摘要:

AbstractThe ascending projections of the dorsal column and external cuneate nuclei (DCN/CuE) in the pigeon were investigated in anterograde tracing experiments by using autoradiography or wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). The results show that the majority of ascending projections decussate via internal arcuate fibers to form a contralateral medial lemniscus which ascends in a ventral position. In the brainstem, terminal fields were observed in the ventral lamella of the inferior olive (OI), the parabrachial nuclei (PB) of the dorsolateral pons, the intercollicular nucleus (ICo) of the midbrain, and the nucleus pretectalis diffusus (PD). In the diencephalon there were terminal fields in the strata cellulare externum and internum (SCE and SCI) of the caudal hypothalamus; in the intercalated (ICT), ventrolateral (VLT), and reticular nuclei of the ventral thalamus; in the nuclei principalis precommissuralis (PPC), spiriform medialis (SpM), and dorsolateralis posterior, pars caudalis (cDLP) of the caudal thalamus; and in the nuclei dorsalis intermedius ventralis anterior (DIVA), dorsolateralis posterior, pars rostralis (rDLP), dorsolateralis anterior (DLA), and dorsolateralis anterior, pars medialis (DLM) of the rostrodorsal thalamus.The origins of these projections within the DCN/CuE complex were verified in retrograde tracing experiments with WGA‐HRP and were found to be partly differentiable with respect to their targets. The projections to DIVA, rDLP, DLA, DLM, cDLP, and SpM arise from all rostrocaudal levels of the DCN/CuE complex; those to ICo arise from caudomedial nuclear regions, while those to the hypothalamus and ventral thalamus arise from rostrolateral nuclear regions. Projections to PB arise from lamina I neurons of the dorsal horn of upper cervical spinal cord segments and from CuE. No evidence was found of a projection to the cerebellum.The distribution of the cells of origin of the medial lemniscus (ML) within the DCN/CuE complex was found to be largely coextensive with the areas of termination of primary spinal (Wild:J. Comp. Neurol. 240:377–395, '85) and some trigeminal (Dubbledam and Karten:J. Comp. Neurol. 180:661–678, '78) afferents. Furthermore, the areas of termination of the ML within the rostrodorsal and caudal thalamus are also either coextensive or closely associated with nuclei which provide a somatosensory projection to separate regions of the telencephalon (Wild:Brain Res. 412:205–223, '87). There are thus clear similarities in the overall pattern of somatosensory projections in the pigeon and in many mammalia

ISSN:0092-7317    

DOI:10.1002/cne.902870102

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe used quantitative autoradiography to examine the distribution of thyrotropin‐releasing hormone (TRH) receptors in the central nervous system (CNS) of the African lungfishProtopterus annectens.We found that the distribution of TRH receptors throughout the CNS of the lungfish was heterogeneous with the highest concentrations (500–800 fmol/mg protein) in the olfactory bulb and telencephalon, moderately high concentrations (200–500 fmol/mg protein) in the diencephalon, and moderate (50–200 fmol/mg protein) to low (<50 fmol/mg protein) concentrations in the brainstem and spinal cord. Except for the motor nuclei of the cranial nerves and spinal cord, TRH receptors were concentrated in the acellular regions. In the telencephalon and diencephalon, the receptor density was inversely related to cellular density. These results provide a neuroanatomic and neuropharmacologic basis for further investigations of TRH in the African l

ISSN:0092-7317    

DOI:10.1002/cne.902870103

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

年代:1989

数据来源: WILEY

摘要:

