bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of myomodulin‐like immunoreactivity in the central nervous system and peripheral tissues of Aplysia californica
Authors: Miller M. W. , Alevizos A. , Cropper E. C. , Vilim F. S. , Karagogeos D. , Kupfermann I. , Weiss K. R.
Published: January 2005

The distribution of myomodulin‐like peptides in the nervous system of Aplysia californica was examined by using immunocytochemical techniques. Neurons and cell clusters containing immunoreactive material were located in each of the major central ganglia. Myomodulin‐like immunoreactivity was also present in fibers in each of the connectives between the ganglia and in peripheral nerves. Varicosities containing immunoreactive material were located on specific regions of peripheral tissues associated with the feeding, digestive, cardiovascular, and reproductive systems.

Double‐labeling experiments were used to demonstrate myomodulin‐like immunoreactivity in two identified neurons, the motor neuron B16 in the buccal ganglion and the widely acting interneuron L10 in the abdominal ganglion. Structures in the eye and cerebral ganglion that may correspond to the optic circadian pacemaker system were also stained. The central and peripheral distribution of myomodulin‐like immunoreactivity indicates that this family of neuropeptides is present in specific efferent, afferent, and interneuronal elements that participate in a diversity of neural circuits in Aplysia.
Calmodulin and calbindin localization in retina from six vertebrate species
Authors: Pochet Roland , Pasteels Brigitte , Seto‐ohshima Akiko , Bastianelli Enrico , Kitajima Satoko , Van Eldik Linda J.
Published: January 2005

Calmodulin is abundant in the central nervous system, including the retina. However, the localization of calmodulin in the retina has not been described in detail. We therefore decided to investigate calmodulin localization in retinae from six vertebrate species, by using immunohistochemical labeling with four different rabbit polyclonal antibodies against calmodulin. The localization of calbindin‐D28k, another calcium‐binding protein already well described in retina, was compared. We found that calmodulin distribution is more highly conserved among species, contrasting with calbindin variability. The most striking result emerging is that calmodulin could not be detected in photoreceptors although other layers are intensely calmodulin‐immunoreactive, casting doubt about a direct role of calmodulin in phototransduction. Horizontal cells are weakly calmodulin‐immunoreactive, bipolar cells are calmodulin‐immunoreactive except in turtle retina, numerous amacrine and ganglion cells are labeled in all species, and the fiber layer is always labeled. These data demonstrate that, while the calmodulin distribution in retina is similar among vertebrate species, selective differences in localization can be detected not only among the same cell types in different species but also among different cell types in the same species. The results showing differences in calmodulin immunoreactivity among cell types also provide further evidence that calmodulin expression in eukaryotes is not constitutive, in the sense that not every cell expresses similar levels of calmodulin.
Postnatal development of the corticotectal projection in cats
Authors: Plummer Kim Lord , Behan Mary
Published: January 2005

Although numerous physiological studies have provided compelling evidence for the involvement of the corticotectal projection in the normal development of visual response properties of neurons in the superior colliculus, little information is available on the morphological development of corticotectal axons. Thus, our goal was to determine the postnatal changes characterizing the development of the topography and morphology of corticotectal axon arbors. Topographically restricted injections of Phaseolus vulgaris leucoagglutinin were made into striate cortex to label corticotectal axons and their terminal arbors.

Following injections of similar size and location in kittens and adult cats, a similar, localized region of the superior colliculus was labeled at all ages. However, while present in the appropriate topographic location in colliculus, the corticotectal projection revealed a greater tangential distribution in kittens than adults. Corticotectal terminal zones underwent a twofold decrease in tangential area during the first 8 weeks after birth. From corticotectal terminal zones in kittens, extended many fine collaterals that ended as growth cones and radiated up to 1 mm from the focus of the terminal zone. By 8 weeks after birth, these immature collaterals were no longer observed, and the corticotectal terminal zone was indistinguishable from those in 12‐week‐old kittens and adult cats. Corticotectal axon arbors became more specialized in the first 8 weeks after birth; both en passant and terminal swellings increased in diameter, and terminal swellings increased in number, although the total number of swellings per unit length of axon remained relatively stable. The number of axonal branches increased threefold between 1 and 8 weeks after birth. Thus, as the corticotectal projection becomes spatially restricted during development, individual arbors become progressively more intricate with regard to focused collateral branching and the elaboration of complex axonal specializations.
Synaptic plasticity in the rod terminals after partial photoreceptor cell loss in the heterozygous rds mutant mouse
Authors: Jansen H. G. , Sanyal S.
Published: January 2005

In the retina of mice heterozygous for the retinal degeneration slow gene (rds/ +) the photoreceptor cells, both rods and cones, develop abnormal outer segments but establish normal synaptic contacts. The other retinal layers also show normal structural organization. Starting from the age of 2 months, a very slow loss of photoreceptor cells progresses throughout life. As a result, the photoreceptor cell population in the retina of the affected mice is reduced to less than half at the age of 9–18 months. In some of the surviving rod terminals during this period, an increase in the number of synaptic ribbons is recorded. At the same time, the profiles of processes originating from the second order neurons and participating in these synapses are also increased in number so that the multiple ribbons appear as centres of multiple synaptic sites.

