bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postsynaptic gephyrin immunoreactivity exhibits a nearly one‐to‐one correspondence with gamma‐aminobutyric acid‐like immunogold‐labeled synaptic inputs to sympathetic preganglionic neurons
Authors: Cabot J. B. , Bushnell A. , Alessi V. , Mendell N. R. 
Published: January 2005

AbstractPeripheral regulation of cardiovascular function is fundamentally influenced by central excitation and inhibition of sympathetic preganglionic neurons in thoracic spinal cord. This electron microscopy study investigated whether the γ‐aminobutyric acid (GABA)‐ergic and glycinergic inhibitory innervation of sympathetic preganglionic neurons arises from mutually exclusive afferent populations. Sympathetic preganglionic neurons were retrogradely labeled with cholera β subunit. GABAergic terminals were identified using strict quantitative statistical analyses as those boutons containing significantly elevated levels of GABA‐like immunogold labeling (GABA+). Glycinergic terminals were classified as those boutons opposite postsynaptic gephyrin immunostaining containing background levels of GABA‐like immunogold labeling (gephyrin+/GABA− association). Approximately 43% of the synaptic terminals that contacted sympathetic preganglionic somata and proximal dendrites and that were opposite gephyrin were GABA−; the remaining 57% were GABA+. Only two GABA+ boutons (4%) that synapsed on identified sympathetic preganglionic neuron (SPN) processes were not opposite gephyrin immunostaining (GABA+/gephyrin‐ association). GABA− /gephyrin+ associations were anticipated given prior anatomical, physiological, and pharmacological data. The observed nearly one‐to‐one correspondence between postsynaptic gephyrin immunoreactivity and GABA+ boutons was unexpected. Prior physiological and pharmacological experiments suggest that the postsynaptic effects of GABAergic inputs to sympathetic preganglionic neurons are mediated by activation of GABAA receptors. Those data, the present results, and other molecular, biochemical, and anatomical studies of gephyrin in the central nervous system (CNS) are consistent with two hypotheses: (1) Postsynaptic gephyrin is associated with GABAA receptors in the membranes of sympathetic preganglionic neurons, and (2) GABA+/gephyrin+ associations do not necessarily predict colocalization of GABA and glycine within single boutons synapsing on sympathetic preganglionic somata and dendrites. © 1995 Wiley‐Liss, Inc.
Pathfinding by retinal ganglion cell axons: Transplantation studies in genetically and surgically blind mice
Authors: Lund Raymond D. , Hankin Mark H. 
Published: January 2005

AbstractOptic axons show a highly stereotypical intracranial course to attain the visual centers of the brainstem. Here we examine the course followed by axons arising from embryonic retinae implanted in neonatal ocular retardation mutant mice in which there had been no prior innervation of the visual centers. Retinae placed on the ventrolateral brainstem adjacent to the normal site of the optic tract send axons dorsolaterally toward the ipsilateral superior colliculus, which they innervate along with a number of other subcortical visual centers. Somewhat unexpectedly, axons also course ventrally to cross at the level of the suprachiasmatic nucleus or, less frequently, caudal to the mammillary body to follow the route of the optic tract and innervate contralateral visual centers. Retinae implanted along the course of the internal capsule emit axons that follow projection fibers through the striatum to innervate the lateral geniculate nucleus and other optic nuclei. These grafts also appear to project to the lateral part of the ventrobasal nucleus of the thalamus.The results show that prior existence of an optic projection is not necessary for axons derived from ectopic retinae to attain visual nuclei, not only on the side of implantation but also on the contralateral side of the brain. The cues that these growing axons follow appear to be stable temporally. The fact that axons can also follow highly anomalous routes, such as through the internal capsule, to attain target nuclei in the brainstem suggests that the normal optic pathway is not an obligatory route for optic outgrowth. © 1995 Wiley‐Liss, Inc.
Premotor neurons for trigeminal motor nucleus neurons innervating the jaw‐closing and jaw‐opening muscles: Differential differential in the lower brainstem of the rat
Authors: Li Yun‐Qing , Takada Masahiko , Kaneko Takeshi , Mizuno Noboru 
Published: January 2005

AbstractThe distribution of premotor neurons for trigeminal motor nucleus neurons innervating the jaw‐closing and jaw‐opening muscles was examined in the lower brainstem of the rat by using retrograde and anterograde labeling techniques. First, Fluorogold, a fluorescent retrograde tracer, was injected into the dorsolateral or ventromedial division of the trigeminal motor nucleus, each of which contains motoneurons innervating the jaw‐closing or jaw‐opening muscles, respectively. Second, Phaseolus vulgaris‐leucoagglutinin, an anterograde tracer, was injected into each of the lower brainstem sites, where clusters of retrogradely labeled premotor neurons had been seen in the first set of experiments. Third, after injection of the anterograde tracer into a lower brainstem site, followed by injection of the retrograde tracer cholera toxin B subunit into a masticatory muscle, termination of anterogradely labeled axons onto retrogradely labeled motoneurons was confirmed with the aid of a confocal laser‐scanning microscope. It was found that the premotor neurons distributed in the mesencephalic trigeminal nucleus, medial part of the parabrachial region, supratrigeminal region, and dorsal parts of the principal sensory, oral spinal and interpolar spinal trigeminal nuclei project preferentially to the dorsolateral division of the trigeminal motor nucleus, whereas those in the lateral part of the parabrachial region, intermediate parts of the principal sensory, oral spinal and interpolar spinal trigeminal nuclei, and alpha part of the gigantocellular reticular nucleus project preferentially to the ventromedial division of the trigeminal motor nucleus. The dorsal and lateral parts of the medullary reticular formation and the medullary raphe nuclei contain premotor neurons of both types. Group k motoneurons, a cluster of trigeminal motoneurons that innervate the tensor tympani muscle, receive projection fibers predominantly from the dorsolateral part of the oral pontine reticular formation. © 1995 Wiley‐Liss, Inc.
Fos‐like immunoreactivity in central auditory neurons of the mouse
Authors: Brown M. C. , Liu T. S. 
Published: January 2005

AbstractFos‐like immunoreactivity was used to study sound‐induced activation of neurons in the auditory brainstem. Immunoreactivity was assayed with a polyclonal antibody to Fos. In response to 6‐kHz tone bursts, the pattern of staining was a band of immunoreactive neurons positioned at the tonotopically appropriate position within the cochlear nucleus and the inferior colliculus. The band was narrow at low sound pressure levels but wider along the tonotopic axis at higher sound levels. In response to noise bursts, the pattern was broader and often extended throughout the auditory nuclei. Often within this broad pattern were “sub‐bands” of immunostained neurons, interspersed with bands of unstained neurons. With increasing sound pressure levels above 35‐‐55 dB, the number of Fos‐like immunoreactive neurons increased for the cochlear nucleus, superior olivary complex, and inferior colliculus. In the cochlear nucleus and inferior colliculus, the stained cells were small, and hence their activity would be difficult to sample in electrophysiological studies. In the medial nucleus of the trapezoid body, the stained neurons had larger somata and other characteristics of principal cells. Anesthesia with Nembutal or Avertin, but not with ketamine or urethane, decreased the number of Fos‐like immunoreactive neurons in the cochlear nucleus. The different anesthetics produced more variable results in the inferior colliculus. In anesthetized, monaurally stimulated animals, the presence of staining in the contralateral cochlear nucleus indicates that some Fos‐like immunoreactivity may be mediated by descending or commissural systems. These observations indicate that Fos assays are useful for studying the pattern of neuronal activation in the auditory system and may also be useful in studying the descending auditory pathways. © 1995 Wiley‐Liss, Inc.
Principal neurons of the lumbar sympathetic ganglia increase in number with body size
Authors: St. Wecker Peter G. R. , Baek Jae‐Kyeong , Farel Paul B. 
Published: January 2005

AbstractNeuron number appears to be matched to body size during early development by the modulation of the processes of proliferation and naturally occurring cell death. However, body size increases rapidly as the juvenile becomes an adult, long after these processes cease to operate. The present study shows that principal neurons of lumbar sympathetic ganglia increase in number four‐ to fivefold during postmetamorphic life of the bullfrog, Rana catesbeiana. This increase in neuron number cannot be attributed to either counting error or selection bias and was associated with greater innervation of particular hindlimb targets, as demonstrated by retrograde labeling with horseradish peroxidase. Injection of [3H] thymidine (a marker of DNA synthesis) every third day for 20‐‐22 weeks failed to provide evidence of neuron proliferation, although, on the basis of changes in body length during this period, substantial numbers of neurons likely were added. These results combined with previous studies of hindlimb motor and sensory neuron addition are consistent with the hypothesis that the population of sympathetic neurons is augmented by late differentiation of existing precursor cells. © 1995 Wiley‐Liss, Inc.
Postnatal changes in the uncrossed retinal projection of pigmented and albino syrian hamsters and the effects of monocular enucleation
Authors: Thompson I. D. , Cordery P. , Holt C. E. 
Published: January 2005

AbstractAnterograde and retrograde tracing techniques have been used to study the uncrossed retinal projection in neonatal pigmented and albino Syrian hamsters. The total number of retinal ganglion cells projecting ipsilaterally peaks at postnatal days 2–4 (P2–P4) and declines to adult values by P12. The change in cell numbers has a similar time course in albino and pigmented animals. Although the population of uncrossed cells in the temporal retina of albino hamsters is always less than that in pigmented hamsters, no difference between the colour phases was found for the population of uncrossed cells in nasal retina. Differential cell death also contributes to the adult albino decussation pattern in hamsters: The relative loss of cells from temporal retina in albinos (72%) is greater than that in pigmented animals (56%). The additional loss in albinos does not appear to depend on binocular interactions: The same proportion (30%) of uncrossed cells is “rescued” from death by neonatal monocular enucleation in both colour phases.Flat‐mount preparations showing the distribution of uncrossed fibres reveal that a distinct focus of terminals emerges in rostral superior colliculus, which is topographically appropriate for a binocular mapping, at the peak of uncrossed ganglion cell numbers (P4). Comparison of uncrossed terminal distributions and ganglion cell death reveals considerable refinement of the terminals prior to the main phase of cell death. Monocular enucleations performed some time after birth have a greater effect on uncrossed terminal distributions than on cell death. These observations suggest that independent mechanisms may be involved in the regulation of terminal distributions and of cell numbers in the developing uncrossed retinal pathways. © 1995 Wiley‐Liss, Inc.
Chick wing innervation. II. Morphology of motor and sensory axons and their growth cones during early development
Authors: Hollyday Margaret , Morgan‐Carr Megan 
Published: January 2005

AbstractThe development and distribution of neuronal projections to the developing chick wing was studied using anterograde transport of horseradish peroxidase (HRP). Small injections of HRP were made into motor or sensory neuronal populations in order to visualize individual axons and their associated growth cones. Motor growth cones were observed in different regions of the embryo at different stages, in a proximal‐to‐distal pattern of distribution which paralleled the process of axon outgrowth and nerve formation. Different growth cone morphologies were associated with differing regions of the developing projection. In the spinal nerves, axons destined for the limb were unbranched and terminated in simply shaped growth cones. As axons approached the developing limb and entered the plexus region, their growth cones became more complex and larger primarily because of widening, and they sometimes branched, producing processes which could extend tens of microns from a tricorne branch point on the parent axon. Both motor and sensory fibers showed similar morphological changes in the plexus region. A distinctively shaped growth cone expanded on its leading edge was observed, sequentially apparent in the distal spinal nerves, in the plexus region, in the loosely organized axonal sheets projecting to the uncleaved dorsal or ventral muscle masses, and where muscle nerves diverged from nerve trunks and within muscle nerves. It is likely that some of these are transitional growth cones preparing to branch, because complex and branched growth cones were also observed in these regions. Branched axons oriented along the anteroposterior axis were similarly observed in the plexus region and distal to the plexus when axons first projected to the limb bud. At somewhat older stages when the basic peripheral nerve branching pattern had formed, motor growth cones were observed in common nerve trunks and in individual muscle nerves, but they were no longer found in the plexus region. Branched axons were likewise restricted to these peripheral Imations. Taken together, these observations suggest that one of the ways in which axons navigate is by exploration in the form of growth cone widening, and in some cases terminal bifurcation which may produce axon branches. Selection of the most appropriately directed growth cone process and/or precocious axonal branches may be one of the ways in which axons respond to specific growth cues which guide axons into the limb bud. Alternatively, this precocious branching may be an early neurotrophic response to developing muscle and play no significant role in axon navigation. © 1995 Wiley‐Liss, Inc.
Are the neurons in the dorsal root ganglion pseudounipolar? A comparison of the number of neurons and number of myelinated and unmyelinated fibres in the dorsal root
Authors: Tandrup T. 
Published: January 2005

