bluuebunny/crossref_metadata_2025 huggingface dataset:
Dendritic morphology of pyramidal neurones of the visual cortex of the rat: III. Spine distributions
Authors: Larkman Alan U.
Published: January 2005

The vast majority of excitatory synaptic inputs to neocortical pyramidal cells terminate on dendritic spines, which can thus serve as markers, visible by light microscopy, for the locations of these synapses. The aim of this study was to provide estimates of the total numbers and distributions of spines on the dendrites of individual pyramidal neurones from layers 2/3 and 5 of the visual cortex of the rat. High magnification camera lucida drawings were made of dendritic segments lying close to the plane of section and the number of spines per unit length of dendrite calculated for each. These spine densities were used to estimate the numbers of spines on the other dendritic segments and the results were entered to a computer program that calculated various statistics.

Mean total numbers of spines per cell were 7,965 ± 2,723 (S.D.) for layer 2/3 cells, 8,647 ± 3,097 for slender layer 5 cells, and 14,932 ± 3,371 for thick layer 5 cells; these figures are in good agreement with previous stereological estimates. For all cell classes, 70% or more of spines were located on the basal and apical oblique dendrites. The distribution of spines with respect to cortical layers was also explored. Most cells had most of their spines in the layer containing the soma, but there were differences within and between cell classes. Layer 2/3 cells showed a progressive reduction in the proportion of their spines in layers 1 and 2 with increasing depth of their soma in the cortex. Thick layer 5 cells had substantial contributions from layers 4, 3, 2, and especially layer 1. Slender layer 5 cells had small contributions from layers 6 and 4, but relatively few spines in layers 3 and 2.

The distribution of spines with path distance from the soma was explored by estimating the numbers of spines contained within a series of concentric shells centred on the soma. All cells showed a rapid increase in the number of spines per shell for the proximal 100 μm or so, followed by a sharp decline to approximately 250 μm, beyond which the number remained relatively constant until the end of the terminal arbor. In each case, the majority of spines were located within a path length of 150 μm from the soma.
Localization of NADPH‐diaphorase‐containing neurons in sensory ganglia of the rat
Authors: Aimi Yoshinari , Fujimura Masaki , Vincent Steven R. , Kimura Hiroshi
Published: January 2005

The presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase activity was studied histochemically in the sensory ganglia of the rat. Supraspinally, the trigeminal ganglion possessed only a few cells positively stained for NADPH‐diaphorase, while a large number of positive neurons was found in the nodose ganglion. In the dorsal root ganglia, the distribution of positive cells showed a peculiar pattern in relation to spinal levels. Very minor populations (less than 2% of the total ganglionic cells) exhibited positive reaction in ganglia at levels ranging from the first cervical (C1) to fourth thoracic (T4) and from the second lumber (L2) through the entire sacral levels. In the middle to lower thoracic levels (from T5 to L1), however, abundant diaphorase‐positive cells were observed. From these positive neurons it was possible to trace intensely stained nerve fibers. In the lower thoracic level, for example, dense positive fibers were seen in the ramus communicans. Retrograde tracing studies revealed that diaphorase‐containing neurons in the lower thoracic level project at least partly to the gastric wall and the celiac ganglion. These results indicate that the diaphorase‐positive ganglionic neurons in the thoracicolumbar levels may carry autonomic visceral afferent information. Double staining with NADPH‐diaphorase histochemistry and peptide immunohistochemistry revealed that NADPH‐diaphorase colocalizes with calcitonin gene‐related peptide and substance P in many of these visceral afferent neurons.
Neurofilament antibodies and spiral ganglion neurons of the mammalian cochlea
Authors: Berglund A. M. , Ryugo D. K.
Published: January 2005

The spiral ganglia of the cat, gerbil, mouse, rat, and human were immunohistochemically stained with various monoclonal neurofilament antibodies. Three antibodies to the 200‐kD neurofilament protein (R‐3, Dräger et al., '84; ICN anti‐200, clone NE14, Debus et al., '83; RT‐97, Wood and Anderton, '81) labeled the somata of type II spiral ganglion neurons but not those of type I ganglion neurons. In the extreme base of the cochlea of cats, mice and rats, there was intense labeling of a few (< 0.5% of the total ganglion population) large neurons resembling type I ganglion neurons.

Several other neurofilament antibodies (Amtersham anti‐68, Amersham and ICN anti‐160, and SMI‐32) did not specifically label type II ganglion neurons but instead labeled all neurons of the spiral ganglion. These two patterns of labeling prompted us to investigate the cause for this difference. Because antibodies against the 200‐kD neurofilament protein preferentially labeled type II neurons and because 200‐kD neurofilament is highly phosphorylated, we treated cochlear tissue with alkaline phosphatase in order to remove phosphate groups. This treatment eliminated the intense labeling of type II neurons with R‐3, ICN anti‐200, and RT‐97, but had no effect on the intense labeling of ganglion cell bodies observed with the other neurofilament antibodies tested. This evidence suggests that labeling occurs because of the cytoplasmic presence of phosphorylated 200‐kD neurofilament protein in type II ganglion neurons. Populations of neurons may thus differ in their neurofilament epitopes and monoclonal antibodies can be used to mark such differences.
Axonal regeneration in the adult lamprey spinal cord
Authors: Lurie Diana I. , Selzer Michael E.
Published: January 2005

Larval sea lampreys recover from complete spinal transection by a process involving directionally specific axonal regeneration. In order to determine whether this is also true of adults, 14 adult lampreys were transected at the level of the 5th gill and allowed to recover for 10 weeks. Müller and Mauthner cells and their giant reticulospinal axons (GRAs) were impaled with microelectrodes and injected with horseradish peroxidase (HRR) The tissue was processed for HRP histochemistry and wholemounts of brain and spinal cord were prepared.

