bluuebunny/crossref_metadata_2025 huggingface dataset:
Vasopressin and oxytocin gene expression in the human hypothalamus
Authors: Sukhov Renat R. , Walker Lary C. , Rance Naomi E. , Price Donald L. , Young W. Scott
Published: January 2005

We studied the distribution of messenger ribonucleic acids coding for vasopressin and oxytocin in the human hypothalamus by means of hybridization histochemistry. Numerous large and medium‐sized neurons contain vasopressin messenger ribonucleic acid in the paraventricular nucleus, supraoptic nucleus, and accessory magnocellular nucleus. Small, lightly labeled vasopressin neurons also were detected in the suprachiasmatic nucleus. In addition, a relatively sparse band of mostly ovoid, medium‐sized vasopressin neurons mingle with unlabeled neurons of the lateral hypothalamic area; these cells extend dorsoventrally from the region ventral to the stria terminalis to the ventrolateral hypothalamus, sometimes transgressing the boundaries of nearby nuclei. We did not detect vasopressin gene expression in neurons of the bed nucleus of the stria terminalis proper, although some of the dorsal‐most labeled neurons of the lateral hypothalamus extend into the region of the caudal bed nucleus. Some lateral hypothalamic neurons also encroach upon other extrahypothalamic structures, such as the zona incerta. The nucleus basalis of Meynert complex was, with only rare exceptions, devoid of cells containing vasopressin messenger ribonucleic acid.

Oxytocin messenger ribonucleic acid is found in the supraoptic nucleus, paraventricular nucleus, accessory magnocellular nucleus and, less frequently, in neurons of the lateral hypothalamus. In the hypothalamic magnocellular nuclei, oxytocin neurons are somewhat smaller than vasopressin neurons. Vasopressin cells outnumber oxytocin cells in the supraoptic nucleus, but their numbers are comparable in the paraventricular nucleus. As with vasopressin neurons, lateral hypothalamic oxytocin cells loosely span several diencephalic nuclei and encroach occasionally upon adjacent regions. These results confirm that the organization of vasopressin and oxytocin neurons in the human hypothalamus is largely comparable to that in nonhuman species and demonstrate the utility of hybridization histochemistry for elucidating the chemoarchitecture of the human brain.© 1993 Wiley‐Liss,Inc.
Visual projections induced into the auditory pathway of ferrets: II. Corticocortical connections of primary auditory cortex
Authors: Pallas S. L. , Sur M.
Published: January 2005

Although the development of corticocortical projections has been well studied, less is known about the role of sensory inputs in the specification of these connections. As part of an ongoing series of studies in our laboratory, we have examined the role of thalamic input modality in the development of corticocortical connections. These studies involve making unilateral lesions and inducing retinal inputs into the auditory thalamus (MGN) during early development in ferrets, thereby conferring visual responsiveness on primary auditory cortex (AI). In this way we can examine the role of input identity in cortical specification in general, and connectivity patterns specifically.

A previous paper (Pallas et al. [1990] J. Comp. Neurol. 298:50‐68) described the pattern of thalamocortical and corticothalamic connections of auditory cortex in normal and lesioned animals. This study comapres the pattern of auditory corticocortical connections in normal and lesioned animals. We injected neuroanatomical tracers into AI and mapped out the distribution of retrogradely labelled cells in the cortex. We report that the cortical inputs to ferret AI resembled those in cats, and that the pattern of ipsi‐ and contralateral corticocortical connections of ferret AI with visual input was similar to the normal pattern. Auditory cortex with visual input did not make ectopic connections with visual cortex, but maintained its connections with other auditory cortical areas. These results suggest that the overall corticocortical connections of an area are not influenced by the modality or activity pattern of its inputs. In particular, altering the input activity to a cortical area does not seem to promote the formation of entirely new connections, although small changes in the strength of existing connections are possible (Sur et al. [1990] Trends Neurosci. 13:227‐233). © 1993 Wiley‐Liss, Inc.
An immunocytochemical study of the FMRFamide neuropeptide gene products in Drosophila
Authors: Schneider Lynne E. , Sun Eric T. , Garland Daniel J. , Taghert Paul H.
Published: January 2005

We have mapped protein expression of the FMRFamide neuropeptide gene in Drosophila with polyclonal antisera against three small peptides whose sequences were derived from the Drosophila proFMRFamide precursor. One antiserum was affinity‐purified and extensively characterized. The enriched antibodies labeled 15–21 bilaterally symmetric pairs of neurons in a pattern that corresponded very closely to the pattern of in situ hybridization that was determined previously (Schneider et al. [1991] J. Comp. Neurol. 304:608–622; O'Brien et al. [1991] J. Comp. Neurol. 304:623–638). The other antisera produced complementary results. These findings suggest that the antisera specifically label cells that express the FMRFamide gene. In larvae we consistently observed strong staining in identified interneurons and neuroendocrine cells, and moderate to weak staining in neurons of unknown function. The adult pattern of expression included both larval neurons whose immunoreactivity persisted through metamorphosis and adult‐specific neurons. During metamorphosis, we observed transient staining in a small number of neurons and in specific neuropil regions that included the central body, the protocerebral bridge, and the optic ganglia. Based on these morphological features, we suggest that the FMRFamide‐like neuropeptides in Drosophila play a number of functional roles, perhaps affecting both physiological and developmental phenomena. Such roles include general modulation throughout all post‐embryonic stages, via the blood, and also more stage‐ and region‐specific modulation within the CNS. © 1993 Wiley‐Liss, Inc.
Distribution of aromatic L‐amino acid decarboxylase mRNA in mouse brain by in situ hybridization histology
Authors: Eaton M. J. , Gudehithlu K. P. , Quach T. , Silvia C. P. , Hadjiconstantinou M. , Neff N. H.
Published: January 2005