Morphometric measurements of the perimeter of the synaptic profiles in rod terminals show a significant increase in the rds/ + retina over that of the control retina. Observations based on serial electron microscopy indicate that multiple synaptic sites are developed while the number of the second order neuronal processes, entering the terminals, remains unchanged. The frequency of terminals with multiple synapses in the rds/+ retina increases with progressive photoreceptor cell loss. Similar changes do not occur in the terminals of the cones.

It is postulated that loss of some rod photoreceptor cells within a group that is presynaptic to common bipolars or horizontal cells results in partial deafferentation which in turn stimulates the growth of the remaining synaptic elements. The possible compensatory effect and functional significance of such synaptic growth are discussed.
Efferent cortical connections of multimodal cortex of the superior temporal sulcus in the rhesus monkey
Authors: Barnes Clifford L. , Pandya Deepak N.
Published: January 2005

The cortex of the upper bank of the superior temporal sulcus (STS) in the rhesus monkey contains a region that receives overlapping input from post‐Rolandic sensory association areas and is considered multimodal in nature. We have used the fluorescence retrograde tracing technique in order to answer the question of whether multimodal areas of the STS project back to post‐Rolandic sensory association areas. Additionally, we have attempted to answer the question of whether the projections from the multimodal areas directed to the parasensory association areas originate from common neurons via axon collaterals or from individual neurons. The results show that multimodal area TPO of the STS projects back to specific unimodal parasensory association areas of the parietal lobe (somatosensory), superior temporal gyrus (auditory), and posterior parahippocampal gyrus (visual). In addition, a substantial number of projections from area TPO are directed to distal parasensory association areas, area PG‐Opt in the inferior parietal lobule, areas Ts1 and Ts2 in the rostral superior temporal gyrus, and areas TF and TL in the parahippocampal gyrus. These latter regions are themselves considered to be higher‐order association areas. It was also noted that the majority of the projections to these higher‐order association areas originate from the middle divisions of area TPO (TPO‐2 and TPO‐3). These neurons are organized in a significantly overlapping manner. Despite this overlap of the projection neurons, only an occasional double labeled neuron was observed in area TPO. Thus, our observations indicate that the multimodal region of the superior temporal sulcus has reciprocal connections with the unimodal parasensory association cortices subserving somatosensory, auditory and visual modalities, as well as with other post‐Rolandic higher‐order association areas. These connections from area TPO to post‐Rolandic association areas may have a modulating influence on the sensory association input leading to multimodal areas in the superior temporal sulcus.
Acoustic chiasm V: Inhibition and excitation in the ipsilateral and contralateral projections of LSO
Authors: Glendenning K. K. , Baker B. N. , Hutson K. A. , Masterton R. B.
Published: January 2005

When this series of experiments was begun in 1984, the activity of each lateral superior olive (LSO) in the mammalian hindbrain was known to encode the hemifield of acoustic space containing a sound source. However, the almost random bilaterality of its ascending projections seemed to jumble that identification before reaching the midbrain. At the same time, electrophysiological studies of LSO and its efferent target in the inferior colliculus, along with the strictly contralateral deficits in sound localization resulting from unilateral lesions above the level of the superior olives, indicated that hemifield allegiance was largely maintained (though reversed) at the midbrain.

Here we present seven lines of biochemical evidence, some combined with prior ablations, supporting the notion that the anatomical segregation of the ipsilateral and contralateral fibers ascending from the LSO is accompanied by a corresponding segregation of their neurotransmitters: most of the ascending ipsilateral projection is probably glycinergic and, hence, inhibitory in effect, while most of the contralateral projection is probably glutamatergic/aspartergic and, hence, excitatory in effect. Taken together, the inhibitory ipsilateral projections and the excitatory contralateral projections serve to amplify functional contralaterality at the higher levels of the auditory system. © 1992 Wiley‐Liss, Inc.
I. Localization of Mu class glutathione‐s‐transferase in the forebrains of neonatal and young rats: Implications for astrocyte development
Authors: Cammer Wendy , Zhang Hong
Published: January 2005

The Yb (Mu class) isoform of glutathione‐S‐transferase has recently been localized in ependymal cells, subependymal cells, and astrocytes in the forebrains of rats 3 weeks to adult in age. It was not known, however, at what age Mu might first be observed during postnatal development and whether the first cells in which it was found would be immature astrocytes or some less differentiated glial precursor cell, if the latter were present in vivo. Tissue sections from the forebrains of neonatal to 16 day old rats were immunostained with antibodies against Mu. In neonates Mu was observed in vimentin‐positive cells and their processes adjacent to the lateral ventricles, and in the corpus striatum. The colocalization with vimentin suggested that these were subependymal cells and radial glia. In the corpus striatum the radial glia, while still vimentin‐positive, rapidly lost Mu from their radial cell processes, whereas the cell‐bodies remained Mu‐positive. During the first postnatal week the Mu‐positive, glial‐fibrillary‐acidicprotein (GFAP)‐positive cell bodies of immature astrocytes appeared in the corpus striatum.

