bluuebunny/crossref_metadata_2025 huggingface dataset:
Nerve innervation of the hand and associated nerve dominance aggregates in the somatosensory cortex of a primate (squirrel monkey)
Authors: Wall John T. , Nepomuceno Vincent , Rasey Sandra K.
Published: January 2005

The cutaneous innervation territories of the median, ulnar, and radial nerves to the hand were determined from neurophysiological recordings of peripheral mechanoreceptor axons in adult squirrel monkeys. These territories were then related to cutaneous receptive fields of cortical area 3b neurons to determine how low‐threshold inputs from each hand nerve map onto the primary somatosensory cortex.

The results indicate that mechanoreceptor axons in each nerve innervate a continuous skin territory covering about 40% of the hand surface. The total territory of each nerve contains subregions of skin that are either autonomously innervated by that nerve or that receive overlapping innervation from more than one nerve. The autonomous, overlap, and total territories of each nerve are relatively constant from hand to hand. In the area 3b cortex, low‐threshold afferents from each nerve provide inputs to aggregates of cortical neurons. The cortical aggregates relating to the median and ulnar nerves are arranged as continuous, rostrocaudally oriented bands, whereas aggregates relating to the radial nerve are discontinuous and more patchlike. Similar patterns of bands and patches, and similar compression ratios of skin/cortical area, are seen across different monkeys.

These findings demonstrate that the primary somatosensory cortex of normal adult primates contains bands or patches of neurons that are dominantly activated by low‐threshold inputs from specific hand nerves. This approach of delineating nerve territories and their related cortical dominance aggregates provides a useful means of analyzing cortical images of nerves and of quantitating peripheral and central patterns of deprivation after nerve injury. © 1993 Wiley‐Liss, Inc.
FMRFamide‐like activity in the female locust during vitellogenesis
Authors: Sevala V. M. , Sevala V. L. , Loughton B. G.
Published: January 2005

The control of oviposition in the locust involves the expulsion of eggs from the lateral oviducts, a process believed to be under neurohormonal control. In this paper we have attempted to identify this putative hormone. Immunohistochemical staining of the brain retrocerebral complex and suboesophageal ganglion of Locusta migratoria with antiserum against FMRFamide revealed a number of FMRFamide‐immunopositive cells. FMRFamide‐like immunoreactivity was present in median neurosecretory cells and lateral neurosecretory cells of the protocerebrum. Other FMRFamide‐immunoreactive cells were detected in the deutocerebrum and tritocerebrum. Immunoreactive cell processes were observed in the mushroom bodies, the central body, the optic lobes, and in the axon tracts leaving the pars intercerebralis and tritocerebrum. FMRFamide‐like material was also seen in the circumoesophageal commissures. Further FMRFamide‐like material was present in cell bodies of the suboesophageal ganglion. FMRFamide‐like staining activity changed dramatically during the oviposition cycle in mature adult females. The median neurosecretory cells stained lightly immediately after oviposition and remained pale until the third day, when staining of perikarya and axon tracts increased. The staining intensity decreased on days 4 and 5. The titre of FMRFamide‐like material in the hemolymph increased during the vitellogenic cycle but plummeted after oviposition. A single band of FMRFamide‐like material was evident on immunoblot following sodium dodecyl sulphate‐polyacrylamide gel electrophoresis of adult female hemolymph. The approximate molecular weight of this molecule was 8,000. Gel permeation chromatography of hemolymph revealed a FMRFamide‐immunoreactive fraction with a molecular weight of 8,000. This fraction possessed myotropic activity when applied to the locust oviduct. It is argued that this molecule functions as an oviposition hormone in the locust.© 1993 Wiley‐Liss, Inc.
Direct projections from the anterior thalamic nuclei to the retrohippocampal region in the rat
Authors: Shibata Hideshi
Published: January 2005

The present study examined the areal and laminar distribution of direct projections from the anterior thalamic nuclei to the retrohippocampal region in the rat, with anterograde transport of Phaseolus vulgaris‐leucoagglutinin. The anteromedial nucleus (AM) projects to the temporal subiculum, medial entorhinal area, perirhinal area, and caudomedial part of the lateral entorhinal area. The interanteromedial nucleus (IAM) projects to the perirhinal area 0and the caudolateral part of the lateral entorhinal area. Furthermore, both the AM and IAM project to the temporal area 2, occipital area 1, and lateral occipital area 2. The projections from the AM and IAM to these retrohippocampal and neocortical regions terminate mainly in deep layers. The anteroventral nucleus (AV) projects to the subicular complex with a complex topographic organization. The most rostral part of the AV projects to layers I and III of the ventral presubiculum, the pyramidal cell layer of the temporal subiculum, and deep layers of the parasubiculum and medial entorhinal area. At the midrostrocaudal level of the AV, the lateral and the dorsal quadrants of the AV project, respectively, to layers I and III and to layers I and IV–VI of the ventral presubiculum, whereas the ventral and the medial quadrants project, respectively, to layers I and III and to layers I and IV–VI of the dorsal presubiculum. Furthermore, the lateral and dorsal quadrants project to the pyramidal cell layer of the temporal subiculum, whereas the ventral and medial quadrants project more septally. At the caudal third level of the AV, the dorsolateral part projects to layers I and III of the presubiculum with a patchy pattern and to the pyramidal cell layer of the septal subiculum. The anterodorsal nucleus projects mainly to deep layers of the presubiculum, parasubiculum, and entorhinal area. The results show that each subdivision of the anterior thalamic nuclei projects to a distinct field in the retrohippocampal region. This suggests that each of these projections may have a distinct modulatory influence upon the activity of retrohippocampal neurons that play important roles in limbic functioning such as memory and learning proceses. © 1993 Wiley‐Liss, Inc.
Secondary olfactory projections and pallial topography in the pacific hagfish, Eptatretus stouti
Authors: Wicht Helmut , Northcutt R. Glenn
Published: January 2005