AbstractLight microscopic immunocytochemistry was used to study the populations of serotoninlike‐immunoreactive cells in the larval tiger salamander retina. Of 1,135 serotonin‐immunostained cells observed in transverse cryosections, 87% were identified as amacrine cells, whereas 13% were tentatively designated as displaced amacrine cells. The somas of the vast majority of serotonin‐amacrine cells were situated in the innermost cell row of the inner nuclear layer. Only a few serotonin‐immunostained amacrine cell somas were observed in the second row of cells from the inner nuclear layer. Serotonin‐immunoreactive processes generally appeared as a diffuse plexus distributed evenly throughout all levels of the inner plexiform layer.As determined in whole‐mount preparations, serotonin‐amacrine cells were divisible into two populations on the basis of the diameters of their somas. Large cells (45%) ranged from 16 to 19 μm in diameter with the vast majority measuring 17 to 18 μm. Smaller and sometimes less intensely stained cells ranged from 14 to 16 μm in diameter with the large majority measuring 15 μm. The diameters of serotonin‐displaced amacrine cells ranged from 19 to 22 μm with the large majority measuring 20 μm in diameter. An examination of whole‐mount retinas revealed that serotonin‐immunoreactive amacrine and displaced amacrine cells were distributed throughout the center and the periphery of the retina. The density of serotonin‐amacrine cells (large and small combined) was calculated to be 173 ± 4.5 (mean ±

ISSN:0092-7317    

DOI:10.1002/cne.902870104

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe connections of the cortical dysgranular “unresponsive zone” (UZ) (Sur et al.:J. Comp. Neurol. 179:425–450, '78) in the grey squirrel were studied with horseradish peroxidase and autoradiographic techniques. The results of these experiments show that the major subcortical connections of the unresponsive zone are in large part reciprocal. Connections are distributed within the thalamus in a poorly defined region including restricted portions of several nuclei that lie along the rostral, dorsal, and caudal borders of the ventral posterior nucleus. Additional thalamic connections of the UZ terminate in the reticular nucleus and are reciprocally related to the paralaminar and central median nuclei. Extrathalamic terminations were observed in the zona incerta, the intermediate and deep layers of the superior colliculus, the red nucleus, and several subdivisions of the pontine nuclei. The similarity between the pattern of subcortical connections of the UZ in the grey squirrel and patterns reported for the parietal septal region in rats (Chapin and Lin:J. Comp. Neurol. 229:199–213, '84) and for area 3a in primates (Friedman and Jones:J. Neurophysiol. 45:59–85, '81), suggests that the UZ in the grey squirrel may represent a counterpart of at least part of area 3a as described in primates. The results are further discussed with respect to a possible role of the thalamus in control or modulation of interhemispheric circuits and of the UZ in the modulation of nociceptive and kinesthetic pathways through the thalamus. Finally, the term parietal dysgranular cortex (PDC) is proposed as an alternative to denote the region currently called the unrespon

ISSN:0092-7317    

DOI:10.1002/cne.902870105

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe levator palpebrae superioris and orbicularis oculi are antagonistic muscles that function during movements of the eyelid. The levator also functions in conjunction with superior and inferior rectus muscles in coordinated eye/lid movements. The present study examined the innervation and morphology of these muscles in Cynomolgous monkeys (Macaca fascicularis) in order to provide a better understanding of the anatomical substrate for lid movements. Motoneurons innervating the levator and orbicularis muscles were identified and localized by retrograde transport of WGA/HRP and HRP. Retrogradely labelled levator motoneurons were distributed bilaterally throughout the caudal central division of the oculomotor nucleus. A few labelled cells were also present within the contralateral superior rectus division, possibly because of the spread of tracer at the injection site. The possibility that individual motoneurons collateralize to innervate the levator muscle bilaterally was tested by using double retrograde labelling techniques. Doubly labelled levator motoneurons could not be detected by suing a combination of tracers (HRP and Fast Blue). Motoneurons innervating the upper lid portion of the orbicularis oculi muscle were distributed within the dorsal subdivision of the ipsilateral facial motor nucleus, with a few neurons in the corresponding locus of the contralateral facial nucleus. Species differences in levator motoneuron distribution, particularly distinctions in lateral‐eyed versus frontal‐eyed mammals, are discussed in relation to the neural control of lid movements.The levator palpebrae superioris contains three of the same ultrastructurally defined types of singly innervated muscle fiber found in the global layer of other extraocular muscles and an additional, unique slow‐twitch fiber type. Moreover, the multiply innervated fiber types so characteristic of the other extraocular muscles are conspicuously absent from levator muscles. Unlike the rectus and oblique extraocular muscles, the levator lacks a layered distribution of fiber types. The morphological profiles of levator muscle fiber types are such that they generally do not respect traditional fiber classification schemes, but are consistent with a role for the levator in sustained elevation of the lid.The orbicularis oculi muscle, by contrast, exhibited three distinct fiber types that resembled categories of skeletal muscle twitch fibers. One slow‐twitch and two fast‐twitch fiber types were noted. On the basis of oxidative enzyme profiles and mitochrondrial content, the majority of orbicularis oculi fibers would be fatigue‐prone, an assessment consistent with their rapid onset/offset of action in blinks. Morphological differences between the levator palpebrae superioris and orbicularis oculi muscles reflect not only their dis‐tinct functional roles in blinking and other lid movements, but also their diverse embryolo