Aromatic L‐amino acid decarboxylase (AAAD) is the second enzyme in the sequence leading to the synthesis of catecholamines or serotonin. Antisense riboprobes for aromatic L‐amino acid decarboxylase mRNA were used to map the gene in mouse brain by in situ hybridization. The substantia nigra, the ventral tegmental nucleus, the dorsal raphe nucleus, the locus coeruleus, and the olfactory bulb contained the highest signal for AAAD mRNA. After treatment with the dopaminergic neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP), the signal disappeared in the substantia nigra, decreased somewhat in the ventral tegmental area, and remained unchanged in the dorsal raphe nucleus. Hypothalamic and cerebellar Purkinje neurons known to contain histidine decarboxylase or glutamic acid decarboxylase, respectively, were unlabeled by the probes. However, neurons in the deep layers of the frontal cortex, many thalamic nuclei, and the pyramidal neurons of the hippocampus were lightly to moderately labeled for mouse AAAD mRNA. The presence of AAAD message in these neurons suggests that the enzyme has functions other than that for the synthesis of the classical biogenic amine neurotransmitters. © 1993 Wiley‐Liss,Inc.
Frontal granular cortex input to the cingulate (M3), supplementary (M2) and primary (M1) motor cortices in the rhesus monkey
Authors: Morecraft Robert J. , van Hoesen Gary W.
Published: January 2005

Although frontal lobe interconnections of the primary (area 4 or M1) and supplementary (area 6m or M2) motor cortices are well understood, how frontal granular (or prefrontal) cortex influences these and other motor cortices is not. Using fluorescent dyes in rhesus monkeys, we investigated the distribution of frontal lobe inputs to M1, M2, and the cingulate motor cortex (area 24c or M3, and area 23c). M1 received input from M2, lateral area 6, areas 4C and PrCO, and granular area 12. M2 received input from these same areas as well as M1; granular areas 45, 8, 9, and 46; and the lateral part of the orbitofrontal cortex. Input from the ventral part of lateral area 6, area PrCO, and frontal granular cortex targeted only the ventral portion of M1, and primarily the rostral portion of M2. In contrast, M3 and area 23c received input from M1, M2; lateral area 6 and area 4C; granular areas 8, 12, 9, 46, 10, and 32; as well as orbitofrontal cortex. Only M3 received input from the ventral part of lateral area 6 and areas PrCO, 45, 12vl, and the posterior part of the orbitofrontal cortex.

This diversity of frontal lobe inputs, and the heavy component of prefrontal input to the cingulate motor cortex, suggests a hierarchy among the motor cortices studied. M1 receives the least diverse frontal lobe input, and its origin is largely from other agranular motor areas. M2 receives more diverse input, arising primarily from agranular motor and prefrontal association cortices. M3 and area 23c receive both diverse and widespread frontal lobe input, which includes agranular motor, prefrontal association, and frontal limbic cortices. These connectivity patterns suggest that frontal association and frontal limbic areas have direct and preferential access to that part of the corticospinal projection which arises from the cingulate motor cortex. © 1993 Wiley‐Liss,Inc.
Effect of unilateral partial cochlear lesions in adult cats on the representation of lesioned and unlesioned cochleas in primary auditory cortex
Authors: Rajan R. , Irvine D. R. F. , Wise L. Z. , Heil P.
Published: January 2005

We examined the effect of unilateral restricted cochlear lesions in adult cats on the topographic representations (“maps”) of the lesioned and unlesioned cochleas in the primary auditory cortex (AI) contralateral to the lesioned cochlea. Frequency (tonotopic) maps were derived by conventional multineuron mapping procedures in anesthetized animals. In confirmation of a study in adult guinea pigs (Robertson and Irvine [1989] J. Comp. Neurol. 282:456–471), we found that 2–11 months after the unilateral cochlear lesion the map of the lesioned cochlea in the contralateral AI was altered so that the AI region in which frequencies with lesion‐induced elevations in cochlear neural sensitivity would have been represented was occupied by an enlarged representation of lesion‐edge frequencies (i.e., frequencies adjacent to those with elevated cochlear neural sensitivity). Along the tonotopic axis of AI the total representation of lesion‐edge frequencies could extend up to ≈ 2.6 mm rostral to the area of normal representation of these frequencies. There was no topographic order within this enlarged representation. Examination of threshold sensitivity at the characteristic frequency (CF, frequency to which the neurons were most sensitive) in the reorganized regions of the map of the lesioned cochlea established that the changes in the map reflected a plastic reorganization rather than simply reflecting the residue of prelesion input.