The earliest Mu‐positive cells in the immature white matter of the corpus callosum were vimentin‐positive and had striking longitudinal processes that also were vimentin‐ and Mu‐positive, Like the processes of radial glia, the longitudinal processes lost their Muimmunoreactivity, only later and more gradually. Mu‐positive, GFAP‐positive cells appeared later in the corpus callosum than in the corpus striatum. The data suggest that (1) Mu is localized in the astrocyte line in the rat brain at all postnatal ages; (2) astrocytes in the white matter may have precursors corresponding to those of astrocytes in gray matter, but developing several days later; and (3) the loss of Mu from radial glial processes may be an early event in the retraction of those processes. © 1992 Wiley‐Liss, Inc.
Morphology of identified preganglionic neurons in the dorsal motor nucleus of the vagus
Authors: Fox Edward A. , Powley Terry L.
Published: January 2005

To determine the degree of variation of neuronal morphology both within and between the subnuclei of the dorsal motor nucleus of the vagus (dmnX), structural features of the preganglionic neurons of each of the five primary subnuclei in the rat dmnX were characterized quantitatively. Each of the columnar subnuclei was separately labeled by application of the retrograde tracer fast blue to its corresponding subdiaphragmatic vagal branch. Fixed brain slices of 100 μm thickness were then prepared in coronal, sagittal, and horizontal orientations. Next, randomly selected fast blue labeled neurons (n = 1,256) were injected with Lucifer yellow, drawn with camera lucida, and digitized. For each cell, three features of the perikaryon and twelve of the dendritic tree were measured.

Dorsal motor nucleus neurons with up to eight primary dendrites, 30 dendritic segments, and seventh order dendritic branches were observed. Throughout the dmnX, the dendrites of preganglionic neurons were preferentially oriented in the horizontal plane. Consistent with an organizing role for the columnar subnuclei, most dendrites remained within their column of origin. However, between 5 and 30% of the neurons in each of the columns projected dendrites into adjacent dmnX subnuclei or other brainstem nuclei, including the nucleus of the solitary tract (NTS). The cyto‐ and dendroarchitectural analyses revealed systematic gradations in morphology, although they did not support the idea that the dmnX was composed of multiple distinct preganglionic types. The most parsimonious interpretation of the data is that dmnX motorneurons are variants of a single prototype, with dendrites varying widely in length and degree of ramification. The extent of an individual preganglionic neuron's dendritic field was predicted by three factors: the cell's rostrocaudal position within the dmnX, its location within a transverse plane (i.e., its coronal position within or ectopic to the dmnX), and its subnucleus of origin. Neurons at rostral and midlongitudinal levels of each column had more extensive dendritic arbors than those at caudal levels. Ectopic neurons had more extensive dendritic fields than similar cells in the corresponding columns; in fact, of all vagal preganglionic neurons, ectopics had the most extensive dendritic fields. Somata and dendrites of celiac column neurons were more extensive than those of hepatic and gastric column cells. These differential regional distributions of vagal preganglionics suggest that their structure and function are correlated. © 1992 Wiley‐Liss, Inc.
Functional degeneration of isolated central stumps of crayfish sensory axons
Authors: Govind C. K. , Blundon J. A. , Kirk M. D.
Published: January 2005

In the crayfish, Procambarus clarkii, nerve 5 carries primarily sensory axons from the tail fan to the 6th abdominal ganglion where they synaptically activate interneuron A. Since the sensory neurons have their somata located at the periphery, transection of nerve 5 part way to the ganglion allowed us to examine the fate of their soma‐less central stumps. Up to 3 weeks postlesion the response to stimulation of nerve 5 consisted of a brief latency spike in interneuron A, similar to that in control animals and to stimulation of the intact nerve 4. Stimulation of the lesioned nerve 5 beyond 3 weeks failed to fire interneuron A. This loss of function was correlated to loss of axons in nerve 5 deduced by comparing the numbers in the lesioned nerve 5 to its contralateral intact counterpart. The numbers are about equal in the paired nerves but rapidly decline on the lesioned side to 50% within 1 week, 20% within 3 weeks, and less than 10% in subsequent weeks. This loss affects all size classes of axons. However, in the 3 week lesioned nerve large glial infoldings subdivided some of the larger axons and single nuclei were seen in a few of the medium‐sized axons, Possibly subdivision of large axons by glial infolding may introduce glial nuclei into axons. © 1992 Wiley‐Liss, Inc.
Cortical and striatal structure and connectivity are altered by neonatal hemidecortication in rats
Authors: Kolb Bryan , Gibb Robbin , van der Kooy Derek
Published: January 2005

The cortical cytoarchitecture, cortical thickness, corticostriatal connections, cortical dendritic arborization, and striatal patch‐matrix compartmentalization were compared in rats with neonatal (1 day of age) or adult hemidecortication. Neonatal hemidecortication produced few changes in cytoarchitecture of the remaining hemisphere and did not preclude the development of a patch‐matrix compartmentalization in either striatum. There was a significant modification of contralateral cortical‐striatal connections, however, as there were extensive crossed connections from layer II/III of the prefrontal cortex in the neonatal hemidecorticates, which contrasts with connections from layer V in the normal brain. Adult hemidecorticates had no crossed corticostriatal connections. Neonatal hemidecortication also led to an increase in cortical thickness relative to adult operates or controls and the neonatal hemidecorticates, and led to an increase in dendritic arborization in layer II/III pyramidal cells of the somatosensory and motor cortex but not in the visual or temporal cortex. The results suggest that the behavioral sparing of sensorimotor and some prefrontal functions after neonatal hemidecortication could be supported, in part, by the anatomical changes in the prefrontal and sensorimotor connectivity and dendritic arborization. © 1992 Wiley‐Liss, Inc.
Relationships between dendritic morphology and cytochrome oxidase compartments in monkey striate cortex
Authors: Hübener Mark , Bolz Jürgen
Published: January 2005