ISSN:0092-7317    

DOI:10.1002/cne.902870106

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

年代:1989

数据来源: WILEY

摘要:

AbstractTransganglionic tracing with a combination of horseradish peroxidase (HRP) and wheat germ agglutinin–conjugated HRP (WGA‐HRP) was employed to compare the trigeminal (V) innervation of the brainstem in adult rats that sustained transection of the infraorbital nerve (ION) on either the day of birth or just prior to the beginning of the 17th embryonic day (E‐17). The same methods were also employed to assess the effects of such lesions upon the innervation of the brainstem by the lingual, inferior alveolar, mylohyoid, and auriculotemporal V branches. Previous experiments (Chiaia et al.:Dev. Brain Res. 36:75–88, '87) showed that application of HRPand WGA‐HRP to the ION in normal adult rats (N = 3) labelled 12,553 ± 1,455 (mean ± s.d.) V ganglion cells while application of these tracers to the regenerated ION after neonatal transection (N –9) labelled 5,001 ± 1,287 ganglion cells. Application of HRP and WGA‐HRP to the regenerated ION in adulthood (N = 6) after fetal transection labelled 5,476 ± 3,056 ganglion cells. Thus, the numbers of ganglion cells giving rise to the regenerated ION after fetal and neonatal transection were equivalent (P>.05).The central projections of the ION after fetal transection were qualitatively different from those observed after neonatal injury. After neonatal transection, the central terminal field of regenerated ION fibers in adulthood is almost completely restricted to layers I and II of subnucleus caudalis (SpC; Jacquin and Rhoades:Brain Res. 269:137–144, '83; Chiaia et al.:Dev. Brain Res. 36:75–88, '87). After fetal transection, regenerated ION axons terminate heavily in all portions of the V brainstem complex.After neonatal ION transection, we (Jacquin and Rhoades:J. Comp. Neurol. 235:129–143, '85) have been unable to detect central sprouting of undamaged V mandibular axons by means of transganglionic tracing with HRP and WGA‐HRP. Such sprouting was evident in both V subnucleus interpolaris (SpI) and SpC after fetal ION transection.We carried out one additional experiment to determine whether ION ganglion cells that survived fetal axotomy were more resistant to axonal damage than the population of neurons that normally contribute to this nerve on theday of birth. Rats (N = 9) sustained transection of the ION on E‐17 and again on the day of birth. The regenerated ION was then labelled with HRP and WGA‐HRP when the animals reached adulthood. Anaverage of 1,798 ± 1,050 ganglion cells were labelled in these rats and the transganglionic labelling was restricted to layers I and II of SpC. Thus, V ganglion cells that sustain axotomy on E‐17 respond to damage on the day of birth in the same manneras primary afferent neurons that have not b

