bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perineuronal nets provide a polyanionic, glia‐associated form of microenvironment around certain neurons in many parts of the rat brain
Authors: Brückner Gert , Brauer Kurt , Härtig Wolfgang , Wolff Joachim R. , Rickmann Michael J. , Derouiche Amin , Delpech Bertrand , Girard Nicole , Oertel Wolfgang H. , Reichenbach Andreas 
Published: January 2005

AbstractThe nature and function of previously described perineuronal nets are still obscure. In the present study their polyanionic components were demonstrated in the rat brain using colloidal iron hydroxide (CIH) staining. In subcortical regions, such as the red nucleus, cerebellar, and vestibular nuclei, most neurons were ensheathed by CIH‐binding material. In the cerebral cortex perineuronal nets were seen around numerous nonpyramidal neurons. Biotinylated hyaluronectin revealed that hyaluronan occurs in perineuronal nets. Two plant lectins [Wisteria floribunda agglutinin (WFA) and Vicia villosa agglutinin (VVA)] with affinity for N‐acetylgalactosamine visualized perineuronal nets similar to those rich in anionic components. Glutamic acid decarboxylase (GAD)‐immunoreactive synaptic boutons were shown to occupy numerous meshes of perineuronal VVA‐positive nets. Electron microscopically, VVA binding sites were scattered throughout perisynaptic profiles, but accumulated at membranes and in the extra‐cellular space except not in synaptic clefts. To investigate the spatial relationship between glial cell processes and perineuronal nets, two astrocytic markers (S100‐protein and glutamine synthetase) were visualized at the light and electron microscopic level. Two methods to detect microglia by the use of Griffonia simplicifolia agglutinin (GSA I‐B4) and the monoclonal antibody, OX‐42, were also applied. Labelled structures forming perineuronal nets were observed with both astrocytic, but not with microglial, markers. It is concluded that perineuronal nets are composed of a specialized type of glia‐associated extracellular matrix rich in polyanionic groups and N‐acetylgalactosamine. The net‐like appearance is due to perisynaptic arrangement of the astrocytic processes and these extracellular components. Similar to the ensheathment of nodes of Ranvier, perineuronal nets may provide a special ion buffering capacity required around various, perhaps highly active, types of neurons. © 1993 Wiley‐Liss, Inc.
Insulin‐like growth factor I: A mitogen for rat schwann cells in the presence of elevated levels of cyclic AMP
Authors: Jung‐Testas Ingrid , Robel Paul , Baulieu Etienne‐Emile , Schumacher Michael 
Published: January 2005

AbstractTo develop effective procedures for improving the regeneration of peripheral nerves and for preventing the formation of neurofibromas, it is necessary to identify the different mitogens that stimulate the proliferation of Schwann cells. Insulinlike growth factor I (IGF‐I), which is a potent autocrine growth factor in many tissues, is synthesized by proliferating Schwann cells. However, the role of IGF‐I in stimulating their division is still uncertain. Here we show that nanomolar concentrations of IGF‐I stimulate the growth of Schwann cells in primary culture. IGF‐I alone was uneffective but in the presence of forskolin (5 μM) or dibutyryl cyclic AMP (dbcAMP, 10 μM), it became a potent mitogen. Neither IGF‐II nor epidermal growth factor (EGF) were effective, even in the presence of forskolin. Insulin also stimulated Schwann cell proliferation in the presence of forskolin, but only at micromolar concentration.Receptors for IGF‐I were visualized on the Schwann cell surface by indirect immunofluorescence staining using anti‐human IGF‐I receptor antibodies. Their presence was also assessed by binding assays using [125I]‐IGF‐I as a ligand. Scatchard analysis showed a single class of high‐affinity receptors (Kd = 1.5 nM). Competition studies with unlabeled IGF‐I or insulin indicated a half‐maximal displacement of [125I]‐IGF‐I by IGF‐I at about 5 nM, while insulin was about 500‐fold less effective. The number of binding sites for IGF‐I was increased by exposing cells for 3 days to forskolin (‐ forskolin: about 5,100; + forskolin: about 12,200 binding sites/cell). These results suggest that forskolin increases available receptors for IGF‐I, which is consistent with the synergism between cAMP and IGF‐I in stimulating Schwann cell growth. © 1993 Wiley‐Liss, Inc.
Development of radial glia and astrocytes in the spinal cord of the north american opossum (Didelphis virginiana): An immunohistochemical study using anti‐vimentin and anti‐glial fibrillary acidic protein
Authors: Ghooray Ganesh T. , Martin George F. 
Published: January 2005

