摘要:

AbstractPatterns of connections of Area 17 with extrastriate visual areas V‐II and MT were studied in macaque monkeys by using3H‐proline and HRP as anatomical tracers. The results support previous conclusions that V‐II is a split representation of the visual hemifield with most of the outer border formed by the zero horizontal meridian, and that MT is a topological representation of the visual hemifield. V‐II was estimated to be about 10–12 mm wide, 110 mm long along its shared border with V‐I, and 920 mm2in surface area, thereby almost equaling Area 17 in size. MT was judged to be 7 mm wide and 12 mm long, with a surface area of 68 mm2, or roughly 7% of the area of Area 17. In some cases, there was evidence for projections from Area 17 to a third area (or areas) of cortex of about 2 mm wide and of uncertain length on the outer boundary of V‐II. Terminationsin V‐II and MT werecon‐centrated in layer IV and extended into inner layer III. Cells projecting back to Area 17 were largely in layers III and V in V‐II and in laye

ISSN:0092-7317    

DOI:10.1002/cne.902200302

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

年代:1983

数据来源: WILEY

摘要:

AbstractProjections to the trigeminal, facial, ambiguus, and hypoglossal motor nuclei were determined by using horseradish peroxidase histochemistry. Most of the afferent projections to these motor nuclei were from the brain‐stem reticular formation, frequently in areas adjacent to other synergetic motor nuclei. The reticular formation lateral to the hypoglossal nucleus and reticular structures surrounding the trigeminal motor nucleus projected to each of these other brainstem motor nuclei involved in oral‐facial function. Afferent projections to these motor nuclei also were organized along the ros‐trocaudal axis. Within the reticular formation most of the afferent projections to the trigeminal motor nucleus originated rostral to the majority of neurons projecting to the hypoglossal and ambiguus nuclei, which in turn were rostral to the primary source of reticular afferents to the facial nucleus. In comparison, projections from the sensory trigeminal nuclei and nucleus of the solitary tract were sparse. The interneuron pools that project to the orofacial motoneurons provide one further link in understanding the brain‐stem substrates for integrating oral and ingestive be

ISSN:0092-7317    

DOI:10.1002/cne.902200303

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe morphology of the lateral descending nucleus of V (LTTD) in three species of Boidae and nucleus reticularis caloris (RC) of the rattlesnake have been studied with the light and electron microscope. First‐ and second‐order relays in the infrared receptor pathway to the tectum are contained within LTTD in the Boidae, whereas in the rattlesnakes the secondary relay to tec‐tipetal neurons is in nucleus RC. The lateral descending nucleus in the boids contains small and large neurons. The larger cells project to the optic tectum and morphologically are quite similar to those of nucleus RC.It has been determined at the ultrastructural level that LTTD of the three species of boids studied have very similar morphology and organization. A marginal neuropil, located near the lateral descending tract, consists of terminals of thin unmyelinated axons in synaptic contact with thin den‐drites. Deeper within the nucleus primary afferent terminals containing clear spherical vesicles form synaptic clusters with dendrites and are post‐synaptic to other axon terminals containing pleomorphic vesicles. The large, tectipetal neurons are postsynaptic to two morphological types of synapses, one with clear spherical vesicles, asymmetric membranes, and subsynaptic web and the other with flattened vesicles and symmetrical membranes. Similar synapses are also present on the cells of nucleus RC in the rattlesnake.There is a close similarity in function, structure, and synaptic organization between the LTTD of boids and the LTTD plus nucleus RC of pit vipers, suggesting similar or identical evolutiona