In primate striate cortex, staining for the mitochondrial enzyme cytochrome oxidase reveals a regular pattern of intense staining, the blobs, which are surrounded by the lighter stained interblob regions. Neurons in both compartments exhibit profound functional differences: blob cells have color selective, unoriented receptive fields, whereas interblob cells are usually not color selective and have oriented receptive fields, Neuroanatomical tracing studies have shown that blob and interblob cells receive different inputs and participate in different projections. It is not known, however, whether this compartmental organization is also reflected in the dendritic morphology of individual cells. We therefore combined intracellular staining with cytochrome oxidase histochemistry to study the relationship between cell morphology and blob pattern in layers 2 and 3 of macaque striate cortex. Single cells were injected with the fluorescent dye lucifer yellow in lightly fixed tangential sections. Adjacent sections were reacted for cytochrome oxidase to reveal the blobs. The spatial relationship between stained cells and the pattern of the blobs were subsequently determined by aligning the sections by using radially running blood vessels as landmarks.

Our results show that pyramidal cells located in blob and interblob regions do not differ in their soma size, spine density, and basal dendritic field structure. This indicates that the characteristic functional properties of the neurons in both compartments do not depend on the morphology of their dendritic trees. Since the elongation of the dendritic fields of blob and interblob cells was also found to be similar, we conclude that cortical orientation selectivity is not generated through elongated dendritic fields.

We found several cells with dendrites freely crossing the borders between blob and interblob regions. These cells might correspond to cells with “mixed” receptive field properties, e.g., color selective oriented cells, which in physiological studies were found at the transition from blob to interblob regions. However, there were also a number of cells that respected the borders. A quantitative analysis of the dendritic fields revealed that 67% of the cells located close to the borders have a tendency to confine their dendrites to only one compartment. Thus the pattern of basal dendrites of these cells might be shaped by the parcellation of the striate cortex in blob and interblob regions. These dendritic field asymmetries may help to maintain the segregation at the single cell level into different processing channels in monkey striate cortex.
Sexual dimorphism in the vasotocin system of the bullfrog (Rana catesbeiana)
Authors: Boyd Sunny K. , Tyler Chris J. , de Vries Geert J.
Published: January 2005

Arginine vasotocin (AVT) is widespread in amphibian brains, where its levels have been correlated with reproductive behaviors. To better understand which neural systems are involved in central actions of AVT, we used immunocytochemistry to compare the distribution of AVT in the brains of male and female bullfrogs (Rana catesbeiana). AVT‐immunoreactive cells were observed in the septal nucleus, amygdala pars lateralis, magnocellular preoptic area, suprachiasmatic nucleus, and hypothalamus. AVT‐immunoreactive cells were also found in the pretrigeminal nucleus, but only in animals killed in the fall. Immunoreactive fibers were broadly distributed in hypothalamic and extrahypothalamic areas. The most obvious sex differences were found in the amygdala pars lateralis, where the density of immunoreactive cells and fibers was significantly greater in male than in female bullfrogs. In addition, in the habenular nucleus, males had a denser distribution of AVT‐immunoreactive fibers than females. In the suprachiasmatic nucleus, AVT‐immunoreactive cells were larger in females than in males but did not differ in number. Since the areas that showed sex differences in AVT distribution have also been implicated in control of reproductive behaviors, they may form the neural substrates for the effects of AVT on sexually dimorphic behaviors in amphibians. © 1992 Wiley‐Liss, Inc.
Noradrenergic modulation of noxious heat‐evoked fos‐like immunoreactivity in the dorsal horn of the rat sacral spinal cord
Authors: Jones S. L.
Published: January 2005

This tail‐flick withdrawal reflex commonly is used to study spinal nociceptive mechanisms; noradrenergic agonists administered intrathecally inhibit the tail‐flick‐ reflex in a dose‐dependent manner. The objectives of the present study, were: (1) to use fos‐like immunoreactivity as a marker for neuronal activity to examine the population of neurons in the spinal cord dorsal horn that are engaged by activation of nociceptive tail afferents, and (2) to determine whether fos‐like immunoreactivity can be modulated by intrathecally administered alpha adrenoceptor agonists.

Neurons demonstrating heat‐evoked fos‐like immunoreactivity were identified bilaterally in the sacral spinal cord in superficial and deep dorsal horn laminae. Heat‐evoked fos‐like immunoreactivity was inhibited dose‐dependently by intrathecal norepinephrine (NE). The inhibition was attenuated significantly by: (1) phentolamine (PHEN), a nonselective alpha adrenoceptor antagonist; (2) yohimbine (YOH), an alpha‐2 adrenoceptor antagonist; and (3) prazosin (PRAZ), an alpha‐1 adrenoceptor antagonist. Thus, both spinal alpha‐1 and alpha‐2 adrenoceptors mediate the inhibition of heat‐evoked fos‐like immunoreactivity produced by intrathecal NE. ST‐91, an alpha‐2 adrenoceptor agonist, also inhibited significantly the expression of fos‐like immunoreactivity; the inhibition was antagonized by YOH.

