bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fetal homotypic transplant in the excitotoxically neuron‐depleted thalamus: Light microscopy
Authors: Peschanski Marc , Isacson Ole 
Published: January 2005

AbstractOne month after an in situ injection of kainic acid into the ventrobasal thalamic complex (VB), the lesioned area is totally depleted of neurons. The present study has been undertaken to determine the cytoarchitecture and connectivity of the nucleus constructed by fetal thalamic neurons implanted into the excitotoxically lesioned area.Adult rats received an injection of kainic acid inducing a total neuronal depletion of the right lateral thalamus (including both the nucleus reticularis thalami and the lateral portion of the ventrobasal complex). One month later, homotypic neurons were taken from the dorsal thalamic primordium of rat embryos (gestational age 15–16 days), dissociated, and injected into the lesioned area as a cell suspension. After 2–4‐month survival, the cytoarchitecture of the neonucleus formed by the grafted neurons within the previously neuron‐depleted area was analyzed. Additionally, connectivity was analyzed in seven rats in which dorsal column nuclei and/or cortical projections to the area were labeled anterogradely with either 3H‐leucine or wheat‐germ agglutinin conjugated to HRP, and the animals were perfused and processed following various histological procedures (Nissl staining, autoradiographic processing, and histochemistry for visualization of peroxidase).Fetal neurons grew, differentiated, and progressively occupied the previously neuron‐depleted area of the adult host CNS. They organized themselves into a neonucleus with particular cytoarchitecural features including (1) the existence of two concentric zones–a central zone containing neurons and glial cells and a marginal zone only filled with a band of glial cells, (2) an increase in cellular density compared to the intact thalamus, (3) the grouping of neurons in spherical clusters, and (4) apparent polymorphism of neuronal somata. Lemniscal and corticothalamic afferents originating from the host were observed in the neonucleus when the fetal neurons had been implanted correctly into the lesioned area but not when they had been misplaced into either normal thalamic tissue or the internal capsule. The afferents labeled from either the dorsal column nuclei or the somatosensory cortex were, however, less dense in the neonucleus than in the normal thalamus.These results are discussed with regard to the normal cytoarchitecture and connectivity of the ventrobasal complex of the rat thalamus.
A Population of ascending intersegmental interneurones in the locust with mechanosensory inputs from a hind leg
Authors: Laurent Gilles , Burrows Malcolm 
Published: January 2005

AbstractA population of some 35 intersegmental interneurones with somata in the metathoracic ganglion has been characterized by intracellular recording and staining. These interneurones integrate signals from extero‐ and proprioceptors on a hind leg. The somata are clustered in an anterior and lateral region of the dorsal cortex, and the axons project to more anterior ganglia in either the ipsilateral or contralateral connectives.Some of these interneurones are excited by afferents from a proprioceptor at the femorotibial joint, the femoral chordotonal organ. An afferent spike evokes a chemically mediated EPSP in an interneurone with a latency and consistency that suggest that the connection is direct. An individual interneurone codes particular features of the movement about the femorotibial joint, responding to flexion, extension, or both directions of movement with either phasic or tonic responses. These interneurones have an extensive field of fine branches ipsilateral to the hind leg from which they receive input. These branches are in lateral and intermediate regions of neuropil to which the afferents of the chordotonal organ also project. Axonal branches, from either an ipsilateral and contralateral axon, are sparse and varicose and occur in dorsal neuropil.Other interneurones are excited by afferents from exteroceptive hairs (trichoid sensilla). An individual interneurone is excited by a particular array of hairs on specific regions of a hind leg. The connections between the afferents and the interneurones appear direct. These interneurones have a dense and compact array of fine branches ipsilateral to the hind leg from which they receive input. These branches are in the most ventral region of neuropil, to which the hair afferents also project. Branches from the ipsilateral axons are sparse and varicose and occur in more dorsal neuropil.The interneurones can thus provide the more anterior ganglia with precise information about the movement of a joint in a hind leg and of the location of an exteroceptive stimulus. This information would be of importance in ensuring the correct co‐ordination of the legs during walking.
Somatotopic mapping of sensory neurons innervating mechanosensory hairs on the larval prolegs of Manduca sexta
Authors: Peterson Barbara A. , Weeks Janis C. 
Published: January 2005

