bluuebunny/crossref_metadata_2025 huggingface dataset:
Periterminal synaptology of dorsal root glomerular terminals in the substantia gelatinosa of the spinal cord in the rhesus monkey
Authors: Knyigar‐Csillik E. , Csillik B. , Rakic Pasko
Published: December 2004

The synaptic glomerular complexes surrounding dorsal root terminals in the substantia gelatinosa were reconstructed from six sets of 50–140 gapless ultrathin serial sections prepared in the transverse plane of the spinal cord in adult rhesus monkeys. All three types of glomeruler terminals described in the preceding paper (Knyihar‐Csillik et al., 1982) were identified: (1) DSA (endings of superificial collaterals); (2) LDCV (endings of marginal collaterals); and (3) RSV (endings of deep collaterals). Each type of terminal forms a glomerular complex which invariably includes presynaptic dendrites which are intercalated between primary terminals and the postsynaptic (conventional) dendrite. Since the latter also receives direct input from the primary sensory terminal the synaptic organization assumes triadic arrangements, suggesting that primary afferent impulses my be subjected to a postsynaptic modulation through inhibitory action of presynaptic dendrites.

In glomeruli with DSA as the central element, several triadic systems are usually interrelated, possibly as a structural basis for prolonged retardation of impulses. Adjacent glomeruli, containing DSA and LDCV terminals, are coupled together by a series of triadic systems fed by DSA terminals enabling association between superficial and marginal collaterals. RSV terminals are presynaptic to somata and dendrites of substantia gelatinosa cells that presumably exert inhibition upon terminals of all three kinds of primary sensory collaterals. In addition RSV terminals are postsynaptic to numerous F boutons which presumably derive mainly from axons of substantia gelatinosa cells; similar F boutons impinge upon presynaptic and other dendrites surrounding DSA terminals. The Complicated but orderly synaptic architecture of these three types of primary afferents may be regarded as a structural basis for first‐order analysis and modulation of the nociceptive information within the primate central nervous system.
The organization of monoamine‐containing neurons in the brain of the salamander, Necturus maculosus
Authors: Dubé Lorraine , Parent André
Published: December 2004

The organization of monoamine (MA)‐containing neuronal systems in the brain of the salamander (Necturus maculosus) was studied by means of paraformaldehyde and glyoxylic acid histofluorescence methods. The MA neurons were further characterized morphologically andhistochemically in material prepared for the demonstration of cholinesterase activity.

In the brain ofNecturus, the most caudally located catecholamine (CA)‐containing cells occur in the nucleus of the solitary tract. A large population of serotonin (5‐HT)‐containing cells is also found along the entire rostrocaudal extent of the raphe region of the brainstem. At isthmal levels, a few scattered CA cells lie dorsolaterally in the so‐called acousticolateral area. These neurons can be seen to send axonal projections to the spinal cord and the cerebellum, but not to the telencephalon, and thus can not be considered as fully homologous to the locus coeruleus of reptiles, birds, and mammals. Within the midbrain, some cells displaying a strong CA fluorescence and staining intensely for cholinesterases are present near the oculomotor nerve root fibers. They give rise to a long ascending fiber system arborizing in the striatum, and this system appears homologous to the mesostriatal CA pathway of amniotic vertebrates. At diencephalic levels a multitude of CSF‐contacting cells of both CA and 5‐HT types occurs. They abound particularly in the ventral thalamus, along the infudibular recess, in the dorsal infundibular nucleus, and in the ventral thalamus. As a whole, this population of CSF‐contacting MA cells is considered homologous to the paraventricular organ present in all nonmammalian vertebrates. Some CA cells also occur along the preoptic recess, around the hippocampal commissure, and even within the caudalmost aspect of the medial pallium. The presence of CA cell bodies among telencephalic cell groups has not been demonstrated in other vertebrates. The heaviest CA innervation in the telencephalon is found in the neuropil of the corpus striatum and in the “prominentia ventralis” (nucleus accumbens septi), both of which also stain significantly for cholinesterases. Finally, numerous CA cells are scattered throughout the magnocellular, molecular, and granular cell layers of the olfactory bulb. These cells provide a strong CA innervation to the glomerular layer of the bulb which also exhibits a high cholinesterase activity seemingly derived from the processes ofperiglomerular cells. Thus, the pattern of organization of MA systems in Necturus appears unique in many aspects, but it also displays striking similarities to the arrangement of brain MA neurons disclosed in other vertebrates.
The cytoarchitecture of the dorsal cochlear nucleus in the 3‐month‐ and 26‐month‐old C57BL/6 mouse: A golgi impregnation study
Authors: Browner Robert H. , Baruch Alice
Published: December 2004

The cytoarchitecture of the dorsal cochlear nucleus (DCN) was compared in 3‐ and 26‐month‐old C57BL/6 mice. The effects of genetically controlled progressive hearing loss present in the CNS in this mouse strain were analyzed with Nissl‐stained and Golgi‐impregnated material. The DCN was divided into the superficial molecular, an intermediate fusiform‐granule, and the deep polymorphic layers. The molecular layer (ML) consisted of many fibers and a few small ovoid to spherical, fusiform, and granule cells. The fusiform‐granule layer (FL) contained large fusiform and many granule cells. Most FL fusiform cells were oriented with their long axes perpendicular to the DCN surface and were present as small aggregations or individually. Cartwheel cells were adjacent to the FL fusiform cells. The deep polymorphic layer (PL) contained spherical, fusiform, granule, and multipolar neurons. The granule cells formed a dorsal cap of the DCN. From this cap, sheets of granule cells separated the DCN from the posterior ventral cochlear nucleus (PVCN) and from the brainstem.

