bluuebunny/crossref_metadata_2025 huggingface dataset:
Somal size and location within the ganglia for electrophysiologically identified myenteric neurons of the guinea pig ileum
Authors: Schutte Irma W. M. , Kroese Alfons B. A. , Akkermans Louis M. A.
Published: January 2005

The main goal of the present study was to examine the possibility of electrophysiologically identifying the excitable enteric S and AH neurons by use of one single criterion. Intracellular recordings were made from 189 cells of 64 ganglia in isolated preparations of the myenteric plexus of the guinea pig distal ileum. The recordings were made under visual control of the cells by using Hoffman Modulation Contrast optics at high magnification (600 X). From photomicrographs, the soma size and the location within the ganglion of the individual (unstained) cells were determined.

The cells were classified into three types according to their electrical excitability and the shape of the action potential. Excitable cells were classified as AH cells (n = 84) if the action potential showed a shoulder on the falling phase, otherwise as S cells (n = 56). Cells in which no action potential could be evoked by current injection were classified as nonspiking (NS) cells (n = 49). The three classes of cells showed significant differences with respect to membrane potential, input resistance and fast synaptic input. The AH cells had significantly larger somata (P < 0.01) than the S cells. The NS cells were significantly smaller than the AH and S cells (P < 0.01). AH and S cells were found to be randomly located in the ganglia, whereas the NS cells clustered (P < 0.008) in close proximity to the onsets of internodal strands.

We conclude that the shoulder of the action potential canbe used as a single criterion to distinguish “on line” S and AH neurons unequivocally.
Prenatal development of rat primary afferent fibers: I. Peripheral projection
Authors: Mirnics Károly , Koerber H. Richard
Published: January 2005

Development of the peripheral innervation patterns of the L1‐S1 lumbosacral ganglia and motor segments in embryonic day 12‐17 (E12‐17) rat embryos was examined using carbocyanine dyes. Individual dorsal root ganglia (DRGs) and/or isolated ventral horn (VH) segments, or individual peripheral nerves, were isolated in rat embryos fixed at different stages and filled with one of three carbocyanine dyes; DiI, DiA, and DiO. Individual experimental preparations included labeling of (1) single DRGs; (2) multiple DRGs with alternating dyes, DiO, DiI, and DiA; (3) single isolated VH segments; (4) multiple VH segments with alternating dyes; (5) single VH segments and the corresponding segmental DRGs with different dyes; and (6) two or more individual peripheral nerves labeled with different dyes.

Results from these preparations have shown that the first fibers exited the lumbar ventral horn and DRGs at E12. At E13 major nerve trunks (e. g., femoral and sciatic) were visible as they exited the plexus region. By E14 afferent fibers were present in the epidermis of the proximal hindlimb, and the major nerve trunks extended into the leg. Fibers originating from L3 to L5 (DRG and VH) reached the paw by E14. 5‐E15, and the epidermis of the most distal toes was innervated by E16‐E16. 5. While afferent fibers and motor axons of the same segmental origin mixed extensively in the spinal nerve, fibers of different segmental origin combined in the plexus and major nerve trunks with little or no interfascicular mixing.

Dermatomes observed at E 14 were in general spotty and non‐contiguous. However, by E 16 the dermatomes resembled mature forms with substantial overlap only between adjacent ones. Thus the adult pattern of spatial relationships between cutaneous afferent fibers in the periphery is established early in development.
Zonal organization of the flocculovestibular nucleus projection in the rabbit: A combined axonal tracing and acetylcholinesterase histochemical study
Authors: Tan J. , Epema A. H. , Voogd J.
Published: January 2005

With the use of retrograde transport of horseradish peroxidase we confirmed the observation of Yamamoto and Shimoyama ([1977] Neurosci Lett. 5:279‐283) that Purkinje cells of the rabbit flocculus projecting to the medial vestibular nucleus are located in two discrete zones, FZII and FZIV, that alternate with two other Purkinje cell zones, FZI and FZIII, projecting to the superior vestibular nucleus. The retrogradely labeled axons of these Purkinje cells collect in four bundles that occupy the corresponding floccular white matter compartments, FC1 –4, that can be delineated with acetylcholinesterase histochemistry (Tan et al. [1995a] J. Comp. Neurol., this issue). Anterograde tracing from small injections of wheat germ agglutin‐hoseradish peroxidase in single Purkinje cell zones of the flocculus showed that Purkinje cell axons of FZII travel in FC2 to terminate in the medial vestibular nucleus. Purkinje cell axons from FZI and FZIII occupy the FC2 and FC3 compartments, respectively, and terminate in the superior vestibular nucleus. Purkinje cell axons from all three compartments pass through the floccular peduncle and dorsal group y. In addition, some fibers from FZI and FZII, but not from FZIII, arch through the cerebellar nuclei to join the floccular peduncle more medially. No anterograde tracing experiments were available to determine the projections of the FZIV and C2 zones. The functional implications of these results are discussed. © 1995 Wiley‐Liss, Inc.
Double labeling of GABA and cytochrome oxidase in the macaque visual cortex: Quantitative EM analysis
Authors: Nie Feng , Wong‐Riley Margaret T. T.
Published: January 2005