ISSN:0092-7317    

DOI:10.1002/cne.902200304

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe immunocytochemical distribution of [Leu]enkephalin and an adrenal enkephalin precursor fragment (BAM‐22P) immunoreactivity was investigated in the diencephalon and brainstem of rats pretreated with relatively high doses of colchicine (300–400 μg/10 μl intracerebroventricularly). The higher ranges of colchicine pretreatment allowed the visualization of extensive enkephalin‐containing systems in these brain regions, some of which are reported for the first time. Immunoreactive perikarya were found in many hypothalamic and thalamic nuclei, interpeduncular nucleus, substan‐tia nigra, the colliculi, periaqueductal gray, parabrachial nuclei, trigeminal motor and spinal nuclei, nucleus raphe magnus and other raphe nuclei, nucleus reticularis paragigantocellularis, vestibular nuclei, several nor‐adrenergic cell groups, nucleus tractus solitarius, as well as in the spinal cord dorsal horn. In addition to the above regions, immunoreactive fibers were also noted in the habenular nuclei, trigeminal sensory nuclei, locus coeruleus, motor facial nucleus, cochlear nuclei, dorsal motor nucleus of the vagus, and hypoglossal nucleus. When adjacent sections to those stained for [Leu]enkephalin were processed for BAM‐22P immunoreactivity, it was found that these two immunoreactivities were distributed identically at almost all anatomical locations. B AM‐22P immunoreactivity was generally less pronounced and was preferentially localized to neuronal perikarya. The results of the present as well as the preceding studies (Khachaturian et ai., '83) strongly suggest substantial structural similarity between the adrenal proenkephalin precursor and that which occurs in the brain. Also discussed are some differences and parallels between the distribution of [Leu]enkeph‐alin and dynorphin i

ISSN:0092-7317    

DOI:10.1002/cne.902200305

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

年代:1983

数据来源: WILEY

摘要:

AbstractRecent histochemical evidence suggests that neurons in the gray matter surrounding the central canal may play a role in nociception. We attempted to evaluate this possibility by studying the response properties and ascending projections of these cells in the rat.In the first series of experiments, the ascending projections of neurons around the central canal were studied by the method of retrograde transport of horseradish peroxidase (HRP). Predominantly contralateral labeling of neurons around the central canal appeared after HRP injections into the paramedian medullary or pontine reticular formation in intact or cerebellec‐tomized animals. Far fewer cells were labeled by injections into the lateral medulla and/or pons. A small number of cells was retrogradely labeled by HRP injections into the vermal and ntermediate regions of the cerebellum or the periaqueductal gray matter. Injections into other brainstem areas outside of the reticular formation also failed to label large numbers of neurons around the central canal.In a second set of experiments, we recorded extracellular unitary activity from the lumbar enlargement in spinalized, decerebrate, unanesthetized rats. Thirteen units were functionally characterized and histologically localized within 300 μ of the central canal. All of the units identified responded exclusively to noxious stimuli applied within highly circumscrioed receptive fields.Thus, neurons around the central canal contribute strongly to long ascending spinal cord projections. Physiologically, neurons found within this region are reminiscent of the noxious‐specific cells in the outer most layers of the dorsal

ISSN:0092-7317    

DOI:10.1002/cne.902200306

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

年代:1983

数据来源: WILEY

摘要:

