摘要:

AbstractThe afferent connections of the substantia innominata (SI) in the rat were determined employing the anterograde axonal transport ofPhaseolus vulgarisleucoagglutinin (PHA‐L) and the retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP), in combination with histochemical procedures to characterize the neuropil of the SI and identify cholinergic cells. Both neurochemical and connectional data establish that the SI is organized into a dorsal and a ventral division. Each of these divisions is strongly affiliated with a different region of the amygdala, and, together with its amygdalar affiliate, forms part of one of two largely distinct constellations of interconnected forebrain and brainstem cell groups.The dorsal SI receives selective innervation from the lateral part of the bed nucleus of the stria terminalis, the central and basolateral nuclei of the amygdala, the fundus of the striatum, distinctive perifornical and caudolateral zones of the lateral hypothalamus, and caudal brainstem structures including the dorsal raphe nucleus, parabrachial nucleus, and nucleus of the solitary tract. Projections preferentially directed to the ventral SI arise from the medial part of the bed nucleus of the stria terminalis, the rostral two‐thirds of the medial nucleus of the amygdala, a large region of the rat amygdala that lies ventral to the central nucleus, the medial preoptic area, anterior hypothalamus, medialmost lateral hypothalamus, and the ventromedial hypothalamus. Both SI divisions appear to receive afferents from the dorsomedial and posterior hypothalamus, supramammillary region, ventral tegmental area, and the peripeduncular area of the midbrain. Projections to the SI whose selectivity was not determined originate from medial prefrontal, insular, perirhinal, and entorhinal cortex and from midline thalamic nuclei. Findings from both PHA‐L and WGA‐HRP experiments additionally indicate that cell groups preferentially innervating a single SI division maintain numerous projections to one another, thus forming a tightly linked assembly of structures.In the rat, cholinergic neurons that are scattered throughout the SI and in parts of the globus pallidus make up a cell population equivalent to the primate basal nucleus of Meynert (Mesulam et al.:Neuroscience 10:1185–1201, '83). PHA‐L‐filled axons, labelled from lectin deposits in the dorsal raphe nucleus, peripeduncular area, ventral tegmental area, or caudomedial hypothalamus were occasionally seen to approach individual cholinergic neurons in the SI, and to contact the surface of such cells with axonal varicosities (putative synaptic boutons). Pending confirmation in an electron microscopic study, such findings suggest that several sources of innervation of the SI may provide afferents to the cholinergic cell