In the primate striate cortex, cytochrome oxidase (CO)‐rich puffs differ from CO‐poor interpuffs in their metabolic levels and physiological properties. The neurochemical basis for their metabolic and physiological differences is not well understood. The goal of the present study was to examine the relationship between the distribution of gamma aminobutyric acid (GABA)/non‐GABA synapses and CO levels in postsynaptic neuronal profiles and to determine whether or not a difference existed between puffs and interpuffs. By combining CO histochemistry and postembedding GABA immunocytochemistry on the same ultrathin sections, the simultaneous distribution of the two markers in individual neuronal profiles was quantitatively analyzed. In both puffs and interpuffs, GABA‐immunoreactive (GABA‐IR) neurons were the only cell type that received both non‐GABA‐IR (presumed excitatory) and GABA‐IR (presumed inhibitory) axosomatic synapses, and they had three times as many mitochondria darkly reactive for CO than non‐GABA‐IR neurons, which received only GABA‐IR axosomatic synapses. GABA‐IR neurons and terminals in puffs had a larger mean size, about twice as many darkly reactive mitochondria, and a higher ratio of non‐GABA‐IR to GABA‐IR axosomatic synapses than those in interpuffs (2.3:1 vs. 1.6:1; P < 0.01). There were significantly more synapses of both non‐GABA‐IR and GABA‐IR types in the neuropil of puffs than of interpuffs; however, the ratio of non‐GABA‐IR to GABA‐IR synapses was significantly higher in puffs (2.86:1) than in interpuffs (2.08:1; P < 0.01). Our results are consistent with the hypothesis that the level of oxidative metabolism in postsynaptic neurons and neuronal processes is tightly governed by the strength and proportion of excitatory over inhibitory synapses. Thus, the present results suggest that (1) GABA‐IR neurons in the macaque striate cortex have a higher level of oxidative metabolism than non‐GABA ones because their somata receive direct excitatory synapses and their terminals are more tonically active; (2) the higher proportion of presumed excitatory synapses in puffs imposes a greater energy demand there than in interpuffs; and (3) excitatory synaptic activity may be more prominent in puffs than in interpuffs because puffs receive a greater proportion of excitatory synapses from multiple sources including the lateral geniculate nucleus, which is not known to project to the interpuffs. © 1995 Wiley‐Liss, Inc.
Ultrastructural localization of SNAP‐25 within the rat spinal cord and peripheral nervous system
Authors: Duc Christophe , Catsicas Stefan
Published: January 2005

Synaptosomal associated protein of 25 kDa (SNAP‐25) has been implicated in the membrane fusion machinery of neurotransmitter release and axonal growth. Using immunocytochemistry, we have analyzed the distribution and ultrastructural localization of SNAP‐25 in selected areas of the central and peripheral nervous systems of adult rats. We show that the protein is specifically expressed in the trans face of the Golgi apparatus and in the axonal compartment. In axons and nerve endings, SNAP‐25 is localized to discrete areas of the membranes of most organelles such as the axoplasmic reticulum, the axolemma, the outer membrane of mitochondria and synaptic vesicles. This wide distribution of SNAP‐25 suggests that the protein is involved in the fusion of membranes in the whole axonal compartment of neurons. © 1995 Wiley‐Liss, Inc.
Distribution of fine neurites of stomatogastric neurons of the crab Cancer borealis: Evidence for a structured neuropil
Authors: Baldwin David H. , Graubard Katherine
Published: January 2005