The extent of the secondary olfactory projections shows great variation among different groups of craniates. Gnathostomes typically display restricted secondary olfactory projections, whereas lampreys have more extensive projections. Any attempt to determine the phylogenetic polarity of these characters, that is, to decide which is primitive and which is derived, requires an investigation of the secondary olfactory system in the sister group of lampreys and gnathostomes, the hagfishes. Therefore the secondary olfactory projections of the Pacific hagfish, Eptatretus stouti, were traced with the use of horseradish peroxidase and the lipophilic fluorescent tracing compound Dil. The projections are bilateral and massive to all pallial areas and the septum, moderate to the striatum, and relatively weak to the preoptic and infundibular regions of the hypothalamus, reaching caudally to the diencephalic‐mesencephalic boundary. Afferents to the olfactory bulb arise from the pallium, the preoptic area, and the ventral thalamus. We compare the secondary olfactory projections in hagfishes with those in lampreys and in gnathostomes, and we conclude that the presence of extensive secondary olfactory projections is a primitive character of craniate brains. © 1993 Wiley‐Liss,Inc.
Comparative distribution of mammalian GnRH (gonadotrophin‐releasing hormone) and chicken GnRH‐II in the brain of the immature siberian sturgeon (Acipenser baeri)
Authors: Leprêtre Emmanuel , Anglade Isabelle , Williot Patrick , Vandesande Frans , Tramu Gérard , Kah Olivier
Published: January 2005

The brain of the sturgeon has recently been shown to contain at least two forms of GnRH (gonadotropin‐releasing hormone), mammalian GnRH (mGnRH) and chicken GnRH‐II (cGnRH‐II). In this study, we compared the distribution of immunoreactive (ir) mGnRH and cGnRH‐II in the brain of immature Siberian sturgeons (Acipenser baeri). The overall distribution of mGnRH was very similar to the distribution of sGnRH in teleosts such as salmonids or cyprinids. mGnRH‐ir perikarya were observed in the olfactory nerves and bulbs, the telencephalon, the preoptic region, and the mediobasal hypothalamus. All these cell bodies are located along a continuum of ir‐fibers that could be traced from the olfactory nerve to the nerve to the hypothalamopituitary interface. No ir‐fibers were observed in the anterior lobe of the pituitary, but a few were seen to enter the neurointermediate lobe. mGnRH‐ir fibers were detected in many parts of the brain, particularly in the forebrain. mGnRH‐ir cerebrospinal fluid‐containing cells were observed in the telencephalon, the preoptic region, and the mediobasal hypothalamus. In contrast, cGnRH‐II was present mainly in the posterior brain, although a few ir axons were seen in the above‐mentioned territories. In particular, cGnRH‐II‐ir cell bodies, negative for mGnRH, were consistently observed in the nucleus of the medial longitudinal fasciculus of the midbrain tegmentum. The cGnRH‐II innervation in the optic tectum, cerebellum, vagal lobe, and medulla oblongata was more abundant than the mGnRH innervation in the same areas. This study provides evidence that the organization of the GnRH systems in a primitive bony fish is, highly similar to that reported in teleosts and further documents the differential distribution of two forms of GnRH in the brain of vertebrates. © 1993 Wiley‐Liss,Inc.
Dendritic arbors of spiny neurons in the primate striatum are directionally polarized
Authors: Walker Ruth H. , Graybiel Ann M.
Published: January 2005

Despite the relatively unfeatured cytoarchitecture of the striatum, this large subcortical region has been found to have a modular macroscopic substructure comprising the neurochemically distinct striosomes and matrix, and, within the matrix, patchy input and output arrangements called matrisomes. In the study reported here, we explored the possibility that the cellular architecture of the striatum is also more specialized than previously suspected. We injected medium spiny neurons in lightly fixed slices of the squirrel monkey caudate nucleus, reconstructed their dendritic arbors, and analyzed the orientations of these arbors with respect to the cardinal planes of the striatum. The data were unequivocal in suggesting that many spiny neurons, whether near striosomes or not, have dendritic arbors with preferred orientations along a diagonal axis running from rostral, dorsal, and medial to caudal, ventral, and lateral. This axis corresponds to the orientations of many striosomes and matrisomes in the squirrel monkey's caudate nucleus. We therefore suggest that the primate striatum is characterized not only by a macroscopic organization dividing it into striosomes and matrisomes, but also by a microscopic architecture observed by the dendritic arbors of many of its projection neurons. We obtained comparable supplementary observations for the ferret caudate nucleus, suggesting that such spatial alignment of spiny dendritic arbors may be a general feature of striatal organization. These polarized dendritic arrangements could provide a cellular framework for compartmental input‐output processing within the striatum. © 1993 Wiley‐Liss,Inc.
Neurotoxic effects of neonatal injections of monosodium L‐glutamate (L‐MSG) on the retinal ganglion cell layer of the golden hamster: Anatomical and functional consequences on the circadian system
Authors: Chambille I. , Serviere J.
Published: January 2005