ISSN:0092-7317    

DOI:10.1002/cne.902770302

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe efferent connections of the substantia innominata (SI) were investigated employing the anterograde axonal transport ofPhaseolus vulgarisleuoagglutinin (PHA‐L) and the retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). The projections of the SI largely reciprocate the afferent connections described by Grove (J. Comp. Neurol. 277:315–346, '88) and thus further distinguish a dorsal and a ventral division in the SI. Efferents from both the dorsal and ventral divisions of the SI descend as far caudal as the ventral tegmental area, substantia nigra, and peripeduncular area, but projections to pontine and medullary structures appear to originate mainly from the dorsal SI. Within the amygdala and hypothalamus, which receive widespread innervation from the SI, the dorsal SI projects preferentially to the lateral part of the bed nucleus of the stria terminalis; the lateral, basolateral, and central nuclei of the amygdala; the lateral preoptic area; paraventricular nucleus of the hypothalamus; and certain parts of the lateral hypothalamus, prominently including the perifornical and caudolateral zones described previously. The ventral SI projects more heavily to the medial part of the bed nucleus of the stria terminalis; the anterior amygdaloid area; a ventromedial amygdaloid region that includes but is not limited to the medial nucleus; the lateral and medial preoptic areas; and the anterior hypothalamus. Modest projections reach the lateral hypothalamus, with at least a slight preference for the medial part of the region, and the ventromedial and arcuate hypothalamic nuclei.Both SI divisions appear to innervate the dorsomedial and posterior hypothalamus and the supramammillary region. In the thalamus, the subparafascicular, gustatory, and midline nuclei receive a light innervation from the SI, which projects more densely to the medial part of the mediodorsal nucleus and the reticular nucleus. Cortical efferents from at least the midrostrocaudal part of the SI are distributed primarily in piriform, infralimbic, prelimbic, anterior cingulate, granular and agranular insular, perirhinal, and entorhinal cortices as well as in the main and accessory olfactory bulbs.The cells of origin for many projections arising from the SI were identified as cholinergic or noncholinergic by combining the retrograde transport of WGA‐HRP with histochemical and immunohistochemical procedures to demonstrate acetylcholinesterase activity or choline acetyltransferase immunoreactivity. Most of the descending efferents of the SI appear to arise primarily or exclusively from noncholinergic cells.Overall, the subcortical projections of the dorsal division of the SI were found to be strikingly reminiscent of those reported previously for two adjoining structures: the lateral part of the bed nucleus of the stria terminalis and the central nucleus of the amygdala. A second tissue continuum with common subcortical efferents appears to be formed by the medial part of the bed nucleus, ventral SI, and the rostral parts of both the medial nucleus of the amygdala and an amygdaloid region that lies ventral to the central nucleus and dorsal to the cortical nuclei (Krettek and Price:J. Comp. Neurol. 178:225–254, '78; Price and Amaral:J. Neurosci. 1:1242–1359, '81; Holstege et al.:Exp. Brain Res. 58:379–391, '85; Grove:J. Comp. Neurol. 277:

ISSN:0092-7317    

DOI:10.1002/cne.902770303

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThalamic efferent connections of the basal forebrain (BF); medial septal nucleus (MS), vertical limb of the diagonal band (VDB), horizontal limb of the diagonal band (HDB), nucleus basalis (NB), and ventral pallidum (VP) were investigated in twelve rhesus monkeys. In five animals, injections of radioactively labeled amino acids were placed in the BF. In four animals, the injections involved different divisions of the NB, HDB, and the most ventral part of the VDB. In those four cases, labeled fibers in the medial forebrain bundle were observed traveling caudally towards the hypothalamus where some turned dorsally to enter the inferior thalamic peduncle. These fibers terminated in the ventral half of the magnocellular part of the medial dorsal thalamic nucleus (MDmc). In a fifth case, the amino acid injection involved most of the MS and the VDB. Labeled fibers traveled caudally from the injection site and entered the stria medullaris. These fibers then traveled caudally before turning ventrally to terminate in the dorsal half of MDmc. To determine which of the diverse neuronal types in the BF gives rise to these thalamic projections, in two monkeys injections of horseradish peroxidase (HRP) were placed into MDmc. Labeled neurons were observed throughout the full extent of the NB, the VDB, the MS, and part of the VP. In order to determine the extent of the cholinergic input to MDmc from the BF, one of the HRP cases was processed for the simultaneous visualization of HRP, and acetylcholinesterase (AChE), the hydrolytic enzyme for acetylcholine, and a second case was processed for simultaneous visualization of HRP, and choline acetyltransferase (ChAT), the synthetic enzyme for acetylcholine. We observed that 30–50% of the HRP‐labeled neurons were putatively cholinergic. In order to determine if the NB projection to MD is a collateral of the NB projection to orbital frontal cortex, one fluorescent retrograde tracer was injected into the orbital frontal cortex and one into MD. This case showed that approximately 5% of the BF neurons that project to MDmc also project to the orbital frontal cortex. These results confirm a significant subcortical projection by which the cholinergic system of the basal forebrain may influence higher cortical functions through the thala

