connections between the NIP and zone C and, very rarely, the NL and zone D. Symmetrical projections from the dorsolateral hump and the lateral NIA and NIP have not been fo

ISSN:0092-7317    

DOI:10.1002/cne.902880208

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe have examined the effect of the degeneration of sciatic nerve afferents on the distribution of saphenous terminals in the adult rat dorsal horn. Deafferentation was produced by injection into the sciatic nerve of pronase, a combination of proteolytic enzymes, which causes death of ganglion cells and degeneration of their terminal fields. The saphenous terminal fields were labelled by exposing the cut nerve to a combination of horseradish peroxidase (HRP) and wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). Terminals were mainly found in the superficial dorsal horn, indicating that small‐diameter afferents were heavily labelled. In one group of control animals, the normal sciatic and normal saphenous terminal fields were shown to be bilaterally symmetrical. In the experimental group, the initial injection of one sciatic nerve with pronase was followed 4 months later by bilateral HRP/WGA‐HRP labelling of both saphenous nerves. In each animals, the terminal field of the saphenous nerve on the lesioned side was expanded in the medial, lateral, and caudal directions. Medially and laterally, the expanded terminal field overlapped more of the sciatic territory than normal; caudally, saphenous terminals were found in the rostral portion of the L5 segment, in an area normally filled by sciatic terminals and devoid of saphenous terminals. The expansion resulted in a total saphenous area 26% larger than the control side. Electron microscopy demonstrated that the label in both the normal and expanded territories was primarily contained in axons and terminals, with minor transneuronal labelling. Labelled terminals in the expanded areas were both simple terminals with round, clear vesicles, and glomerular terminals with multiple synaptic contacts; these terminal types resemble those previously described for primary afferents in the superficial dorsal horn. Although the preexistence of “silent” synaptic terminals in the expanded areas cannot be disproven, the data support the hypothesis that primary afferents in the adult have the potential to sprout and establish synapses when the conditions of the deafferentation ar

ISSN:0092-7317    

DOI:10.1002/cne.902880209

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe report on computer‐assisted three‐dimensional reconstruction of spinal cord activity associated with stimulation of the plantar cushion (PC) as revealed by [14C]‐2‐deoxy‐D‐glucose (2‐DG) serial autoradiographs. Moderate PC stimulation in cats elicits a reflex phasic plantar flexion of the toes.Four cats were chornically spinalized at about T6 under barbiturate anesthesia. Four to 11 days later, the cats were injected (i.v.) with 2‐DG (100 μCi/kg) and the PC was electrically stimulated with needle electrodes at 2–5 times threshold for eliciting a reflex. Following stimulation, the spinal cord was processed for autoradiography. Subsequently, autoradiographs, representing approximately 8–18 mm from spinal segments L6–;S1, were digitized for computer analysis and 3‐D reconstruction.Several strategies of analysis were employed: (1) Three‐dimensional volume images were color‐coded to represent different levels of functional activity. (2) On the reconstructed volumes, “virtual” sections were made in the horizontal, sagittal, and transverse planes to view regions of 2‐DG activity. (3) In addition, we were able to sample different regions within the grey and white matter semi‐quantitatively (i.e., pixel intensity) from section to section to reveal differences between ipsi‐ and contralateral activity, as well as possible variation between sections.These analyses revealed 2‐DG activity associated with moderate PC stimulation, not only in the ipsilateral dorsal horn as we had previously demonstrated, but also in both the ipsilateral and contralateral ventral horns, as well as in the intermediate grey matter. The use of novel computer analysis techniques—combined with an unanesthetized preparation—enabled us to demonstrate that the increased metabolic activity in the lumbosacral spinal cord associated with PC stimulation was much more

ISSN:0092-7317    

DOI:10.1002/cne.902880210

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe early neurogenesis of the mouse olfactory nerve, from its exit at the nasal epithelium to its entrance into the embryonic telencephalon, has been investigated by using the rapid Golgi method and electron microscopy. Previously unrecognized anatomical and possible functional interrelationships between developing olfactory nerve axons and their sheath cells have been observed: (1) at their exit from sensory epithelium (nasal compartment), (2) at their contact with the CNS surface (intracranial compartment), and 3) at their entrance into the embryonic telencephalon (central nervous tissue compartment). Based on these observations the anatomy of the mouse olfactory nerve is herein redefined. Exiting olfactory nerve axons and sheath cells from the same regions of the nasal epithelium establish an early association which is maintained up to their terminal glomerular neuropile. No disruptions have been found in either the olfactory nerve axons or in the continuity of their sheath cells from exit at the nasal epithelium to entrance into the developing olfactory bulb. Corresponding olfactory nerve axons with their sheath cells enter together and become incorporated into the developing olfactory bulb as units. Consequently, the cellular envelope of the olfactory glomerulus must be composed of olfactory sheath cells rather than of glial (astroglial) cells from the CNS. With this simple anatomical arrangement, a topographic map of the sensory epithelium could be established progressively in the developing olfactory bulb. Eventually, “regenerating” olfactory nerve axons from different nasal regions could be guided by their specific sheath cell conduits toward their target glomeruli; hence, the olfactory message may be maintained undisturbed throughout the life span of the animal. In addition, olfactory nerve axons establish synaptic‐like contacts with their corresponding sheath cells prior to or during the perforation of the CNS surface. Reciprocal recognition between corresponding axons and their sheath cells at this crucial stage in their neurogenesis may play a significant role in the establishment of their terminal glomerulus. This new concept of the anatomy of the mammalian olfactory nerve should provide insights helpful in clarifying some of the still‐unresolved questions regarding the structural and functional organizations of this primitive

ISSN:0092-7317    

DOI:10.1002/cne.902880211

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

年代:1989

数据来源: WILEY