bluuebunny/crossref_metadata_2025_split huggingface dataset:
A quantitative investigation of spine and dendrite development of neurons in visual cortex (area 17) of Macaca nemestrina monkeys
Authors: Boothe Ronald G. , Greenough William T. , Lund Jennifer S. , Wrege Kathy 
Published: January 2005

AbstractIn a previous Golgi study (Lund et al., '77) which examined the development of the macaque monkey striate cortex (area 17) it was observed that the dendrites of neurons within the visual cortex show a marked increase in the number of spines on their surface during the first eight weeks of postnatal life. The qualitative observation was also made that all neurons then showed a marked decrease in spine numbers by the time the animal was adult. Since these spines are known to be sites of synaptic contact, changes in their numbers may reflect changes in synapse populations on these neurons.This study examines quantitatively spine frequency and total dendritic development of Golgi impregnated neurons in monkeys ranging in age from 145 days gestation to adult. Four cell types were studied: spiny stellate neurons from laminae IVCα and IVCβ and pyramidal neurons with soma in either lamina IIIB or upper lamina VI. After consideration of possible sources of variation in spine numbers several conclusions are made: (1) Dendritic spine development appears to be a tightly controlled process both in terms of actual numbers of spines on a neuron at any one age and in the rate of change of spine frequency. (2) The neurons populations examined all show a gradual increase in spine numbers up to eight weeks of age. (3) At least two different trends are found in spine population maturation after the eight week point: (A)‐the spine population may remain constant at the eight week level for same period of time or (B)‐there may be a rapid decline in spine numbers following the eight week peak. (4) There is a suggestion that those neurons associated with direct input, or early stages in the relays, from the parvocellular geniculate laminae show trend B, while those associated with magnocellular input, or later order combined relays within the cortex, show trend A. (5) Different parts of a single pyramidal neuron dendrite may show either trend A or trend B, depending on the lamina location of the dendritic segment considered. (6) All neurons show spine population decreases between nine months of age and adult (5–7 years) suggesting continuing long term maturational changes.
Origin and organization of brainstem catecholamine innervation in the rat
Authors: Levitt Pat , Moore Robert Y. 
Published: January 2005

AbstractThe catecholamine (CA) innervation of the rat brainstem was studied by biochemical analysis of discrete nuclei or areas and by glyoxylic acid‐formaldehyde freeze dry fluorescence histochemistry. CA assays demonstrate that the highest norepinephrine (NE) content in brainstem is present in the trigeminal motor nucleu, nucleus tractus solitarius, dorsal motor nucleus of the vagus and nucleus raphe dorsalis. Bilateral locus coeruleus (LC) lesions do not significantly alter NE content in these nuclei but do decrease NE content in the superior and inferior colliculi, medial geniculate body, interpeduncular nucleus, pontine nuclei and the main sensory trigeminal nucleus (60–75%). Dopamine (DA) and epinephrine (E) are found in significant concentration in only a few of the nuclei examined.Fluorescence histochemical analysis indicates that two groups of NE axons innervate rat brainstem. LC neuron axons with a distinctive morphology principally innervate sensory and association nuclei of the brainstem. These disappear completely after bilateral LC lesions. The second group of axons originates from lateral and dorsal tegmental NE cell groups. Primary motor and visceral nuclei are densely innervated by fine and thick axons from these groups. Lesions of LC do not alter the NE innervation in any of the nuclei which contain axons of the second group.These results indicate that the brainstem NE innervation is divided into two major systems. The locus coeruleus complex innervates mainly primary sensory and association nuclei whereas the lateral tegmental NE neurons innervate primary motor and visceral nuclei. Although some overlap is present, the LC and lateral tegmental NE system predominantly innervate separate and functionally distinct areas of the brainstem. DA and E neurons provide a very minor component of the brainstem CA innervation.
Terminal proliferation in the partially deafferented dentate gyrus: Time coureses for the appearance and removal of degeneration and the replacement of lost terminals
Authors: McWilliams Randall , Lynch Gary 
Published: January 2005

AbstractThe time courese for the appearance and removal of degenerating terminals and the loss and reappearance of intact terminals were investigated in the partially denervated inner molecular layer of the dentate gyrus of the adult rat. Dense degeneration was evident in the neuropil within 26 hours following contralateral hippocampectomy. These profiles increased rapidly in number until the maximal degree was reached at two to tree days postlesion, after which the degenerating terminals were quickly removed from the neuropil. A more rapid rate of removal occurred during the 3‐ to 5‐ day survival period than from 6 to 50 days postlesion.The intact terminal population dropped by 35% within two days of the lesion and remained at this level until six to eight days postlesion when the number began to steadily increase. The time course for this reappearance cat be divided into two phases: a period of rapid terminal addition from 6 to 15 days followed by a phase of slower acquisition. This recovery continued until the normal synaptic density was regained by 50 to 65 days postlesion.These results indicate that a substantial proportion of degenerating endings are removed well in advance of the time at which terminal proliferation begins, suggesting that certain changes other than merely the removal of competitive inputs must take place prior to the gowth of new terminals. Possible explanations suggested by the present results for the delay in the onset of sprouting in clude: (1) an absence of appropriate postsynaptic targes during the 2‐ to 5‐ day postlesion period and (2) inhibition of axonal growth by the glial cells which are phagocytizing the degenerating products.Beyond the sixth postlesion day the rate at which new terminals appear does correlate with the rate at which degeneration is removed. This suggests that once underway the time course for sprouting may be determined by the availability of postsynaptic sites.
Afferent connections to the amygdaloid complex of the rat and cat. I. Projections from the thalamus
Authors: Ottersen Ole P. , Ben‐Ari Y. 
Published: January 2005

AbstractBy the use of the retrograde transport of horseradish peroxidase (HRP), the projections from the thalamus to the amygdala were investigated in the rat and cat, with main emphasis on the former species. HRP was injected stereotactically by microiontophoresis in the various amygdaloid nuclei. Several control procedures including the use of different approaches for the introduction of the micropipette were undertaken to eliminate the possibility of misinterpretation due to uptake of the protein by adjacent structures or fibers en passant.The paraventricular and parataenial nuclei of the thalamus were found to project throughout the entire amygdaloid complex. The medial geniculate complex and the basal nucleus of the ventromedial complex (the thalamic taste relay) mainly project to the centromedial part of the amygdala. The basolateral nucleus is the main recipient of a hitherto undescribed bilateral thalamo‐amygdaloid pathway originating in the interanteromedial nucleus. The parafascicular nucleus projects to the central nucleus of the amygdala; in the cat mainly to the lateral subdivision of the central nucleus.The findings are discussed in relation to previous anatomical and electrophysiological studies centered on the amygdaloid complex. Special reference is made to the possible role of the thalamo‐amygdaloid connections in the conveyance of sensory information to the amygdala.
Cell death of motoneurons in the chick embryo spinal cord. IV. Evidence that a functional neuromuscular interaction is involved in the regulation of naturally occurring cell death and the stabilization of synapses
Authors: Pittman Randall , Oppenheim Ronald W. 
Published: January 2005

AbstractEmbryos immobilized with neuromuscular blocking agents for differing periods between 4.5 and 9 days of incubation had an increased number of motoneurons in the brachial and lumbar lateral motor columns. Treatment with α‐cobratoxin (α‐CTX) on days 4‐9 for instance, was able to prevent virtually all natural cell death during this period; control embryos had an average of 22,500 lumbar motoneurons on day 5.5, and 13,500 on day 10, whereas treated embryos had approximately 21,000 cells on day 10. Curare, α‐CTX, α‐bungarotoxin (α‐BTX) and botulinum toxin were all about equally effective in preventing cell death. Similar treatment begun after day 12, however, had no effect on cell number. If even a partial immobilization was continued after day 10 (in embryos totally immobilized earlier) most of the excess neurons were maintained, in some cases right up to hatching, at which time the embryos died due to respiratory failure. In contrast, when administration of the immobilizing agents was stopped, allowing the embryos' motility to return to control levels, the excess neurons underwent a delayed cell death and total cell number fell to below control levels by days 16‐18.Limb muscles from embryos with exces motoneurons exhibited relatively normal differentiation and had acetylcholinesterase (AChE) stained endplates which were innervated. Following curare treatment the two wing muscles, anterior and posterior latissimus dorsi, were found to have an increased number of AChE‐stained endplates, whereas the only leg muscle examined quantitatively – the ischioflexorius (IFL) –did not; the IFL, did, however, have a markedly reduced variance in endplate distance, as well as other apparent differences suggesting an altered pattern of innervation.Our findings imply that the number of motoneurons undergoing natural cell death is closely related to muscle activity. Thus, functional interactions at the developing neuromuscular junction seem to be critical in controlling cell death. If a retrograde trophic factor is involved its action is somehow related to muscle activity.
Quantitative electron microscopic evidence for reinnervation in the adult rat interpeduncular nucleus after lesions of the fasciculus retroflexus
Authors: Murray M. , Zimmer J. , Raisman G. 
Published: January 2005