AbstractWe have shown previously that rubrospinal axons grow around a lesion of their pathway in developing opossums and that a critical period exists for that plasticity. As a first step toward addressing the possibility that glial maturation and/or the development of an astrocytic response to lesioning contribute to loss of rubrospinal plasticity, we have studied the normal development of radial glia and astrocytes in the spinal cord of the opossum by immunostaining for vimentin (Vim) and glial fibrillary acidic protein (GFAP). Vim‐like immunoreactivity (Vim‐LI) was present in radial glia throughout the spinal cord at birth (12 days after conception), whereas GFAP‐like immunoreactivity (GFAP‐LI) was limited to cells of comparable morphology in the ventral part of the cervical cord. The subsequent appearance of GFAP‐LI followed ventral to dorsal and rostral to caudal gradients and by postnatal day (PD) 15, it was found in radial glia throughout the cord. At the same age, processes immunostained by either antibody had lost their radial orientation in the ventral horn of the cervical cord. The subsequent transformation from radial glia to astrocytes also followed ventral to dorsal and rostral to caudal gradients. By PD30, mature appearing astrocytes were immunostained by both antibodies at thoracic levels of the spinal cord, the levels lesioned in the plasticity experiments referred to above, and by PD41, they were found at all levels of the cord. Since rubral axons are able to grow around a lesion of the thoracic cord until PD26–30, there is a rough temporal correlation between the transition from radial glia to mature appearing astrocytes and the end of the critical period for plasticity. © 1993 Wiley‐Liss, Inc.
Hospital survival time in dementia: A controlled study of the effect of marital status on the interval between first admission and death
Authors: Ryan D. H. 
Published: January 2005

AbstractThe influence of marital status on ‘hospital survival time’ (the interval between first admission and death) was investigated in a controlled study of hospital dementia patients. There was no evidence of a significant relationship between marital status and hospital survival time after controlling for age and sex differences. The presence of a supporting spouse did not apparently shorten hospital survival time or postpone admission. Mortality following admission was analysed during the period of the study 1971–86. The probability of death during the six months following first admission was 45% for males and 32% for female patients (patients of all marital status combined), and the respective 12‐month figures were 59% and 44%. The median hospital survival time for married male and female patients was 0.6 years and 1.8 years, which suggests that first admission to hospital occurred as a late event. It follows that additional community support to families may not be effective in further reducing the demand for hospital care during the terminal stages of dementia.
A pilot study of interictal cognitive changes in elderly patients during ECT
Authors: Rosen Jules , Mulsant Benoit H. , Nebes Robert D. 
Published: January 2005

AbstractTen elderly patients were evaluated serially for interictal cognitive changes during the course of ECT using the Mini Mental State Exam (MMSE) and a modification of the Digit Symbol Substitution task (M‐DSS), an assessment of attention that measures the speed of mental processing. Performance decrease on the M‐DSS and MMSE correlated with both the number of seizures and cumulative seizure duration. The M‐DSS correlated with the MMSE items of ‘orientation’ and ‘attention’, but not with the ‘recall’ item, suggesting that the interictal memory and attentional changes induced by ECT may occur independently. For most patients, the serial performance on both the MMSE and M‐DSS decreased significantly during the course of ECT; however, the increase in the M‐DSS (indicating a performance decrement) was greater than 100%, compared to a decrease in MMSE score of less than 10%. These data are preliminary and replication with more patients and extension of the assessment for several weeks following cessation of treatment is needed.
Mapping of SPECT regional cerebral perfusion abnormalities in obsessive‐compulsive disorder
Authors: Harris Gordon J. , Hoehn‐Saric Rudolf , Lewis Robert , Pearlson Godfrey D. , Streeter Chris 
Published: January 2005