In rodents, daily injection of neurotoxic monosodium L‐glutamate (MSG) during the postnatal period induces retinal lesions, optic nerve degeneration with an alteration of visual pathway and an absence of the b‐wave in the electroretinogram. Despite this damage, electrophysiological responses subsist in the lateral geniculate bodies and synchronization of circadian rhythms to the light/dark cycle can still occur. Using two formal properties of the circadian system (entrainment and phase‐shift by light), we assessed the functionality of retinal projections to the circadian clock in MSG‐treated hamsters. Displaced amacrine and ganglion cell populations were quantified and retinal terminals in the suprachiasmatic nuclei were estimated. Animals received daily doses of glutamate during the first ten days after birth according to two protocols. The two treatments similarly destroyed 56% of the overall population of the ganglion cell layer: 30% of displaced amacrine and 89% of ganglion cells. Surviving ganglion neurons (7,500 cells) were evenly distributed across the entire retina except in one area of high cell density located in the temporoventral quadrant. Retinal projections of the “image‐forming” pathway were drastically reduced in the dorsal lateral geniculate bodies, less in their ventral part. The “nonimage‐forming” pathway was also affected since the volume of labeled terminals in the suprachiasmatic nuclei was reduced by one‐half to one‐third. Nevertheless, treated hamsters exhibited a free‐running locomotor activity rhythm after several months in constant darkness, could be entrained by the light/dark cycle and phase‐shifted by light pulses. These results suggest that a damaged retinohypothalamic tract can still assume the photic entrainment of the circadian clock. 1993 Wiley‐Liss, Inc. © 1993 Wiley‐Liss, Inc.
Prenatal development of the retinohypothalamic pathway and the suprachiasmatic nucleus in the sheep
Authors: Torrealba F. , Parraguez V. H. , Reyes T. , Valenzuela G. , Serón‐Ferré M.
Published: January 2005

Circadian rhythms are present during fetal life in several mammalian species. To characterize the ontogeny of the neural mechanisms that account for circadian rhythmicity in a precocious species, we studied the prenatal development of the retinohypothalamic pathway in lambs (gestation period of 147 days), using horseradish peroxidase and wheat germ agglutinin as anterograde tracers. The suprachiasmatic nucleus was present as early as embryonic day 52 (E52). After E58, the suprachiasmatic nucleus reached its full number of neurons, estimated by the disector method in about 160,000 cells per nucleus at E62. The retinohypothalamic axons invaded the suprachiasmatic nucleus from E58, while neuroblasts were still migrating to the nucleus. At E62, there was a strong retinal projection that evolved until E121, when the retinal afferents established their definitive pattern of distribution in the ventral and central regions of the suprachiasmatic nucleus, and adjacent hypothalamic structures. The development of the retinohypothalamic pathway was delayed by about a week relative to the innervation of other subcortical visual centers.

The present findings demonstrated an early prenatal development of the visual pathways in lambs, including the retinohypothalamic pathway, suggesting that the mechanisms for the visual entrainment of circadian rhythms in lambs may be functioning several weeks before birth. © 1993 Wiley‐Liss, Inc.
Serotonin‐like immunoreactivity in the adult and developing retina of the leopard frog Rana pipiens
Authors: Liu Qin , Debski Elizabeth A.
Published: January 2005

Recent work in nonmammalian vertebrate retinas has suggested that other cell types besides the generally accepted amacrine cells may contain serotonin. We have used immunocytochemical methods to study serotonin‐like immunoreactivity (5‐HTLI) in the retina of the developing and mature frog Rana pipiens. In the adult, two types of serotonin immunoreactive (5‐HT‐ir) cells were found in the inner nuclear layer (INL) of the retina. Additionally, a large population of cells in the retinal ganglion cell layer (RGCL) had 5‐HTLI. These cells were grouped into three types based on their soma size and their primary dendritic branching pattern. The optic nerve fiber layer was also intensely stained with serotonin antisera although staining intensity decreased progressively as the fibers approached the optic nerve head. Severing the optic nerve resulted in 5‐HT‐ir elements that extended up the optic nerve shaft from the lesion site toward the retina. Both regional and temporal changes in the pattern of 5‐HTLI were seen. In middle regions of retina, approximately 30% of the cells in the RGCL were 5‐HT‐ir. Nasal and temporal regions of central retina had significantly fewer 5‐HT‐ir cells. Early in development only scattered cells in the RGCL were 5‐HT‐ir. As the animals matured there was an increase in both the proportion and the staining intensity of these cells. Our results suggest that in studying the function and development of the visual system in this animal, the role of serotonin must be examined. © 1993 Wiley‐Liss, Inc.
Localization of NADPH diaphorase in the lumbosacral spinal cord and dorsal root ganglia of the cat
Authors: Vizzard Margaret A. , Erdman Susan L. , Erickson Vickie L. , Stewart Robert J. , Roppolo James R. , De Groat William C.
Published: January 2005