AbstractThe neurons in the dorsal root ganglion have classically been described as pseudounipolar. Previous studies have questioned this simple organisation because an equality between the number of fibres in the dorsal root and neurons could not be established.In this study the number of neurons in the fifth lumbar dorsal root ganglion of the adult rat is compared to the number of fibres in the dorsal root. The methods used are founded on unbiased stereological principles and includes the optical disector, the Cavalieri principle, unbiased counting rules in two and three dimensions, and systematic random sampling. The number of A‐ and B‐cells is estimated with light microscopy, and the number of myelinated and unmyelinated fibres is estimated with electron microscopy.The present study demonstrates that there is a 1:1 ratio (mean: 0.98, CV: 0.12, 95% confidence interval: 0.90‐1.07) of fibres in the dorsal root to neurons in the dorsal root ganglion, as the classical theory predicts. Furthermore, the study of the two neuron subtypes supports the hypothesis that myelinated fibres originate from the A‐cells and the unmyelinated fibres from the B‐cells. © 1995 Wiley‐Liss, Inc.
Fos expression in the medullary dorsal horn of the rat after chronic constriction injury to the infraorbital nerve
Authors: Vos Bart P. , Strassman Andrew M. 
Published: January 2005

AbstractChronic constriction injury to the rat's infraorbital nerve (IoN‐CCI) induces asymmetric face grooming directed to the injured nerve territory and, beginning at 7‐‐12 days postoperative, hyperresponsiveness to mechanical stimulation in this territory (B. P. Vos, A. M. Strassman, and R. J. Maciewicz, 1994, J. Neurosci. 14:2708‐‐2723). To examine central mechanisms involved in these behavioral alterations, changes in nonevoked and mechanical stimulationevoked fos‐like immunoreactivity (fos‐LI) following IoN‐CCI were quantified in the medullary dorsal horn.Following the appearance of hyperresponsiveness in IoN‐CCI rats, experimental and matched sham‐operated rats were anesthetized with urethane and received either no stimulation or repeated stimulation with either a 2‐ or 15‐g von Frey hair applied to the hairy skin between vibrissae B3‐4/C3‐4 on the operated side.Unstimulated IoN‐CCI rats had increased fos‐LI in laminae I‐IV of the ipsilateral medullary dorsal horn. In both groups, mechanical stimulation produced a distinct pattern of fos‐LI in the ipsilateral medullary dorsal horn, the quantity of which was related to stimulus intensity. For both stimulus intensities, the total amount and the rostrocaudal spread of evoked fos‐LI were significantly larger in IoN‐CCI rats. In IoN‐CCI rats, stimulation‐evoked increases in fos‐LI were proportionally larger in laminae I‐II than in III‐IV. This laminar effect was also present in sham‐operated rats but only for 15‐g stimulation. Neither condition nor stimulus intensity affected fos‐LI in the contralateral medullary dorsal horn. Positive correlations were found between the behavioral parameters of increased trigeminal nociceptive activity and the total amount of fos‐LI in the ipsilateral medullary dorsal horn.The results demonstrate that IoN‐CCI induces significant alterations in the central processing of afferent signals, which may underlie behavioral manifestations of increased nociceptive activity. © 1995 Wiley‐Liss, Inc.
Differential synaptic innervation of neurons in the internal and external segments of the globus pallidus by the GABA‐ and glutamate‐containing terminals in the squirrel monkey
Authors: Shink E. , Smith Y. 
Published: January 2005