AbstractLocations of cerebral perfusion abnormalities in obsessive‐compulsive disorder (OCD) were mapped with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). This report is a new, more thorough analysis of a previous study of these subjects that used region‐of‐interest methods. Ten obsessive‐compulsive patients and seven age‐ and sex‐matched control subjects were studied. Image sets were converted into stereotaxic space, normalized to each subject's mean cerebral value, then group averaged. Difference images were calculated and searched for regions with significant between‐group cerebral perfusion differences. Obsessive‐compulsive patients had significantly higher relative cerebral perfusion in medial‐frontal and right frontal cortex and in cerebellum, and significantly reduced perfusion in right visual association cortex. Increased frontal Perfusion agrees with several prior reports. The caudate nucleus, which has been controversial in neuroimaging studies of OCD, did not display a difference between groups. The results of this study provide information about the locations and extents of cerebral perfusion abnormalities in OCD. Regional abnormalities were compared with those reported in prior functional neuroimaging studies. Issues related to OCD hyperfrontality and frontal lateralization of psychopathology are discussed. Normal caudate nucleus findings are considered in relation to prior functional imaging studies and hypotheses of OCD pathology. © 1994 Wiley‐Liss, Inc.
Functional neuroanatomy of verbal free recall: A replication study
Authors: Becker James T. , Mintun Mark A. , Diehl David J. , Dobkin Jeffrey , Martidis Adam , Madoff David C. , Dekosky Steven T. 
Published: January 2005

AbstractThe functional neuroanatomy of verbal memory was investigated using verbal free recall during H215O positron emission tomography (PET). Twelve young (25–40 years old) normal control subjects participated in eight scans during a single scanning session during which they performed three memory tasks differing by word list length. Four subjects also had scans during a “rest” condition. Temporal lobe activation was observed during all tasks, including single‐word repetition. The frontal cortices, specifically Brodmann areas 9 and 10, were activated only when the recall word lists exceeded the memory spans (i. e., 12 and 15 words). Activation was also observed in the anterior cingulate cortex (BA24 and BA32). These data, obtained using a within‐subject design, extend previously reported findings that used mixed within‐and between‐subject designs and demonstrate important functional components of normal auditoryverbal short‐term memory. © 1994 Wiley‐Liss, Inc.
Activation of the prefrontal cortex in a nonspatial working memory task with functional MRI
Authors: Cohen Jonathan D. , Forman Steven D. , Braver Todd S. , Casey B. J. , Servan‐Schreiber David , Noll Douglas C. 
Published: January 2005

AbstractFunctional magnetic resonance imaging (fMRI) was used to examine the pattern of activity of the prefrontal cortex during performance of subjects in a nonspatial working memory task. Subjects observed sequences of letters and responded whenever a letter repeated with exactly one nonidentical letter intervening. In a comparison task, subjects monitored similar sequences of letters for any occurrence of a single, prespecified target letter. Functional scanning was performed using a newly developed spiral scan image acquisition technique that provides high‐resolution, multislice scanning at approximately five times the rate usually possible on conventional equipment (an average of one image per second). Using these methods, activation of the middle and inferior frontal gyri was reliably observed within individual subjects during performance of the working memory task relative to the comparison task. Effect sizes (2–4%) closely approximated those that have been observed within primary sensory and motor cortices using similar fMRI techniques. Furthermore, activation increased and decreased with a time course that was highly consistent with the task manipulations. These findings corroborate the results of positron emission tomography studies, which suggest that the prefrontal cortex is engaged by tasks that rely on working memory. Furthermore, they demonstrate the applicability of newly developed fMRI techniques using conventional scanners to study the associative cortex in individual subjects. © 1994 Wiley‐Liss, Inc.
Structural equation modeling and its application to network analysis in functional brain imaging
Authors: McLntosh A. R. , Gonzalez‐Lima F. 
Published: January 2005