AbstractThe abdominal prolegs are the principal locomotory appendages of the larval tobacco hornworm, Manduca sexta. The prolegs bear numerous mechanosensory bristle sensilla, each innervated by an afferent neuron that arborizes within the central nervous system (CNS). Based on their positions on the proleg, we have divided the sensilla into planta hairs (PHs), lateral hairs (LHs), and medial hairs (MHs). Previously, we found that PH afferents produce monosynaptic excitatory postsynaptic potentials (EPSPs) in proleg retractor muscle motoneurons, the size of which depends on the position of the hair in the PH array. In this paper we examined the central arbors of the proleg afferents to determine whether there was an anatomical correlate to the pattern of synaptic strengths. We found that the afferent arbors are arranged somatotopically within the CNS in a pattern similar to that for bristle afferents elsewhere on the abdomen; i.e., the anterior‐posterior and medial‐lateral position of a hair on the proleg was reflected in the location of the afferent arbor along the corresponding axes within sensory neuropil. All afferents terminated within a similar ventral region of neuropil. The arbors of PH, MH, and to a lesser extent, LH afferents, were enlarged as compared to afferents innervating hairs elsewhere on the abdomen. This feature, combined with the dense innervation of the proleg, causes the proleg region to be relatively overrepresented in sensory neuropil. We also examined the afferents innervating a pair of ventral midline hairs (VMHs) present in each abdominal segment, which, unlike the other afferents, showed segment‐specific central arbors. We conclude that the somatotopic mapping of afferent arbors may contribute to the specificity of synaptic connections in this system.
Organization of a sensory neuropile in the auditory pathway of two groups of orthoptera
Authors: Römer Heiner , Marquart Volker , Hardt Martin 
Published: January 2005

AbstractThe anterior intermediate sensory neuropile (aISN) is a prominent neuropile in the ventral nerve cord of locusts and bushcrickets. Previous studies have shown that it receives its main sensory input from auditory receptors. In this paper we examine the structural and physiological relationship between tympanal receptor terminations and the dendrites of sound‐sensitive interneurones in the homologous neuropile of locusts and bushcrickets.Each individual receptor fibre of the bushcricket terminates in a some what different target area of the neuropile. The ordering is with respect to the characteristic frequency of the fibres (tonotopic) in the anterior‐posterior and dorsoventral axis. In the locust, representatives of the four tympanal receptor groups branch in different areas of the aISN. Most of the dorsal neuropilar region, and the anterior ventral region, do not receive input from tympanal receptors.The dendrites of identified sound‐sensitive interneurones were examined in the context of this afferent projection. Local interneurones as well as intersegmental interneurones in bushcrickets have dendritic branches in the whole aISN or part of it and thus overlap with at least some receptors. By recording intracellularly from their main neurites, short‐latency synaptic potentials were found in response to receptor spikes indicating monosynaptic input. The tuning of these neurones could be predicted by their dendritic morphology. In contrast, in the locust only local and bisegmental neurones are monosynaptically connected with tympanal receptors, but not the studied intersegmental neurones. This is consistent with the finding that most or all branches of intersegmental neurones lie in the dorsal area of neuropile where no receptors terminate. Anatomical and physiological evidence is presented for identified local neurones providing the excitatory and inhibitory synaptic input for such intersegmental neurones.The difference in the basic wiring diagram in the homologous neuropile of the two orthopteran groups is discussed with respect to the possible different roles that sound plays in their behaviour.
Representation of the visual field in the second visual area in the Cebus monkey
Authors: Rosa Marcello G. P. , Sousa Aglai P. B. , Gattass Ricardo 
Published: January 2005

AbstractThe representation of the visual field in the second visual area (V2) was reconstructed from multiunit visual responses and anatomical tracers. Receptive field plotting was performed during multiple recording sessions in seven Cebus apella monkeys under N2 O/O2 and immobilized with pancuronium bromide. V2 forms a continuous belt of variable width around striate cortex (V1) except at the most anterior portion of the calcarine sulcus. In each hemisphere V2 contains a visuotopic representation of the contralateral visual hemifield. The representation of the vertical meridian is adjacent to that of V1 and forms the posterior border of V2. The representation of the fovea of V2 is adjacent to that of V1. The representation of the horizontal meridian (HM) is continuous with that of V1; then it splits to form the anterior border of V2, both dorsally and ventrally. The lower quadrant of the visual field is represented dorsally and the upper quadrant ventrally. The visual topography of V2 is coarser than that of V1. In V2, receptive fields corresponding to recording sites separated by a cortical distance of up to 4 mm may represent the same portion of the visual field.In three additional animals, combined injections of fluorescent tracers along the HM representation in V1 yielded two projection sites at the anterior border of V2. The split of the HM representation is estimated to occur at an eccentricity below 1°.Quantitative analysis showed that in V2 the representation of the central visual field is magnified relative to that of the periphery. The cortical magnification factor is greater along the isopolar dimension than along the isoeccentric one. Receptive field size in V2 increases with increasing eccentricity.In sections stained for myelin by the Heidenhein‐Wöelcke method V2 can be distinguished from the surrounding cortex for most of its extent.
The development of the corpus callosum in cats: A light‐ and electron‐ microscopic study
Authors: Berbel P. , Innocenti G. M. 
Published: January 2005

AbstractChanges in the size and shape of the corpus callosum (CC)–and in number, size, and structure of callosal axons–between embryonic day 38 E38 and postnatal day 150 (P150) were studied by light and electron microscope in 25 kittens. The development of the CC was divided into three phases: Embryonic development (E38, 53, 58): At E38, only part of the body of the CC was formed. At E53 and E58, the CC was still very short, but its different parts genu, body, and splenium) had formed. The cross‐sectional callosal area (CCA) was 5.4 mm2 at E53 and 5.6 mm2 at E58. The CC contained 46.3 and 56.4 million axons at E53 and E58 respectively. Mean axon diameters were 0.26 μm at E53 and 0.27 μm at E58. Early postnatal development (P4, 9, 15, 18, 21, 26): The CC at P4 was much longer than at E58 and still slightly elongated during this phase; CCA reached 8.55 mm2 at P4 and 8.88 mm2 at P26. There was a substantial axonal loss (66.8 million at P4 and 52.6 million at P26). From P15 onward, premyelinated and myelinated axons were seen. Mean axon diameter increased from 0.30 μm at P4 to 0.33 μm at P26. Late postnatal development (P39, 57, 92, 107, 150). The CC grew dramatically in both length and thickness, the latter especially in the genu. CCA was 10.1 mm2 at P39 and 15.3 mm2 at P150. The number of axons still decreased (46.5 million at P39 and 31.9 million at P150). The growth of the CCA paralleled the increase of myelinated axons (0.5% a t P26 and 29.6% at P150 and in the mean axon diameters (0.34 μm at P39 and 0.42 μm at P150). A number of axonal ultrastructural peculiarities (electron‐dense bodies, large vacuoles, lamellated bodies, etc., including those mentioned below) were noticed; their frequency at different ages was estimated as the percent of total axons. Interestingly, accumulations of vesicles inside axons increased from 4.1% a t E53 to 8.9% at P26, dropped to 0.2% at P39, and remained below 1% thereafter. Swollen mitochondria increased from 0.2% at E53 to 0.9% a t P26 and dropped to 0.06% (on the average) from P39 onward. Accumulations of vesicles and swollen mitochondria increased during the phase of rapid axonal elimination; thus, they may indicate axonal retraction and/or degeneration. Microglia‐gitter cells and astrocytes showing signs of phagocytosis were found during the embryonic and early postnatal development and may be involved in axon elimination.
Regional distribution of cholecystokinin receptors in macaque medial temporal lobe determined by in vitro receptor autoradiography
Authors: Kritzer M. F. , Innis R. B. , Goldman‐Rakic P. S. 
Published: January 2005

AbstractCholecystokinin (CCK) binding sites were localized in the hippocampus, amygdala, and medial temporal cortices of macaque monkeys by using techniques of in vitro receptor autoradiography. Binding sites were labeled with 3H‐CCK‐8 and 125I‐CCK‐33, and nonspecific binding was assessed in the presence of 1 μM CCK‐8. Comparison of autoradiograms with Nisslstained sections allowed precise correlation of autoradiographic grain distribution with cytoarchitecture.CCK binding in the amygdala varied among nuclear subdivisions. It was dense in the lateral, basomedial, endopiriform, and cortical nuclei, in the parvicellular portion of the accessory basal nucleus, the periamygdaloid cortex, the cortical transition area, and in the amygdalohippocampal area. Labeling was sparse in the central, medial, and basolateral nuclei as well as in the magnocellular accessory basal nucleus. In the hippocampal formation, a single dense band of CCK binding was observed over the granule cell layer and adjacent few millimeters of the molecular layer of the dentate gyrus, while in the polymorph and remaining portions of this layer binding was of very low density. Prominent label over the pyramidal layer in the presubiculum clearly distinguished this region from the adjacent subiculum in which binding just exceeded background levels. Moderate to light label was observed in the hilus and stratum pyramidale of CA3, CA2, and CA1, while other hippocampal layers showed minimal specific binding.Variation in CCK binding in the medial temporal cortex showed close correspondence to cytoarchitectonic subdivisions. In entorhinal cortex, for example, binding was concentrated in layers III‐VI while label in area 35 was prominent in all laminae except layer IV. Area TH of von Bonin and Bailey ('47) was distinguished from other regions by evenly distributed binding across all layers, while in area TF a bilaminar pattern of label in layers II and IV was observed.The highly specific patterns of CCK binding in amygdala and transitional cortices of the medial temporal lobe can be related to terminal fields of neo‐ and allocortical afferents to these regions, while label in the hippocampal formation coincides with the terminals of intrinsic neurons which ramify among the somata of cells that are targets of neocortical afferents. Thus, in all structures of the medial temporal lobe the disposition of peptidergic binding sites suggests that CCKergic systems may be important in the modulation of cortical afferents.
The projection of the medial and posterior articular nerves of the cat's knee to the spinal cord
Authors: Craig A. D. , Heppelmann B. , Schaible H.‐G. 
Published: January 2005

AbstractWe studied the spinal projections of the medial and posterior articular nerves (MAN and PAN) of the knee joint in the cat with the aid of the transganglionic transport of horseradish peroxidase. The afferent fibers of the MAN entered the spinal cord via the lumbar dorsal roots L5 and L6 and those of the PAN entered via the dorsal roots L6 and L7. Within the dorsal root ganglia, most labeled neurons had small to medium diameters. A relatively higher number of medium‐size cell bodies were labeled from the PAN than from the MAN. In the spinal cord labeled MAN afferent fibers and terminations were most dense in the L5 and L6 segments, and those of the PAN were most dense in L6 and L7, that is, in the respective segments of entry. Labeled afferent fibers from both nerves projected rostrally at least as far as L1 and caudally as far as S2. Labeled fibers were found in Lissauer's tract as well as in the dorsal column immediately adjacent to the dorsal horn. In the spinal gray matter, both nerves had two main projection fields, one in the cap of the dorsal horn in lamina I, the other in the deep dorsal horn in laminae V‐VI and the dorsal part of lamina VII. Both nerves, but particularly the PAN, projected to the medial portion of Clarke's column. No projection was found to laminae II, III, and IV of the dorsal horn or to the ventral horn. Since these findings parallel observations on hindlimb muscle afferent fibers, the present data support the existence of a common pattern for the central distribution of deep somatic afferent fibers.
Glycine receptor immunoreactivity in the ventral cochlear nucleus of the guinea pig
Authors: Wenthold Robert J. , Parakkal Merianne H. , Oberdorfer Michael D. , Altschuler Richard A. 
Published: January 2005