ISSN:0092-7317    

DOI:10.1002/cne.902870107

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe representation of the visual field in the dorsal portion of the superior temporal sulcus (ST) was studied by multiunit recordings in eightCebus apella, anesthetized with N2O and immobilized with pancuronium bromide, in repeated recording sessions. On the basis of visuotopic organization, myeloarchitecture, and receptive field size, area MT was distinguished from its neighboring areas.MT is an oval area of about 70 mm2located mainly in the posterior bank of the superior temporal sulcus. It contains a visuotopically organized representation of at least the binocular visual field. The representation of the vertical meridian forms the dorsolateral, lateral, and ventrolateral borders of MT and that of the horizontal meridian runs across the posterior bank of ST. The fovea is represented at the lateralmost portion of MT, while the retinal periphery is represented medially.The representation of the central visual field is magnified relative to that of the periphery in MT. The cortical magnification factor in MT decreases with increasing eccentricity following a negative power function. Receptive field size increases with increasing eccentricity. A method to evaluate the scatter of receptive field position in multiunit recordings based on the inverse of the magnification factor is described. In MT, multiunit receptive field scatter increases with increasing eccentricity.As shown by the Heidenhain‐Woelcke method, MT is coextensive with two myeloarchitectonically distinct zones: one heavily myelinated, located in the posterior bank of ST, and another, less myelinated, located at the junction of the posterior bank with the anterior bank of ST.At least three additional visual zones surround MT: DZ, MST, and FST. The areas of the dorsal portion of the superior temporal sulcus in the diurnal New World monkeyCebusare comparable to those described for the diurnal Old World monkey,Macaca.This observation suggests that these areas are ancestral characters of the simian lineage and that the differences observed in the owl monkey may be secondary adaptations to a nocturnal ecological nich

ISSN:0092-7317    

DOI:10.1002/cne.902870108

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

年代:1989

数据来源: WILEY

摘要:

AbstractRecordings were made with a new form of low‐noise carbon fibre microelectrode from 75 units in the superficial laminae of the lumbar dorsal horn of the anaesthetized rat. The response of each unit to adequate stimulation of its peripheral receptive field, to noradrenaline (NA) applied iontophoretically, and to electrical stimulation of the periaqueductal gray (PAG) was investigated. Only units that could be excited by iontophoresis of glutamate (10–100 nA) were analyzed. Recording sites in the spinal cord and stimulation sites in the brainstem were identified histologically at the end of each experiment.Forty‐six units with low‐threshold receptive fields and small spike amplitudes were found, mainly located in laminae II and III. Both stimulation of the PAG and NA iontophoresis excited the majority (32/46) of these units. The rest were unaffected. Eight high‐threshold (HT) units were located in the region of lamina I. Twenty‐one wide‐dynamic‐range (WDR) units were found mainly in deeper laminae. Both WDR and HT units were inhibited by NA and PAG stimulation. This inhibition affected both glutamate‐evoked activity and responses to nociceptive stimuli.We suggest that the small LT units are inhibitory interneurones of the substantia gelatinosa (SG), which act on the WDR and HT units to produce nociceptive‐specific inhibition. The inhibition can be modality‐specific without necessarily being presynaptic because of the laminar arrangement of the dorsal horn. The PAG could thus exert its known antinociceptive effects at least partly via descending noradrenergic axons that

ISSN:0092-7317    

DOI:10.1002/cne.902870109

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

年代:1989

数据来源: WILEY

摘要:

AbstractTo determine the brainstem origins and axonal routes of stapedius motoneurons, we labeled motoneurons by injecting cat stapedius muscles with horseradish peroxidase. Some injections were made in normal cats and some in cats in which the middle segment of the internal facial genu had been cut. By tracing labeled axons and by comparing the locations of labeled cell bodies in normal and lesioned cats, we divided stapedius motoneurons into two groups: “perifacial” and “accessory.” Perifacial stapedius motoneurons have cell bodies located around the motor nucleus of the facial nerve and axons which follow the classical course of facial motor axons through the internal genu of the facial nerve. Accessory stapedius motoneurons have cell bodies near the descending facial motor root and axons which ascend to the rostral tip of the internal facial genu, abruptly reverse direction, and then join the descending facial motor root. The sharply hooked course of axons of accessory stapedius motoneurons is similar to the course of axons from other accessory nuclei of cranial nerves V‐VII. Our present results, with those of McCue and Guinan (J. Neurophysiol. 60:1160–1180, '88), demonstrate that cats have two groups of stapedius motoneurons which can be separated anatomically by the locations of their cell bodies or by the courses of their axons, and which, on the average, have different response

ISSN:0092-7317    

DOI:10.1002/cne.902870110

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

年代:1989

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902870101

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

年代:1989

数据来源: WILEY