The internal organization, neuronal location, orientation, and morphology were similar in both age groups. The granule cells had four to five primary dendrites, varicosities, and few to no dendritic appendages. The FL fusiform cells displayed different dendritic morphology in the two ages. One or two elaborate primary ML apical dendrites in the 3‐month‐old mice were covered with spikelike dendritic spines. The basal one or two PL dendrites were less elaborate and had few dendrite spines. In contrast, FL fusiform neurons in 26‐month‐old mice had regular dendritic varicosities and fewer spines which were short and stumpy. Basal dendrites had varicosities and interruptions. Cartwheel neurons in 3‐month‐old mice had elaborate ML dendritic trees covered with dendritic spines. In 26‐month‐old mice the dendrites had many varicosities and fewer short blunted dendritic spines. Large multipolar neurons in older mice had thinner dendrities with more varicosities than were in the 3‐mcnth group. In both age groups multipolar cells had few dendritic spines limited distally. Small and large spherical cells had two to five primary dendrites with varicosities, little higher‐order branching, and spines. Fusiform cells had one or two primary dendrites, little secondary branching, and few to no spines. Minor degenerative changes were noted in spherical and fusiform cells in the two age groups. These included dendritic varicosities, interruptions, and some irregularities of somata surface. Degenerative changes present in the cochlea had significant effects on a limited population of DCN neurons. Finally, the neusronal morphology and architecture of the DCN in C57BL/6 mouse is similar to other mammalian species.
Studies of retinal representations within the cat's optic tract
Authors: Torrealba F. , Guillery R. W. , Eysel U. , Polley E. H. , Mason C. A.
Published: December 2004

The manner in which each retina can be mapped onto a single cross section of the optic tract of the cat has been defined by neuroanatomical methods. It has been found that the contralateral nasal hemi‐retina and both temporal hemi‐retinae are represented in each tract by multiple, rough maps which partially overlap one another. All maps show the same general orientation, with area centralis represented dorsomedially, lower retina represented dorsolaterally, and upper retina represented ventromedially. The peripheral part of the horizontal meridian is represented ventrolaterally.

Labeling all of the fibers from one eye by axonal degeneration or autoradiographic methods shows that the crossed map is displaced dorsally and medially relative to the uncrossed map, leaving a dorsomedial crescent of pure crossed fibers. Localized retinal lesions or injections of 3H‐amino acid show the general orientation of the maps. Lesions within the dorsomedial pure crossed crescent show that fibers in this crescent arise from retinal areas close to the optic disc, near the site of the early fetal fissure. Localized injections of horseradish peroxidase into the optic tract show the relationships of the several maps in terms of the retinal distribution of retrogradely labeled retinal ganglion cells. They show that axons of large and small cells map ventrolaterally in the tract while intermediate sizes map dorsomedially. They confirm that the crossed map is displaced relative to the uncrossed map.

It is suggested that the optic tract develops by fibers taking a position in the tract in accordance with their time of arrival at the chiasm. The several maps are displaced because they develop sequentially and the optic tract can be read as a developmental record, the most dorsomedial axons being the oldest.
The origin of lipid phagocytes in the central nervous system: II. The adventitia of blood vessels
Authors: Brierley J. B. , Brown A. W.
Published: December 2004

The source of the lipid phagocytes that occupy a cerebral infarct has been determined by light and electron microscopy in the brains of rodents and by light microscopy only in the brains of primates. The infarcts (in neocortex, hippocampus, and thalamus) were the consequence of hypoxiaischemia of various types. Hemorrhagic infarcts were excluded. After in vivo perfusion‐fixation, paraffin‐ and celloidin‐embedded material was used for light microscopy. Semithin plastic sections from the neocortex and thalamus were studied with the light microscope and ultrastructural studies were confined to the same regions.

In all animals after about 2 days there was evidence of phagocytic activity in the fibroblasts in the adventitia of the remaining large vessels and also proliferation by mitotic division. At 5‐7 days fibroblasts appeared to migrate from the vessels in a semifluid or fluid milieu and to give rise to typical phagocytes. These increased in size and number but signs of degeneration became apparent after 10 days and they had largely disappeared by 32 days. Smooth muscle cells and pericytes showed evidence of degeneration and phagocytic activity was never seen in the latter.
Quantitation of propriospinal fibers in the tract of lissauer of the rat
Authors: Chung Kyungsoon , Coggeshall Richard E.
Published: December 2004

The present study uses a spinal cord isolation procedure to remove extrinsic axons but leave intrinsic axons intact. The isolation is done by sectioning the spinal cord in two places and then cutting all dorsal roots between the two sections. The axons that survive the isolation procedure are thought to be propriospinal axons. Following isolation, approximately one‐third of the axons in sacral tracts of Lissauer in the rat survive. Thus approximately one‐third of the axons in sacral tracts of Lissauer in the rat are propriospinal. Proportionately more myelinated than unmyelinated axons are lost. There are approximately equal numbers of surviving axons in the medial as opposed to the lateral part of the tract. This implies that there is, as yet, no morphological basis for dividing the tract into medial and lateral halves. The fact that the number of propriospinal axons in the tract of Lissauer has been quantitated offers more precision in our thinking about the organization of the dorsal horn.
Insula of the old world monkey. III: Efferent cortical output and comments on function
Authors: Mesulam M.‐Marsel , Mufson Elliott J.
Published: December 2004

The insula sends neural efferents to cortical areas from which it receives reciprocal afferent projections. A collective consideration of afferents and efferents indicates that the insula has connections with principal sensory areas in the olfactory, gustatory, somesthetic (SI and SII), and auditory AI and AII) modalities. There are additional connections with association areas for the visual (TEm), auditory (supratemporal plane), and somesthetic (posterior parietal cortex) modalities; with parameter cortex (area 6 and perhaps MII); with polymodal association cortex; and with a wide range of paralimbic areas in the orbital, temporopolar, and cingulate areas.

The topographic distribution of these connections suggests that the posterodorsal insula is specialized for auditory‐somesthetic‐skeletomotor function whereas the anteroventral insula is related to olfactory‐gustatory‐autonomic function. Most of the insula, especially its anteroventral portions, have extensive interconnections with limbic structures. Through its connections with the amygdala, the insula provides a pathway for somatosen‐sory, auditory, gustatory, olfactory, and visceral sensations to reach the limbic system.

The cortical areas connected with the granular sector of the insula are also granular in architecture whereas virtually all the connections of the agranular insula arise from allocortical, agranular, or dysgranular areas. Thus, there is a correspondence between the architecture of insular sectors and the areas with which they have connections. The insula is heavily interconnected with temporopolar and lateral orbital areas. Furthermore, many cortical connections of the lateral orbital cortex are quite similar to those of the insula. These common connectivity patterns support the conclusion, based on architectonic observations, that the insulo‐orbito‐tempo‐ropolar component of the paralimbic brain should be considered as an integrated unit of cerebral organization.
Origins of substance P‐containing fibers in the lateral septal area of young rats: Immunohistochemical analysis of experimental manipulations
Authors: Sakanaka Masahiro , Shiosaka Sadao , Takatsuki Kenichi , Inagaki Shinobu , Hara Yoshinobu , Kawai Yuriko , Senba Emiko , Tohyama Masaya
Published: December 2004

The majority of substance P‐like immunoreactive (SPLI) fibers in the lateral septal area (LS) are supplied by SPLI cells in the area (BAL between the anterior hypothalamic nucleus and the lateral hypothalamus, and by those in the nucleus latero‐dorsalis tegmenti (TLD)). These conclusions are based on following: (1) Unilateral destruction of the BAL resulted in an ipsilateral decrease in the septal SPLI fibers similar to that seen after the destruction of the TLD, and (2) simultaneous destruction of the BAL and TLD caused a marked reduction of SPLI fibers in the LS on the operated side. The possibility that the destruction of the BAL affected the ascending SPLI system from the TLD seems to be excluded, because (1) the destruction of the TLD resulted in a decrease in SPLI fibers in the ipsilateral medial forebrain bundle (MFB), but failed to reduce the number of SPLI fibers in the BAL, and (2) the destruction of the BAL caused a decrease in SPLI fibers in the perifornical area rostral to the lesion, but failed to reduce the number of SPLI fibers in the MFB. These facts further suggest that ascending SPLI fibers from the BAL travel in the perifornical area and those from the TLD pass through the MFB. It should be noted that a few SPLI fibers remained intact following the simultaneous destruction of the BAL and TLD. The present study suggests that these remaining SPLI fibers might be innervated by intrinsic SPLI cells. In support of this, several SPLI cells were detected in the septal area after colchicine pretreatment.
Pathways connecting the right and left cochlear nuclei
Authors: Cant Nell B. , Gaston Karen C.
Published: December 2004

Connections between the right and left cochlear nuclei were studied with retrograde and anterograde axonal transport techniques. Large, multipolar neurons in the anterior and posterior divisions of the anteroventral cochlear nucleus and in the posteroventral cochlear nucleus project to the ventral and dorsal cochlear nuclei on the opposite side. In addition, giant cells in the deep layers of the dorsal cochlear nucleus project to the contra‐lateral posteroventral cochlear nucleus and possibly also to the contralateral dorsal cochlear nucleus. The pattern of terminal distribution of the crossed connections was determined by using the anterograde axonal transport of horseradish peroxidase‐labelled wheat germ lectin. Although no part of the cochlear nuclear complex is completely free of anterograde label, the densest labelling is found in the anterior division of the anteroventral cochlear nucleus, throughout the posteroventral cochlear nucleus (where it is closely associated with cell bodies), and in the fusiform and superficial layers of the dorsal cochlear nucleus.

These direct synaptic connections from one cochlear nucleus to the other could play a significant role in processes that depend on binaural interactions within the central nervous system.
Bilateral interactions within the vocal control pathway of Birds: Two evolutionary alternatives
Authors: Paton J. A. , Manogue K. R.
Published: December 2004

Bilateral interactions between the right and left sides of the vocal control pathway of three avian species, the budgerigar (Melopsittacus undulatus), the zebra finch (Poephila guttata), and the canary (Serinus can‐arius), were compared by using microstimulation. Stimulation of the neo‐striatal nucleus, hyperstriatum ventrale pars caudale (HVc), caused a constant‐latency increase in neural activity of the tracheosyringeal (ts) nerve. This nerve supplies the avian vocal organ, the syrinx.

Unilateral stimulation of HVc in budgerigars caused equal responses in both right and left ts nerves, whereas in canaries and zebra finches, much larger responses with lower thresholds and shorter latencies were evoked in the ipsilateral ts nerve than in the contralateral ts nerve. Furthermore, contralateral responses in the oscines were seen only at high rates of stimulation, whereas ipsilateral responses could be evoked by a single stimulus pulse.

Simultaneous bilateral stimulation of HVc in budgerigars evoked a greater than linear summation of responses on each ts nerve, evidence for convergence of ipsi‐ and contralateral inputs onto the same set of motor neurons. No such summation was detected in zebra finches or canaries.

The bilateral distribution of excitation within the song control pathway of budgerigars should lead to coactivation of bilaterally paired muscles on each side of the syrinx. This type of interaction should ensure that the two sides of the parrot syrinx operate as parts of a unitary, or single‐voiced, syrinx. In contrast, the two sides of the song control pathway in canaries and zebra finches are almost completely isolated from each other, and are thus free to act independently. This type of organization lends itself to the separate control of simultaneously produced, harmonically unrelated sound elements by the two independent sound sources present in the songbird's two‐voiced syrinx.
Structure of the mitral cell in the olfactory bulb of the goldfish (Carassius auratus)
Authors: Kosaka Toshio , Hama Kiyoshi
Published: December 2004

The mitral cell in the olfactory bulb of the goldfish was examined by means of light microscopy, high‐voltage electron microscopy, and conventional electron microscopy.

Mitral cells are located rather diffusely throughout the glomerular and plexiform layers. They do not make their own discrete layer. The cell bodies are rounded or triangular, and are about 10–25 μm in diameter. In Golgi‐impregnated material, thick cylindrical dendrites can be seen arising from the cell bodies and branching in the glomerular layer. Dendritic branches of some cells make two or more rather compact tufts, while the dendrites of other cells intermingle loosely with one another.

In semithin and thin sections, darkly stained nodules appear to be scattered diffusely in the glomerular layer without clustering into discrete spheres, which are characteristic of the mammalian glomerulus. Hence, instead of the glomerulus, the “glomerular area” is defined as an area consisting of darkly stained nodules with rather pale granular regions surrounding them. Branches of mitral cell dendrites in the glomerular area consist of cylindrical shafts and irregular appendages arising from them. The shafts appear in the pale granular region and the appendages are found in the darkly stained nodules.

Synapses can be found on all parts of the mitral cell: the soma, axon hillock, axon initial segment, thick dendritic stems, and dendritic branches. The abundance of synapses seems to vary considerably from part to part, and is highest on the dendritic branches in the glomerular area. The mitral cell is postsynaptic to olfactory nerve terminals and granule cell dendrites, and presynaptic to granule cell dendrites and some processes of unknown origin. Olfactory nerve terminals make asymmetrical synapses specifically on the appendages of the dendritic branches. Of the synapses on the shafts of the mitral cell dendritic branches in the glomerular area, 90% are with granule cell dendrites. Of the synapses between two different kinds of processes 30% are mitral‐to‐granule asymmetrical synapses, 20% are granule‐to‐mitral symmetrical synapses, and 50% are reciprocal pairs. Gap junctions and mixed synapses are also seen on branches of mitral cell dendrites.

Features of the goldfish mitral cell are compared with those of the mammal. The differences in neuronal organization between the olfactory bulbs of teleosts and mammals are discussed.
The structural correlate of saltatory conduction along the mauthner axon in the tench (Tinea tinea L.): Identification of nodal equivalents at the axon collaterals
Authors: Yasargil Guenay M. , Greeff Nikolaus G. , Luescher Hans R. , Akert Konrad , Sandri Clara
Published: December 2004

The spiny collaterals of the Mauthner axon were reinvestigated in the tench (Tinea tinea L.) with the electron microscope and special staining procedures. These collaterals, as demonstrated by intraaxonal labelling with lucifer yellow, are more or less regularly spaced (100–300 μm) and make synaptic contacts with processes of spinal motoneurons and interneurons. The unrnyelinated tips of the collaterals are further characterized by the following structural features: (1) an electron‐dense undercoating of the axolemma, (2) a positive Prussian blue reaction of the inner surface of the axolemma following ferric ion‐ferrocyanide staining (Waxman and Quick, '78a), (3) expanded extracellular spaces which react specifically to inorganic phosphate, metallic ions, and diaminobenzidine. All these properties are known to be shared by the axolemma of central and peripheral nodes of Ranvier. Previous studies from this laboratory have shown that the nerve impulse is propagated along the Mauthner axon in a saltatory mode. Since classical nodal gaps could not be identified within the myelin sheath of this giant fiber, it is concluded on the basis of the present findings that the unrnyelinated tips of the spiny collaterals represent nodal equivalents, and thus provide the morphological substrate for the saltatory propagation of the nerve impulse along the Mauthner axon. The typical latency steps, as demonstrated in the latency plot of the longitudinal current signals (Greeff and Yasargil, '80), and the distances between the identified membrane specializations at the axon collaterals are consistent with this conclusion.
The distribution of dorsal root axons to laminae IV, V, and VI of the macaque spinal cord: A quantitative electron microscopic study
Authors: Ralston Henry J. , Ralston Diane Daly
Published: December 2004

The projections of dorsal root axons to the deeper laminae (IV, V, and VI) of the Macaque spinal cord were examined by the use of experimentally induced degeneration following dorsal rhizotomy or by injection of dorsal root ganglia with tritiated amino acids followed by light and electron mi‐croscopic autoradiography.

Following dorsal rhizotomy, neurofilamentous degeneration of synaptic profiles occurs in each of the three deep laminae, more commonly in laminae IV and V than in lamina VI. The neurofilamentous degeneration is seen both in central glomerular (C) profiles and in many of the round vesicle (R) profiles. Neurofilamentous degeneration occurs as early as 18 hours following rhizotomy and the degenerating terminals are most numerous at 3–4 days postrhizotomy. None are seen after 7 days survival. The neurofilamentous profiles form axodendritic and, occasionally, axosomatic synapses with neurons of the dorsal horn. They are also seen to be postsynaptic to flat vesicle (F) profiles in axoaxonal synapses.

A second type of degeneration, electron‐lucent degeneration, is seen in laminae V and VI, and only occasionally in lamina IV. The lucent degeneration occurs somewhat later after rhizotomy than does the neurofilamentous degeneration and reaches its peak at 5 days postrhizotomy. No lucent terminals are seen after 7 days survival. Electron‐dense degeneration, so common in lamina II, is not seen in the deeper dorsal horn.

Autoradiographic techniques show that both C and R terminals are labelled in the deeper dorsal horn. Both of these terminals form axodendritic synapses and a significant number are found to be postsynaptic in axoaxonal synapses.

Most of the C terminals degenerate following rhizotomy or are labelled following injection of the parent dorsal root ganglia with tritiated amino acids. Approximately one‐fifth of the R profiles are derived from dorsal roots. F profiles do not appear to be of dorsal root origin in any case.

It is concluded that neurofilamentous alterations represent the degeneration of larger‐diameter (Aβ) axons which distribute to the deeper dorsal horn and that electron‐lucent degeneration represents the termination of Aδ fibers. Electron‐dense degeneration thought to represent the termination of nonmyelinated axons (C fibers) in the superficial dorsal horn is not seen in the deeper dorsal horn and it is concluded that C fibers do not project to the deeper laminae.
Subcortical projections to lateral geniculate and thalamic reticular nuclei in the hooded rat
Authors: Mackay‐Sim Alan , Sefton Ann Jervie , Martin Paul R.
Published: December 2004

Restricted injections either of horseradish peroxidase conjugated with wheat germ agglutinin, or of unconjugated horseradish peroxidase were made into hooded rats in order to distinguish subcortical sources of afferents to dorsal lateral geniculate nucleus from those to the adjacent visually responsive thalamic reticular nucleus, which modulates geniculate activity. Five “nonvisual” brainstem regions project to the dorsal lateral geniculate nucleus: mesencephalic reticular formation, dorsal raphe nucleus, periaqueductal gray matter, dorsal tegmental nucleus, and locus coeruleus. Projections are generally bilateral, but ipsilateral projections dominate. Of these regions, three also project ipsilaterally to the thalamic reticular nucleus: mesencephalic reticular formation, periaqueductal gray matter, and dorsal tegmental nucleus.

Similar discrete injections of horseradish peroxidase into ventral lateral geniculate nucleus allowed a comparison of afferents to dorsal and ventral lateral geniculate nuclei. In addition to the five nonvisual brainstem regions which project to the dorsal division, the ventral lateral geniculate nucleus receives afferents from the perirubral reticular formation and the central gray matter at the thalamic level. The dorsal and ventral lateral geniculate nuclei receive substantially different afferents from subcortical visual centres. The dorsal division receives projections from superior colliculus, pretectum, and parabigeminal nucleus whereas the ventral division receives afferents from superior colliculus, additional pretectal nuclei, lateral terminal nucleus of the accessory optic system, and the contralateral ventral lateral geniculate nucleus.
Local cerebral glucose consumption in the rat. I. Effects of halothane anesthesia
Authors: Savaki Helen. E. , Desban Marcel , Glowinski Jacques , Besson Marie‐Jo
Published: December 2004

Rates of cerebral glucose utilization were measured by means of the autoradiographic 2‐deoxy‐D‐(l‐14C)glucose technique in normal rats under light halothane‐anesthesia. Three types of region‐specific metabolic alterations were elicited by inhalation of 0.5% halothane. The most striking effect observed was a significant increase of glucose consumption within the locus coeruleus, substantia nigra compacta and reticulata, interpeduncular nucleus, hippocampus, and fornix of the anesthetized animals in comparison to the corresponding brain areas of the conscious control rats. Halothane‐anesthesia was also associated with significant metabolic depression in 21 (out of the 74 examined) discrete regions of the rat brain, distributed within the pons, cerebellum, diencephalon, and cortex, and was more prevalent in thalamus and neocortex. However, halothane failed to alter consistently the rates of glucose utilization in the rest of the rat brain areas investigated. The present findings suggest that halothane specifically alters the regional cerebral glucose utilization, with some limbic system components and the basal ganglia displaying increased metabolism, in contrast to the sensori‐motor system which demonstrates significantly decreased metabolic activity.
Local cerebral glucose consumption in the rat. II. Effects of unilateral substantia nigra stimulation in conscious and in halothane‐anesthetized animals
Authors: Savaki Helen E. , Desban Marcel , Glowinski Jacques , Besson Marie‐Jo
Published: December 2004

The energy metabolism of 74 anatomically discrete central nervous structures was investigated by means of the autoradiographic 2‐deoxy‐D‐(1‐14C) glucose method (14C‐DG) in conscious awake, as well as in halothane anesthetized rats, following unilateral substantia nigra (SN) electrical stimulation.

All the basal ganglia structures displayed bilateral metabolic activation in conscious animals, with only the contralateral subthalamic nucleus being unaffected. In anesthetized rats only the SN reticulata, globus pallidus, and subthalamic nucleus were affected ipsilaterally whereas anesthesia masked the effects of SN stimulation in SN compacta and striatum ipsilaterally, as well as within‐all the above structures contralaterally. The entopeduncular nucleus was bilaterally activated no matter the state of consciousness. Unilateral SN stimulation also increased glucose utilization within several thalamic regions (ventromedial, ventrolateral, ventroanterior, intralaminar, ventrobasal, and mediodorsal nuclei), the habenular complex, a few mesencephalic, brainstem (locus coeruleus and dorsal raphe) and cerebellar structures, mostly bilaterally and independently of the state of consciousness.

Some of the factors suggested to be responsible for the masking effects of halothane‐anesthesia on the metabolic activations elicited by unilateral SN stimulations are the following: (1) absence of movements in anesthetized rats, (2) halothane‐induced depression of polysynaptic pathways mostly mediated through the thalamus, and (3) the stimulatory effect of halothane‐anesthesia itself on metabolic activity in both parts of the SN.
A type of aspiny neuron in the rat neostriatum accumulates [3H]γ‐aminobutyric acid: Combination of golgi‐staining, autoradiography, and electron microscopy
Authors: Bolam J. P. , Clarke D. J. , Smith A. D. , Somogyi P.
Published: December 2004

Light microscopic autoradiography was used to identify cells in the neostriatum that became labelled after the local injection of [3H]γ‐amino‐butyrate (GABA). The GABA‐accumulating cells comprised up to 15% of the total population of neurons. Thirty‐seven of these cells were examined in the electron microscope and it was found that they all had similar cytological characteristics, i.e., prominent nuclear indentations, a moderate volume of cytoplasm, rich in organelles, and sparse synaptic input to the perikaryon. Nine of the cells that had accumulated GABA were also impregnated following Golgi staining. These Golgi‐impregnated neurons were of medium size and all had dendrites that were aspiny, often varicose, and that occasionally followed a recurving path. After gold toning, the Golgi‐impregnated, GABA‐accumulating neurons were examined in the electron microscope and were found to receive boutons forming symmetrical or asymmetrical synaptic contacts on their somata and dendrites; the symmetrical synapses were most common on the cell body and proximal dendrites, while the distal dendrites mainly received boutons forming asymmetrical contacts.

We conclude that one type of GABAergic neuron in the neostriatum is a type of medium‐sized aspiny neuron and that this neuron is likely to receive synaptic input both from neurons within the striatum and from neurons in distant brain regions. We suggest that this neuron is a local circuit neuron in the neostriatum since its morphological features are quite distinct from those of identified projecting neurons.
Topological analysis of the brainstem of the reedfish, Erpetoichthys calabaricus
Authors: Nieuwenhuys Rudolf , Oey P. Liam
Published: December 2004

The ventricular sulcal pattern and the cellular structure of the brainstem of the reedfish Erpetoichthys calabaricus were studied in transversely cut Nissl‐, Klüver‐Barrera‐, and Bodian‐stained serial sections. Six longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, the sulcus medianus superior, and the sulcus lateralis mesencephali could be distinguished. A seventh groove, the sulcus isthmi, clearly deviates from the overall longitudinal pattern of the other sulci. Although in Erpetoichthys most neuronal perikarya are contained within a diffuse periventricular gray, 32 cell masses could be delineated; six of these are primary efferent or motor nuclei, seven are primary afferent or sensory centers, nine are considered to be components of the reticular formation, and the remaining ten may be interpreted as “relay” nuclei.

In order to study the zonal pattern of the brainstem, this structure was subjected to a topological analysis (cf. Nieuwenhuys, '74 and Fig. 15) which yielded the following result. In the rhombencephalon the gray matter is arranged in four longitudinal columns or areas termed area ventralis, area intermedioventralis, area intermediodorsalis, and area dorsalis. In many places the sulcus intermedius ventralis, the sulcus limitans, and the sulcus intermedius dorsalis mark the boundaries between these morphological entities. These longitudinal areas coincide largely, but not entirely, with the so‐called functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the nucleus of the solitary tract, three nonviscerosensory cell masses, namely, the nucleus vestibularis magnocellularis and parvocellularis and the nucleus of the tractus descendens of V. The four longitudinal zones cannot be distinguished in the mesencephalon nor can the sulcus limitans be recognized here. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extreme of the somatomotor column, whereas the remainder of the midbrain contains a number of somatosensory centers.
Anterograde transneuronal degeneration in the ectomamillary nucleus and ventral lateral geniculate nucleus of the chick
Authors: Peduzzi J. D. , Crossland W. J.
Published: December 2004

The effects of anterograde transneuronal atrophy were studied in two visual nuclei of the chick—the ectomamillary nucleus (EMN), which shows marked degenerative changes following enucleation, and the ventral lateral geniculate nucleus (GLv), which shows less severe changes following enucleation. The chicks were enucleated on the day of hatching and killed between 2 and 81 days later.

Reconstructions of the EMN and GLv revealed that enucleation retarded the growth of these two nuclei. The volume of the control EMN and GLv, ipsilateral to the removed eye, continued to increase after eye removal. The experimental EMN did not increase in volume during this time while the experimental GLv increased in volume but at a slower rate than the control GLv. The volume of the experimental GLv remained smaller than the control volume.

In order to determine whether the volumetric changes were due to arrest of cellular growth or to atrophy of the neurons, a morphometric study was carried out in the two nuclei. Measurements of the cross‐sectional area of EMN neurons revealed a 20% decrease in soma area in the experimental EMN in comparison with those in the control EMN. Since neurons in the control EMN did not increase in area after hatching, it was concluded that the changes were due to atrophy rather than arrest of neuron growth. Furthermore, there was a 35% neuron loss in the EMN. The GLv, which is composed of two laminae, consistently showed a greater decrease in soma cross‐sectional area and neuron loss in its neuropil lamina (comparable to the transneuronal effects in the EMN) than in its lamina interna. Thus, in both nuclei, eye removal led to neuron loss and a decrease in soma cross‐sectional area when compared with the contralateral (control) nucleus.
Developmental relationships between trigeminal ganglia and trigeminal motoneurons in chick embryos. I. Ganglion development is necessary for motoneuron migration
Authors: Moody Sally A. , Heaton Marieta B.
Published: December 2004

The migration and early development of trigeminal (V) motoneurons were studied in chick embryos in which two different populations of primary trigeminal sensory neurons had been removed prior to the birthdate of the V motoneurons. Ablation of mesencephalic neural crest cells, which eliminates monosynaptic sensory input, did not affect the migration, early development, or later differentiation of the V motoneurons. However, when the anlagen of the V ganglion were removed, the V motor root did not exit from the brainstem and the V motor nucleus did not develop. Although the neurons of the V ganglion do not innervate adult V motoneurons, these populations are related developmentally. In those embryos in which the V ganglion did not develop, medial column cells, which are midline, postmitotic, premigratory V motoneurons, and a few medial, elongated cells (possibly migratory) were present until days 5–6, but these cells did not complete their lateral migration to form the lateral nucleus of V. In cases where the ganglion anlagen were not completely removed, the number of postmigratory V motoneurons was positively correlated to the size of the ganglion remnant. There also was a correlation between the axial position of the postmigratory V motoneurons and the ganglion remnants. If a caudal remnant developed, only caudal V motoneurons, whose axons reached the ganglion, migrated; if a rostral remnant developed, only rostral V motoneurons, with axons reaching this remnant, migrated. Additionally, if the central axons of the ganglion remnant entered the metencephalon in either dorsal or ventral ectopic positions, the V motor nucleus was located in a corresponding aberrant position. Thus, some characteristic of the V ganglion cells appears to guide the motor axons and somas to their final brainstem position.
Supramedullary afferents of the nucleus raphe magnus in the rat: A study using the transcannula HRP gel and autoradiographic techniques
Authors: Carlton Susan M. , Leichnetz George R. , Young Eric G. , Mayer David J.
Published: December 2004

Afferents of the nucleus raphe magnus (NRM) were retrogradely la‐belled by using a transcannula HRP gel technique in conjunction with tetramethylbenzidine nuerohistochemistry to determine the sources of in‐puts to the nucleus which could potentially influence the descending antio‐ciceptive raphe‐spinal system. Large numbers of HRP‐labelled neurons were seen in the frontal cortex, dorsomedial nucleus of the hypothalamus, zona incerta, nucleus parafascicularis prerubralis (NPfPr), pretectum, dorsal and lateral periaqueductal gray, nucleus cuneiformis (NC), deep superior col‐liculus (dSC), a paraoculomotor cell group which may be the medial acces‐sory nucleus of Bechterew, dorsal column nuclei, and spinal trigeminal nucleus. Smaller numbers of labelled cells were also observed in the preoptic area, nucleus of Darkschewitsch, ventral peri(third)ventricular gray, nu‐cleus reticularis pontis oralis and caudalis, medial and lateral vestibular nuclei, and a subdivision of the hypoglossal nucleus. Confirmational an‐terograde autoradiographic studies were performed by injecting tritiated leucine into two of the principal sources of afferents to NRM: NPfPr, and dSC/NC.

The results are compared with control HRP gel implants in the inferior olive, spinal cord, nucleus reticularis paragigantocellularis, and medial fa‐cial nucleus. Comments are also made concerning the parcellation of the ventromedial medulla and the possible role of both NRM and its afferents in central analgesic mechanisms.
Brainstem projections to the normal and noradrenergically hyperinnervated trigeminal motor nucleus
Authors: Vornov James J. , Sutin Jerome
Published: December 2004

The noradrenergic innervation of the trigeminal motor nucleus of the rat can be increased severalfold by neonatal treatment with the neurotoxin, 6‐hydroxydopamine. The brainstem projections to the nucleus were studied by injecting HRP into the nucleus of normal and noradrenergically hyper‐innervated rats. In order to identify the source of the noradrenergic inner‐vation, the fluorescent dye, True Blue, was used as a retrograde tracer in combination with the glyoxylic acid histofluorescence method for catechol‐amines.

