摘要:

AbstractThe accessory optic system (AOS) was studied in an anthropoid primate by using anterograde transport of tritiated amino acids and autoradiographic techniques. The course of the accessory optic tract (AOT) and the retinal projection to the terminal nuclei are described in the gibbon and compared to that of other mammals.The AOT consists of a superior fasciculus, which includes both an anterior and a posterior fiber branch. An inferior fasciculus of the AOT is absent. In contrast to previous reports in haplorhine primates, which describe the AOS as consisting of only the dorsal (DTN) and the lateral (LTN) terminal nuclei, we find that in the gibbon, three cellular groups receive a bilateral projection, predominantly from the contralateral retina. According to cytoarchitecture and topographic location, two of these nuclei correspond to the DTN and the LTN. The third cellular group, situated dorsomedial to the substantia nigra, receives a distinct retinal projection and extends rostrocaudally for 2.0 mm in the mesencephalon. This nucleus is homologous to the dorsal division of the medial terminal nucleus (MTN) in other mammals. There was no evidence for a ventral division of the MTN, which in nonprimates is typically situated at the ventromedial base of the cerebral peduncle.Examination of brain morphology in primates suggests that the ventral division of the MTN has been displaced from its phylogenetically stable location in the medial part of the ventral midbrain to a more dorsal position. This shift appears to be a consequence of the overall morphological influences resulting from the relative enlargement of the pons in this region. The demonstration of a direct retinal projection to the MTN in the gibbon, as well as recent reports in other primates, indicates that a complete AOS consisting of three terminal nuclei is a feature common to all mammals.

ISSN:0092-7317    

DOI:10.1002/cne.902590402

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe pedunculopontine tegmental nucleus (PPTn) was originally defined on cytoarchitectonic grounds in humans. We have employed cytoarchitectonic, cytochemical, and connectional criteria to define a homologous cell group in the rat. A detailed cytoarchitectonic delineation of the mesopontine tegmentum, including the PPTn, was performed employing tissue stained for Nissl substance. Choline acetyltransferase (ChAT) immunostained tissue was then analyzed in order to investigate the relationship of cholinergic perikarya, dendritic arborizations, and axonal trajectories within this cytoarchitectonic scheme. To confirm some of our cytoarchitectonic delineations, the relationships between neuronal elements staining for ChAT and tyrosine hydroxylase were investigated on tissue stained immunohistochemically for thesimultaneousdemonstration of these two enzymes.The PPTn consists of large, multipolar neurons, all of which stain immunohistochemically for ChAT. It is present within cross‐sections that also include the A‐6 through A‐9 catecholamine cell groups and is traversed by catecholaminergic axons within the dorsal tegmental bundle and central tegmental tract. The dendrites of PPTn neurons respect several nuclear boundaries and are oriented perpendicularly to several well‐defined fiber tracts. Cholinergic axons ascend from the mesopontine tegmentum through the dorsal tegmental bundle and a more lateral dorsal ascending pathway. A portion of the latter terminates within the lateral geniculate nucleus.It has been widely believed that the PPTn is reciprocally connected with several extrapyramidal structures, including the globus pallidus and substantia nigra pars reticulata. Therefore, the relationships of pallidotegmental and nigrotegmental pathways to the PPTn were investigated employing the anterograde autoradiographic methodology. The reciprocity of tegmental connections with the substantia nigra and entopeduncular nucleus was investigated employing combined WGA‐HRP injections and ChAT immunohistochemistry.The pallido‐ and nigrotegmental terminal fieldsdid not coincidewith the PPTn, but, rather, were located just medial and dorsomedial to it (the midbrain extrapyramidal area). The midbrain extrapyramidal area, but not the PPTn, was reciprocally connected with the substantia nigra and entope‐duncular nucleus. We discuss these results in light of other cytoarchitec‐tonic, cytochemical, connectional, and physiologic studies of the functional anatomy of the mesopo