AbstractThe analysis of brain imaging data has recently focused on the examination of the covariances of activity among neural regions during different behaviors. We present some of the theoretical and technical issues surrounding one of these covariance‐based methods: structural equation modeling. In structural equation modeling, connections between brain areas are based on known neuroanatomy, and the interregional covariances of activity are used to calculate path coefficients representing the magnitude of the influence of each directional path. The logic behind the use of structural equation modeling stems from the suggestion that brain function is the result of changes in the covariances of activity among neural elements. The technical foundations for neural structural equation models are presented, emphasizing the ability to make inferential comparisons to evaluate the experimental changes in path coefficients. Simulated data sets were used to test the effects of omitted regions and omitted connections. The results suggested that structural modeling algorithms can give hints as to possible external influences and missing paths, but that the final decision as to model modifications requires the guidance of the researcher. The utility of anatomically based models to distinguish between the direct effect of one region on another, and indirect effects of darkness or patterned light on the metabolic activity in the rat visual system. The anatomical framework for the structural equation models revealed that the total impact of ascending thalamocortical influences was modified by corticocortical interactions. Extensions of structural equation modeling to human brain imaging experiments are presented. We conclude by suggesting that neural covariances may be a more accurate way to examine the dynamic functional organization of the central nervous system. ©1994 Wiley‐Liss, Inc.
Emergence and propagation of interictal spikes in the subcortically denervated hippocampus
Authors: Buzsáki György , Hsu Melissa , Slamka Craig , Gage Fred H. , Horváth Zsolt 
Published: January 2005

AbstractSpontaneous and evoked field potentials and cellular discharges of the subcortically denervated dorsal hippocampus were studied by multisite recordings in the freely behaving rat. Characteristic short‐duration (<100 ms), large‐amplitude (up to 10 mV) transients, termed interictal spikes (IIS), were seen after fimbria–fornix (FF) lesion. Both pyramidal cells and putative interneurons fired maximally during IIS, with some interneurons sustaining long bursts (up to 400 ms) of highfrequency discharges (400–600 Hz) after the IIS. The speed of propagation of IIS along the longitudinal axis of the hippocampus varied from 0.2 m/s to >3 m/s. The majority of IIS (type 1) could be accounted for by an enhanced activity of the intrahippocampal associational systems; a second class of IIS (type 2) had positive polarities in the stratum radiatum of CA1 and CA3 and propagated very rapidly (>1.5 m/s). The authors propose that type 2 IIS reflect somatic depolarization and discharge of pyramidal neurons due to nonsynaptic (probably ephaptic) effects. Ephaptic interactions may also explain the longitudinal propagation of IIS at speeds higher than the conduction velocities (0.5 m/s) of hippocampal fiber systems.IIS emerged during the first 3 weeks after fimbria–fornix lesion, their incidence reaching a plateau of 2/min thereafter. During the same time period, paired‐pulse suppression increased in the dentate gyrus. The amplitude of test responses to angular bundle stimulation was potentiated by small‐amplitude IIS but suppressed by large‐amplitude IIS. The incidence of IIS was significantly suppressed during walking relative to standing still. Tetanic stimulation of the angular bundle or handling‐induced stress resulted in a 10‐ to 20‐fold increase in the incidence of IIS that lasted for about 30 minutes. There was a negative correlation between evoked field PSP slope and population spike amplitude in the dentate gyrus of FF‐lesioned rats; this correlation was positive in intact rats.The authors attribute the above pathophysiological changes to sprouting of both excitatory and inhibitory GABAergic pathways as a result of denervation of the intrahippocampal circuitry. They hypothesize that the majority of the observed physiological alterations can be traced to a weakening of feedforward inhibition coupled with an enhancement of feedback inhibition and excitation.
Origins of the variations in long‐term potentiation between synapses in the basal versus apical dendrites of hippocampal neurons
Authors: Arai Amy , Black Joel , Lynch Gary 
Published: January 2005