The distribution of NADPH‐d activity in the spinal cord and dorsal root ganglia of the cat was studied to evaluate the role of nitric oxide in lumbosacral afferent and spinal autonomic pathways. At all levels of the spinal cord NADPH‐d staining was present in neurons and fibers in the superficial dorsal horn and in neurons around the central canal and in the dorsal commissure. In addition, the sympathetic autonomic nucleus in the rostral lumbar segments exhibited prominent NADPH‐d cellular staining whereas the parasympathetic nucleus in the sacral segments was not well stained. The most prominent NADPH‐d activity in the sacral segments occurred in fibers extending from Lissauer's tract through laminae I along the lateral edge of the dorsal horn to lamina V and the region of the sacral parasympathetic nucleus. These fibers were very similar to VIP‐containing and pelvic nerve afferent projections in the same region. They were prominent in the S1–S3 segments but not in adjacent segments (L6–L7 and Cx1) or in thoracolumbar and cervical segments. NADPH‐d activity and VIP immunoreactivity in Lissauer's tract and the lateral dorsal horn were eliminated or greatly reduced after dorsal‐ventral rhizotomy (S1–S3), indicating the fibers represent primary afferent projections. A population of small diameter afferent neurons in the L7–S2 dorsal root ganglia were intensely stained for NADPH‐d. The functional significance of the NADPH‐d histochemical stain remains to be determined; however, if NADPH‐d is nitric oxide synthase then this would suggest that nitric oxide may function as a transmitter in thoracolumbar sympathetic preganglionic efferent pathways and in sacral parasympathetic afferent pathways in the cat. © 1994 Wiley‐Liss, Inc.
Colocalization of excitatory and inhibitory neurotransmitter markers in striatal projection neurons in the rat
Authors: White Leonard E. , Hodges Harlan D. , Carnes Kenneth M. , Price Joseph L. , Dubinsky Janet M.
Published: January 2005

The principle neuronal output of the neostriatum comes from medium spiny neurons that project from the caudate/putamen to the globus pallidus and substantia nigra. Although current evidence generally indicates that γ‐aminobutyric acid (GABA) is the principal neurotransmitter in this pathway, this cannot account for the excitatory synaptic activity present among cultures of striatal neurons or the short latency excitatory postsynaptic potentials which often proceed or obscure inhibitory activity evoked by striatal stimulation. In this study, retrograde transport of [3H]D‐aspartate has been used to demonstrate striatopallidal and striato‐nigral neurons that possess a high‐affinity uptake system for glutamate and aspartate and are therefore putatively glutamatergic. Injections of [3H]D‐aspartate into the globus pallidus or substantia nigra, pars reticularis of the rat retrogradely labeled mediumsized neurons throughout the rostral‐caudal extent of the neostriatum. To characterize this population further, adjacent sections were immunoreacted with antibodies to either GABA, glutamic acid decarboxylase (GAD), calbindin, or parvalbumin prior to autoradiographic processing. Under these conditions, autoradiographically labeled neurons displayed positive immunoreactivity for GABA, GAD, or calbindin. Autoradiographic label did not colocalize with parvalbumin immunoreactivity. The colocalization of anatomical markers of GABAergic and glutamatergic neurotransmission raises the possibility that both neurotransmitters are functionally expressed within single striatal projection neurons. © 1994 Wiley‐Liss, Inc.
Corticofugal connections between the cerebral cortex and brainstem vestibular nuclei in the macaque monkey
Authors: Akbarian Schahram , Grüsser Otto‐Joachim , Guldin Wolfgang O.
Published: January 2005

The distribution of cortical efferent connections to brainstem vestibular nuclei was quantitatively analysed by means of retrograde tracer substances injected into different electrophysiologically identified parts of the brainstem vestibular nuclear complex of five Java monkeys (Macaca fascicularis). Three polysensory vestibular areas were found to have a substantial projection to the vestibular nuclei: area 2v located at the tip of the intraparietal sulcus, the parietoinsular vestibular cortex (PIVC) covering the most occipital part of the granular insula (Ig) and the retroinsular area (Ri or reipt), and the dorsolateral part of the somatosensory area 3a (“area 3aV” neck/trunk region). From physiological recording experiments, these three cortical fields were known to contain many neurons responding to stimulation of semicircular canals as well as to optokinetic (area 2v, PIVC) and somatosensory stimuli (PIVC, area 3a). These three regions form the inner cortical vestibular circuit. Besides these polysensory vestibular cortical fields, three other circumscribed cortical regions of the macaque brain were also found to project directly to the brainstem vestibular nuclei: a circumscribed part of the postarcuate premotor cortex (area 6pa), part of the agranular and the adjacent dysgranular cortex located around the cingulate sulcus (area 6c/23c), and a predominantly visual (optokinetic) association field located at the fundus of the lateral sulcus (area T3). These areas are known to have connections with the structures of the inner cortical vestibular circuit. Only a few efferent connections to the brainstem vestibular nuclei were found for the different parts of cytoarchitectonic area 7. Significant differences were found between the efferent innervation patterns of the axons originating in the six cortical areas mentioned and ending in the various compartments of the vestibular nuclear complex. Vestibular nuclei with a dominant output to the gaze motor system of the brainstem receive efferent connections preferably from the parietoinsular vestibular cortex. Vestibular structures with their primary output to skeletomotor centers, however, receive stronger efferent connections from areas 6pa and 3a. The ventrolateral nucleus, which sends efferent axons to both the oculomotor and skeletomotor systems of the brainstem and the spinal cord, also receives its main cortical efferents from the somatomotor area 6 and from area 3aV. Through these connections the cortical somatomotor system may directly influence vestibuloocular and vestibulocollic reflexes. It is speculated that the corticofugal connections to the vestibular brainstem nuclei are predominantly inhibitory, suppressing vestibular reflexes during cortically controlled goal‐directed movements. © 1994 Wiley‐Liss, Inc.
Reorganization of visual interneurons during metamorphosis in the swallowtail butterfly Papilio xuthus
Authors: Ichikawa Toshio
Published: January 2005