ISSN:0092-7317    

DOI:10.1002/cne.902590403

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe representation of the visual field in the striate cortex (VI) was mapped with multiunit electrodes in theCebusmonkey.Nine Cebus apella, anesthetized with N2O and immobilized with pancuromium bromide were studied in repeated recording sessions.In each hemisphere, VI contains a continuous representation of the contralateral visual hemifield. The representation of the vertical meridian (VM) forms the external border of V1 except at the anteriormost portion of the calcarine fissure. The representation of the horizontal meridian (HM) divides the area so that the representation of the lower visual field is located dorsally, and that of the upper field ventrally.The convoluted surface of VI can be only partially unfolded, and no precise “flattened” map can be obtained without introducing surface discontinuities. The visual topography of VI is presented in a series of coronal sections and in “flattened” maps.The representation of the central visual field is magnified relative to that of the periphery in VI. The evaluation of the cortical magnification factors measured along isoeccentric and isopolar dimensions in the partially unfolded model of VI revealed anisotropies in the representation of the visual field with larger magnification along isopolar lines than along isoeccentric lines. Receptive field size increases with increasing eccentricity, whereas point image size decreases with increasing eccen

ISSN:0092-7317    

DOI:10.1002/cne.902590404

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe effects of aging on the intercellular transfer of the low molecular weight fluorescent dye 5,6‐carboxyfluorescein was studied in subfields fascia dentata, CA1, and CA3 of rat hippocampal slices maintained in vitro. All three areas exhibited a statistically significant increase in dye coupling with age. The increased dye coupling was accompanied by an apparent increase in postsynaptic excitability as assessed by the ratio of the population spike to EPSP components of the extracellulary recorded field potential. The possibility that artifaciual dye coupling due to cell fusion contributed significantly to these results was ruled out by the demonstrations that a high molecular weight, dextran‐coupled fluorescein compound did not produce multiple fills and that dye coupling with carboxyfluorescein could be prevented by prior intracellular loading with Ca++, a procedure that decouples gap junctions in other tissue. The increase in extent of electrical coupling suggested by these data may largely account for the apparent increase in cellular excitability of this tissue with age and may reflect the mechanism by which the senescent hippocampus compensates for the loss of afferent input during the course of normal aging. The additional possibility is raised that increased electrical couping may reflect a mechanism for permanent associative storage of information in this sys

ISSN:0092-7317    

DOI:10.1002/cne.902590405

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractQuantitative14C‐deoxyglucose autoradiography was used to determine the local cerebral glucose metabolic rate (lCMRG) of nuclei in the septal region and anterior hypothalamus of awake, unanesthetized rats. The lCMRG of the medial and lateral septal areas, preoptic areas, medial preoptic nuclei, suprachiasmatic nuclei, supraoptic nuclei, anterior hypothalamic nuclei, and paraventricular nuclei were measured. The lCMRG of each nucleus was mapped at successive rostral‐caudal levels to determine significant internuclear and intranuclear variations. These data provide a detailed neuroanatomic map of cerebral energy metabolism of the septal and anterior hypothalamic regions in animals under standardized conditi

ISSN:0092-7317    

DOI:10.1002/cne.902590406

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe fastigiocerebral projection in the cat was investigated electrophysiologically by recording field potentials and unit activities and also morphologically by anterograde and retrograde HRP methods. Three cortical areas mostly hidden in sulci, two in the frontal cortex and one in the insular cortex, were responsive to fastigial stimulation under pentobarbital anesthesia. The responsive areas in the frontal cortex were the ventral bank of the cruciate sulcus and the area surrounding the fundus of the presylvian sulcus; the latter area corresponds to a subregion of the frontal eye field. The responsive area in the insular cortex Was the ventral bank of the anterior ectosylvian sulcus, which overlaps largely with the “anterior ectosylvian visual area.” The response in the frontal cortex was a surface‐positive, depth‐negative wave, whereas the response in the insular cortex was a surface negative, depth‐positive wave. Anterogradely labeled terminals of the fastigiothalamic projection were most dense in the ventromedial (VM) nucleus in which retrogradely labeled neurons were numerous when WGA‐HRP was injected into any one of the three cortical areas. In agreement with the results of the HRP studies, units that responded orthodromically to fastigial stimulation and antidromically to cortical stimulation were located in the thalamic VM nucleus. There was a marked difference between the frontal and insular cortices in laminar distribution of terminals of the thalamocortical projection fibers. Anterogradely labeled terminals after injection of WGA‐HRP into the VM nucleus were distributed mainly in layers I and III in the frontal cortex, whereas they were distributed mainly in layer I in the i