The neuropil of the stomatogastric ganglion of the crab Cancer borealis contains many neuronal processes that may be arranged either at random or in some form of orderly structure. In this study, we provide evidence for two types of order in the neuropil, a segregation of the processes based on their size and a cell‐specific distribution to the fine neurites. Identified neurons were injected with Lucifer yellow, fixed, and imaged as whole mounts with a confocal microscope. Four cell types were analyzed using the serial images, two pyloric neurons, one mixed pyloric/gastric neuron, and one gastric neuron. All of the neurons consisted of a ∼ 60‐μm‐diameter soma, a ∼ 20‐μm‐diameter primary neurite projecting into the center of the neuropil, a number of < 10‐μm‐diameter medium‐sized neurites radiating away from the center, and many < 3‐μm‐diameter fine neurites around the periphery of the neuropil. The neuropil can, therefore, be divided into three layers, a central core containing the largest neurites, an intermediate region containing both medium‐sized and fine neurites, and a peripheral neuropil containing mostly fine neurites. The distribution of the fine neurites was mapped using a three‐dimensional grid. We found that the fine neurites were distributed not at random within the neuropil but in consistent, cell‐specific patterns. © 1995 Wiley‐Liss, Inc.
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

Peripheral 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

Optic 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

The 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

Fos‐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

Neuron 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

Anterograde 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

The 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

The 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

Chronic 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

The 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

A 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.
An anatomical substrate for the inhibitory gradient in the VLVp of the owl
Authors: Takahashi Terry T. , Barberini Crista L. , Keller Clifford H.
Published: January 2005

The interaural difference in the level of sounds is an important cue for the localization of the sound's source. In the barn owl, a keen auditory predator, this binaural cue is first computed in the nucleus ventralis lemnisci laterale, pars posterior (VLVp), a cell group found within the fibers of the lateral lemniscus. Its neurons are excited by inputs from the contralateral ear and inhibited by inputs to the ipsilateral ear and are therefore sensitive indicators of interattral level difference. The excitation arrives by a direct input from the contralateral nucleus arigularis, a cochlear nucleus, and the inhibition is mediated by a commissural projection that interconnects the VLVps of the two sides. The dorsally located neurons in the VLVp are more heavily inhibited than those found more ventrally, thus giving rise to a gradient of inhibition. This inhibitory gradient plays a central role in recent models of VLVp function. We present evidence based on standard anterograde tracing methods that this gradient of inhibition is mediated by a dorsoventral gradient in the density of synaptic inputs from the contralateral VLVp, the source of inhibition. Specifically, injection of tracers into one VLVp, regardless of the position of the injection within the nucleus, produced a vertically oriented field of label that was densest along the dorsal margin of the contralateral VLVp and became sparser at more ventral levels. Furthermore, we found that injections into the medial and lateral aspects of the nucleus produced this dorsoventrally graded field of label along the medial and lateral aspects of the contralateral VLVp, respectively. Finally, we confirmed an earlier observation suggesting that the anterior and posterior aspects of one VLVp project to the anterior and posterior aspects of the contralateral nucleus, respectively. © 1995 Wiley‐Liss, Inc.
Colocalization of γ‐aminobutyric acid with vasopressin, vasoactive intestinal peptide, and somatostatin in the rat suprachiasmatic nucleus
Authors: Buijs Ruud M. , Wortel Joke , Hou Yang‐Xun
Published: January 2005

The seemingly contradictory observations in previous publications that γ‐aminobutyric acid (GABA) is detected in all cell bodies of the suprachiasmatic nucleus (SCN) and that terminals originating from the SCN are only 20–30% GABA positive prompted us to investigate whether this might be explained by a preference of colocalization in terminals of certain peptidergic neurons in the SCN or by a day/night rhythm in GABA synthesis. At three different circadian times, animals were perfusion fixed, and their SCNs were stained for vasopressin (VP), somatostatin (SOM), or vasoactive intestinal polypeptide (VIP). Subsequently, the number of GABA peptide‐positive terminals was determined using GABA postembedding staining in ultrathin sections. It appeared that the highest percentage of colocalization with GABA was detected in VIP terminals (38%) and the lowest in VP terminals (15%). No differences in colocalization percentages could be observed in any parameter at any circadian time. In the dorsomedial hypothalamus, one of the target areas of the VP and VIP fibers from the SCN, a colocalization of GABA within VP and VIP terminals was found similar to that in the SCN. In the region of the somatostatin‐containing neurons in the SCN, a number of axoaxonal contacts could be observed that sometimes exhibited synaptic specializations. In nearly all cases, the axoaxonic terminals contained GABA and/or SOM. The conclusion is that the high level of intrinsic GABAergic connections in the SCN represents a putatively powerful mechanism to synchronize or shut down the activity of the SCN. We discuss the possibility that, depending on the firing frequency of the neurons, the colocalization of GABA with all peptides under investigation allows for the selection of which transmitter is released, the peptidergic one or the amino acid. © 1995 Wiley‐Liss, Inc.
Long‐term sensory hyperinnervation following neonatal skin wounds
Authors: Reynolds M. L. , Fitzgerald M.
Published: January 2005