All animals recovered coordinated swimming; 61 of 121 (50%) neurites emanating from 30 axons regenerated caudal to the scar into the distal stump. Of the neurites which had grown beyond the scar, 92% were correctly oriented, i.e., caudalward and ipsilateral to the parent axon. Retransection in two additional animals eliminated the recovered swimming. Thus, behavioral recovery in adult sea lampreys is accompanied by directionally specific axonal regeneration.
The edinger‐westphal nucleus: Sources of input influencing accommodation, pupilloconstriction, and choroidal blood flow
Authors: Gamlin Paul D. R. , Reiner Anton
Published: January 2005

This study used neuroanatomical techniques to investigate sources of afferents to the Edinger‐Westphal nucleus (EW) of the pigeon. The EW contains the parasympathetic preganglionic neurons that, by way of the oculomotor nerve, project to the ciliary ganglion (Narayanan and Narayanan, '76; Lyman and Mugnaini, '80). The ciliary ganglion, in turn, innervates the internal musculature of the eye; the ciliary body, the iris sphincter muscle, and the smooth muscle of choroidal blood vessels (Marwitt et al., '71; Pilar and Tuttle, '82), In the bird, the neurons in the ciliary ganglion that innervate the iris sphincter muscle and the ciliary body receive input specifically from cells in the lateral EW (EWl), whereas those that innervate choroidal blood vessels receive input from cells in the medial EW (EWm) (Reiner et al., '83). Thus neurons in the EWl mediate pupilloconstriction and accommodation, whereas neurons in the EWm modulate choroidal blood flow.

To study the afferents to EW, injections of horseradish peroxidase (HRP) were placed in this nucleus. These injections resulted in labeled cells in the area pretectalis, a retinorecipient pretectal nucleus and the suprachiasmatic nucleus, a retinorecipient hypothalamic nucleus. We have previously identified both these areas as being sources of afferents to EW (Gamlin et al., '82, '84). In addition, these HRP injections into EW resulted in labeled cells in the medial mesencephalic reticular formation (MRF) lateral and ventral to the oculomotor nucleus and in a localized area of the rostral lateral mesencephalic reticular formation (LRF) dorsolateral to nucleus subpretectalis. Injections of tritiated amino acids into the MRF labeled the entire EW, while such injections into the LRF labeled only the lateral EW. Both of these projections were predominantly contralateral.

This study has identified the sources of two previously undocumented inputs to the avian EW. Both sources of input, the MRF and rostral LRF, receive afferents from visuomotor areas of the telencephalon and visual structures in the midbrain. The MRF input to EW could have either direct or modulatory influences on pupil diameter, accommodation, and choroidal blood flow, The LRF input to EW could play a role in controlling accommodation and possibly the pupillary near response.
Cortical connections of the caudal subdivision of the dorsolateral area (V4) in monkeys
Authors: Steele G. E. , Weller R. E. , Cusick C. G.
Published: January 2005

Evidence suggests that all primates have rostral and caudal subdivisions in the region of visual cortex identified as the dorsolateral area (DL) or V4. However, the connections of DL/V4 have not been examined in terms of these subdivisions. To determine the cortical connections of the caudal subdivision of DL (DLc) in squirrel monkeys, injections of the neuroanatomical tracers wheat germ agglutinin conjugated to horseradish peroxidase, Diamidino Yellow, and Fluoro‐Gold were made in cortex rostral to V II. To aid in delineating the borders of DLC, cortex was also evaluated architectonically.

Based on similar patterns of connections, DLC extends from dorsolateral to ventrolateral cortex. DLC receives strong, feedforward input from V II and projects in a feedforward fashion to the rostral subdivision of DL (DLR) and caudal inferior temporal (IT) cortex, including a separate location in the inferior temporal sulcus. DLC has weaker connections with V I, the middle temporal area (MT), cortex rostral to MT in the location of the fundal superior temporal area (FST), cortex dorsal to DLC, ventral cortex‐rostral to V II, and cortex in the frontal lobe, lateral to the inferior arcuate sulcus. Only lateral DLC has connections with V I, and only dorsolateral DLC has connections with cortex dorsal to DLC. The topographic organization of DLC was inferred from its connections with V II. Thus, dorsolateral DLC represents the lower field, lateral DLC represents central vision, and ventrolateral DLC represents the upper field.