In contrast to the change in the map of the lesioned contralateral cochlea, the map of the unlesioned ipsilateral cochlea did not differ from those in normal animals. Thus, in contrast to the normal very good congreuency between ipsilateral and contralateral AI maps, in the lesioned animals ipsilateral and contralateral maps differed in the region of AI in which there had been a reorganization of the map of the lesioned cochlea. Outside the region of contralateral map reorganization, ipsilateral and contralateral AI maps remained congruent within normal limits. The difference between the two maps in the region of contralateral map reorganization suggested, in light of the physiology of binaural interactions in the auditory pathway, that the cortical reorganization reflected subcortical changes.

Finally, response properties of neuronal clusters within the reorganized map of the lesioned cochlea were compared to normative data with respect to threshold sensitivity at CF, the size of frequency “response areas,” and response latencies. In the majority of cases, CF thresholds were similar to normative data. The frequency “response areas” were slightly less sharply tuned than normal, but not significantly. Response latencies were significantly shorter than normal in three animals and significantly longer in one animal. © 1993 Wiley‐Liss, Inc.
The patterns of afferent innervation of the core and shell in the “Accumbens” part of the rat ventral striatum: Immunohistochemical detection of retrogradely transported fluoro‐gold
Authors: Brog Judith S. , Salyapongse Aimee , Deutch Ariel Y. , Zahm Daniel S.
Published: January 2005

Recent data have emphasized the neurochemically distinct nature of subterritories in the accumbens part of the rat ventral striatum termed the core, shell, and rostral pole. In order to gain a more comprehensive understanding of how afferents are distributed relative to these subterritories, immunohistochemical detection of retrogradely transported Fluoro‐Gold was carried out following iontophoretic injections intended to involve selectively one of the subterritories. The data revealed that a number of cortical afferents of the medial shell and core originate in separate areas, i.e., the dorsal peduncular, infralimbic, and posterior piriform cortices (to medial shell) and the dorsal prelimbic, anterior agranular insular, anterior cingulate, and perirhinal cortices (to core). The lateral shell and rostral pole are innervated by cortical structures that also project either to the medial shell or core. The orbital, posterior agranular insular, and entorhinal cortices, hippocampus, and basal amygdala were observed to innervate the accumbens in a topographic manner. Following core injections, strong bilateral cortical labeling was observed. Few labeled cortical cells were observed contralaterally following injections in the medial shell. Intermediate numbers of labeled neurons were observed in contralateral cortices following lateral shell injections.

Robust subcortical labeling in a variety of structures in the ventral forebrain, lateral hypothalamus, deep temporal lobe, and brainstem was observed after shell injections, particularly those that involved the caudal dorsomedial extremity of the shell, i.e., its “septal pole.” Selective ipsilateral labeling of subcortical structures in the basal ganglia circuitry was observed following injections in the core and, to a lesser extent, lateral shell.

It was concluded that a number of afferent systems exhibit varying degrees of segregation with respect to the accumbal subterritories. © 1993 Wiley‐Liss, Inc.
Survey of the morphology of macaque retinal ganglion cells that project to the pretectum, superior colliculus, and parvicellular laminae of the lateral geniculate nucleus
Authors: Rodieck R. W. , Watanabe M.
Published: January 2005

In common with other vertebrates, the primate retina contains a number of different ganglion cell types that project to different regions in the brain. We wanted to determine how the different ganglion cell types, distinguished morphologically, mapped to these regions of the brain. We injected a fluorescent dye into one of three regions of a macaque brain: the superior colliculus (SC), the pretectal region, and the parvicellular laminae of the lateral geniculate nucleus. By means of an in vitro preparation, the retrogradely labelled ganglion cells were intracellularly injected with horseradish peroxidase, so as to reveal their dendritic morphology. When the dendritic‐field diameters of the injected cells were plotted against retinal eccentricity, each of the three regions was found to receive input from a distinctive population of cells. The pretectal projection was dominated by cells with large dendritic fields. The SC projection was composed of a number of distinct types, with smaller dendritic fields. Parasol cells project to SC but are extremely rare.

In addition to midget ganglion cells, the parvicellular laminae receive inputs from at least two additional groups. Parvicellular bistratified (PB) cells have bistratified dendritic fields, slightly larger than those of parasol cells. Parvicellular giant (PG) cells have dendritic‐field, diameters larger than that of any parasol cell, ranging from 250 μm to greater than 850 μm—the largest of any primate ganglion cells.

In contrast to the retinal projections of the cat, in which a specific ganglion cell type can project to different regions of the brain, each of the regions in this survey appears to receive inputs from its own distinct group of ganglion cells. © 1993 Wiley‐Liss, Inc.
Developmental changes in layer I of the human neocortex during prenatal life: A DiI‐tracing and AChE and NADPH‐d histochemistry study
Authors: Meyer Gundela , González‐Hernández Tomás
Published: January 2005