Skin innervation during wound healing was investigated using immunocytochemical staining with the panneuronal marker antiprotein gene product (PGP) 9.5, which labels the entire innervation of the skin throughout development and in the adult. Full‐thickness skin wounds in the hairy skin of the foot in neonatal rats result in pronounced hyperinnervation of the tissue that persists long after the wound has healed (at least 12 weeks). Quantification of this hyperinnervation by image analysis indicates that slcoin innervation density in the wounded area can increase up to 300%. The effect is greatest when wounds are performed at postnatal day (P) 0 or 7, declining when performed at P14 and P21 to resemble the weaker and transient effect in the adult. Staining with selective markers for different neuronal populations innervating skin (monoclonal anti‐RT97 staining the myelinated axons of large light sensory ganglion cells; anticalcitonin gene‐related peptide staining unmyelinated C axons, thinly myelinated Aδ axons, and a subpopulation of large A fibres) reveal that both A‐ and C‐fibre sensory axons contribute to this response. Destruction of the majority of the C‐fibre population with neonatal capsaicin pretreatment, which leaves large, A fibres intact, significantly reduces the hyperinnervation response at 14 days, confirming a major contribution from both A and C‐fibres. Sympathetic axons, stained with anti‐tyrosine hydroxylase, do not sprout into the wounded area. Furthermore, pretreatment of neonates with 6–hydroxydopamine, which destroys the sympathetic innervation, does not significantly reduce the overall sprouting response, as identified by anti‐PGP9. 5 staining. Behavioural sensory testing revealed a 50% drop in the mechanical threshold in the wounded area after 3 weeks. These remarkably long‐term and specific effects on sensory terminal axons following neonatal skin wounding indicate the plasticity of cutaneous innervation density following alterations in the target tissue at a critical stage of development. © 1995 Wiley‐Liss, Inc.
Trigeminal, vagal, and spinal projections of supramedullary cells in the puffer fish, Takifugu niphobles
Authors: Funakoshi Kengo , Abe Toshio , Kishida Reiji
Published: January 2005

The supramedullary cells (SMCs) of teleosts have been studied for nearly 100 years, but their peripheral connectional have remained obscure. We examined the supramedullary cells of the puffer fish, Takifugu niphobles, using horseradish peroxidase transport. Horseradish peroxidase labeling was found bilaterally after application to the trigeminal, the posterior branch of the vagal, and thee spinal nerves, No labeled neurons were found after application to the anterior or visceral branches of the vagal nerve. Thus, labeled SMCs were found only after application to the nerves containing cutaneous branches.

Some rostrocaudal topographical labeling was found after selective application to each of the four branches of the trigeminal nerve. Labeled neurons were more common in the rostral than in the central or caudal part of the SMC region. Some topographical labeling was also found after application to the first, second, and third spinal nerves, but the topography was not very clear, and there was considerable overlap in the distribution of labeled cells. The sum total of labeled SMCs after unilateral horseradish peroxidase application to each peripheral nerve was more than three times the total number of ipsilateral SMCs, indicating that a single SMC projects several peripheral processes into different nerves.

From these results, and taking previous studies into consideration, we propose that supramedullary neurons have a phylogenetic relationship with the spinal dorsal cells of the lamprey and with the extramedullary cells of the amphibian embryo. © 1995 Wiley‐Liss, Inc.
Dark‐rearing changes dendritic microtubule‐associated protein 2 (MAP2) but not subplate neurons in cat visual cortex
Authors: Reid S. N. M. , Daw N. W.
Published: January 2005

Sensory‐dependent modification of cortical morphology is one component of the cortical plasticity that occurs during the critical period for ocular dominance changes. In this study, we used dark‐rearing to examine the sensory dependency of subplate neuron death and the quantity of microtubule‐associate protein 2 (MAP2)‐positive dendrites. Kittens reared in total darkness until the peak of the critical period had fewer laterally extended MAP2‐positive dendrites than age‐matched normal kittens. This reduction was found in layer IV but not in layer V. Subsequent exposure to light for 10 days after dark‐rearing was sufficient to bring the number of MAP2‐positive dendrites to the normal level. Contrarily, dark‐rearing did not prevent subplate neurons from dying. Exposure to light after dark‐rearing did not increase the number of potential dying neurons. These results show that the quantity of MAP2‐positive dendrites is sensory‐dependent; however, the death of the subplate neurons is not. Therefore, the death of subplate neurons is probably not directly involved in sensory‐dependent modifications of synaptic connections. The possible involvement of laterally extended MAP2‐dendrites in visual plasticity is discussed. © 1995 Wiley‐Liss, Inc.
Cajal‐Retzius neurons in human cerebral cortex at midgestation show immunoreactivity for neurofilament and calcium‐binding proteins
Authors: Verney Catherine , Derer Paul
Published: January 2005

Along with subplate neurons, Cajal‐Retzius cells (CRc) are the first neurons to be generated in the cortical anlage. Studies of their chemical content, such as neurofilament and calcium‐binding proteins, might give indications on their role in cortical development at midgestation in human fetuses (20–24 gestation weeks), when the CRc are morphologically mature. Cajal‐Retzius cells were immunolabeled with antibodies to subunits of neurofilament proteins SMI31 and SMI32. The SMI32 antibodies (directed against the nonphosphorylated epitope) specifically labeled the CR cell bodies, dendrites, and proximal axons in a Golgilike fashion. Specific acetylcholinesterase activity is known to be typical of all the CRc, and double labeling for SMI32 immunoreactivity and acetyleholinesterase histochemistry demonstrated that all the CRc exhibited SMI32 immunoreactivity. The SMI31 antibodies (directed against the phosphorylated epitope) exclusively labeled the CRc axons, forming a dense positive network in the deep one‐half of layer 1. This plexus was much denser than the one described with the Golgi method (Marin‐Padilla, 1990: J. Comp Neurol 239:89–105). Calbindin D28k, parvalbumin, and calretinin immunoreactivities were visualized in the CRc. Double‐labeling experiments showed that most of the CRc contained both calbindin and calretinin and sometimes parvalbumin. These colocalizations revealed a chemical heterogeneity within the CRc population even though they were described as morphologically homogeneous. These colocalizations of calcium‐binding proteins in the CRc differed from the other nonpyramidal neurons where calbindin, calretinin, and parvalbumin are contained in different (mutually exclusive) neuronal populations.

Based on the morphological features and differential chemical contents described for the CRc, different hypotheses on their possible role and fate are discussed. © 1995 Wiley‐Liss, Inc.
Efferent projections of the paraventricular thalamic nucleus in the rat
Authors: Moga Margaret M. , Weis Roger P. , Moore Robert Y.
Published: January 2005

The paraventricular nucleus of the thalamus (PVT) receives input from all major components of the circadian timing system, including the suprachiasmatic nucleus (SCN), the intergeniculate leaflet and the retina. For a better understanding of the role of this nucleus in circadian timing, we examined the distribution of its efferent projections using the anterograde tracer Phaseolus vulgarl's leucoagglutinin (PHA‐L). The efferent projections of the PVT are loosely organized along its dorsal‐ventral and anterior‐posterior axes. The anterior PVT sends projections to the SCN; the dorsomedial and ventromedial hypothalamic nuclei; the lateral septum; the bed nucleus of the stria terminalis; the central and basomedial amygdaloid. nuclei; the anterior olfactory nucleus; the olfactory tubercle; the nucleus accumbens; the infralimbic, piriform, and perirhinal cortices; the ventral subiculum; and the endopiriform nucleus. A small PHA‐L injection, restricted to the ventral portion of the anterior PVT, produces a similar pattern of labeling, except for a marked decrease in the number of labeled fibers in the hypothalamus, cortex, and lateral septum and an increase in labeling in the endopiriform nucleus and basolateral amygdaloid nucleus. The posterior PVT has a more limited efferent distribution than the anterior PVT, terminating in the anterior olfactory nucleus; the olfactory tubercle; the nucleus accumbens; and the central, basolateral, and basomedial nuclei of the amygdala. Our results show that the anterior PVT is ideally situated to relay circadian timing information from the SCN to brain areas involved in visceral and motivational aspects of behavior and to provide feedback regulation of the SCN. © 1995 Wiley‐Liss, Inc.