AbstractResponses to theta pattern stimulation, and the long‐term potentiation (LTP) they induce, were compared in the basal versus apical dendrites of neurons in field CA1 of hippocampus. A series of 10 theta bursts produced more than twice as much LTP in basal synapses as in their apical counterparts as measured with field EPSPs. This confirms earlier field potential studies showing that the maximum degree of potentiation (the LTP ceiling) is considerably greater in stratum oriens than stratum radiatum. Experiments with whole‐cell clamp recording obtained similar results, indicating that synapses at different loci on the same neuron reach different LTP ceilings following prolonged theta burst stimulation. The basal synapses also required fewer theta bursts to reach their LTP ceiling than did the apical synapses. Tests with paired‐pulse facilitation and an antagonist of the NMDA receptor gave no indication that the greater LTP in basal synapses was qualitatively different from the lesser effect obtained in apical contacts. Intracellular recording revealed significant differences between basal versus apical responses to single theta bursts and trains of bursts: the within‐burst depolarization was greater and the between‐burst hyperpolarization was smaller for the basal dendritic responses. These two variables have previously been proposed to influence the magnitude of LTP and the observed differences between basal versus apical synapses are in accord with this hypothesis. Together with recently described immunocytochemical results, the findings reported here suggest that variations in LTP across dendritic subfields of hippocampus reflect a differential distribution of a subclass of GABAergic interneurons.
Properties of GABA and glutamate responses in identified glial cells of the mouse hippocampal slice
Authors: Steinhäser Christian , Jabs Ronald , Kettenmann Helmut 
Published: January 2005

AbstractIn this study, the patch‐clamp technique was applied to brain slices to test for the presence of GABAA and glutamate receptors in glial cells of an intact tissue preparation, the hippocampus from 9–12 day old mice. Two types of glial cells were studied in the CA1 stratum pyramidale, termed passive and complex cells, which were distinct by their characteristic pattern of voltage‐dependent currents. Both cell types were previously identified as glial by combining electrophysiology with ultrastructural inspection (Steinhäuser et al., 1992, Eur J Neurosci 4:472–484). A subpopulation of passive cells was positive, all complex cells were negative for immunocytochemical staining against glial fibrillary acidic protein, a marker of mature astrocytes. In both cell types, GABA activated currents compatible with GABAA‐receptor mediated responses. The glutamate response in complex and in most of the passive cells was mediated by a ligand‐gated ion channel and closely matched the pharmacology of the kainate receptor. Activation of glutamate receptors led to a transient decrease of the resting K+ conductance in complex cells and to an irreversible decrease in the passive cells. In three passive cells, glutamate‐activated currents were most likely dominated by an electrogenic uptake. In a small group of passive cells NMDA‐activated currents were observed. This study provides evidence that glial cells from an intact tissue express receptors for the most abundant transmitters in the central nervous system, glutamate, and GABA.
Relational features of acetylcholine, noradrenaline, serotonin and GABA axon terminals in the stratum radiatum of adult rat hippocampus (CA1)
Authors: Umbriaco Denis , Garcia Sylvia , Beaulieu Clermont , Descarries Laurent 
Published: January 2005

AbstractIn a well‐defined sector of adult rat hippocampus (CA1, stratum radiatum), the ultrastructural features of acetylcholine (ACh), noradrenaline (NA), serotonin (5‐HT) and GABA axon terminals (varicosities) were compared by electron microscopy after immunostaining with antibodies against choline acetyltransferase, NA, 5‐HT and glutamic acid decarboxylase. Approximately 100 sectional profiles of each type were analyzed for size, presence of a synaptic membrane specialization (synaptic incidence) and composition of the microenvironment. An equivalent number of immunonegative varicosity profiles selected at random from the same micrographs were similarly examined. ACh, NA and 5‐HT varicosity profiles were of comparable size, and significantly smaller than GABA profiles. They exhibited a low frequency of junctional specialization, amounting to 7%, 15% and 21%, respectively, when extrapolated to the whole volume of these terminals. In contrast, GABA varicosities appeared entirely synaptic. The ACh, NA and 5‐HT varicosities also differed from their GABA counterparts in being juxtaposed to a greater number of unlabeled axonal varicosities and a lower number of dendritic branches. In addition, the microenvironment of immunostained terminals showed a much lower number of dendritic spines than that of immunonegative varicosities. This latter finding was viewed as another indication that predominantly asynaptic varicosities do not maintain particular relationships with their immediate surround. It was also concluded that volume transmission represents a major mode of transmission for ACh, NA and 5‐HT in adult rat hippocampus, thus contributing to the properties and functions assigned to these transmitters in this part of brain. © 1995 Wiley‐Liss, Inc.