AbstractGlycine appears to be a major inhibitory neurotransmitter in the cochlear nucleus. In order to determine more precisely the distribution of glycinergic synapses, we have studied the immunocytochemical distribution of the glycine postsynaptic receptor. Two monoclonal antibodies were used, Gly Rec Ab 2, which recognizes the 48kD polypeptide and Gly Rec Ab 7, which primarily recognizes the 93kD subunit of the glycine receptor complex. At the light microscopic level, glycine receptor immunoreactivity was found throughout the ventral cochlear nucleus with a punctute distribution often found outlining large cell bodies. Indistinguishable patterns of staining were obtained with the two antibodies. Ultrastructural localization was done with Gly Rec Ab 7 because immunoreactivity remained after fixation with glutaraldehyde containing solutions. At the ultrustructural level, immunoreactivity was concentrated at postsynaptic sites on dendrites and cell bodies. In the anteroventral cochlear nucleus, neurons identified as spherical cells contained numerous inmunoreactive synapses on their cell bodies, whereas most immunoreactive synapses on stellate cells were on their proximal dendrites. In the posteroventral cochlear nucleus, neurons identified as octopus cells were immunoreactive on their cell bodies and proximal dendrites. In the granule cell layer, immunoreactivity was found only in the neuropile. Throughout the ventral cochlear nucleus, glycine receptor immunoreactivity was found postsynaptic to terminals containing flattened synaptic vesicles as well as those containing oval/pleomorphic synaptic vesicles.
Distribution of histamine in the cockroach brain and visual system: An immunocytochemical and biochemical study
Authors: Pirvola Ulla , Tuomisto Leena , Yamatodani Atsushi , Panula Pertti 
Published: January 2005

AbstractThe distribution of histamine‐immunoreactivity in the carbodiimide‐fixed brain and visual system of the cockroach was revealed immunocytochemically with an antiserum against histamine (HA). Histamine levels were measured with high‐pressure liquid chromatography. The results show a widespread distribution of histamine‐containing somata and fibers in the brain, particularly in the visual system. The most intense immunolabeling was seen in the retinal photoreceptors and in the first optic ganglion, the lamina, where the short visual fibers make synaptic connections with the monopolar neurons, which also displayed immunofluorescence. Immunoreactive long visual fibers traversed the lamina and outer chiasma, terminating in the distal medulla. Tracts of histamine‐immunopositive fibers appeared to link the optic ganglia to the protocerebrum. Prominent histamine‐containing neurons were situated in the lateral protocerebrum. Immunolabeled pathways consisting of large‐diameter fibers also were seen in the cockroach brain. The central parts of the brain, including the central body, were reached by thick immunoreactive fibers that gave rise to intensely fluorescent varicose processes there. In the mushroom bodies, immunoreactivity was limited to the calyces. The protocerebral bridge was nonreactive. Immunofluorescence was seen also in the antennal lobes, but not in the antennal nerves. The biochemical measurements correlated well with the immunocytochemical data. The retinas and optic lobes, measured together, contained remarkably large amounts of histamine. These results reinforce the hypothesis presented by Hardie ('87) and Elias and Evans ('83) that histamine functions as a neurotransmitter in the photoreceptors of some, if not all, insect species.
Development of neurons in the ectostriatum of normal and monocularly deprived zebra finches: A quantitative Golgi study
Authors: Herrmann Kathrin , Bischof Hans‐Joachim 
Published: January 2005

AbstractThe postnatal development of the main neuron type in the ectostriatum, the telencephalic station of the tectofugal pathway, was followed in normally reared and monocularly deprived zebra finches by using the Golgi method. Three parameters were investigated: dendritic field radius, branching index, and spine density. The results show that all three exhibit the same developmental trend—namely, an increase from day 5 until day 20, followed by a subsequent reduction until adulthood (> 100 days). Monocular deprivation from birth until day 20, 40, or at least 100 does not seem to interfere with the development of the dendritic field radius or branching index. Clear changes in spine density result from depriving the birds for at least 40 days. In these birds, neurons in the deprived hemisphere bear significantly fewer spines than those in the nondeprived hemisphere, which is mainly due to a lack of normally occurring spine reduction in the nondeprived hemisphere rather than to spine reduction in the deprived hemisphere.