The development of fetal layer I (marginal zone, MZ) was studied in the human neocortex by using DiI tracing and AChE and NADPH‐d histochemistry, and examining the Nissl‐stained material of the Yakovlev Collection. We describe the sequential maturation of the Cajal‐Retzius (CR) cells and the granule cells of the subpial granular layer (SGL), and the close relationship between both. The first CR cells appear in the primordial plexiform layer, at 6 gestational weeks (GW). After the formation of the cortical plate, they settle under the pial surface. At 13 GW, the SGL begins to form around the CR cells. The horizontal members of a polymorphic population of CR cells begin to mature at 13 GW, and the intermediate and vertical forms differentiate at 16 and 18 GW, respectively. All CR cells project into an axonal plexus in the lower third of the MZ. From 18 GW, CR cells and SGL become segregated, and the polymorphic CR cells lie now below the SGL, with which they remain connected by ascending processes. Granule cells invade the lower MZ contacting somata and processes of CR cells. The somata of vertical CR cells elongate until 23/24 GW when they show degenerative signs. After 24 GW, all polymorphic CR cells die. Granule cells degenerate after 24 GW; the SGL disappears at 28/30 GW. A population of persisting CR cells, morphologically different from the transient polymorphic forms, appears in a subpial position and survives in small numbers throughout life. Small non‐CR neurons differentiate first in the lower half of layer I, thereafter also in the upper half. Histochemically, all CR cells are AChE‐positive; they contain NADPH‐d only transiently at 20 GW. We propose that CR cells and SGL provide a transient innervation network for the developing cortical plate at a time when the definitive fiber systems of the molecular layer are not yet established. © 1993 Wiley‐Liss, Inc.
Ontogeny of GABAA receptor subunit mRNAs in rat spinal cord and dorsal root ganglia
Authors: Ma Wu , Saunders Paul A. , Somogyi Roland , Poulter Michael O. , Barker Jeffery L.
Published: January 2005

Relatively little is known about the development of GABAA receptor subunits and their gene expression in mammalian spinal cord. The expressions of mRNAs encoding 13 GABAA receptor subunits (α1–6, β1–3, γ1–3, and δ) in embryonic, postnatal, and adult rat spinal cord and dorsal root ganglia (DRG) cells were studied by in situ hybridization and reverse transcription‐polymerase chain reaction (RT ‐ PCR) analysis. Both techniques revealed the presence of all subunit mRNAs originally found in the rat brain, except for α6, which was not detectable, and δ, which was weakly detected only by RT‐PCR. Two anatomically distinctive sets of subunit mRNAs were found by in situ hybridization within the ventricular zone (VZ) and mantle zone (MZ). The trio of α4, β1, and γ1 subunit mRNAs emerged exclusively in neuroepithelial cells at embryonic day 13 (E13) and remained detectable in the VZ until E17. In the MZ, β3 subunit mRNA was first detected at E12, while α2, α3, α5, β2, γ2, and γ3 transcripts appeared at E13. Expressions of the subunit mRNAs in the MZ rapidly increased and expanded in a ventrodorsal sequence from motoneurons to dorsal horn neurons before reaching a peak in the late embryonic/early postnatal period. The mRNA expressions declined during postnatal development, by region‐selective depletion, with α4, α5, β1, β2, γ1, and γ3 subunit mRNAs becoming barely detectable. In contrast, α2, α3, β3, and γ2 transcripts persisted into adulthood with distinct anatomical distributions. RT‐PCR analysis revealed unique developmental patterns in the intensities of PCR products, most of which were in good agreement with developmental changes in the densities of hybridized mRNA signals. However, RT‐PCR amplified minute amounts of mRNAs for α1, α4, α5, β1, β2, γ1, γ3, and δ subunits in adults, which were not found in film autoradiograms, but could be detected in a few grain‐positive cells in emulsion‐dipped sections. DRG cells expressed α2, α3, α5, β2, β3, and γ2 subunit mRNAs during embryogenesis but only α2, β3, and γ2 subunit mRNAs were reliably detected in the adult. The transient expression of α4β1γ1 subunit mRNAs primarily in the VZ correlates with the period of neurogenesis, while the developmental changes of α2, α3, β3, and γ2 subunit mRNAs in the MZ parallels previously reported changes in GABA expression and in synapse formation and elimination. These results implicate a role of early‐expressed GABA and GABAA receptors in the development of rat spinal cord. © 1993 Wiley‐Liss, Inc.
Distinct distributions of five N‐methyl‐D‐aspartate receptor channel subunit mRNAs in the forebrain
Authors: Watanabe Masahiko , Inoue Y. , Sakimura K. , Mishina M.
Published: January 2005

The distributions of five NMDA receptor channel subunit mRNAs in the mouse forebrain at postnatal day 21 were semiquantitatively examined by in situ hybridization with subunit‐specific oligonucleotide probes. In contrast to ubiquitous distribution of the ζ1 subunit mRNA throughout the forebrain, distributions of four ϵ subunit mRNAs were highly variable from nucleus to nucleus. The telencephalon (except for the septum) expressed the ϵ1 and ϵ2 subunit mRNAs. Various combinations of the ϵ1, ϵ2, ϵ3, and ϵ4 subunit mRNAs were present in different nuclei of the septum, the olfactory bulb, and the thalamus. In the hypothalamus, the suprachiasmatic nucleus expressed distinct signals for the ϵ3 subunit mRNA alone, whereas other nuclei showed faint signals for the ϵ1, ϵ2, and ϵ4 subunit mRNAs. Moreover, different signal levels of the ϵ subunit mRNAs were found in various regions. The hippocampal CA1 region expressed higher signals for the ϵ1 and ϵ2 subunit mRNAs than the CA3 region and the dentate gyrus. In the cerebral cortex, signal levels of the ϵ1 subunit mRNA were higher in the laminae II/III, IV, and VI than the lamina V, whereas those of the ϵ2 subunit mRNA were highest in laminae II/III and lowest in laminae IV and V. Different signal levels between the ϵ1 and ϵ2 subunit mRNAs were also discerned in the amygdala, the caudate‐putamen, and the thalamus. The distinct anatomical distributions and differential signal levels of the ϵ subunit mRNAs strongly suggest different subunit organizations of the NMDA receptor channel in different forebrain neurons, which may result in functional diversity of the channel in vivo. © 1993 Wiley‐Liss, Inc.
Capacity of the retinogeniculate pathway to reorganize following ablation of visual cortical areas in developing and mature cats
Authors: Lomber Stephen G. , Payne Bertram R. , Cornwell Paul , Pearson Helen E.
Published: January 2005