ISSN:0092-7317    

DOI:10.1002/cne.902770304

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractCell suspensions derived from the ventral mesencephalon of CD‐1 mice were unilaterally transplanted into the striatum of neonatal Sprague‐Dawley rats that had been bilaterally dopamine depleted. Thirty‐eight percent of the grafts survived. Tyrosine‐hydroxylase‐immunoreactive neurons within the transplant innervated the host striatum with a dense fiber plexus. The grafts appeared to exert some degree of functional control over motor behavior in that these animals made contralateral rotations in response to amphetamine and tail pinch. In order to provide additional evidence that the motor behavior is associated with the transplant itself, the graft was removed. This was achieved by using a mouse skin graft to provoke an immunological response against the transplanted neural tissue. The immunological response resulted in the specific loss of the transplant with little or no damage to the surrounding neural tissue. The amount of rotation observed after tail pinch and amphetamine injection was severely affected by neural graft rejection. The loss of turning was associated most directly with the loss of tyrosine hydroxylase immunoreactivity within the transplant rather than with the massive reduction of tyrosine‐hydroxylase‐positive fibers in the ipsilateral host striatum. These data suggest that dopamine cells in mouse nigral grafts play an essential role in eliciting rotational behavior in neonatally dopamine depleted rats. They also show the value of skin grafting as a technique for specifically removing neur

ISSN:0092-7317    

DOI:10.1002/cne.902770305

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe goldfish optic pathway is regenerated after an optic nerve crush. We have examined the axonal topography of the regenerated pathway by labeling, with horseradish peroxidase (HRP), axons originating from retinal sectors or annuli. The positions of the labeled axons in the cross section of the pathway were compared to the normal and related to the factors that may influence axonal pathfinding.The positions of retinal axons in the cross section of the normal pathway are predictable from the retinal addresses of the ganglion cells described by the polar coordinates r (the distance from the optic disc) and θ (the sectoral or clockface position). The two coordinates map orthogonally onto the cross section of the pathway; r varies monotonically along one axis; θ varies along a perpendicular axis.The normal r‐order, present in the nonregenerated stump of the experimental nerve, was severely degraded and perhaps lost entirely in the regenerated optic nerve, tract, and brachia. Sectoral order was also lost as the axons passed the crush site, but it was reestablished, albeit crudely, in the regenerated tract and brachia where axons tended to occupy positions appropriate to their dorsal, ventral, nasal, and temporal retinal origins. The exit sequence of the regenerated axons from the stratum opticum into the tectal neuropil was normal: temporal first, nasal last.These results suggest that the regenerating fibers followed some θ specific cue located in the nonaxonal environment. It seems likely that the original axons probably followed the same cue. In contrast, the absence of r‐order suggests that there is no r‐specific cue for the regenerates to follow. It seems likely that the original r‐order was a consequence of nonspecific influences—the orderly spatiotemporal growth of the retina and the existence of a permissive region for a

ISSN:0092-7317    

DOI:10.1002/cne.902770306

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThroughout a goldfish's life, new generations of ganglion cells are added on the retinal margin and their axons extend centrally to occupy predictable positions in the retinotectal pathway, adjacent to their predecessors and subjacent to the pia. The stacking of successive generations of axons defines the age‐axis of the pathway. This study examined whether an ordered array of predecessor axons is a prerequisite for the patterned growth of new axons. One optic nerve was crushed intraorbitally and the fish was injected with 3H‐thymidine to label the proliferating cells on the retinal margin. The ring of 3H‐thymidine‐labeled cells separated retina that was present at the time of nerve crush (inside the ring) from new retina added afterward (outside). After a period of 14–16 months postcrush, both tectal lobes received two punctate applications of horseradish peroxidase (HRP), one in the central and the other in peripheral tectum, to retrogradely label contralateral retinal ganglion cell bodies and their axons.The pattern of HRP labeling from the control tectum confirmed earlier work: axons on the central tectum had somata in the central retina, and axons on the peripheral tectum had somata in the peripheral retina. The labeled cells and axons were both in predictable patterns. The somata that were backfilled from applications to thecenterof theexperimentaltectum layinsidethe radioactive ring and had therefore regenerated their axons. The patterns of their labeled axons in the optic pathway and of their somata in the retina were typical of the regenerated condition as described in earlier studies. The somata backfilled from theperipheryof theexperimentaltectum wereoutsidethe radioactive ring and had been added after the optic nerve crush. The patterns of their labeled axons and somata were comparable to the normal pattern. These observations indicate that new axons do not depend on an ordered array of predecessors to reestablish normal order along the age‐axis of