In the absence of noxious heat, intrathecal NE dose‐dependently evoked the expression of fos‐like immunoreactivity in the superficial dorsal horn, which was antagonized by PHEN and PRAZ, but not by YOH, suggesting that the effect is mediated by spinal alpha‐1 adrenoceptors. © 1992 Wiley‐Liss, Inc.
Analysis of low affinity nerve growth factor receptor during pulpal healing and regeneration of myelinated and unmyelinated axons in replanted teeth
Authors: Byers Margaret R. , Kvinnsland Inger , Bothwell Mark
Published: January 2005

Nerve regeneration was examined in rat molars that were briefly extracted and then replanted in the socket for 1–90 days. Immunocytochemistry was used to evaluate neural and nonneural immunoreactivity (IR) for low affinity nerve growth factor receptor (p75‐NGFR) and for laminin and calcitonin gene‐related peptide (CGRP). Three different types of pulpal response to replantation were found. Type I: Some replanted teeth had mild injury and still contined coronal odontoblasts and associated fibroblasts that retained p75‐NGFR‐IR; they continued regular dentin formation and had excellent reinnervation. Type II: Teeth with intermediate injury lost most or all of the coronal pulp tissue, but they regenerated odontoblast‐like cells that formed irregular dentin, they had numerous dispersed p75‐NGFR‐IR fibroblasts in crown pulp during early regeneration, and they had excellent reinnervation. Type III: Severely injured teeth lost their original pulp; they filled with dense connective tissue and bone and had poor reinnervation. After Type I or II injury the Schwann cells around degenerating myelinated and unmyelinated axons had increased expression of p75‐NGFR by 1–3 days. By 7–10 days those Schwann cells had formed hollow tubes (bands of Bungner) along the degenerating axon tracks. They maintained their increased p75‐NGFR‐IR during and after regeneration of unmyelinated axons, whereas Schwann cells involved in remyelination lost p75‐NGFR‐IR at that stage. The number of CGRP‐IR axons in the regenerating pulp increased from 7 to 90 days. Laminin‐IR increased in all replanted teeth at 3–10 days and only returned to normal patterns in teeth with Type I or Type II response at 20–90 days. The special p75‐NGFR‐IR of pulpal fibroblasts of adult rat molars did not usually persist in regenerated, reinnervated pulp. The extensive depletion of fibroblast p75‐NGFR‐IR and the continuing enhanced p75‐NGFR‐IR in unmyelinated nerve fibers at 90 days show that altered growth factor conditions characterize regenerated pulp of replanted teeth. © 1982 Wiley‐Liss, Inc. © 1992 Wiley‐Liss, Inc.
Immunocytochemical study of somatostatin, neurotensin, GABA, and glycine in rat spinal dorsal horn
Authors: Proudlock F. , Spike R. C. , Todd A. J.
Published: January 2005

In order to determine whether somatostatin coexists with GABA or glycine in neurones in rat spinal dorsal horn, a combined pre‐ and post‐embedding immunocytochemical study was carried out. One hundred six somatostatin‐immunoreactive neurones located in lamina II and the dorsal half of lamina III were tested with antiserum or monoclonal antibody to GABA and none of these cells showed GABA‐like immunoreactivity. However, 8 out of 13 somatostatin immunoreactive neurones located deeper in the dorsal horn (ventral lamina III and lamina IV) showed glycine‐like immunoreactivity, and 6 of these were also GABA‐immunoreactive. We have previously shown that neurotensin‐immunoreactive neurones in laminae II and III are also not immunoreactive when tested with GABA antiserum (Todd et al.: Neuroscience 47: 685–691, 1992), and a double‐labelling fluorescence method was therefore used to compare the distribution of somatostatin and neurotensin within the superficial dorsal horn. The two types of peptide‐immunoreactivity were never found in the same profile.

These results suggest that somatostatin and neurotensin are present in different populations of non‐GABAergic neurones in rat superficial dorsal horn, but that some somatostatin containing neurones in the deeper part of the dorsal horn contain glycine, with or without GABA. © 1993 Wiley‐Liss, Inc.
Network of GABAergic large basket cells in cat visual cortex (area 18): Implication for lateral disinhibition
Authors: Kisvárday Zoltán F. , Beaulieu Clermont , Eysel Ulf T.
Published: January 2005

Anatomical and immunohistochemical data indicate that, in addition to pyramidal neurons, nonpyramidal cells are exposed to perisomatic inhibition mediated by γ‐aminobutyric acid (GABA)‐containing terminals. However, no direct information is available as yet for the origin of GABAergic inputs to morphologically identified GABAergic neurons. In the present paper, we studied the topographical and synaptic relationship between identified GABAergic large basket cells and their immunohistochemically characterized target neurons revealed by parvalbumin‐(PV) and GABA immunostaining in the same material.

Extracellularly applied biocytin labelled a total of 36 and 9 large basket cells in layers III and V, respectively. Of these, the axonal arborizations of two basket cells, BC1 and BC2, were reconstructed. The axon of BC1 occupied an area of about 2.3 × 2.2 mm2 in layer III, providing a total of 2,755 terminals. The axon of BC2 showed an overall extent of 3.8 × 1.7 mm2 in layer V elongated in the anteroposterior direction, and gave off 1,599 terminals. Immunostaining for PV was carried out to reveal putative nonpyramidal targets for BC1 and BC2. It was found that in addition to immunonegative cells, they established an average of 4–6 perisomatic contacts onto each of 58 (BC1) and 33 (BC2) PV‐immunopositive neurons. For electron microscopic verification, 23 terminals apposing the somata of 12 PV‐immunopositive neurons were selected. Each terminal was found to establish symmetrical (type II) contacts with its targeted cell. Furthermore, the distribution of soma area of the targeted PV‐immunopositive cells and of identified large basket cells showed remarkable similarity, implying that the two populations were actually the same. In addition, the average horizontal distance between neighbouring PV‐immunopositive target cells was found to be about 100 μm both in layers III and V.

The results suggest that in area 18 the same large basket cell provides direct inhibition to certain pyramidal cells and facilitation to other pyramidal neurons, by inhibiting their presynaptic large basket cells at regular intervals. 1993 Wiley‐Liss, Inc.
Functional and anatomical organization of cardiovascular pressor and depressor sites in the lateral hypothalamic area. II. Ascending projections
Authors: Allen Gary V. , Cechetto David F.
Published: January 2005

Microinjections of L‐glutamate or D, L‐homocysteic acid were used to stimulate cell bodies in the region of the lateral hypothalamic area (LHA) selectively. Subsequent iontophoretic injections ofPhaseolus vulgaris‐leucoagglutinin or pressure injections of wheat germ agglutininhorseradish peroxidase were made into regions containing identified pressor and depressor sites and their connections with the forebrain and cerebral cortex were traced.

The results indicate that decreases in blood pressure (10–45 mm Hg) and heart rate (20–70 bpm) could be elicited from tuberal (LHAt) and posterior (LHAp) sites in the LHA and that these regions have ascending projections to the insular cortex, the ventral forebrain including the septal‐diagonal band of Broca complex, the ventral palladium, substantia innominata, amygdala, and the lateral preoptic area. In contrast, increases in blood pressure (10–40 mm Hg) and heart rate (20–70 bpm) were elicited primarily from neurons located adjacent to the fornix in the perifornical area (PFA). Injections of tract tracers into this region produced terminal labeling that differed markedly from the pattern seen following injections of tracer into depressor sites in the LHA. In addition, the pattern of anterograde labeling seen following injections of tracer into the anterior PFA differed from that seen following injections of tracer into posterior PFA. Injections of tracer into the anterior PFA resulted in dense terminal labeling in the medial preoptic area and the parvicellular paraventricular nucleus of the hypothalamus whereas injections into the posterior PFA resulted in dense terminal labeling in the lateral septal nucleus, nucleus accumbens, bed nucleus of the stria terminalis, as well as the medial preoptic area and the parvocellular paraventricular nucleus of the hypothalamus.

The results demonstrate that the posterolateral hypothalamus of the rat contains two regions with specific cardiovascular function and highly organized connections with diencephalic, forebrain, and cortical structures.
Efferent projections from the anterior thalamic nuclei to the cingulate cortex in the rat
Authors: Shibata Hideshi
Published: January 2005

The organization of projections from the anterior thalamic nuclei to the cingulate cortex was analyzed in the rat by the anterograde transport of Phaseolus vulgaris‐leucoagglutinin.

The rostral part of the anteromedial nucleus projects to layers I, V and VI of the anterior cingulate areas 1 and 2, layers I and III of the ventral orbital area, layers I, V and VI of area 29D of the retrosplenial area, and layers I and V of the caudal part of the retrosplenial granular and agranular areas. In contrast, the caudal part of the anteromedial nucleus projects to layer V of the frontal area 2, and layers I and V of the rostral part of the retrosplenial granular and agranular areas. The interanteromedial nucleus projects to layers I, III and V of the frontal area 2, layer V of the agranular insular area, and layers I, V and VI of area 29D. The anteroventral nucleus projects to layers I and IV of the retrosplenial granular area, whereas the anterodorsal nucleus projects to layers I, III and IV of the same area. Projections from the anteroventral and anterodorsal nuclei were, furthermore, organized such that their ventral parts project to the rostral part of the retrosplenial granular area, whereas their dorsal parts project to the more caudal part.

The results suggest that the anterior thalamic nuclei project to more widespread areas and laminae of the cingulate cortex than was previously assumed. The projections are organized such that the anteromedial and interanteromedial nuclei project to layer I and the deep layers of the anterior cingulate and retrosplenial cortex, whereas the anteroventral and anterodorsal nuclei project to the superficial layers of the retrosplenial cortex. These thalamocortical projections may play important roles in behavioral learning such as discriminative avoidance behavior.
GABAergic regulation of noradrenergic spinal projection neurons of the A5 cell group in the rat: An electron microscopic analysis
Authors: Kwiat Geoffrey C. , Liu Hantao , Williamson Andrew M. , Basbaum Allan I.
Published: January 2005

Recent studies have demonstrated an important contribution of the A5 noradrenergic cell group of the rostral medulla in the regulation of nociceptive messages at the level of the spinal cord. These noradrenergic controls parallel those arising from the serotonin‐containing neurons of the nucleus raphe magnus. In the present study, we used postembedding immunogold staining to identify GABA‐immunoreactive terminals that synapse upon identified spinally projecting noradrenergic neurons of the A5 cell group in the rat. A5 projection neurons were identified by Fluoro‐Gold transport from the spinal cord; sections containing retrogradely labelled cells were then immunoreacted for tyrosine hydroxylase (TH) to identify the catecholamine‐containing, presumed noradrenergic, neurons. Double‐labelled A5 cells were intracellularly filled with Lucifer Yellow (LY) and then the LY was photo‐oxidized to an electron‐dense product.