The purpose of the present study was to determine the pattern and density of retinal projections to the dorsal lateral geniculate nucleus (dLGN) following ablation of visual cortical areas in developing cats of different postnatal ages and in mature cats. The terminations of retinal projections to the dLGN were evaluated following the injection of tritiated amino acids into one eye. Regardless of age, a visual cortical ablation of areas 17 and 18 induces massive death of neurons within the regions of the dLGN that are linked topographically to the cortical areas removed. However, the pattern of retinal projections to these degenerated regions of the dLGN differs depending upon whether the cortical lesion is incurred early in postnatal life or in adulthood. Following ablation on the day of birth (P1), virtually all surviving cells were found in the C‐complex of dLGN with only a token number in the A‐laminae. Correspondingly, retinal projections were maintained to the C‐complex of the nucleus and were barely detectable in the degenerated A‐laminae. However, in cats in which areas 17 and 18 had been removed in adulthood (≥ 6 months of age) retinal projections were maintained to the A‐laminae even though nearly all neurons in those laminae had degenerated. Moreover, a subgroup of animals that incurred area 17 and 18 ablations at P1 showed that the modification of retinal projections to the A‐laminae occurs within the first postnatal month, and an additional subgroup showed that retinal projections become increasingly resistant to the degenerative events in the dLGN that follow ablation of areas 17 and 18 at progressively older ages during the first postnatal month. Furthermore, retinal inputs also respond, in an age‐dependent way, to degeneration of neurous in the C‐complex induced by extension of the cortical ablation to include extrastriate visua areas. © 1993 Wiley‐Liss, Inc.
Distribution and neurochemical phenotypes of caudal medullary neurons activated to express cFos following peripheral administration of cholecystokinin
Authors: Rinaman Linda , Verbalis J. G. , Stricker E. M. , Hoffman G. E.
Published: January 2005

Immunocytochemical localization of the protein product of the proto‐oncogene C‐fos allows anatomical identification of physiologically activated neurons. The present study examined the subnuclear distribution of cFos protein in the rat caudal medulla following peripheral administration of cholecystokinin octapeptide, which reduces feeding and gastric motility by a vagally mediated mechanism. To begin phenotypic characterization of neurons activated to express cFos following cholecystokinin treatment, double‐labeling techniques were used to identify vagal motor neurons and neurons immunoreactive for tyrosine hydroxylase, neuropeptide Y, and neurotensin. Activated cells were most prevalent in the subnucleus medialis of the nucleus of the solitary tract, less prevalent in the subnucleus commissuralis, and virtually absent in the subnuclei centralis and gelatinosus. Many activated cells occupied the caudal area postrema; some of these were catecholaminergic. In contrast, activated cells were sparse within the medial rostral area postrema. Other activated cells occupied the dorso‐ and ventrolateral medulla and the midline raphe nuclei. Retrograde labeling of vagal motor neurons confirmed that very few were activated. Those that were activated occupied the caudal dorsal motor nucleus. In the dorsomedial medulla, 51% of catecholaminergic neurons and 39% of neurons positive for neuropeptide Y were activated, but no neurotensin‐positive neurons were activated. In the ventrolateral medulla, 25% of catecholaminergic neurons and 27% of neuropeptide Y‐positive neurons were activated. By characterizing the subnuclear distribution and chemical phenotypes of neurons activated by exogenous cholecystokinin, these data contribute to elucidation of the neural circuits mediating the behavioral, physiological, and neuroendocrine effects produced by this peptide. © 1993 Wiley‐Liss, Inc.
Organization of the cerebral ganglion of the colonial ascidian Polyandrocarpa misakiensis
Authors: Koyama Hiromichi , Kusunoki Toyokazu
Published: January 2005

The cerebral ganglion of a budding styelid ascidian, Polyandrocarpa misakiensis, whose phylogenetic location is midway between vertebrates and invertebrates, was studied by light and electron microscopy to obtain some insight into the evolution of the central nervous system. The lateral and ventral sides of the ganglion are surrounded by blood sinuses. The ganglion is covered with a thin fibrous sheath through which many nerve fibers run. The ganglion is composed of a cellular cortex and a fibrous medulla. The cortex consists of three to six layers of large and small neurons. Some neurons are also scattered within the medulla. Many neurons are monopolar, and some are bi‐ or multipolar. The cytoplasm of the large neurons is dense with extensive rough endoplasmic reticulum, free ribosomes, mitochondria, one or more Golgi complexes, large dense bodies, and many clear or dense vesicular structures. Some neurons send their processes directly into the lumen of the sinuses. The medulla is composed of loosely arranged nerve fibers without cellular wrappings. The medullary fibers contain vesicles and granules of various sizes, and microtubules. At the anterior and posterior ends of the ganglion, the medullary fibers are assembled into thick peripheral nerve fiber bundles. The peripheral nerve fibers are enveloped and subdivided by fibrous structures. Synapses are found in the medulla, in the cortex, and between the peripheral nerve fibers. The presence of neurons and axodendritic or axoaxonic synapses in the peripheral nerve fibers is consistent with a diffuse organization of the central nervous system of the ascidians. The morphology of the central nervous system synapses is comparable to that of other invertebrates, but the locations of the synapses are similar to those of vertebrates. © 1993 Wiley‐Liss, Inc.
Motoneuron morphology in the dorsolateral nucleus of the rat spinal cord: Normal development and androgenic regulation
Authors: Goldstein L. A. , Sengelaub D. R.
Published: January 2005