Limited observations were made on DLR. Confirming earlier observations (Cusick and Kaas: Visual Neurosci. 1:211, 1988), DLR is paler than DLC myeloarchitectonically. DLR receives only sparse feedforward input from V II, but stronger input from DLC. DLR has strong connections with cortex just rostral to dorsal V II, ventral posterior parietal cortex in the sylvian fissure, MT, the medial superior temporal area, FST, and the inferior temporal sulcus. DLR also shares connections with IT cortex. Thus, while both DLC and DLR are involved in the pathway relaying visual information to IT cortex, an area specialized for object vision, DLR also projects densely to areas such as MT involved in the pathway relaying to posterior parietal cortex, a region specialized for spatial localization and motion perception.
Activity‐dependent changes in eye influence during monocular blockade: Increases in the effects of visual stimulation on 2‐DG uptake in the adult rat geniculostriate system
Authors: Thurlow G. A. , Cooper R. M.
Published: January 2005

We examined the effects of loss of monocular retinal activity 2‐deoxyglucose (2‐DG) uptake in the adult rat geniculostriate system. Of particular interest was whether the influence of the normally functioning eye changed during long‐term contralateral retinal silence. Group 1 rats were subjected to short‐term (24 hours) and group 2 rats to long‐term (21–90 days) monocular tetrodotoxin (TTX) blockade, and metabolic activity was assessed during exposure to square‐wave gratings. Group 1 rats exhibited patterns of cortical glucose utilization commensurate with complete monocular loss of retinal activity: minimal 2‐DG uptake in contralateral monocular area 17 and dorsal lateral geniculate nucleus (LGN), and a bilateral depression in the binocular regions; 2‐DG uptake was highest in the monocular regions fed by the stimulated normal eye (in both area 17 and the LGN) and these regions appeared unaffected by the monocular blockade. After repeated injections of TTX (group 2), metabolic activity in binocular area 17 and binocular LGN increased bilaterally relative to the metabolically active monocular regions contralateral to the normal eye. Group 3 rats were monocularly TTX‐injected for 30 or 60 days, and, 24 hours before 2‐DG, all retinal activity was eliminated by means of binocular TTX injections or binocular enucleation. Glucose utilization in the binocular regions of both area 17 and the LGN in these rats was depressed to levels seen in monocular area 17 after complete and recent loss of activity from the contralateral eye, indicating that the metabolic increase which occurred in the binocular regions during long‐term monocular retinal blockade was dependent upon the neuronal processing of retinal information from the non‐TTX eye. We conclude that, in the adult rat, an activity‐dependent, physiologically based shift in ocular influence occurred in the binocular geniculostriate system during long‐term monocular retinal inactivation.
Gonadotropin hormone‐releasing hormone (GnRH) immunoreactivity in the mesencephalon of sharks and rays
Authors: Wright Douglas E. , Demski Leo S.
Published: January 2005

Other than association with the terminal nerve (TN), little is known concerning the distribution of gonadotropin hormone‐releasing hormone (GnRH) in elasmobranchs. The purpose of this study was to identify GnRH immunoreactivity in the brains of three elasmobranch species with special regard to the mesencephalon. The round stingray (Urolophus halleri), thornback guitarfish (Platyrhinoidis triseriata), and leopard shark (Triakis semifasciatus) were used und immunocytochemistry was performed with antisera to both salmon and mammalian GnRH. A large GnRH‐immunoreactive (ir) nucleus extends rostrocaudally for approximately 1.5 mm along and adjacent to the midline of the midbrain near the area of the oculomotor nerve. GnRH‐ir fibers surround the nucleus and are found diffusely throughout the mesencephalon; some of the fibers may contact the ventricle. The medulla and spinal cord contain ir fibers that most likely originate from the midbrain nucleus. Mesencephalic GnRH‐ir cell groups have been reported in representatives of all vertebrate classes with the exception of agnathans and mammals. Such a well‐developed cell group in elasmobranchs may aid in understanding the evolution of GnRH systems with regard to the mesencephalon as well as providing insight to the functional significance of this cell group. Possible homologies to mesencephalic GnRH systems reported in other vertebrates is discussed as well.
Lateral asymmetries and testosterone‐induced changes in the gross morphology of the hypoglossal nucleus in adult canaries
Authors: DeVoogd Timothy J. , Pyskaty D. James , Nottebohm Fernando
Published: January 2005

The caudal portion of the hypoglossal nucleus (tracheosyringeal, nXIIts) contains the motor neurons that innervate the syrinx in songbirds. It receives projections from telencephalic and midbrain nuclei that are necessary for song production. Its neurons concentrate androgens. The present study assesses the gross morphology of the hypoglossal nucleus in canaries. In this species song is more frequent, elaborate, and stereotyped in males than in females. Adult females respond to testosterone by developing a stereotyped song that is sung frequently. Song in male canaries is much more disrupted by damage on the left side of the song system than by damage on the right. We find anatomical correlates for each of these attributes in the nXIIts. This nucleus is 83% larger in males than in females. This is caused primarily by a sex difference in neuropil volume as there is no significant sex difference in the number of neurons in nXIIts. nXIIts grows by 34% in females given testosterone as adults. It is about 8% larger on the left than on the right in males, females, and females treated with testosterone. Sex differences are also found in the rostral (lingualis) portion of nXIIts which controls muscles of the tongue, but there is no effect here of adult treatment with testosterone. Comparisons of these data with earlier measures of synaptic density and morphology in nXIIts suggest that the testosterone acts on this nucleus by inducing a modest increase in synapse numbers and by altering the efficacy of synapses in nXIIts. This contrasts with the effects of testosterone on n. robustus archistriatalis, a telencephalic component of the song system in which testosterone induces massive amounts of synaptogenesis.
Origin and distribution of neuropeptide‐FF‐like immunoreactivity in the spinal cord of rats
Authors: Kivipelto Leena , Panula Pertti
Published: January 2005