Seven intracellularly filled TH‐immunoreactive projection neurons were studied with postembedding immunocytochemistry. Each A5 neuron received a significant GABA‐immunoreactive terminal input. Out of a pooled total of 151 terminal profiles found in apposition to intracellularly labelled somatic and dendritic profiles, 31 (20.5%) were GABA‐immunoreactive. The proportion of GABA‐immunoreactive terminals that contacted somatic profiles (12/72; 17%) was similar to the proportion that contacted TH‐labelled dendritic profiles (19/79; 24%). There was a discernible synaptic specialization in about 50% of the labelled terminals that contacted the TH projection neuron. Both symmetric and asymmetric synaptic specializations were found. Labelled terminals contained round or pleimorphic vesicles, but not flat vesicles; many also contained dense‐core vesicles.

Our results indicate that noradrenergic neurons of the A5 cell group, which contribute to both antinociceptive and cardiovascular controls through their projection to the spinal cord, are regulated by local GABAergic, presumably inhibitory, mechanisms. Whether the initiation of A5 neuron activity results from a lifting of tonic GABAergic inhibitory control, as has been proposed for the neurons of the nucleus raphe magnus, remains to be determined.
Hair cell regeneration after streptomycin toxicity in the avian vestibular epithelium
Authors: Weisleder Pedro , Rubel Edwin W
Published: January 2005

Recent reports documented the ability of the posthatch avian vestibular epithelia to produce hair cells continually at a low rate. This project was designed to investigate whether, in addition, the chicken vestibular system is capable of regenerating its sensory epithelium in response to a lesion. Aminoglycoside injections were given to young birds in order to damage the vestibular epithelium. Tritiated thymidine injections were used to label cells produced in response to the lesion. Treatment and age‐matched control animals were killed at 1 day, 20 days, or 60 days after aminoglycoside injections, and vestibular organs were processed for autoradiography. Our results show that the chicken vestibular sensory epithelium is capable of regenerating hair cells after severe damage. Moreover, the epithelium is capable of complete anatomical recovery. Finally, drug damage increases the pace at which hair cells are replaced, compared to the rate of hair cell turnover in untreated tissue. © 1993 Wiley‐Liss, Inc.
Lesion‐induced changes in the central terminal distribution of galanin‐immunoreactive axons in the dorsal column nuclei
Authors: Hoeflinger Brian F. , Bennett‐Clarke Carol A. , Chiaia Nicolas L. , Killackey Herbert P. , Wall John T. , Rhoades Robert W.
Published: January 2005

Rats that sustained forelimb removal on either embryonic day (E) 16, on the day of birth (P‐0), or transection of the brachial plexus in adulthood had brainstem sections stained for galanin, calcitonin gene‐related peptide (CGRP), or substance P (SP) at various intervals after these lesions were made. In normal adult rats, only a few galanin‐immunoreactive fibers are present in the cuneate nucleus and most are located in its caudal portion. CGRP‐positive axons are also sparse in the cuneate and are distributed mainly in the periphery of the nucleus. SP‐positive axons are seen throughout the cuneate nucleus. In rats that sustained forelimb removals at birth or transection of the brachial plexus in adulthood, dense galanin immunoreactivity was present throughout the cuneate nucleus at all rostrocaudal levels on the side of the brainstem ipsilateral to the lesion. The changes after lesions that were made in the adult animals were apparent within 1 week, the earliest time analyzed. Increases in galanin immunoreactivity in the cuneate of animals that sustained forelimb removals on P‐0 were first visible on P‐2. Neither forelimb removal at birth nor brachial plexus lesions in adulthood had any qualitative effect upon the distribution or density of CGRP‐ or SP‐immunoreactivity in the cuneate nucleus.

Removal of a forelimb on E‐16 did not increase the density of galanin‐immunoreactive fibers in the cuneate nucleus. Such lesions also failed to produce any appreciable change in the density of either CGRP‐ or SP‐positive fibers in the cuneate nucleus. The present data raise the possibility that large caliber, non‐peptidergic primary afferent axons which innervate the cuneate nucleus may express galanin after damage at birth or in adulthood. © 1993 Wiley‐Liss, Inc.
Developmental plasticity in cerebellar tactile maps: Fractured maps retain a fractured organization
Authors: Gonzalez Leila , Shumway Caroly , Morissette Josée , Bower James M.
Published: January 2005

Plasticity following deafferentation has been repeatedly demonstrated in topographic sensory maps in the mammalian brain. In this paper we investigated the developmental plasticity of the fractured somatotopic map found in the tactile regions of the rat cerebellum. At various stages of postnatal development between postnatal days 1 and 30, we cauterized the infraorbital branch of the trigeminal nerve, which innervates the upper lip, furry buccal pad, and vibrissae that are represented within cerebellar folium crus IIa. The organization of the crus IIa map was then examined 2 to 3 months after denervation. We found that tactile receptive fields had reorganized throughout the denervated area but maintained a fractured somatotopy. Comparison of the reorganization in different animals showed that the denervated upper lip region was consistently and predominantly replaced by representation of the upper incisors. Analysis of evoked field potentials revealed an alteration, in denervated animals, of the response of the granule cell layer to brief tactile stimulation. This response in normal animals consists of two components at different latencies. Animals lesioned later in development were less likely to have the short latency component. This result suggests a difference in the developmental sensitivity of different cerebellum‐related pathways to nerve lesions.
Cochlear cytogenesis visualized through pulse labeling of chick embryos in culture
Authors: Katayama Akiko , Corwin Jeffrey T.
Published: January 2005

Cytogenesis in the basilar papilla sensory epithelium of the chicken was investigated through pulse labeling of proliferative cells. Tritiated‐thymidine was injected intravenously in chick embryos cultured in petri dishes. All embryos received the injection on the seventh day of incubation (E7), when the progenitors of hair cells and supporting cells are replicating deoxyribonucleic acid (DNA). Cells that were in the synthesis phase of the cell cycle, either at the time of the 3H‐thymidine pulse or within 2 hours, incorporated detectable levels of the radioactive DNA precursor. Labeled cells were identified in cochleae from embryos fixed at 0.5, 1, 2, 4, 6, 12 hours, 6 and 8 days after the pulse. One hour after the injection the majority of labeled nuclei were in the basal and middle strate of the sensory epithelium. Four to 6 hours after the injection, a greater number of labeled cells appeared in the lumenal stratum. The patterns of labeled cells in embryos fixed immediately after the injection of 3H‐thymidine and in others fixed 6 to 8 days after the injection were unchanged, suggesting that the progenitor cells divide and their progeny differentiate in the sensory epithelium without appreciable transverse migration. Mitotic figures were usually observed only in the lumenal stratum. Analysis of DNA content in the population of Feulgen‐stained nuclei at three levels of depth through the epithelium also produced results consistent with the conclusion that vertical nuclear migration occurs during development of the cells in this sensory epithelium. © 1993 Wiley‐Liss, Inc.
NGF can induce a ‘young’ pattern of reinnervation in transplanted cerebral blood vessels from ageing rats
Authors: Gavazzi Isabella , Cowen Timothy
Published: January 2005

Peripheral target tissues can determine age‐related changes in their density and pattern of innervation. We have shown previously that middle cerebral arteries from young and old rats transplanted in oculo in young hosts become reinnervated with a density and pattern of innervation that is typical of the age of the donor, i.e., the density of reinnervation on old transplants is 50% lower than on young transplants. The alterations in the target tissues responsible for their decreased innervation in old age are still unknown. We have investigated the possibility that increasing the availability of nerve growth factor (NGF) might restore the pattern and density of perivascular nerves on old blood vessels to levels of innervation typical of young tissues. Old middle cerebral transplants were therefore treated with NGF or vehicle by three weekly transcleral injections. NGF treatment markedly increased the reinnervation of old transplants, restoring the density and pattern of innervation to one characteristic of young animals. NGF produced an equivalent increase in nerve growth on young and old transplants, thus confirming that the receptivity of old blood vessels to reinnervation is not impaired. Control experiments were performed by treating transplants with saline, bovine serum albumin, or cytochrome c. Unexpectedly, bovine serum albumin was shown to promote axonal growth, although to a lesser extent and with a different pattern than NGF. © 1993 Wiley‐Liss, Inc.
Topographic organization of rat locus coeruleus and dorsal raphe nuclei: Distribution of cells projecting to visual system structures
Authors: Waterhouse Barry D. , Border Barbara , Wahl Linda , Mihailoff Gregory A.
Published: January 2005

Previous reports from this laboratory and elsewhere have provided evidence that the locus coeruleus (LC) and dorsal raphe (DR) nuclei are topographically organized with respect to their efferent targets. Whereas most of these previous studies have focused on relationships between these monoamine‐containing brainstem nuclei and cerebral cortex, basal ganglia, and limbic structures, they have not systematically examined the distribution of LC and DR cells that project to multiple structures with common sensory or motor functions. The goal of the present study was to characterize and compare the distributions of LC and DR cells which project to different visual areas of the rat central nervous system. Long‐Evans hooded rats received unilateral pressure injections of the retrograde tracer wheat germ agglutinin‐horseradish peroxidase in either the dorsal lateral geniculate, ventral lateral geniculate, or lateral posterior nucleus of thalamus; superior colliculus, cortical area 17, cortical area 18a/b cerebellar vermis (lobules VI and VII); or paraflocculus. Transverse sections through the midbrain and pons were examined by light microscopy after performing routine tetramethyl benzidine histochemical procedures. For all cases studied, retrogradely labeled cells were observed throughout the rostrocaudal extent of the LC and DR; however, labeling patterns which were distinctive for different injection sites were noted in each of these brainstem nuclei. The major conclusion drawn from this work is that subsets of LC and DR cells which project to different target structures within the rat visual system are found in overlapping but not necessarily coextensive zones within these nuclei. These studies provide further evidence of a rough topographic ordering within both the LC and DR nuclei, as well as support a new hypothesis that the outputs from each of these nuclei are organized with respect to the sensory related functions of their efferent targets. © 1993 Wiley‐Liss, Inc.