In both control and neonatally treated rats, the noradrenergic inner‐vation of the motor nucleus' was shown to arise from an ipsilate group of cells located among the fibers of the lateral lemniscusjust rostral to the motor nucleus. Our results confirmed the high degree of specificity of nor‐adrenergic innervation, which arises exclusively from this lateral tegmental noradrenergic cell group. During the process of sprouting, this specificity is maintained since only those noradrenergic cells normally innervating the nucleus were retrogradely labeled in neonatally treated animals. Other noradrenergic projections which are also increased in these animals, such as the nearby locus ceruleus innervation of the main sensory trigeminal nucleus, do not spread to the motor trigeminal nucleus.

HRP‐labeled nonadrenergic cells were concentrated dorsally, with scat‐tered cells surrounding the nucleus. A similar distribution was observed contralateral to the injection site. The mesencephalic trigeminal nucleus was labeled only ipsilateral to the injection. The motor nucleus also receives an extensive bilateral input from the pontine and medullary reticular for‐mation. The medial reticular formation nuclei, including nucleus pontis caudalis, nucleus gigantocellularis, and nucleus reticularis ventralis con‐tained large labeled cells, which were especially numerous in the retrotri‐geminal area. Smaller, lateral reticular formation neurons were concen‐trated rostrally and ipsilaterally in the nucleus pontis lateralis. HRP retrograde labeling revealed no obvious change in the overall pattern of cells innervating the trigeminal motor nucleus following noradrenergic hy‐perinncrvation.
Direct projections from the centre median‐parafascicular complex to the subthalamic nucleus in the cat and rat
Authors: Sugimoto Tetsuo , Hattori Toshiaki , Mizuno Noboru , Itoh Kazuo , Sato Manabu
Published: December 2004

Single injections of a mixture of [3H] leucine and L‐[3H] made into the centre median‐parafascicular complex (CM‐Pf) of the cat. The ipsilateral subthalamic nucleus (STN) was most heavily labeled at its ros‐tral pole and moderately in the ventral and ventromedial portions of its rostral third, At middle subthalamic levels, label was more sparse and disappeared over the caudal third of the nucleus. Labeled fibers appeared to outline the borders of the STN throughout its rostral half. Control in‐jections of isotope into several other thalamic andmesodiencephalic regions produced no terminal labeling in the cat STN. After horseradish peroxidase (HRP) injections into the cat STN, a small number of the CM‐Pf neurons were labeled retrogradely. The labeled neurons were scattered diffusely in the CM‐Pf and were not obviously distinguishable from other unlabeled neurons in the nucleus. Single injections of L‐[3H] leucine were made into the CM‐Pf of the rat. Anterograde labeling was seen in the rostral half of the ipsilateral STN. Heavy labeling was present throughout the most rostral STN, became less prominent more caudally, and was absent from the caudal half of the STN. HRP injections in the rat CM‐Pf produced a distribution of anterograde labeling in the STN similar to the isotope injections. It was concluded that a small number of scattered CM‐Pf neurons project primarily to rostral region of the STN. Thus, the CM‐Pf is in a unique position to regulate the basal ganglia by way of a newly established thalamosubthal‐amic pathway as well as a widespread, conspicuous thalamostriate pathway in those two mammalian species.
Neurons at the origin of the medical component of the bulbopontine spinoreticular tract in the rat: An anatomical study using horseradish peroxidase retrograde transport
Authors: Chaouch A. , Menetrey D. , Binder D. , Besson J. M.
Published: December 2004

An anatomical technique based on the retrograde transport of horseradish perodidase (HRP) was used to investigate the progections of sponal cord neurions to the reticular formations in the rat. Both large and restricted injections were staggered all along the bulbar and pontine levels, involving the nucleus gigantocellularis, the nuclei reticularis pontis, pars oralis and cauladis and in some cases the nucleus raphé magnus.

Labeled cells we constantly encountered in the reticular part of the neck of the dorsal horn throughout the whole length of the cord, mainly contralateral to the central core of the injection iste. This area was taken as the equivalent of lamina V in the cat. Other labeled cells were observed in the medial arts of the intermediate and ventral horns, in areas considered similar to laminae VII and VIII in the cat. The two most rostral cervical nating form the dorsolateral part of ventral horns.

Thus, this study is a clear confirmation that the bulbopontine reticular formations constitute a target for various somatosensory inputs originating in spinal cord. It demonstrates that the medial spinoreticular tract (mSRT) differs from the other main ascending tracts by the absence of projections from (1) superficial layers and nucleus of the dorsolateral funiculus contrary to the spinomesencephalic tract; (2)ventromedial zone of the lumber dorsal horn unlike the spinothalamic tact; (3) the neck of the doral hor in its medial portuion contrary to the spinoreticular component reaching the lateral reticular nucleus; and (4) central cervical nucleus and Clarke's columns, unlike the spinocerebellar tracts. The difficulty in demonstrating retrograde labeling from discrete injections coulde result from the fact that mSRT neu‐rons have sparsely ramified collaterals on their terminal zones.