Neuropeptide FF, or F8Famide (Phe‐Leu‐Phe‐Gln‐Pro‐Gln‐Arg‐Phe‐NH2; “morphine‐modulating peptide”), isolated from bovine brain, is an FMRF‐NH2‐like peptide with morphine‐modulating effects. Neuropeptide FF (NFF) is highly concentrated in spinal cords of various mammalian species. There is evidence that NFF participates in the modulation of nociceptive mechanisms.

The present study was aimed at describing the distribution and origin of the neuropeptide‐FF‐like immunoreactivity (LI) in the rat spinal cord. For distribution studies spinal cord sections from colchicine‐treated animals were processed according to the indirect immunofluorescence method. Retrograde fluorescent tracer was injected in the lumbar dorsal spinal cord to study descending NFF‐LI‐containing spinal pathways.

NFF‐immunoreactive (ir) cell bodies were detected in the substantia gelatinosa, marginal zone, laminae III, IV, and X at all levels of the spinal cord, and the dorsolateral funiculus, and dorsal gray commissure of the lumbosacral transition zone. NFF‐ir fibers and terminals were identified in laminae I‐IV and X, dorsolateral funiculus, intermediolateral cell column, dorsal gray commissure, sacral parasympathetic nucleus, and ventral horn. A spinal NFF‐LI‐containing descending pathway originating in the lamina X neurons was observed, but a supraspinal origin of descending NFF‐ir fibers was not identified.

According to this study the NFF‐LI of the spinal cord is of intrinsic spinal origin. The anatomical distribution supports the concept that the NFF‐like peptides have a role in the nociception. They may also be involved in sensory‐visceral reflex arcs.
Descending projections to the rat sacrocaudal spinal cord
Authors: Masson Robert L. , Sparkes Mary L. , Ritz Louis A.
Published: January 2005

Descending supraspinal and propriospinal neurons projecting to the female rat sacrocaudal spinal cord, the portion of the spinal cord that innervates the tail, were identified following injection of Fluoro‐Gold into the S1‐Ca2, spinal cord segments. This study attempted to determine anatomical substrates for propriospinal and supraspinal control of the tail.

Propriospinal neurons were identified throughout laminae V‐VIII and X at all levels of the spinal cord. The greatest density of labeling was in the lumbar enlargement, followed by the cervical enlargement, with least in the thoracic spinal cord. Within a given cord level, labeling was greatest within the intermediate zone. In addition, other prominent spinal cord collections included neurons in (1) lamina V of the lumbar enlargement, (2) dorsal lamina X of the cervical enlargement, and (3) the lateral spinal nucleus within the cervical enlargement.

Supraspinal cells were identified within raphe nuclei, reticular formation nuclei, dorsal column nuclei, vestibular nuclei, noradrenergic groups, the red nucleus, the periaqueductal gray, the hypothalamus, and the motor cortex.

These data indicate that there are significant descending projections to the sacrocaudal spinal cord, with distributions similar to those of other cord levels. Functionally, important supraspinal and propriospinal influences on tail, pelvic viscera and limbs, such as with locomotion, balance, defense, micturition, defecation, and sexual functions, may be mediated by these connections.
Activity‐dependent regulation of glutamic acid decarboxylase in the rat barrel cortex: Effects of neonatal versus adult sensory deprivation
Authors: Akhtar N. D. , Land P. W.
Published: January 2005

Immunocytochemical techniques were used to study the effects of tactual deprivation on glutamic acid decarboxylase (GAD) containing neurons in rat somatosensory barrel cortex. In normal rats GAD immunoreactive neurons and puncta are present in all laminae, with dense patches of GAD immunoreactive puncta centered on the barrels in lamina IV. Trimming whiskers of adult rats leads to a reversible decrease of GAD immunoreactivity in barrels corresponding to trimmed hairs. Intensity of GAD staining also is reversibly altered in supragranular laminae of nondeprived barrel columns flanked by deprived barrels. This indicates that GAD levels in the barrel cortex ordinarily fluctuate with changes in sensory input. By contrast, animals whose whiskers are trimmed from birth have normal GAD staining in both deprived and nondeprived barrels. Moreover, if trimmed whiskers of neonatally deprived animals are allowed to grow to normal lengths and are retrimmed later in adulthood GAD staining is not affected. Thus early tactual deprivation disrupts mechanisms that permit modulation of transmitter enzyme levels in cortical neurons following changes in sensory experience.
The calcium binding protein calbindin‐D 28K reveals subpopulations of projection and interneurons in the cat superior colliculus
Authors: Mize R. Ranney , Jeon Chang‐Jin , Butler Grace D. , Luo Qian , Emson Piers C.
Published: January 2005