The metamorphic fate of larval visual interneurons in the swallowtail butterfly Papilio xuthus has been examined by using reduced silver impregnation and immunocytochemistry of γ‐amino butyric acid (GABA). Visual interneurons in the second larval optic neuropile (medulla) can be followed throughout metamorphosis because of large somata located in the anterior edge of the imaginal medulla. Ten to 12 neurons in the larval medulla were immunoreactive to a GABAantiserum. They arborize in the larval medulla and extend dendritic processes to the first larval optic neuropile (lamina). After pupation, the medulla neurons lose GABA‐immunoreactive larval processes and differentiate new processes that enter tangentially into the developing imaginal medulla. Axons of the surviving larval neurons follow an optic tract between the lobula and the lobula plate and extend to the lateral area of the protocerebrum. Thus, larval visual interneurons are incorporated into the imaginal optic lobe and may play a new role in the visual processing of the butterfly. © Wiley‐Liss, Inc.
Inverse patterns of myelination and GAP‐43 expression in the adult CNS: Neurite growth inhibitors as regulators of neuronal plasticity?
Authors: Kapfhammer Josef , Schwab Martin E.
Published: January 2005

In the central nervous system (CNS) myelin is present not only in white matter, but also in varying amounts in many gray matter areas. In addition to the function of electrical insulation of axons, myelin and oligodendrocytes contain molecules that are powerful inhibitors of neurite growth. Nevertheless plastic changes involving sprouting of nerve terminals occur in several brain regions of adult animals after partial lesions. In this study we have tried to correlate the plastic potential of CNS regions with the degree of their myelination. The expression of the growth‐associated protein GAP‐43 was used as an indicator of the potential for plastic changes, and a histological myelin stain was used to assess myelination. We have found that myelination and GAP‐43 expression have strikingly inverse expression patterns in the majority of CNS gray matter areas. Densely myelinated regions, that is, most brainstem nuclei, the tegmentum, and the inferior colliculus, are low in GAP‐43. In contrast, unmyelinated or lightly myelinated areas, such as the substantia gelatinosa of the spinal cord, the nucleus of the solitary tract, or the septum, express high levels of GAP‐43. Areas known to show lesion‐induced sprouting are typically high in GAP‐43 and only lightly myelinated. During postnatal development the myelination pattern precedes the GAP‐43 pattern, a sequence that is consistent with a role of myelin and the associated neurite growth inhibitors in modifying GAP‐43 expression.

Our results support the hypothesis that myelin‐associated neurite growth inhibitors are involved in regulating the stability of neural connections. © Wiley‐Liss, Inc.
Localization of preganglionic neurons of the accessory ciliary ganglion in the midbrain: HRP and WGA‐HRP studies in the cat
Authors: Kuchiiwa Satoshi , Kuchiiwa Toshiko , Nakagawa Shiro
Published: January 2005

Localization of preganglionic neurons of the accessory ciliary ganglion (ACG), including ectopic intraocular ganglion cells, was investigated in the cat with the aid of horseradish peroxidase (HRP) and HRP‐conjugated wheat germ agglutinin (WGA‐HRP) methods. When HRP or WGA‐HRP was injected into the anterior and posterior chambers of the eye, no retrogradely labeled cells were found in the visceral oculomotor nuclei, although most neurons of the ACG and the main ciliary ganglion (CG) were intensely labeled. When a microsyringe needle was inserted into the ciliary body, the tracer diffused into the suprachoroid lamina and the intraocular ganglion cells, and a small number of labeled neurons appeared in the midplane between each side of the somatic oculomotor nuclei. After injection into the ACG, many labeled neurons were observed in the anteromedian nucleus, Edinger‐Westphal nucleus, and midplane between the somatic oculomotor nuclei, their ventral continuations of the ventral tegmental area, and the periaqueductal gray. HRP /WGA‐HRP injection into the CG labeled cells in all these areas and in the lateral border zones of the anteromedian, Edinger‐Westphal and somatic oculomotor nuclei, and their ventral continuations of the ventral tegmental area. These findings indicate that the visceral oculomotor neurons which project to the ACG tend to be located more medially than those to the CG. © Wiley‐Liss, Inc.
Map of the synapses formed with the dendrites of spiny stellate neurons of cat visual cortex
Authors: Anderson John C. , Douglas Rodney J. , Martin Kevan A. C. , Nelson J. Charmaine
Published: January 2005