The rat lumbar spinal cord contains two sexually dimorphic motor nuclei, the spinal nucleus of the bulbocavernosus (SNB), and the dorsolateral nucleus (DLN). These motor nuclei innervate anatomically distinct perineal muscles that are involved in functionally distinct copulatory reflexes. The motoneurons in the SNB and DLN have different dendritic morphologies. The dendrites of motoneurons in the medially positioned SNB have a radial, overlapping arrangement, whereas the dendrites of the laterally positioned DLN have a bipolar and strictly unilateral organization. During development, SNB motoneuron dendrites grow exuberantly and then retract to their mature lengths. In this experiment we determined whether the adult difference in SNB and DLN motoneuron morphology was reflected in different patterns of dendritic growth during normal development. Furthermore, the development of both these nuclei is under androgenic control. In the absence of androgens, SNB dendrites fail to grow; testosterone replacement supports normal dendritic growth. Thus, we also examined the development of DLN dendrites for similar evidence of androgenic regulation.

By using cholera toxin‐horseradish peroxidase (BHRP) to label motoneurons retrogradely, we measured the morphology of DLN motoneurons in normal males, and in castrates treated with testosterone or oil/blank implants at postnatal day (P) 7, P28, P49, and P70. Our results demonstrate that in contrast to the biphasic pattern of dendritic development in the SNB, dendritic growth in the DLN was monotonic; the dendritic length of motoneurons increased more than 500% between P7 and P70. However, as in the SNB, development of DLN motoneuron morphology is androgen‐dependent. In castrates treated with oil/blank implants, DLN somal and dendritic growth were greatly attenuated compared to those of normal or testosterone‐treated males. Thus, while androgens are clearly necessary for the growth of motoneurons in both the SNB and DLN, their different developmental patterns suggest that other factors must be involved in regulating this growth. © 1993 Wiley‐Liss, Inc.
Expression of insulin‐like growth factor binding protein‐4 and ‐5 mRNAs in adult rat forebrain
Authors: Stenvers Kaye L. , Zimmermann Ellen M. , Gallagher Michela , Lund P. Kay
Published: January 2005

Accumulating evidence indicates that the insulin‐like growth factors (IGFs) can act as neurotrophic factors. A family of at least six IGF binding proteins (IGFBPs) has been characterized. The IGFBPs prolong the half‐life of IGFs in plasma and may modulate IGF action in a cell‐ or tissue‐specific fashion. Two recently characterized IGFBPs, IGFBP‐4 and ‐5, have been shown by northern blot hybridization to be expressed in rat brain, but their cellular sites of synthesis are poorly characterized. Because IGFBP‐4 and IGFBP‐5 could potentially modulate IGF actions in the brain, we used in situ hybridization histochemistry and 35S‐labeled IGFBP‐4 and IGFBP‐5 riboprobes to localize sites of IGFBP‐4 and ‐5 mRNA expression in adult rat brain. The two IGFBP mRNAs are abundantly expressed within discrete regions of brain. The expression patterns of the two genes are largely nonoverlapping. Notably, IGFBP‐4 mRNA is highly expressed within hippocampal and cortical areas, whereas IGFBP‐5 mRNA is not detected above background in these areas. Within the hippocampus, abundant IGFBP‐4 mRNA expression is detected in pyramidal neurons of the subfields of Ammon's horn and the subiculum and in the granule cell layer of the anterior hippocampal continuation. In the cortex, IGFBP‐4 mRNA is widely expressed in most areas and layers. In contrast, IGFBP‐5, but not IGFBP‐4, mRNA is detected within thalamic nuclei, leptomeninges, and perivascular sheaths. The distinct expression patterns of IGFBP‐4 and ‐5 mRNAs within the brain suggest that these IGFBPs may modulate paracrine/autocrine actions of the IGFs in discrete brain regions or compartmentalization of the IGFs within the brain. © 1994 Wiley‐Liss, Inc.
The candelabrum cell: A new interneuron in the cerebellar cortex
Authors: Lainé Jeanne , Axelrad Herbert
Published: January 2005