ISSN:0092-7317    

DOI:10.1002/cne.902770307

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe cat peroneal muscles have been used in numerous investigations dealing with the physiological properties of motor units, muscle spindles, and Golgi tendon organs. This report presents a study of the organization of peroneal motor pools in the cat spinal cord by means of retrograde axonal transport of horseradish peroxidase from individual muscles to the corresponding motoneurons. The motor nuclei of peroneus longus (PL), peroneus brevis (PB), and peroneus tertius (PT) muscles formed thin columns in the lateral part of the ventral horn in spinal segments L6–S1. In the transverse plane, the PT and PL nuclei occupied, respectively, dorsolateral and ventromedial positions, with PB nucleus in an intermediate position overlapping with the other two nuclei. Measurements of cell body diameters allowed identification of α and γ subgroups in peroneal motoneuron populations. The average numbers of motoneurons were about 96 α and 60 γ in PL, 75 α and 54 γ in PB, and 34 α and 23 γ in PT. Comparison with data from electrophysiological studies indicated that whole populations of motoneurons were labeled in each motor nucleus. The proportions of γ motoneurons were the same, and cell bodies of γ motoneurons had similar sizes in the three peroneal populations. In contrast, α motoneurons were significantly smaller in PB than in the two other pools, in keeping with the fact that PB contains a proportion of slow motor units larger than the two other muscles. In large samples of homonymous motoneurons, the numbers of first‐order dendrites correlated linearly with mo

ISSN:0092-7317    

DOI:10.1002/cne.902770308

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractOligodendrocytes are largely generated postnatally during mammalian CNS development. We have used a variety of antibodies to label immature neuroectodermal cells and developing oligodendrocytes in several areas of the rat CNS. Antibodies included those to GD3ganglioside, a characteristic glycolipid of immature cells; carbonic anhydrase (CA), contained primarily in oligodendrocytes; and galactocerebroside and myelin basic protein, myelin components. Several aspects of oligodendrocyte development were examined: changes in shapes of immature cells with respect to time and to location within the brain, the sequential acquisition of the various markers, and possible sites of origin and pathways of precursor cell migration. Our observations suggest that oligodendrocytes in the forebrain and cerebellum arise from cells of the subventricular zone (SVZ) adjacent to the ventricles and migrate into and through nearby white and gray matter. During maturation, there are distinct patterns of morphological changes that correlate with time, locations of the cells in the brain, and acquisition of specific markers.

ISSN:0092-7317    

DOI:10.1002/cne.902770309

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractImmunocytochemistry and electron microscopy were used to examine the ultrastructural features of immature neuroectodermal cells of the rat forebrain in their early stages of differentiation. We used a monoclonal antibody (AbR24) to GD3ganglioside, which binds to cells of the subventricular zone (SVZ). R24 also labels immature cells in developing white and gray matter (LeVine and Goldman:J. Neurosci.in press, '88, and accompanying paper). Sections of developing cingulum and white matter adjacent to the cingulum were examined at E18, P4, and P10 by using a preembedding immunocytochemical technique with PAP reagents. Labeled cells seen earliest were large, with high nuclear to cytoplasmic ratios and few cytoplasmic organelles. With time, smaller forms appeared, with prominent Golgi apparatus and processes containing microtubules. Labeled cells with similar characteristics but which contained cytoplasmic vacuoles were also observed. The results indicate a series of ultrastructural transformations that are consistent with oligodendrocyte differentiation.

ISSN:0092-7317    

DOI:10.1002/cne.902770310

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902770301

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY