bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local intra‐ and interlaminar connections in mouse barrel cortex
Authors: Bernardo Kerry L. , McCasland James S. , Woolsey Thomas A. , Strominger Robert N. 
Published: May 2005

AbstractFocal injections of horseradish peroxidase (HRP) in dimethylsulfoxide (DMSO) were targeted into mouse somatosensory cortex, in vitro, with a template. Injections were made at different depths and in different locations in the whisker‐barrel‐defined somatosensory map in order to determine quantitative connectivity patterns within and between barrel‐defined cortical columns. Cortices were sectioned in a plane parallel to the pia at 75 βm. Data were collected directly from microscope slides by computer.Data are presented as: (1) Plots of computer‐mapped HRP reaction product density in neurons and cell locations for each section in relation to barrel boundaries; (2) histograms of label in cortical layers related to individual barrel‐defined columns; (3) polar plots of relative amounts of label within individual barrel columns in sections through each barrel column; (4) vectors which represent HRP reaction product density as a function of direction and distance from the injection site; (5) statistical analysis of the shape of the label distribution pattern in the plane of the cortex as a function of injection site depth; and (6) probability of labeling of any other barrel column given a labeled barrel column.The principal findings are: (1) The pattern of label distribution, after an injection directly above or directly below an individual barrel, is hour‐glass shaped with the waist of the hour‐glass in layer IV. (2) Connections within barrel cortex are asymmetrical. Barrel‐related columns within a row are more strongly interconnected than those in different rows. (3) Connections of the small barrels associated with whiskers on the upper lip are strongest with other small barrels, but strong connections also exist between these small barrels and the larger barrels. (4) The pattern of intracortical connections in SII is not asymmetrical; interlaminar connections in SII are fundamentally different from those in barrel cortex. (5) Quantitative intracortical projection patterns are highly consistent with functional data on intracortical processing of whisker information. As such, the quantitative data clearly indicate the spatial extent and relative magnitude of populations of neurons involved in intracortical processing of sensory information.The spatial arrangements of these intracortical connections, in conjunction with known developmental events, make it highly likely that the distribution of intracortical axons in mouse barrel cortex is sculpted in part by experience.
Morphology of antennal motoneurons in the brains of two crickets, gryllus bimaculatus and gryllus campestris
Authors: Honegger Hans‐Willi , Allgäuer Cölestin , Klepsch Ulrike , Welker Jutta 
Published: May 2005

AbstractThe morphology of the antennal muscles of two cricket species, Gryllus campestris and G. bimaculatus, and their innervation are described. The motoneurons innervating the five tentorio‐scapal muscles M4 and M5 and the two scapo‐pedicellar muscles M6 and M7 were stained with cobalt chloride introduced via the cut axonal endings in the muscle. The seven antennal muscles are innervated by a total of 17 excitatory motoneurons and one common inhibitory neuron. These neurons branch in the dorsal neuropil of the deuto‐and tritocerebrum. No difference in the morphology of the motoneurons between the two species was evident. Two dorsal‐unpaired‐medial (DUM) neurons located in the suboesophageal ganglion also innervate the antennal muscles. Intracellular recordings of some motoneurons combined with Lucifer Yellow injections corroborated the motoneuron morphology obtained by cobalt backfilling from the muscles. The recordings showed that the motoneurons are either of the fast or the slow type.
Capsaicin‐induced neuronal degeneration in the brain and retina of preweanling rats
Authors: Ritter Sue , Dinh Thu T. 
Published: May 2005

AbstractCapsaicin is a neurotoxin known for its ability to cause degeneration of small unmyelinated primary sensory neurons in both spinal and cranial nerves. Although lower motor neurons do not degenerate following capsaicin treatment, the extent to which capsaicin may damage neurons in the brain has not been thoroughly evaluated. This study examines the effects of systemic capsaicin (50–150 mg/kg) on the central nervous system of 10‐day‐old rats. Rat pups were injected with capsaicin or the injection vehicle and sacrificed 6 hours–10 days later. Brains, spinal cords, and retinas ware stained with cupric silver to label degenerating neurons. As previously reported for capsiaicin‐treated rats, degenerating nerve terminals were present in areas receiving primary afferent input: the spinal cord dorsal horn, spinal trigeminal nucleus, nucleus of the solitary tract, and area postrema. However, degenerating terminals were also present in areas not known to receive primary sensory innervation: the inferior olivary nucleus, sphenoid nucleus, medial and olivary pretectal nuclei, interpeduncular nucleus, interfascicular nucleus, caudal linear, dorsal, median, and paramedian raphe nuclei, supramammillary area, lateral habenula, ventrolateral geniculate nucleus, ventral reuniens nucleus, ventromedial hypothalamic nucleus, lateral hypothalamic and preoptic areas, suprachiasmatic nucleus, septohypothalamic nucleus, bed nucleus of the stria terminalis, lateral septal nucleus, accumbens shell, olfactory bulb, and retina. Some areas where capsaicin caused degeneration in rat pups do not appear to be capsaicin‐sensitive in adult rats. Results indicate that (1) capsaicin's neurotoxicity is not limited to primary sensory neurons and (2) developmental factors may alter the capsaicin sensitivity of some neuronal projections within the brain.
Cell death of corticospinal neurons is induced by axotomy before but not after innervation of spinal targets
Authors: Merline Michael , Kalil Katherine 
Published: May 2005

AbstractThe response of corticospinal neurons to axotomy at postnatal ages from 5 days to adulthood was studied in the golden hamster (Mesocricetus auratus). Corticospinal neurons were retrogradely labeled with flourescent rhodamine latex beads injected into the cervical or lumbar spinal cord. A unilateral lesion of the medullary pyramidal tract was made 1–2 days later and the brains fixed 1–30 days after axotomy. Comparisons of labeled axotomized corticospinal neurons with labeled normal corticospinal neurons in the contralateral cortex showed that axotomy at 14 days or later caused cell shrinkage but not cell death. Axotomy prior to 14 days caused cell death of corticospinal neurons. More neurons died the earlier the lesion was made, culminating in virtual complete cell death of corticospinal neurons following axotomy at 5 days. Axotomy at a given age did not affect all corticospinal neurons uniformly. Lumbar projection neurons underwent cell death ranging from slight to complete following axotomy at 13 and 9 days, respectively. Cervical projection neurons, in contrast, survived axotomy after a lesion at 9 days but underwent complete cell death if the lesion occurred at 5 days. Since corticospinal axons innervate the cervical cord from postnatal days 4–8 and the lumbar cord from 10–14 days (Reh and Kalil, '81; J. Comp. Neurol. 200:55–67), the ability of corticospinal neurons to survive axotomy appears to be temporally well correlated with their innervation of spinal targets. These neurons die if their axons are cut prior to target innervation but are able to survive if axotomy occurs after their axons innervate spinal targets. The results show that plasticity in the corticospinal pathway documented in previous reports cannot take the form of regrowth of severed axons, since early lesions cause extensive corticospinal cell death. Aberrant corticospinal pathways resulting from early lesions must therefore arise from undamaged axons. Additional retrograde labeling experiments showed that the opposite cortex responded to contralateral pyramidotomy by sprouting into denervated areas of the spinal cord. Thus another source of plasticity after early pyramidal tract lesions is sprouting from corticospinal axons arising from the intact cortex.
Sublaminar organization within layer VI of the striate cortex in Galago
Authors: Conley Michael , Raczkowski Denis 
Published: May 2005

AbstractIn this study we examined the organization of projections from the striate cortex to the dorsal lateral geniculate (GL) and pulvinar (PUL) nuclei in the prosimian Galago by using retrograde transport methods. Injections of wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) into the PUL labeled two bands of cells in the striate cortex: the first consisted of large pyramidal cells in the upper half of layer V; the second consisted of small and medium‐size pyramidal cells located in the deepest part of layer VI. The location of cells within layer VI coincided with a clear cytoarchitectonic sublayer, VIb, which contains fewer and paler staining cells than VIa. Injections of WGA‐HRP involving all layers of the GL produced an uninterrupted band of pyramidal cells distributed throughout layer VI (a and b), including the region labeled after injections into the PUL. Thus as a first approximation, layer VI can be divided into an upper tier (VIa) that projects only to the GL and a lower tier (VIb) that projects to both the GL and PUL. Injections of WGA‐HRP that were restricted to one or a few GL layers revealed a further refinement of the subdivisions within layer VI. Injections into the parvicellular and intercalated (or koniocellular) layers of the GL labeled neurons predominantly in the upper half of layer VIa, whereas injections restricted to the magnocellular layers labeled neurons in the lower half of layer VIa and in layer VIb. In order to determine whether individual neurons in layer VIb send axon collaterals to both the GL and PUL, we injected WGA‐HRP into one nucleus and fluorescent rhodamine latex beads into the other. In three experiments, we found only one double‐labeled cell. In sum, the results provide evidence that layer VI is divided into at least three sublayers: upper VIa, which projects to the intercalated and parvicellular GL layers; lower VIa, which projects to the magnocellular GL layers; and VIb, which sends separate projections to the magnocellular layers of the GL and to the PUL. The segregation observed is sufficiently discrete to propose the existence of multiple, descending pathways from layer VI of the striate cortex that complement those ascending from the GL and PUL.
Central projections from the skin of the hand in squirrel monkeys
Authors: Florence S. L. , Wall J. T. , Kaas J. H. 
Published: May 2005

AbstractCentral termination patterns of afferents from the hands of squirrel monkeys were studied after subdermal injections of wheat germ agglutinin conjugated with horseradish peroxidase (WGA‐HRP) or cholera toxin subunit B conjugated to HRP (BHRP). WGA‐HRP more effectively labeled axons terminating in the superficial dorsal horn of the spinal cord, while BHRP more effectively labeled axons terminating in the deeper layers. Injections of both tracers, when restricted to parts of glabrous digits, palm, or dorsal hand, revealed somatotopic patterns in the spinal cord and pars rotunda of the cuneate nucleus that were, in some respects, similar and, in other respects, quite different from those previously reported for macaque monkeys (Florence et al., J. Comp. Neurol. 286:48–70, 1989). As in macaques, injections in digits 1–5 produced a rostrocaudal sequence of foci of terminations in the cervical spinal cord. However, inputs from the palm were located medial to those from the digits, whereas the palm is represented lateral to the digits in macaque monkeys. Since inputs from the palm are also medial in the dorsal horn in cats (Nyberg and Blomqvist, J. Comp. Neurol. 242:28–39, 1985), the condition in squirrel monkeys may be similar to the generalized state. In the cuneate nucleus, single injections in the hand produced dense label in the pars rotunda, and sparse label in the rostral and caudal poles. As in macaque monkeys, inputs from specific parts of the hand related to rostrocaudal clusters of cells that are cytochrome oxidase dense. The representation of the digits differed from macaques in that the digits were represented dorsal to the palm, rather that ventral to the palm as in macaques. Again, comparisons with cats suggest that squirrel monkeys have the more generalized pattern. Finally, inputs from the hairy, dorsal surfaces of the digits terminated on the same clusters as the inputs from the glabrous, ventral surfaces, apparently overlapping somewhat. The proximity of these terminations from dorsal and ventral surfaces of the digits may be related to observations that cortical representations of the glabrous surfaces of digits become responsive to dorsal surfaces of the same digits when inputs from glabrous skin are chronically deactivated (e.g., Merzenich et al., Neuroscience 3:33–55, 1983).
Topographic organization of the cochlear spiral ganglion demonstrated by restricted lesions of the anteroventral cochlear nucleus
Authors: Leake Patricia A. , Snyder Russell L. , Merzenich Michael M. 
Published: May 2005