The calcium binding protein calbindin‐D 28K (CaBP) has been localized in the cat superior colliculus (SC). Four important features of SC organization have been revealed by using CaBP immunocytochemistry. 1) CaBP neurons formed three laminar tiers in SC, one within the upper one half of the superficial gray layer (SGL), the second bridging the deep optic (OL) and intermediate gray layers (IGL), and the third within the deep gray layer (DGL). 2) CaBP labeled several classes of interneuron in SC. In the upper CaBP tier, the labeled neurons were all small, but they varied in morphology and included horizontal, pyriform, and stellate neurons. A unique class of interneuron was labeled by anti‐CaBP in the OL‐IGL tier. This cell was stellate‐like with highly varicose dendrites and broad dendritic trees. Other labeled neurons in the intermediate and deep tiers included nonvaricose stellate neurons and rare large neurons in the DGL. 3) A few anti‐CaBP neurons were projection neurons. Virtually no CaBP neurons were retrogradely labeled after injections of HRP into the predorsal bundle and dorsolateral midbrain tegmentum or into the lateral posterior nucleus. However, 2.4% of anti‐CaBP neurons were retrogradely labeled after HRP injections into the dorsal and ventral lateral geniculate nuclei. These represented 14.7% of all neurons projecting to the LGN complex. 4) A small percentage of CaBP neurons co‐localized GABA. A two‐chromagen double‐labeling technique showed that about 4.0% of labeled neurons were labeled by both antibodies. In summary, antibodies to CaBP densely labeled subpopulations of neurons in the cat SC, most of which were interneurons, some of which projected to the LGN, and a few of which co‐localized GABA.
Entorhinal cortex of the monkey: V. Projections to the dentate gyrus, hippocampus, and subicular complex
Authors: Witter Menno P. , Amaral David G.
Published: January 2005

The topographic and laminar organization of entorhinal projections to the dentate gyrus, hippocampus, and subicular complex was investigated in the Macaca, fascicularis monkey. Injections of 3H‐amino acids were placed at various positions within the entorhinal cortex and the distribution of anterogradely labeled fibers and terminals within the other fields of the hippocampal formation was determined. Injections of the retrograde tracers Fast blue, Diamidino yellow, and wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) were also placed into the dentate gyrus, hippocampus, and subicular complex, and the distribution of retrogradely labeled cells in the entorhinal cortex was plotted using a computer‐aided digitizing system. The entorhinal cortex gave rise to projections that terminated in the subiculum, in the CA1, CA2, and CA3 fields of the hippocampus, and in the dentate gyrus. Projections to the dentate gyrus, and fields CA3 and CA2 of the hippocampus, originated preferentially in layers II and VI of the entorhinal cortex whereas projections to CA1 and to the subiculum originated mainly in layers III and V. Anterograde tracing experiments demonstrated that all regions of the entorhinal cortex project to the outer two‐thirds of the molecular layer of the dentate gyrus and to much of the radial extent of the stratum lacunosum‐moleculare of CA3 and CA2. While the terminal distributions of entorhinal projections to the dentate gyrus, CA3, and CA2 were not as clearly laminated as in the rat, projections from rostral levels of the entorhinal cortex preferentially innervated the outer portion of the molecular layer and stratum lacunosum‐moleculare, whereas more caudal levels of the entorhinal cortex projected relatively more heavily to the deeper portions of the entorhinal terminal zones. The entorhinal projection to the CA1 field of the hippocampus and to the subiculum followed a transverse rather than radial gradient of distribution. Rostral levels of the entorhinal cortex terminated most heavily at the border of CA1 and the subiculum. More caudal levels of the entorhinal cortex projected to progressively more distal portions of the subiculum (towards the presubiculum) and more proximal portions of CA1 (towards CA2). Lateral portions of the entorhinal cortex projected to caudal levels of the recipient fields and more medial parts of the entorhinal cortex projected to progressively more rostral portions of the fields.
Growth cones and axon trajectories of a sensory pathway in the amphibian spinal cord
Authors: Nordlander Ruth H. , Gazzerro John W. , Cook Holly
Published: January 2005

Central axons of sensory ganglion (SG) neurons of the Xenopus tail enter the spinal cord via the ventral roots and travel dorsally and rostrally following a diagonal course within the lateral marginal zone (LMZ) to reach the dorsolateral fasciculus (DLF) (Nordlander et al.: Brain Res., 440:391–395, 1988). Axons are dispersed as they cross the cord. At the DLF they turn and travel together rostrally, sharing the fascicle with axons of primary sensory neurons (Rohon‐Beard cells) already present in the tract. In this paper we analyze the growth patterns of the central projections of SG axons in the tail by using HRP applied to proximal branches of tail spinal nerves. Growth cones of the diagonal route are variable in configuration, often bearing processes that spread within the LMZ. Once in the DLF, growth cones change shape, becoming distinctly linear. While growth cones navigating the diagonal part of the route never contact or fasciculate with other diagonal SG axons, SG growth cones and axons of the DLF are more closely associated with their fellows. Measurements of the slopes of SG axons in the diagonal route indicated a limited range with a mean of 23° with respect to the cord axis. On the basis of these observations, we conclude that 1) navigational patterns for growth cones of this pathway differ for the diagonal versus the DLF part of its course, and 2) fasciculation is not a mechanism used by SG axons to reach the DLF, but that instead, each axon is able to find its way independently.
Primate supplementary eye field. II. Comparative aspects of connections with the thalamus, corpus striatum, and related forebrain nuclei
Authors: Shook B. L. , Schlag‐Rey M. , Schlag J.
Published: January 2005