The synaptic input of six spiny stellate neurons in sublamina 4A of cat area 17 was assessed by electron microscopy. The neurons were physiologically characterized and filled with horseradish peroxidase in vivo. After processing the neurons were reconstructed at the light microscopic level using computer‐assisted methods and analyzed quantitatively. The extensive branching of the dendritic tree about 50 μm from the soma meant that the distal branches constituted five times the length of proximal dendrite. Proximal and distal portions of a single dendrite from each neuron were examined in series of ultrathin sections (1,456 sections) in the electron microscope. The majority (79%) of the 263 synapses examined were asymmetric; the remainder (21%) were symmetric. Symmetric synapses formed 35% of synapses sampled on proximal dendrites and were usually located on the shaft. They formed only 4% of synapses sampled on distal dendrites. Spines accounted for less than half of the total asymmetric synapses (45%); the remainder were on shafts. Symmetric synapses formed with four of 92 spines. Nine spines formed no synapses. Spiny stellate neurons in cat visual cortex appear to differ considerably from pyramidal neurons in having a significant asymmetric (excitatory) synaptic input to the dendritic shaft.
Ultrastructural organization of GABA in the rabbit superior colliculus revealed by quantitative postembedding immunocytochemistry
Authors: Mize R. Ranney , Whitworth Richard H. , Nunes‐Cardozo Bob , Want Johannes Van Der
Published: January 2005

We have studied the organization of gamma‐aminobutyric acid (GABA)ergic profiles in the superior colliculus of the rabbit to determine whether the synaptic types found in cat and monkey also exist in a mammalian species whose visual system has a different organization. Ultrastructure of GABAergic profiles was examined by use of a polyclonal antibody to GABA and quantitative postembedding immunocytochemistry.

Three distinct types of vesicle‐containing profiles were labeled by the GABA antibody in the rabbit superior colliculus. One type was a putative presynaptic dendrite (PSD profile) that received synaptic input from other profiles and contained pleomorphic synaptic vesicles scattered throughout the profile. These PSD profiles frequently received retinal input and formed dendrodendritic synapses. A second type of profile was a large caliber dendrite, often horizontal in orientation (H profile), that had one or more discrete clusters of pleomorphic synaptic vesicles at sites of synaptic contact with conventional dendrites. These H profiles received few synaptic contacts. A third profile type was a putative axon terminal (F profile) with smaller, more flattened synaptic vesicles that densely and uniformly filled the profile. Quantitative analysis of gold particle density revealed that F profiles had a significantly higher gold particle density (14.3/ μm2) than did PSD or H profiles (10.4 and 10.2/ μm2), suggesting that GABAergic profile types contain different concentrations of GABA. The vesicle density of these profile types also differed, but no obvious relationship between vesicle and particle distributions was observed. We conclude that the profiles labeled by GABA in rabbit superior colliculus are similar to those in cat and monkey and must represent a phylogenetically conserved organization common to many mammals, and that particle density analysis of postembedding immunocytochemistry can distinguish different GABAergic profile types.
Gonadal steroids regulate immunoreactive tachykinin in the ventromedial nucleus of the rat hypothalamus
Authors: Akesson Thomas R.
Published: January 2005

The ventromedial nucleus of the hypothalamus (VMH) is an important site in the mediation of female receptive behavior (lordosis); however, the sequence of events that eventually facilitate this estrogen‐dependent behavior is only partially understood. Here, evidence is presented, suggesting that an interaction between gonadal steroids and tachykinin peptides is involved. Tachykinin‐immunoreactive (TACir) neurons were distributed throughout the anterior (VMHa), dorsomedial (VMHdm), central (VMHc), and ventrolateral (VMHvl) subdivisions in the adult male and female rat. Numbers of cells in the VMH of intact males and males that had been castrated for three weeks were similar. Among females, numbers of TACir cells in the VMHvl were significantly increased over numbers seen in ovariectomized females by a two day (1.5X) and by a two week (1.6X) exposure to estrogen. In the VMHa, numbers of TACir cells were also significantly higher in females that received replacement estrogen compared to ovariectomized females. Since estrogen concentration by TACir neurons is common in the VMHvl and rare in the VMHa, estrogen may have both direct and indirect effects on tachykinin synthesis. In the caudal pole of the VMH, staining intensity of TACir fibers varied with endocrine state. In intact males, castrated males, and ovariectomized females, fibers were lightly stained. In females exposed to estrogen for two days, fibers were moderately intense, and in females exposed to estrogen for two weeks, they formed a darkly stained plexus. These responses to estrogen suggest that production of tachykinin peptides in the VMH is involved in facilitation of female typical sexual behavior.
Reevaluation of area 3b in the cat based on architectonic and electrophysiological studies: Regional variability with functional and anatomical consistencies
Authors: Leclerc S. S. , Avendaño C. , Dykes R. W. , Waters R. S. , Salimi I.
Published: January 2005

Most anatomical and electrophysiological studies of the cat primary somatosensory cortex rely on Hassler and Muhs‐Clement's (J. Hirnforsch. 6:377‐420, 1964) cyto‐ and myeloarchitectonic description distinguishing area 3a from area 3b; however, discrepancies in the delineation of these areas in published studies suggest that many workers have found it difficult to apply those criteria systematically. We examined the cytoarchitecture of area 3b in Nissl stained sagittal sections from which electrophysiological data had been obtained prior to sacrifice. Rostrocaudal rows of electrode penetrations placed at different mediolateral positions in the gyrus located regions responsive to stimulation of either cutaneous or deep structures. Small electrolytic lesions allowed these data to be related to the cytoarchitecture. A systematic study throughout the trunk and limb representations found cutaneous responses in cortical regions characterized by a thick and cell‐dense granular layer IV, however these same regions had a variable population of medium‐sized and/or large pyramidal cells in layer V. Pyramidal cells were practically absent from the forelimb representation, but were present to varying degrees in the trunk and hindlimb representations. Moreover, the relative thickness and cell‐density in layer IV were greater in the forelimb than in the hindlimb representations. Deep responses were found in cortex characterized by a thinner layer IV. Since the characteristics of layer V in area 3a were variable, it was less useful for identification of the border between areas 3a and 3b. Clear changes in the intensity and laminar distribution of acetylcholinesterase staining occurred between areas 3a and 3b, making this a useful adjunct to the Nissl stain.
Birthdates of neurons in the retinal ganglion cell layer of the ferret
Authors: Reese B. E. , Thompson W. F. , Peduzzi J. D.
Published: January 2005

The present study determined the temporal and spatial patterns of genesis for neurons of different sizes in the retinal ganglion cell layer of the ferret. Fetal ferrets were exposed to tritiated thymidine on embryonic days E‐22 through E‐36. One to 3 months after birth, they were perfused and their retinae dissected, and autoradiographs were prepared from resinembedded sections throughout the entire flattened retinal ganglion cell layer. Soma size differences in conjunction with separate retrograde labeling and calbindin immunocytochemical studies were used as criteria for identifying different retinal ganglion cell subtypes in juvenile and adult ferrets.

Neurons of different sizes in the ganglion cell layer were generated at different stages during development. Medium sized cells were generated primarily between E‐22 and E‐26; the largest cells were generated between E‐24 and E‐29; small cells were generated between E‐26 and E‐32; and very small cells were generated between E‐29 and E‐36. The former three groups were interpreted to be three subtypes of retinal ganglion cells, while the latter group was interpreted to be displaced amacrine cells.

This temporal order of the genesis of ganglion cell classes is consistent with the spatial ordering of their fibers in the mature optic chiasm and tract, and it is consistent with the developmental change in decussation pattern recently shown in the optic pathway of embryonic ferrets. The spatial pattern of genesis suggests that ganglion cells of a particular class are added to the ganglion cell layer in a centroperipheral fashion initiated in the dorsocentral retina nasal to the area centralis. No evidence was found for a wave of ganglion cell addition that proceeded in a spiralling pattern around the area centralis, as has been reported in the cat.
Organization of cortical afferents to the rostral, limbic sector of the rat thalamic reticular nucleus
Authors: Lozsádi D. A.
Published: January 2005

The organization of limbic cortical afferents to the thalamic reticular nucleus (TRN) is described. Wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP), biocytin, neurobiotin, or fluorescent dextrans was delivered into the rat cingulate, retrosplenial, and, for comparison, somatosensory cortices, In other species a slab‐like arrengement of cortical terminals has been described for sensory TRN sectors. Here this is seen in the rat somatosen‐sory sector. Terminals from limbic cortices did not cluster into slabs but were found to fill the entire thickness of distinct rostral TRN regions. The cingulate and retrosplenial recipient TRN regions overlap, as do the projections from these cortical areas to anterior thalamic nuclei. Retrosplenial fibres contacted the dorsal and rostral TRN, which is be connected to the retrosplenial‐recipient anteroventral, anterodorsal, and laterodorsal thalamic nucler. Cingulate terminals occupied more ventral regions of the rostral TRN. This area is connected to thalamic nuclei also innervated by the cingulate cortex: the mediodorsal and anteromedial nuclei. A loose, but clear, topography could be defined for the cingulate‐reticular pathway: rostrocaudal and mediolateral directions in the cortex are represented by ventrodorsal and rostrocaudal directions in the TRN, respectively. This organization of limbic corticoreticular pathway corresponds to the arrangement of limbic corticothalamic connections. The ultrastruc‐ture of the limbic cortical axon terminals was similar to that of the cortical boutons (D‐type) described previously. The labelled terminals formed asymmetrical synapses onto dendritic profiles of reticular neurons. These findings, together with data in the literature, show significant morphological and connectional differences within the TRN that imply functional heterogeneities.
Quantitative analyses of neuroepithelial cell shapes during bending of the mouse neural plate
Authors: Smith Jodi L. , Schoenwolf Gary C. , Quan Jan
Published: January 2005