AbstractThe morphological organization of the central projections of the cat cochlear spiral ganglion into the cochlear nucleus has been investigated by creating restricted lesions in the anteroventral cochlear nucleus (AVCN) in order to ablate selectively either the lateral or the medial aspect of isofrequency projection laminae. Such lesions induced highly selective retrograde degeneration of spiral ganglion cells. Ablation of the lateral part of the AVCN resulted in degeneration of cells within the scala tympani portion of the ganglion, whereas medial lesions within the AVCN induced degeneration of the scala vestibuli portion of the ganglion. Since most, if not all, of the primary afferent axons of the cochlear nerve bifurcate into ascending and descending branches as they enter the brainstem, it is noteworthy that selective damage to the ascending branch in the AVCN was sufficient to induce retrograde degeneration of the spiral ganglion cell somata. The peripheral and central axons also degenerated, and the losses of both the radial nerve fibers in the osseous spiral lamina and the central axons passing into the modiolus displayed selective topographies that paralleled the cell loss within the spiral ganglion.The results of this study support our previous hypothesis, based upon earlier horseradish peroxidase labeling experiments, that there is a topographic organization to the projection of the spiral ganglion within the isofrequency laminae that is orthogonal to the frequency representation within the ventral cochlear nuclei (VCN). That is, in addition to the spiral frequency organization of the ganglion, represented by the dorsal‐to‐ventral frequency map in the VCN, there is also an orderly and sequential distribution of inputs from the vertical (scala tympani‐to‐scala vestibuli) dimension of the spiral ganglion across the lateral‐to‐medial axis of the VCN. The interaction of these two topographic representations, distributed across the three dimensions of the VCN, must partly define the selective and/or integrative neuronal response properties at this first level of central nervous system processing of auditory signals within the cochlear nuclei.
Development and distribution of noradrenergic and cholinergic neurons and their trophic phenotypes in the avian ceruleus complex and midbrain tegmentum
Authors: von Bartheld Christopher S. , Bothwell Mark 
Published: May 2005

AbstractWe investigated the development of noradrenergic and cholinergic neurons in the ceruleus complex and mesencephalic tegmentum in embryonic and posthatch chickens and compared the distribution of transmitter phenotypes with the expression of nerve growth factor receptor (NGFR) mRNA and fibroblast growth factor receptor (FGFR) mRNA. Noradrenergic and cholinergic neurons were visualized by using antibodies against dopamine‐beta‐hydroxylase (DBH) and choline acetyltransferase (ChAT), respectively. Expression of receptors for trophic factors was determined by using in situ hybridization techniques.Noradrenergic neurons concentrate in caudal parts of the locus ceruleus and nucleus subceruleus. Cholinergic ceruleus neurons are abundant in the nucleus mesencephalicus profundus, pars ventralis (MPv) as well as in the nucleus subceruleus and locus ceruleus. This cholinergic population resembles the cholinergic pontomesencephalotegmental complex of mammals. Both DBH and ChAT label is evident at and after six days of incubation (E6). The distribution and numbers of immunolabeled neurons are similar in the embryonic and posthatch chick. Initially, many tegmental and ceruleus neurons express substantial levels of NGFR mRNA (E7–E9). After E9, expression of NGFR mRNA decreases in most of these neurons, except for a distinct subpopulation of neurons in caudal parts of the ceruleus complex with increased levels of NGFR transcripts. These NGFR‐positive neurons coincide in number and distribution with the noradrenergic subpopulation of the ceruleus complex (800‐‐900 neurons). Expression of FGFR mRNA was first detected in ceruleus neurons at E13. Neurons with FGFR transcripts have the same number and distribution as the neurons with the cholinergic phenotype (2,000–‐2,300 neurons).Transmitter heterogeneity in the ceruleus complex is reflected by a heterogeneity of receptors for trophic factors, with NGFR expressed in the noradrenergic subpopulation, and FGFR expressed in the cholinergic subpopulation. These findings provide evidence for new chemoarchitectonic subdivisions of the avian ceruleus complex. The data showing onset of ChAT expression prior to the onset of FGFR expression argue against a role of FGFR in the determination of the cholinergic transmitter phenotype. Expression of NGFR in the noradrenergic ceruleus subpopulation reveals remarkable species differences as compared to mammals.
Calcitonin gene‐related peptide in nucleus ambiguus motoneurons in rat: Viscerotopic organization
Authors: Lee Bong Hee , Lynn Richard B. , Lee Heung‐Shik , Miselis Richard R. , Altschulers Steven M. 
Published: May 2005