A new cell type is described in silver‐impregnated sections of the rat cerebellar cortex, uniformly distributed through all the cerebellar folia. The soma is rather small, roughly pyriform, vertically oriented, and squeezed, in a sandwich‐like manner, between the Purkinje cell somata. One or two thick dendrites arise from the upper pole of the cell body and course through the entire molecular layer, dividing into a few, slightly oblique, branches that can reach the pia mater. These dendrites are covered with irregularly distributed spines. Some more slender dendrites emerge from the lower part of the cell body, or from the proximal trunk of a molecular dendrite, and spread tortuously for a short distance in the upper granular layer. A thick initial segment emerges directly from the soma or from the proximal portion of a dendrite, the axon winding then horizontally through or just above the Purkinje cell layer. During this horizontal course it gives off vertically oriented beaded branches ascending through the major part of the molecular layer. These branches, rather closely spaced, occupy different parasagittal planes, separated by about 10 to 30 μm. This axonal arborisation can thus be compared with a candelabrum. The peculiar three‐dimensional spread of the axonal collaterals suggests a functional relationship between these branches and the dendritic trunks of neighbouring Purkinje cells. A comparative analysis of the morphological differences between this candelabrum interneuron and the other corticocerebellar interneurons found in the vicinity of the ganglionic layer confirms the specificity of this new cell class. © 1994 Wiley‐Liss, Inc.
The distribution of GABA‐containing perikarya, fibers, and terminals in the forebrain and midbrain of pigeons, with particular reference to the basal ganglia and its projection targets
Authors: Veenman C. Leo , Reiner Anton
Published: January 2005

Immunohistochemical techniques were used to study the distributions of glutamic acid decarboxylase (GAD) and γ‐aminobutyric acid (GABA) in pigeon forebrain and midbrain to determine the organization of GABAergic systems in these brain areas in birds. In the basal ganglia, numerous medium‐sized neurons throughout the striatum were labeled for GABA, while pallidal neurons, as well as a small population of large, aspiny striatal neurons, labeled for GAD and GABA. GAD+ and GABA+ fibers and terminals were abundant throughout the basal ganglia, and GABAergic fibers were found in all extratelencephalic targets of the basal ganglia. Most of these targets also contained numerous GABAergic neurons. In pallial regions, approximately 10‐12% of the neurons were GABAergic. The outer rind of the pallium was more intensely labeled for GABAergic fibers than the core. The olfactory tubercle region, the ventral pallidum, and the hypothalamus were extremely densely labeled for GABAergic fibers, while GABAergic neurons were unevenly distributed in the hypothalamus. GABAergic neurons and fibers were abundant in the dorsalmost part of thalamus and the dorsal geniculate region, while GABAergic neurons and fibers were sparse (or lightly labeled) in the thalamic nuclei rotundus, triangularis, and ovoidalis. Further, GABAergic neurons were abundant in the superficial tectal layers, the magnocellular isthmic nucleus, the inferior colliculus, the intercollicular region, the central gray, and the reticular formation. GABAergic fibers were particularly abundant in the superficial tectal layers, the parvocellular isthmic nucleus, the inferior colliculus, the intercol‐licular region, the central gray, and the interpeduncular nucleus. These results suggest that GABA plays a role as a neurotransmitter in nearly all fore‐ and midbrain regions of birds, and in many instances the observed distributions of GABAergic neurons and fibers closely resemble the patterns seen in mammals, as well as in other vertebrates. © 1994 Wiley‐Liss, Inc.
Distribution and morphology of immunoreactive gonadotropin‐releasing hormone (GnRH) neurons in the basal forebrain of ponies
Authors: Melrose P. A. , Pickel C. , Cheramie H. S. , Henk W. G. , Littlefield‐Chabaud M. A. , French D. D.
Published: January 2005

Recent reports have indicated that analysis of changes in the staining characteristics of gonadotropin‐releasing hormone (GnRH) neurons and characterization of morphological plasticity of the related structural framework may help to elucidate the physiological mechanisms involved in neuroendocrine control of mammalian reproduction. Whether comparative studies will facilitate this process or simply elucidate species‐specific mechanisms is not yet clear. The present study was performed in order to begin analysis of GnRH neurons in a seasonally breeding species that exhibits an unusually long ovulatory luteinizing hormone (LH) surge. To this end, light microscopy and image analysis were used to characterize distribution and morphology of GnRH neurons in 15 adult male and female ponies. Samples were collected in the middle of the normal ovulatory season. Unipolar, bipolar, and multipolar GnRH neurons were organized in a loosely defined continuum that extended from the medial septum to tuberoinfundibular areas in the medial basal hypothalamus (MBH). Most cells were bipolar, and the majority of neurons were located in the MBH. Fiber projections to the median eminence included presumptive pathways similar to those previously described in other species. Image analysis of cell size indicated that cells in the MBH were larger than those in preoptic areas and GnRH neurons in both of these locations were larger than neurons in rostral areas of the medial septum. Results from this experiment suggest that the large population of MBH GnRH neurons in the equine species is likely to be of primary importance to reproductive function, whereas cells in other areas are fewer and smaller. Further work is needed to characterize morphological characteristics that may be related to physiological fluctuations in reproductive function of the equine species. © 1994 Wiley‐Liss, Inc.
Auditory brainstem of the ferret: Long survival following cochlear removal progressively changes projections from the cochlear nucleus to the inferior colliculus
Authors: Moore David R.
Published: January 2005