AbstractThe present study aimed at comparing the pattern of synaptic innervation of neurons in the external (GPe) and internal (GPi) pallidum by gamma‐aminobutyric acid (GABA)‐ and glutamate‐immunoreactive terminals in the squirrel monkey. Four major populations of terminals were encountered in GPe and GPi. Our findings combined with those obtained in previous tract‐tracing studies reveal that the synaptic innervation of perikarya in GPe is strikingly different from that ba GPi. Although the GABA‐positive type I boutons (from the striatum) represent 85% of the terminals in contact with somata in GPe, only 32% of the axosomatic synapses involve this type of terminal in GPi. However, the type II terminals (from GPe), which display a moderate level of GABA and glutainate immunoreactivities, account for 48% of the boutons in contact with perikarya in GPi but only 10% in GPe. In both pallidal segments, less than 10% of the axosomatic synapses involve the glutamate‐immunoreactive type I11 terminals (from the subthalamic nucleus). Finally, the type IIa boutons (unknown source), which show levels of immunoreactivities similar to the type II terminals, account for 12% of the boutons in contact with perikarya in GPi but only 4% in GPe. In contrast to perikarya, the innervation of dendritic shafts is similar in both GPe and GPi; more than 80% of the axodendritic synapses involve the type I terminals, 10–15% involve the type III terminals, less than 5% are formed by the type II boutons, and less than 1% involve the type IIa terminals. Three other categories of boutons (types IV, V, VI) account for less than 1% of the total population of terminals in GPe and GPi.In conclusion, our findings demonstrate a differential synaptic innervation of neuronal perikarya in GPe and GPi in primates. These data suggest that the two pallidal segments are separate functional entities of which the neuronal activity is largely controlled by extrinsic inputs that are differentially distributed at the level of single cells. © 1995 Wiley‐Liss, Inc.
Topographic organization of a forebrain pathway involved with vocal learning in zebra finches
Authors: Johnson Frank , Sablan Michelle M. , Bottjer Sarah W. 
Published: January 2005

AbstractA serial pathway from a thalamic nucleus (DLM; the medial portion of the dorsolateral nucleus of the anterior thalamus) to a cortical region (lMAN; the lateral magnocellular nucleus of the anterior neostriatum) to a motor‐cortical region (RA; the robust nucleus of the archistriatum) is necessary for vocal production during song learning in juvenile zebra finches but not for the recitation of a song already learned by adults. To obtain new information about the possible function of the DLM‐lMAN‐RA pathway in vocal learning, we used anterograde and retrograde tract‐tracing techniques (pressure injections of DiI and DiA) to map the pattern of axonal connections between t these brain regions in adult male zebra finches. Results revealed two topographically organized pathways that traverse the songbird forebrain in parallel. An oval‐shaped dorsal/lateral portion of DLM projects solely to the central core of lMAN (lMANcore), whereas a crescent‐shaped region, including ventral and medial DLM, projects exclusively to a parvicellular shell that encircles IMANcore (lMANshell). In turn, IMANshell neurons project solely to an arc‐shaped region of dorsal archistriatum just lateral to RA (Ad; archistriatum, pars dorsalis), whereas IMANcore neurons project exclusively to RA. We also identified crossed and reciprocal pathways between IMANcore/shell and the lateral portion of the ventral archistriatum, which may contribute to interhemispheric coordination of vocal behavior. A robust topographic organization was observed in the axonal projections from dorsal/lateral‐DLM→IMANcore→RA and from ventral/medial‐DLM→IMANshell→Ad, raising the question of what is being mapped within these two forebrain pathways. Because RA projection neurons are organized myotopically with respect to the major vocal (syringeal) muscles (D. S. Vicario, 1991, J. Comp. Neurol. 309:486–494), one possibility is that a mapping of vocal/expiratory musculature is preserved “upstream” within these pathways. Similarly, the presence of song‐selective auditory neurons in DLM, lMAN, and RA (A. J. Doupe and M. Konishi, 1991, Soc. Neurosci. Abstr. 18:527) suggeststhat thesepathways might subserve some form of auditory or auditory‐motor mapping. © 1995 Wiley‐Liss, Inc.