ISSN:0092-7317    

DOI:10.1002/cne.902590407

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractWe studied the organization of projections from the C1 adrenergic and A1 noradrenergic cell groups in the ventrolateral medulla (VLM) to the hypothalamus and the spinal cord by using a combination of retrograde transport of fluorescent tracers and immunocytochemistry. Three issues were addressed.1Neurons in the VLM that stain immunohistochemically for phenylethanolamine N‐methyltransferase (PNMT) have been assumed to be adrenergic. However, the presence of PNMT‐immunoreactive neurons in the hypothalamus that do not stain for tyrosine hydroxylase (TH) prompted us to re‐evaluate the VLM by an elution‐restaining immunohistochemical procedure. We confirmed that nearly all of the rostral medullary PNMT‐immunoreactive neurons also stained for TH. By contrast, in the caudal medulla, very few TH‐positive neurons stained for PNMT.2Neurons of the C1 group in the rostral VLM project both to the thoracic spinal cord and to the hypothalamus. To determine whether individual C1 neurons send collaterals to the hypothalamus and spinal cord, we injected different‐colored fluorescent dyes (diamidino yellow or fast blue) into the thoracic spinal gray matter and either the median preoptic (MnPO) or paraventricular (PVH) nuclei of the hypothalamus. Very few doublelabeled neurons were found in the VLM, indicating that hypothalamic and spinal cord projections arise from almost completely independent populations of cells. Approximately half of the neurons projecting to the spinal cord from rostral VLM were not immunoreactive for TH or PNMT, indicating that a substantial part of this projection is noncatecholaminergic.3The MnPO and the PVH both receive extensive catecholaminergic inputs from the VLM. We also used fluorescent retrograde tracers to determine whether individual VLM neurons send collaterals to both hypothalamic sites. Approximately 20% of neurons projecting to the MnPO in the rostral two thirds of the VLM also sent collaterals to the PVH, nearly all of these neurons being TH‐positive.The collateralization of the VLM catecholaminergic projection to the hypothalamus may provide an anatomical susbstrate for integration of fore‐brain participation in cardiovascular regulation. In contrast, the adrenergic projection from the VLM to the intermediolateral column of the spinal cord arises from a separate popu

ISSN:0092-7317    

DOI:10.1002/cne.902590408

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe neuroanatomy of a serotonin neurohemal system in the head ofPeriplaneta americanawas studied by means of immunohistochemistry, cobalt backfilling, transmission electron microscopy, and nerve transection.This neurohemal system is supplied by bilateral groups of two or three neurons whose somata are located ventrally in the subesophageal ganglion, near the root of each mandibular nerve. Axons of these serotoninergic neurons extend into all of the nerves of the mouth parts but reach most of these nerves by a very circuitous route. Initially the axons extend from the subesophageal ganglion, through the ipsilateral mandibular nerve trunk, and into the third branch of the mandibular nerve. From here the axons extend into the second branch of the maxillary nerve by way of a link nerve, and then they project retrogradely to reenter the subesophageal ganglion. In the ganglion, branches of these axons extend into the labial nerves, and the axons run dorsally through the subesophageal ganglion, circumesophageal connectives, and tritocerebrum to reach the labral nerves. In the nerves of the mouth parts the serotoninergic axons give rise to numerous secondary branches that form an extensive neurohemal system at the surface of these nerves. The relatively large surface and cephalic location of this system probably indicate that the timely release of relatively large amounts of serotonin plays an important role in the physiology of feeding in this insect.The somata, neurites, and dendritic fields of the serotonin neurohemal neurons and those of the motor neurons of the mandibular abductor muscle occur together, and some of the mandibular abductor motor neurons also stain for serotonin. In order to distinguish clearly between these neurohemal and motor neurons, the anatomy of the mandibular abductor motor neurons has also been determined. Similarly, in the course of this study it has been necessary to work out the anatomy of the motor neurons of the maxillary retractor and cardo rotator muscles in order to distinguish them from the serotoninergic neurons.A nonserotoninergic peripheral neuron is associated with the serotonin neurohemal system, and its soma is located on the mandibular‐maxillary link nerve. This link nerve neuron appears to be neurosecretor

ISSN:0092-7317    

DOI:10.1002/cne.902590409

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902590410

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902590401

出版商:Alan R. Liss, Inc.    

年代:1987

数据来源: WILEY