Some effects on auditory brainstem connections of long (1–2.3 years) survival following unilateral cochlear removal in infant and adolescent ferrets were examined by making multiple injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) in either the left or the right inferior colliculus (IC). Previous studies have shown that, in normal adult ferrets, about 50 times as many cochlear nucleus (CN) neurons project to the contralateral as to the ipsilateral IC. Right cochlear removal at P25 increased, within 30 days, the number of retrogradely labeled left CN neurons projecting to the left ipsilateral IC by 17% (from n = 235 to n = 275), relative to normals. In this study, longer survival (3 months to 1 year) after right cochlear removal at P25 resulted in larger increases (38–47%; n ≈ 100) in the number of neurons labeled in the left CN after injections of WGA‐HRP in the left IC. No change occurred in the number of neurons labeled in the right CN. Taken together, the results of these experiments show that the ratio of the number of labeled neurons in the left CN to that in the right CN increases progressively with survival time out to the maximum time tested (1 year). In contrast to these results, we have previously reported that right cochlear removal at P90 did not change the number of neurons projecting from the left CN to the left IC after 90 days of survival. However, in this study, very long survival (2–3 years) following right cochlear removal at P90 resulted in an increased (51%, from n = 235 to n = 355) number of left CN neurons labeled by WGA‐HRP injections into the left IC, relative to normals. The increased number of labeled neurons included neurons throughout each division of the CN and all of the principal morphological types. In a separate series of experiments involving long survival (1‐2 years), right cochlear removal at P25 or P40 did not significantly change the number of neurons in either CN retrogradely labeled by injections of WGA‐HRP in the right IC, or the ratio between the number of neurons labeled in each CN. Long survival following cochlear removal at P25–P90 did not result in any loss of neurons in the ipsilateral CN or in any shrinkage of CN neurons further than the 10–20% seen at a shorter survival time (90 days). These results show that at least one pathway within the auditory brainstem continues to be changed in later life following either early or late cochlear removal. They provide a possible anatomical basis for long‐term changes seen in sensory systems following lesions of the sense organs of mature animals. © 1994 Wiley‐Liss, Inc.
Quantitative aspects of the GABA circuitry in the primary visual cortex of the adult rat
Authors: Beaulieu Clermont , Campistron Ghislaine , Crevier Claire
Published: January 2005

The number and size of synaptic contacts made by GABA‐immunoreactive axonal boutons were estimated in each layer of the primary visual cortex (area Oc1M) of adult rats by using the disector method. Immunoreactivity for GABA was detected with the postembedding immunogold technique on ultrathin sections. Targets of GABA synaptic contacts were also identified to predict the sites of GABA influence in the rat visual cortex.

For the total cortical depth, 82 million out of an overall population of 666 million synaptic contacts per mm3 of tissue (or 1 in 8 contacts, 12%) were GABA. Layer IV averaged 62% more GABA contacts per unit volume than did any other cortical layer. Consequently, these represented a larger proportion (1 in 6, 17%) of the overall population of layer IV synaptic contacts. This higher number of GABA contacts was not due to a greater density of GABA boutons, but to an increased number of contacts made by each layer IV GABA bouton (mean of 1.4 contacts per bouton compared to 1.1 in other cortical layers).

The total area occupied by the contacts on an average GABA bouton was similar in all layers; the higher number of contacts per GABA bouton in layer IV being compensated for by their smaller size. This observed constancy in the area of synaptic contacts suggests the presence of one or more regulatory mechanisms maintaining optimal numbers of the different macromolecules forming the synaptic contacts.

The increased density of GABA contacts in layer IV compared to other cortical layers was due to their greater number targeting distal regions of the dendritic tree. Since layer IV receives the vast majority of thalamocortical terminals and since these axons preferentially target dendritic spines, the specific arrangement of GABA synaptic contacts in this layer could be designed to exert a precise inhibition near the site of the thalamic input and thus serve as the structural basis for the strong GABA‐related hyperpolarization that followed the excitatory response after physiological stimulations of the thalamocortical pathway. © 1994 Wiley‐Liss, Inc.
Identification and viuotopic organization of areas PO and POd in Cebus monkey
Authors: Neuenschwander Sergio , Gattass Ricardo , Sousa Aglai P. B. , Piñon Maria Carmen G. P.
Published: January 2005

Two visual areas of the anterior bank of the parietooccipital sulcus, areas PO and POd, were identified and their visual field representations were studied in six anesthetized and paralyzed Cebus monkeys. The definition of these areas was based on electrophysiological mapping and myeloarchitecture. PO is located in the ventral aspect of the anterior bank of the parietooccipital sulcus and ventral precuneate gyrus. It borders area V2 posteriorly and ventrally in the depth of the parietooccipital sulcus, area V3d laterally, and another undescribed visual area medially. POd was located dorsal to area PO and ventral to architectonic area PE. The representations of the visual field in areas PO and POd are complex. In each hemisphere, these areas have a virtually complete representation of the contralateral visual hemifield. Different from the previously described visual areas, in PO and POd there is a precise organization of isopolar lines and a complex organization of the isoeccentric ones. In PO, as well as in POd, the representation of the horizontal meridian runs dorsoventrally along the parietooccipital sulcus. The upper visual quadrant is represented medially and the lower visual quadrant laterally. A large and complex representation of the periphery, from 20° to 60° eccentricity is present at the lateral and medial portions of these areas. By contrast, the representation of the central 20° is very small in both PO and POd. The central visual field is represented ventrally in PO and dorsally in area POd. Area POd shows a more stratified myeloarchitectonic pattern than PO and both areas can be distinguished from other surrounding areas by their heavier myelinated pattern. © Wiley‐Liss, Inc.