The supplementary eye field (SEF) was defined electrophysiologically in behaving monkeys to study its connections with the diencephalon and corpus striatum. The specificity of SEF pathways was determined with horseradish peroxidase (HRP) histochemistry to compare its connections with those of the arcuate frontal eye field (FEF), contiguous dorsocaudal area 6 (6DC), and primary motor cortex (M1, arm/hand region). Results indicate that patterns of SEF connectivity were similar to the FEF and markedly different from areas GDC and Ml. Primary reciprocal thalamic pathways of the SEF were with the magnocellular ventral anterior (VA) nucleus, medial parvicellular VA, medial area X, and paralaminar medialis dorsalis (multi‐formis and parvicellularis). FEF showed similar connections but its most robust pathway was with MD rather than VA. In contrast, area 6DC showed the most extensive reciprocal connections with lateral VApc and lateral area X with only sparse connections with paralaminar MD. Area 6DC also exhibited reciprocal connections with the ventral lateral (VL) complex and the ventral posterior lateral nucleus, pars oralis (VPLo). M1 showed dense bidirectional connections with VPLo, and to a lesser extent, with VL. M1 pathways with the medial dorsal nucleus were negligible. All areas exhibited connections with the paracentral and central lateral nuclei and only M1 lacked connections with the central superior lateral nucleus.

SEF and FEF exhibited similar efferent projections to the caudate and putamen. In the caudate, terminal fields were restricted to a central longitudinal core while those from area 6DC were more widely distributed. Eye field efferents were restricted to the putamen's face region while 6DC projections were more exuberant. The arm/hand region of Ml projected to the arm/hand region of the putamen.

Pathways are discussed with respect to their significance in oculomotor control.
Neuroglial arrangements in the olfactory glomeruli of the hedgehog
Authors: Valverde Facundo , Lopez‐Mascaraque Laura
Published: January 2005

The olfactory glomeruli represent morphological and functional units in which olfactory information is processed in specialized synaptic arrangements established between the central processes of sensory neurons, whose cell bodies are located in the olfactory epithelium, and the terminal (intraglomerular) portions of the dendrites of periglomerular, tufted, and mitral cells. The olfactory glomeruli are surrounded by distinctive glial formations in which the peripheral glia interacts with the central glia. We have studied the morphology and organization of neuroglial cells in the layer of olfactory nerves and the glomerular layer of the olfactory bulb in the insectivorous hedgehog (Erinaceus europaeus) with the electron microscope, Golgi method, and immunohistochemistry by using antibodies to glial fibrillary acidic protein (GFAP) and “rip,” a monoclonal antibody that stains oligodendrocytes and their processes in the rat (Friedman et al.: Glia 2:380–390, 1989).

The peripheral glia is represented by a special category of cells that are closely related to astrocytes and known as sheathing cells. They accompany olfactory axons to their entrance in the glomeruli where they interact with the central glia, represented by astrocytes and oligodendrocytes. The sheathing cells typically display indented nuclei and protoplasmic expansions forming laminar processes wrapping several axons together. Astrocytes surrounding the glomerular neuropil belong to the velate type. They display numerous sheet‐like processes enveloping dendritic segments and periglomerular cell bodies. Oligodendrocytes were found surrounding the glomeruli and at the interstices separating different glomeruli. Myelinated dendritic segments and cell bodies were found surrounding the olfactory glomeruli. These myelin coverings probably derive from oligodendrocytes. Together with the astrocytic lamellar expansions, they provide a rigid structural support that contributes to the segregation of groups of different cells while remaining relatively isolated from other influences at the periphery of the glomeruli.
Immunocytochemistry of gamma‐aminobutyric acid, glutamate, serotonin, and histamine in Necturus taste buds
Authors: Jain S. , Roper S. D.
Published: January 2005

Little information is currently available about which neurotransmitters are involved in signal processing in the peripheral sensory organs of taste, taste buds. Synaptic contacts between taste cells and sensory axons have long been known to exist, but what substances are active at these synapses is not known. Our objective in this study was to test for the presence of the neurotransmitter candidates, GABA, glutamate, serotonin, and histamine in taste buds of Necturus maculosus. Light microscopic irnmunocytochemical techniques were used to investigate the location of these substances in taste buds and surrounding epithelium. GABA and glutamate were detected in nerve fibers that innervate the taste buds, and, to a substantially lesser extent, in fine, varicose axons that penetrated the surrounding nontaste epithelium. Serotonin immunostaining was strong in basal cells in frog taste discs but was only faintly detected in Necturus taste buds. Histamine was not detected at all in taste buds. We conclude that amino acid neurotransmission may be involved in taste mechanisms and that monoamines may also play a role in chemosensory transduction in the taste bud. On the basis of our inability to detect histamine with immunocytochemical techniques, we conclude that this substance is unlikely to be a major neurotransmitter in Necturus taste buds.
Morphology and distribution of catecholaminergic amacrine cells in the cone‐dominated tree shrew retina
Authors: Müller Brigitte , Peichl Leo
Published: January 2005

The tree shrew (Tupaia belangeri) has a cone‐dominated retina with a rod proportion of only 5%. This is in contrast to the usual mammalian pattern of rod‐dominated retinae. Rod bipolar cells are present at relatively low densities in the tree shrew retina, suggesting that a reduced, but normal, rod pathway might be preserved. The present study investigated another common constituent of the rod pathway, the dopaminergic amacrine cells, and analysed their morphology and distribution by light and electron microscopy.

Catecholaminergic (presumed dopaminergic) amacrine cells were labelled with an antibody against tyrosine hydroxylase (TH). Intense TH‐immunoreactivity was found in perikarya and dendrites of a uniform amacrine, cell population. TH‐immunoreactive amacrine cell density varies across the retina from 10 cells/mm2 in the periphery to 40 cells/mm2 in more central regions (mean cell density about 25 cells/mm2). The relatively large cell bodies are located exclusively in the innermost part of the inner nuclear layer. The dendrites form a dense plexus at the border between the inner plexiform layer and the inner nuclear layer. The finer dendritic processes contain many varicosities and form characteristic dendritic “rings” like those seen in other mammals. TH‐immunoreactive processes also run between cell bodies in the vitread inner nuclear layer; a few extend into the sclerad inner nuclear layer and occasionally reach the outer plexiform layer (possible interplexiform cells). A few TH‐immunoreactive processes are seen in the middle of the inner plexiform layer. Electron microscopy of TH‐immunoreactive processes revealed conventional synapses onto somata and processes of unlabelled amacrine cells.
Myelinated fiber regeneration after crush injury is retarded in sciatic nerves of aging mice
Authors: Tanaka Kaoru , deF. Webster Henry
Published: January 2005

To compare nerve regeneration in young adult and aging mice, the right sciatic nerves of 6‐ and 24‐month‐old mice were crushed at the sciatic notch. Two weeks later, both groups of mice were perfused with an aldehyde solution, and, after additional fixation, the sciatic nerves were processed so that the transverse sections of each, nerve subsequently studied by light and electron microscopy included the entire posterior tibial fascicle 5 mm distal to the crush site. The same level was sectioned in unoperated contralateral nerves; these nerves served as controls. Electron micrographs and the Bioquant Image Analysis System IV were used to measure areas of posterior tibial fascicles and count the number of myelinated axons, the number of unmyelinated axons, and their frequency in Schwann cell units. In aging mice, the total number of regenerating myelinated axons was significantly reduced, but totals of regenerating unmyelinated axons in aging and young adults did not differ significantly. In aging mice, the frequency of Schwann cells that contained a single unmyelinated axon was greater, suggesting that before myelination began, Schwann cell ensheathment of axons also was slowed. After axotomy by a crush injury, the area of the posterior tibial fascicle was less than that in young adults and the distal disintegration of myelin sheath remnants also appeared to be retarded. The results indicate that responses of neurons, axons, and Schwann cells could be important in slowing the regeneration of myelinated fibers found in sciatic nerves from aging mice.
Calcitonin gene‐related peptide (CGRP) immunoreactive projections from the thalamus to the striatum and amygdala in the rat
Authors: Yasui Yukihiko , Saper Clifford B. , Cechetto David F.
Published: January 2005

The organization of calcitonin gene‐related peptide‐like immunoreactive (CGRPir) innervation of the amygdala and caudate‐putamen in the rat was examined by using immunohistochemistry for CGRP combined with retrograde transport of the fluorescent dye fluoro‐gold, as well as anterograde transport of Phaseoleus vulgaris leucoagglutinin (PHA‐L).

The lateral part of the central nucleus of the amygdala and the amygdalostriatal transition zone was densely innervated by CGRPir terminals at all anterior‐posterior levels. More caudally, the lateral part of the caudate‐putamen also had large numbers of CGRPir terminals. Injections of fluoro‐gold into the amygdala and amygdalostriatal transition area followed by immunohistochemistry for CGRP revealed double‐labeled neurons in the subparafascicular, lateral subparafascicular, and posterior intralaminar nuclei of the thalamus and peripeduncular nucleus. Injections into the caudate‐putamen demonstrated double‐labeled neurons in the more lateral parts of this same nuclear complex.

PHA‐L injections into the posterior thalamic nuclei from which the CGRPir projections arise confirmed the medial‐to‐lateral organization of the projections to the amygdala and striatum. The subparafascicular nucleus and the rostral portion of the lateral subparafascicular nucleus primarily projected to the medial amygdala and the amygdalostriatal transition area, while the more lateral cell groups, including the caudal part of the lateral parafascicular, posterior intralaminar, and peripeduncular nuclei projected to the lateral amygdala and the caudate‐putamen. These CGRPir projections may be involved in mediating conditioned autonomic and behavioral responses to acoustic stimuli or somatosensory stimuli.
Reidentification of larval interneurons in the pupal stage of the tobacco hornworm, Manduca sexta
Authors: Sandstrom David J. , Weeks Janis C.
Published: January 2005