Despite a wealth of information about cell behaviors contributing to neurulation in chick embryos, similar behaviors in mouse embryos have yet to be well characterized. This study examines cell behaviors occurring during bending of the mouse neural plate, in particular, qualitative and quantitative changes in neuroepithelial cell shape. Our current results demonstrate that in mouse embryos (1) the median hinge point (MHP), a localized region of neural plate that becomes anchored to the underlying prechordal plate mesoderm or notochord/ notochordal plate and forms a midline longitudinal furrow around which folding of the remaining neural plate (i.e., the part of the neural plate not involved in MHP formation) occurs, develops during stages of neural fold elevation; (2) the MHP is enriched with wedge‐shaped neuroepithelial cells but has significantly fewer spindle‐shaped, inverted wedge‐shaped, and globular neuroepithelial cells than do the adjacent paired lateral areas of the neuroepithelium (L); and (3) each L is enriched with spindle‐shaped, inverted wedge‐shaped, and globular neuroepithelial cells but has significantly fewer wedge‐shaped neuroepithelial cells than does the MHP. Thus wedging of neuroepithelial cells occurs during bending of the mouse neural plate and is localized to the MHP during neural fold elevation. Similarly, previous studies in the chick have shown that neuroepithelial cells become wedge shaped during bending of the neural plate and that such cell wedging is localized to the MHP during neural fold elevation. Such studies also have shed light on the roles of MHP formation and localized wedging of neuroepithelial cells within the MHP in the chick; however, such roles have yet to be elucidated in the mouse. It is probable that the MHP in mouse embryos, like that in chick embryos, provides a locus for bending of the neural plate and that wedging of neuroepithelial cells within the MHP provides the force necessary to generate the longitudinal midline furrow around which subsequent folding of the neural plate (i.e., neural fold elevation) occurs. Further studies are necessary to define these roles more precisely. © 1994 Wiley‐Liss, Inc.
Distribution of VIP mRNA and two distinct VIP binding sites in the developing rat brain: Relation to ontogenic events
Authors: Hill Joanna M. , Agoston Denes V. , Gressens Pierre , McCune Susan K.
Published: January 2005

The peptide neurotransmitter vasoactive intestinal peptide (VIP) has neurotrophic properties and influences neurobehavioral development. To assess the role of VIP during neural ontogeny, the present work traces the development of VIP mRNA with in situ hybridization and VIP receptors with in vitro autoradiography in rat central nervous system (CNS) from embryonic day 14 (E14) to the adult.

VIP mRNA was not evident in the CNS until birth. Postnatally, it was expressed in several distinct brain regions, but its distribution bore little relation to that of VIP receptors.

VIP receptors were present and expressed changing patterns of distribution throughout CNS development. The changing patterns were the result of (1) the transient appearance of GTP‐insensitive VIP receptors in several regions undergoing mitosis or glial fasciculation and (2) the transient appearance of GTP‐sensitive VIP receptors homogeneously distributed throughout the CNS during the first 2 postnatal weeks, the period of the brain growth spurt. At E14‐16 VIP binding was dense throughout the brainstem and spinal cord, but limited in the rest of the brain. From E19 to postnatal day 14 (P14), while VIP binding was higher in germinal zones, it tended to be uniformly dense throughout the remainder of the brain. By P21 the adult pattern began to emerge; VIP binding was unevenly distributed and was related to specific cytoarchitectural sites.

Since the expression of VIP in the CNS is limited to postnatal development but VIP receptors are abundant prenatally, we suggest that extraembryonic VIP may act upon prenatal VIP receptors to regulate ontogenic events in the brain. © 1994 Wiley‐Liss, Inc.
Direct projections from the entopeduncular nucleus to the lower brainstem in the rat
Authors: Takada Masahiko , Tokuno Hironobu , Ikai Yoshiaki , Mizuno Noboru
Published: January 2005

The present study reports the existence of projection fibers from the entopeduncular nucleus to the superior colliculus and lateral parts of the pontobulbar tegmental regions (so‐called lateral tegmental field) in the rat, suggesting that the entopeduncular nucleus may control eye‐head and orofacial movements via these projection fibers. The anterograde axonal tracing with Phaseolus vulgaris‐leucoagglutinin has revealed that the entopedunculotectal fibers terminate, bilaterally, with an ipsilateral predominance, in the deep layers of the superior colliculus through its rostral one‐third level and that the entopedunculotegmental fibers terminate, bilaterally, with an ipsilateral predominance, in the parabrachial area, reticular formation surrounding the trigeminal motor nucleus, and parvicellular, dorsal, and ventral reticular nuclei. The cells of origin of the entopedunculotectal and entopedunculotegmental projections have been identified by retrograde axonal tracing with Fluoro‐Gold and cholera toxin B subunit. The entopedunculotectal or entopedunculotegmental fibers originate, respectively, from the dorsal or ventral part of the entopeduncular nucleus. Additionally, a series of fluorescent retrograde double‐labeling experiments with Fast Blue and Diamidino Yellow have indicated that single entopeduncular nucleus neurons projecting to the superior colliculus or lateral tegmental field often send their axon collaterals to the lateral habenular nucleus.

The entopedunculotectal fibers are assumed to control head movements, which may be provoked via the tectospinal fibers, and further to participate in eye movements as the nigrotectal fibers that have been known to arise from the substantia nigra pars reticulata to end in the deep layers of the superior colliculus primarily through its caudal two‐thirds level. The entopedunculotegmental fibers are presumed to be involved in control of orofacial movements, because the sites of termination of the entopedunculotegmental fibers correspond well with the reported areas of distribution of premotor interneurons for the trigeminal motor, facial, and hypoglossal nuclei. © 1994 Wiley‐Liss, Inc.