AbstractCalcitonin gene‐related peptide has been reported in the rat nucleus ambiguus. This nucleus comprises a dorsal division that is the source of special visceral efferents innervating the striated muscle of the upper alimentary tract and a ventral division supplying general visceral efferents primarily to the heart. The distribution of caldtonin gene‐related peptide immunoreactive neurons in the two divisions was determined by using a combination of immunocytochemical techniques and fluorescent retrograde tracing. In 22 rats, injections of Fluoro‐Gold were made into either the supranodosal vagus nerve, palatopharynx, larynx, esophagus, or heart. Following colchicine injection, medullary sections were processed immunocytochemically for calcitonin gene‐related peptide.Injection of Fluoro‐Gold into the supranodosal vagus resulted in prominent labeling of neurons in the dorsal and ventral divisions of the nucleus ambiguus. The majority of fluorescent labeled neurons in the dorsal division were found to be immunoreactive for calcitonin gene‐related peptide, while those labeled neurons in the ventral division were unreactive for the peptide. With esophageal, and palatopharyngeal and cricothyroid injections, many fluorescent labeled neurons that were immunoreactive for calcitonin gene‐related peptide were found respectively in the compact and semicompact formations of the dorsal division. In contrast, injections of the heart resulted in fluorescent labeled neurons, which were unreactive for calcitonin gene‐related peptide, localized to the external formation.The results demonstrate that calcitonin gene‐related peptide immunoreactive neurons are localized entirely to the dorsal division of the nucleus ambiguus and that all striated muscular areas of the alimentary tract are innervated by calcitonin gene‐related peptide containing motoneurons. The localization of calcitonin gene‐related peptide to vagal motoneurons also known to contain acetylcholine and the increase in acetylcholine receptor synthesis caused by this peptide suggest that calcitonin gene‐related peptide acts as a cotransmitter with acetylcholine in special visceral efferent vagal motoneurons.
Olfactory bulb organization and development in Monodelphis domestica (grey short‐tailed opossum)
Authors: Brunjes Peter C. , Jazaeri Amir , Sutherland Mark J. 
Published: May 2005

AbstractThe olfactory bulbs of adult and developing Monodelphis domestica were examined with a number of techniques. Golgi, Nissl, and Timm stains as well as acetylcholinesterase histochemistry revealed a high degree of order within the adult bulb. All major cell classes characteristic of most mammalian species were observed. Tufted cells appeared to be restricted to the superficial portion of the external plexiform layer. Developing Monodelphis pups were examined with Nissl‐stained semithin sections and with immunocytochemistry for tyrosine hydroxylase, microtubule‐associated protein 2, vimentin, and glial fibrillary acidic protein. Newborn pups are extremely immature, with few postmitotic cells present in the forebrain. Considerable maturation occurs over the first four postnatal weeks, and by postnatal day 30, the bulb assumes an adult‐like organization. The extreme immaturity of the bulb at birth, coupled with its strict organization, suggest that Monodelphis is a particularly appropriate species for experimental examinations of olfactory system development.
Glutamate‐immunoreactive terminals synapse on primate spinothalamic tract cells
Authors: Westlund Karin N. , Carlton Susan M. , Zhang Dongxian , Willis William D. 
Published: May 2005

AbstractGlutamate has been shown to excite spinothalamic tract (STT) neurons and has been localized to primary afferent neurons, spinal cord projection neurons, and interneurons in the spinal cord dorsal horn. The likelihood that glutamate‐immunoreactive (GLU‐IR) terminals directly innervate STT neurons was investigated. For these studies three lamina IV or V STT cells in the lumbar spinal cords of three monkeys (Macaca fascicularis) were identified electrophysiologically and characterized. Two were identified as high threshold neurons and one as a wide dynamic range neuron. Following intracellular injection of the cells with HRP and reaction to give the cells a Golgi‐like appearance, the tissues were processed for electron microscopy. Postembedding immunogold methods with antibodies specific for glutamate were used to identify GLU‐IR terminals apposing the somata and dendrites of the STT neurons, including dendrites that extended into laminae IV and III. The GLU‐IR terminals were numerous and constituted a mean of 46% of the population counted that appose the STT soma and 50% of the profiles apposing the dendrites. Fifty‐four percent of the somatic and 50% of the dendritic surface length was contacted by GLU‐IR terminals. Most terminals contained round clear vesicles and some contained a variable number of large dense core vesicles. For one of the three cells examined it was determined that 45% of the terminals apposing the soma were GLU‐IR and 30% of the terminals were gamma aminobutyric acid‐immunoreactive (GABA‐IR). In an additional monkey, a lamina I cell retrogradely labeled from the ventral posterolateral nucleus of the thalamus was found to be ensheathed in glial processes. Of the 9 terminals observed apposing the retrogradely filled STT neuron in one plane of section, 2 were GLU‐IR and 3 were GABA‐IR. The data suggest that a large percentage of the profiles adjacent to STT neurons in intermediate laminae of the spinal cord contain glutamate and many synapse directly with STT neurons.