The abdominal prolegs are the primary locomotory appendages of Manduca sexta larvae. After the prolegs are lost at pupation, some of the proleg motoneurons die while the survivors are respecified to carry out different functions in the adult moth. As a first step toward investigating the process of functional respecification at the synaptic level, we searched for larval interneurons that affected the activity of proleg motoneurons, and followed these interneurons into the pupal stage. Interneurons were judged to be individually identifiable based on their effects on proleg motoneuron activity and their anatomical features. Seven larval interneurons were identified and placed in five physiological classes based on their effects on proleg motoneurons: ipsilateral excitors, contralateral exciters, ipsilateral inhibitors, contralateral inhibitors, and bilateral inhibitor‐excitors. Four of the larval interneurons produced apparently monosynaptic postsynaptic potentials in proleg motoneuron. Of the five larval interneurons that were reidentified in the early pupal stage, two showed minor but consistent structural modifications from the larval stage. Interneurons that produced unitary postsynaptic potentials in larval motoneurons continued to do so in pupal motoneurons. These studies demonstrate that individually identified interneurons can be followed through the larval‐pupal transformation, during the initial stages of motoneuron respecification.
Histochemical demonstration of zinc in the hippocampal region of the domestic pig: III. The dentate area
Authors: Holm Ida E. , Geneser Finn A.
Published: January 2005

The distribution of zinc was described in the dentate area, a part of the hippocampal region, of the domestic pig. A modification of Timm's sulphide silver procedure, the Neo‐Timm method, was used for the histochemical demonstration of zinc. The staining of the dentate area exhibited a well‐defined stratified pattern, the predominant part of the staining being restricted to the neuropil, although weakly stained nerve cell bodies were observed in the hilus fasciae dentatae.

In the molecular layer, three distinct sublaminae were seen at most septotemporal levels. The outer and inner sublaminae displayed medium staining intensity, whereas the intermediate sublamina appeared extremely pale. The granular cell layer was well stained in its superficial two thirds, because of dense masses of staining occupying the interstices between the unstained granular cells. In the hilus fasciae dentatae, extreme differences in staining intensity were seen between the layers, ranging from very intense staining of the outer hilar cell layer to generally weak staining of the inner plexiform layer.

The distribution of zinc in the pig was compared with that in the guinea pig and rat, described previously. The staining pattern of the molecular layer showed striking species differences, whereas the granular cell layer appeared very near identical. The stratified staining pattern seen in the hilus of the pig is very similar to the distribution observed in the guinea pig, but differs from the essentially homogeneous staining of the rat hilus. However, the differences in hilar staining pattern between the pig and guinea pig on the one hand and the rat on the other essentially display variation in the cytoarchitectural organization of the hilus, rather than expressing a true species difference.
Musculotopic organization of the hypoglossal nucleus in the grass frog, Rana pipiens
Authors: Sokoloff Alan J.
Published: January 2005

Recent neural tracer studies in several mammalian species have demonstrated a similar musculotopic organization of the hypoglossal motoneurons which innervate individual tongue muscles. The distribution of this musculotopic organization in nonmammalian tetrapods, however, has not received detailed investigation. As part of an ongoing study on the comparative organization of the vertebrate hypoglossal nucleus, the musculotopic organization of the hypoglossal nucleus of Rana pipiens was studied by injection of lectin‐conjugated horseradish peroxidase into four distinct tongue muscles and the geniohyoid muscle. Injections into the hyoglossus muscle label neurons in dorsal regions of the hypoglossal nucleus in middle and rostral nucleus levels. Injections into the genioglossus basalis muscle label neurons in ventral and lateral regions of the hypoglossal nucleus in caudal nucleus levels. Injections into the genioglossus medialis muscle label neurons in dorsal regions in caudal levels, throughout the nucleus in middle levels, and in ventral regions in more rostral levels. Injections into the geniohyoid muscle label neurons in the ventral tip of the hypoglossal nucleus and in the ventromedial corner of the medullary gray matter in middle and rostral nucleus levels. These results demonstrate that the organization of the hypoglossal nucleus in Rana pipiens is more complex than previous tracer studies indicated. Similarities in the musculotopic organization of the amphibian and mammalian hypoglossal nuclei suggest an evolutionary conservatism of the motor system controlling tongue movement.
A golgi study of dendritic development in the dorsal lateral geniculate nucleus of normal ferrets
Authors: Sutton J. Keith , Brunso‐Bechtold Judy K.
Published: January 2005

The development of neurons in the dorsal lateral geniculate nucleus (dLGN) of pigmented ferrets was studied by using the Golgi‐Hortega technique. In adult ferrets, four dLGN cell classes were defined on the basis of somatic and dendritic morphology. Classes 1 and 2 were divided into stellate and oriented subtypes. Class 1 and 4 cells are characterized by filiform appendages, class 2 cells by club‐like appendages, and class 3 cells by stalked appendages. At birth, dLGN neurons have simple dendritic arbors. During the first postnatal week, dendritic length and proximal branching density increase markedly. By postnatal day 21 (P21), dendritic morphology begins to take on mature characteristics and by the time of eye opening (P30‐P35), most neurons can be classified. Also by that time, dLGN cells are covered with abundant filiform appendages. Developmental changes in appendage density were quantified for class 1 stellate cells. These data reveal that appendage density reaches a peak at P56, decreases sharply until P90, and then gradually declines to mature levels by P180. Elaboration and elimination of transient appendages occurs centrifugally; at maturity appendage density remains greater distally.