AbstractThe method of electron dense degeneration has been used to make a quantitative study of the projection from the habenula through the fasciculus retroflexus (FR) to the interpeduncular nucleus (IPN) in the rat. The IPN is a midline structure onto which the right and left fasciculi converge. In the rostral part of the IPN the fascicular axons from each side form synapses throughout the mediolateral extent of the ventral two‐thirds of the nucleus. In the caudal part of the IPN the fascicular axons from each side terminate to an equal extent in two discrete, parasagittal zones, situated one on each side in the mid‐mediolateral extent of the IPN. These zones contain clusters of neurons located along the course of a characteristic row of arterioles and venules penetrating the IPN from its ventral surface.In both rostral and caudal parts of the IPN the fascicular axons form single synaptic contacts with the dendrites of the interpeduncular neurons, but caudally, in the two parasagittal zones they also form crest synapses. Crest synapses are only found in this part of the IPN. In crest synapses two presynaptic terminals form markedly asymmetrical contacts with the parallel opposing sides of an attenuated dendritic appendage (the crest). After unilateral fascicular lesions only one member of a pair of axon terminals contacting a crest degenerates. After bilateral fascicular lesions, however, there are many instances in which both members of a crest pair degenerate. This indicates that the axon terminals from the right and left fasciculi are segregated at the level of the crests, in such a way that one terminal comes from the right fasciculus and one from the left.At longer survivals after unilateral or bilateral fascicular lesions the degeneration is completely removed, but crest synapses are still present, indicating that the presence of fascicular axons is not necessary for the maintenance of crests in the IPN.To investigate the effects of chronic deafferentation, the left fasciculus was destroyed and, after a survival of at least six weeks (sufficient for all degeneration to be removed) the right fasciculus was destroyed one day before killing. Under these conditions there are many crests in which both axon terminals show degeneration. The proportion of such doubly degenerating crest synapses is similar to that found after acute (1 day) bilateral lesions, indicating that axons from the right fasciculus have reinnervated sites formerly occupied by the left fasciculus. We conclude that during normal development there is some constraint which prevents both sides of a crest being innervated by axons from the fasciculus of the same side of the brain, but that this constraint is not effective after unilateral fascicular lesions in the adult.
Further observations on hippocampal neurons in dispersed cell culture
Authors: Banker Gary A. , Cowan W. Maxwell 
Published: January 2005

AbstractThe growth of the processes of dissociated hippocampal neurons from 18‐ to 20‐day‐old rat fetuses has been studied in vitro using a method that permits cells to be maintained at relatively low plating densities for periods up to three weeks (Banker and Cowan, '77). Most of the cells are spherical or ovoid when they first attach to the substratum (either polylysine or collagen) but within 24 to 48 hours they begin to put out processes, and by the end of the first week in culture a significant proportion (∼45%) come to resemble normal pyramidal cells with a more‐or‐less triangular shaped soma, a single dominant dendrite‐like process emerging from the apex of the soma, and several “basal dendrites” arising from the opposite pole of the cell. Comparisons of the lengths of these dendrite‐like processes with those of hippocampal cells in the brains of animals sacrificed on the fourth post‐natal day and impregnated by a variant of the Golgi‐Cox method, indicate that in some cases the rate of process formation in vitro approximates that in vivo and that the general form of the neurons is remarkably like that of immature pyramidal cells. After a week in culture a second type of process can be recognized. These tend to be finer than those we have identified as dendrites; they are relatively uniform in diameter, frequently give off branches at right angles, and in the electron microscope can be seen to form synapses upon the larger processes and cell somata. These axon‐like processes differ from the axons of normal pyramidal cells in two important respects: (i) most commonly they arise from one of the dendritic processes, including, on occasion, the putative “apical” dendrites, and only rarely from the base of the perikaryon; (ii) there may be two or more such processes from a single cell. The thicker, tapering processes can be shown (after incubation in 3H‐uridine) to contain large amounts of RNA; newly‐synthesized RNA does not extend into the finer, axon‐like processes.
Cerebellar corticonuclear – nucleocortical topography: A study of the tree shrew (Tupaia) paraflocculus
Authors: Haines D. E. , Pearson J. C. 
Published: January 2005

AbstractFollowing injections of horseradish peroxidase (HRP) into parafloccular cortex, the location of nucleocortical cells in the cerebellar nuclei was determined and compared to the distribution of corticonuclear fibers arising from the same cortical region. Parafloccular corticonuclear fibers, visualized utilizing the Fink and Heimer (1967) method, project to caudal and lateral NIP and caudal and ventral NL. No degeneration is seen in either the NIA or NM. HRP‐positive nucleocortical cells (DAB‐technique) are found in caudal and lateral NIP and caudal NL with the former containing greater numbers of reactive somata. Rostral regions of the NL, medial NIP as well as the NIA and NM are divoid of cells containing HRP reaction product.At least two identifiable populations of HRP‐positive nucleocortical cells are seen. Numerous reactive cells are found in the NIP and NL ipsilateral to the injection site and sparse numbers of HRP‐containing somata are present in homologous areas of the contralateral NL and NIP. Contralateral nucleocortical cells are not only sparse in number but do not receive direct input from the opposite cortex to which they project. Consequently, these particular cells represent non‐reciprocal neurons in corticonuclear –; nucleocortical feedback loops. Ipsilateral nucleocortical cells are numerous and found almost exclusively within the distribution of parafloccular corticonuclear fibers. Also seen on the ipsilateral side interspersed among the HRP‐positive somata are numerous fibers which contain non‐granular homogeneous reaction product. These fibers represent diffusely filled axons of Purkinje cells which were damaged during the injection process. The location of ipsilateral nucleocortical cells within the borders of corticonuclear terminal fields coupled with their intimate opposition to some orthogradely filled terminal branchlets of Purkinje axons, indicates the probability of a precise interaction between these two fiber systems. Although a few HRP‐positive ipsilateral cells are found outside the boundaries of corticonuclear terminal fields they represent only a small fraction of the total number of reactive cells and, indeed, may function as part of the reciprocal cell population.
Accessory abducens nucleus and its relationship to the accessory facial and posterior trigeminal nuclei in cat
Authors: Hutson K. A. , Glendenning K. K. , Masterton R. B. 
Published: January 2005