AbstractTen cats ranging in age from 4 weeks postnatal to adult received large bilateral injections of horseradish peroxidase (HRP) into cortical areas 17 and 18. In one cat additional unilateral injections of HRP were made into the lateral suprasylvian visual area (PMLS). The purpose of these injections was to label relay cells in lamina A of the dorsal lateral geniculate nucleus (LGN), in order to distinguish them from neurons that could not be labeled retrogradely.Several factors thought to influence the effectiveness of HRP as a retrograde marker were varied in an effort to label as many relay cells as possible. These factors included the (1) rate and duration of HRP injections; (2) volume and concentration of HRP injected; (3) addition of L‐α‐lysophospha‐tidylcholine or dimethyl sulfoxide to the injected HRP; and (4) aldehydes and buffers used for fixation. In all experiments DAB (3,3′‐diaminobenzidine tetrahydrochloride) was used as the chromogen, either alone or with the addition of cobalt chloride, nickel, and cobalt salts, or cobalt‐glucose oxidase. In l‐μ plastic sections, the influence of each of the above factors and DAB methods was determined by measuring the percentage of unlabeled neurons and the cytoplasmic HRP grain density of cells that were labeled.Our results show that approximately 22% of the neurons in lamina A of the LGN remain unlabeled following injections of HRP into areas 17 and 18 alone or combined with injections into PMLS. The percentage of unlabeled cells is similar at each of the ages that we studied and is not affected significantly by any of the factors that were varied or DAB methods that were used.Cross‐sectional area measurements show that unlabeled cells tend to be among the smallest neurons in lamina A. Regardless of age, the mean size of labeled neurons was about twice that of unlabeled cells. However, we found only a weak correlation between the size of a labeled cell and the cytoplasmic density of HRP grains. Thus it is unlikely that small cell body size alone can account for tne unlabeled cells in lamina A, since small neurons can be as effective in transporting HHP retrogradely as large neurons.We therefore conclude that there is a distinct population of small neurons in lamina A of the LGN that do not project to cortex. Although we cannot rule out the possibility that these cells project subcortically, we believe that it is reasonable to regard the

ISSN:0092-7317    

DOI:10.1002/cne.902200307

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe origins of the axons terminating in the mesencephalic tectum in Python reticulatus were examined by unilateral tectal injections of horseradish peroxidase. Kutrogradely labeled cells were observed bilaterally throughout the spinal cord in all subdivisions of the trigeminal system, with the exception of nucleus principalis, which showed labeled cells only on the ipsilateral side. Labeling of the reticular formation occurred bilaterally in nucleus reticular is interiormagnocellularis, nucleus reticularis lateralis, nucleus reticularis medius and the mesencephalic reticular formation. The tectum also receives bilateral projections from the dorsal tegmentaJ field, the nucleus of the lateral lemniscus and nucleus isthmi, and ipsilateral projections from nucleus profundus mesencephali. A few labeled cells were found ipsilaterally in the locus coeruleus and in nuclei vestibulares ventrolateralis and centromedialis. In the diencephalon labeled cells were observed ipsilaterally in nucleus ventrolateralis thalami, nucleus ventromedialis thalami, nucleus suprapeduncularis, and in the dorsal and ventral lateral geniculate nuclei. Bilateral labeling was observed in nucleus periventricularis hypo‐thalami. Furthermore, labeling was ipsilaterally present in the ventral telen‐cephalic areas. The tectum inPython reticulatusreceives a wide variety of afferent connections which confirm the role of the tectum as an integration center of visual and exteroceptive informat

ISSN:0092-7317    

DOI:10.1002/cne.902200308

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

年代:1983

数据来源: WILEY

摘要:

AbstractTo compare the size and pattern of the terminal distribution of cortico‐cortical projections in two primate species with brains of different size, triti‐ated amino acids were injected into the prefrontal cortex of New World squirrel monkeys(Saimiri sciureus)and Old World rhesus monkeys(Macaca mulatta), and their brains were processed for light microscopic autoradiog‐raphy. In both species, prefrontal efferents are directed to a number of cortical targets in the same and opposite hemispheres, where in coronal sections, they generally terminate as radially oriented columns. In the rhesus monkey, the median width of the columns in transverse sections is 685 μ. In squirrel monkey, corresponding columns have a median width of 555 μ. Considering that the volume of the neocortex in rhesus monkey is approximately 4.5 × larger than that of squirrel monkey, the dimensions of cortical columns in the two species are surprisingly similar. This finding suggests that phylogenetic expansion in cortical surface area is accompanied by an increase in the number, rather than the width, of afferent fiber columns. The increase in number of modular units may be relevant to the increasing computational and information processing capacity of the cerebral cortex in the course of e

ISSN:0092-7317    

DOI:10.1002/cne.902200309

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

年代:1983

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902200301

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

年代:1983

数据来源: WILEY