AbstractRetrograde transport of HRP by the abducens nerve results in the labelling of its principal nucleus and, in addition, a second nucleus about 2.5 mm ventrolateral to the principal nucleus. The presence of this second or accessory nucleus of the abducens in a mammal confirms the observations of several Nineteenth Century anatomists and rebuts the conclusions of more recent investigators who argued that the nucleus was allied instead to the facial or trigeminal nerves.The same HRP technique applied to the facial or trigeminal nerves shows that the accessory nucleus of the abducens is in the same parasagittal plane as the accessory nucleus of the facial nerve and the most caudal cells of the motor trigeminal nucleus. The accessory abducens and accessory facial nuclei fall in a ventrocaudal to dorsorostral line between the principal nucleus of the facial and the motor nucleus of the trigeminal with the accessory abducens just caudal and ventral to the accessory facial.
The effect of the sequence of contralateral cortical and collicular lesions on the rate of relearning a visual discrimination by cats
Authors: Stern Judith F. , Winterkorn Jacqueline M. S. , Meikle Thomas H. 
Published: January 2005

AbstractVisual field deficits which follow ablation of the posterior two‐thirds of one cerebral hemisphere in the cat have been shown to be ameliorated by ablation of the contralateral superior colliculus. The present study was designed to determine whether the sequence in which contralateral cortical and collicular lesions are made is a significant factor affecting the rate of monocular relearning through the eye ipsilateral to the cortical lesion. Nine adult cats had the optic chiasm sectioned, were trained to criterion monocularly on a dark‐light discrimination, and were divided into two groups. Four cats (Group S) had one superior colliculus ablated, followed one month later by ablation of the contralateral two‐thirds of the neocortex. Five cats (Group C) had the same lesions in the reverse order. One month after the second brain lesion, each cat was retrained monocularly through each eye on the dark‐light discrimination for food reward in a Y‐maze. Through the eye ipsilateral to the cortical lesion, all cats in Group S relearned to criterion more rapidly than cats previously reported with only unilateral neocortical lesions. Four of the five cats in Group C were severely retarded in relearning and two of these cats failed to relearn. The results show that when chiasm‐sectioned cats are trained monocularly in a Y‐maze on a dark‐light discrimination, ablation of the superior colliculus prior to ablation of the contralateral neocortex facilitates relearning through the eye ipsilateral to the cortical ablation. When ablation of the superior colliculus follows the neocortical lesion, learning occurs but is not facilitated by the additional lesion.
Cell growth in the monocular segment of the lateral geniculate nucleus following the opening or closing of one eye
Authors: Anker Robyn , Cragg Brian 
Published: January 2005

AbstractBoth eyes were closed in 12 kittens soon after birth, and one eye was reopened at 23 days. From 14 to 26 days later, the cells in the monocular segment of the LGN connected to the open eye became significantly larger than the corresponding cells on the other side of the brain that were connected to the eye that was still closed. Up to 26 days after eye opening, the response of the monocular segment was similar to that of the binocular segment, so the latter may not be dependent on mutual inhibition or competition between sets of cells connected to each eye. From 30 to 60 days after eye opening, however, there were no differences between the monocular segments, but marked differences between the binocular A laminae where mutual inhibition and competition can occur.In seven more kittens both eyes were untouched until 23 days, when one eye was closed. Between 3 and 31 days later the deprived cells in the monocular segment of the LGN were not more than 8% smaller than those on the other side of the brain, and the measurements were not significantly different in any one cat. Within the binocular part of lamina A, cell growth is retarded by eye closure in two phases. Neither the early phase from 4‐6 days nor the later phase from 21 days onwards occurred in the monocular segment, so both may be dependent on mutual inhibition or competition between the sets of cells connected to each eye.Two possible explanations of this difference between the effects of eye opening and eye closing are discussed.