bluuebunny/crossref_metadata_2025_split huggingface dataset:
Roles of glutamate transporters in shaping excitatory synaptic currents in cerebellar Purkinje cells
Authors: Takayasu Yukihiro , Iino Masae , Ozawa Seiji 
Published: March 2004

AbstractSeveral subtypes of glutamate transporters are abundantly expressed near the excitatory synapses on cerebellar Purkinje cells. We investigated the roles of the glutamate transporters in shaping the excitatory postsynaptic currents (EPSCs) and regulating the levels of extracellular glutamate in the mouse cerebellum using a potent blocker of glutamate transporters, dl‐threo‐β‐benzyloxyaspartate (dl‐TBOA). This drug markedly prolonged AMPA receptor‐mediated EPSCs in Purkinje cells evoked by stimulating both parallel fibres and climbing fibres. The decay phase of the prolonged EPSCs was fitted by double exponentials, of which the slower component was preferentially inhibited by a low‐affinity competitive antagonist of AMPA receptors, γ‐d‐glutamyl‐glycine, indicating that the slow component induced by dl‐TBOA was the AMPA receptor‐mediated current activated by lower concentrations of glutamate than those contributing to the peak of the EPSC. This result suggests that dl‐TBOA prolongs the stay of synaptically released glutamate in the synaptic cleft and also induces glutamate spillover to extrasynaptic targets as well as neighbouring synapses. Furthermore, high concentrations of dl‐TBOA in the presence of cyclothiazide generated a continuous inward current in Purkinje cells, of which the amplitude reached the peak level of the climbing‐fibre EPSC. This continuous inward current was abolished by the blocker of AMPA receptors, indicating that the strong inhibition of glutamate uptake causes the rapid accumulation of glutamate in the extracellular space. These results highlight the importance of glutamate transporters in maintaining the proper glutamatergic transmission in Purkinje cell synapses.
Convergence of excitatory and inhibitory inputs onto CCK‐containing basket cells in the CA1 area of the rat hippocampus
Authors: Mátyás Ferenc , Freund Tamás F. , Gulyás Attila I. 
Published: March 2004

AbstractThe number and distribution of excitatory and inhibitory inputs affect the integrative properties of neurons. These parameters have been studied recently for several hippocampal neuron populations. Besides parvalbumin‐ (PV) containing cells that include basket and axo‐axonic cells, cholecystokinin (CCK)‐containing interneurons also form a basket cell population with several properties distinct from PV cells. Here, at the light microscopic level, we reconstructed the entire dendritic tree of CCK‐immunoreactive (IR) basket cells to describe their geometry, the total length and laminar distribution of their dendrites. This was followed by an electron microscopic analysis of serial ultrathin sections immunostained against γ‐aminobutyric acid, to estimate the density of excitatory and inhibitory synapses on their somata, axon initial segments and different subclasses of dendrites. The dendritic tree of CCK‐IR basket cells has an average length of 6300 µm and penetrates all layers. At the electron microscopic level, CCK basket cells receive dendritic inputs with a density of 80–230 per 100 µm. The ratio of inhibitory inputs is relatively high (35%) and increases towards the soma (83%). The total numbers of excitatory and inhibitory synapses converging onto CCK‐IR cells are ∼ 8200. Comparison of the two, neurochemically distinct basket cells reveals that CCK‐containing basket cells receive much less synaptic input than PV cells; however, the relative weight of inhibition is higher on CCK cells. Additional differences in their anatomical and physiological properties predict that CCK basket cells are under a more diverse, elaborate control than PV basket cells, and thus the function of the two populations must be different.
High‐frequency synaptic input contributes to seizure initiation in the low‐[Mg2+] model of epilepsy
Authors: Lasztóczi Bálint , Antal Károly , Nyikos Lajos , Emri Zsuzsa , Kardos Julianna 
Published: March 2004

AbstractHigh‐frequency field potential activity between 50 and 400 Hz occurs throughout seizure‐like events recorded from the CA3 region of juvenile rat hippocampal slices under low‐[Mg2+] condition. Another (400–800 Hz) component occurred mainly during preictal paroxysmal spiking and the onsets of seizure‐like events (97%) and less frequently during tonic and clonic phases (38% and 70%, respectively). Short epochs of oscillations in this range were associated with fast negative field potential deflections at the start of field potential transients. Voltage‐clamp recordings from putative CA3 pyramidal cells showed the occurrence of synaptic inputs in the same frequency range at the onset of seizure‐like events and the beginning of preictal or clonic paroxysmal spikes, while the frequency of action potentials never reached that range. The amplitude of fast negative field potential deflection, the rise time of membrane potential or voltage‐clamp current changes and the mean phase coherence were consistent with an increase of synchronization towards the onset of a seizure‐like event. Their parallel changes indicate the involvement of both synaptic and nonsynaptic mechanisms in the synchronization of neuronal activity and the development of seizure‐like events in the low‐[Mg2+] model of epilepsy.
Cloning and expression of short interspersed elements B1 and B2 in ischemic brain
Authors: Kalkkila Juha‐Pekka , Sharp Frank R. , Kärkkäinen Iivari , Reilly Melinda , Lu Aigang , Solway Karen , Murrel Matt , Honkaniemi Jari 
Published: March 2004

AbstractGlobal ischemia causes an extensive cell death 3 days after the ischemia in the CA1 region of the hippocampus, which is preceded by induction of a spectrum of genes with both neuroprotective and detrimental properties. This delayed cell death has been suggested to be mainly caused by programmed cell death. Here we applied differential display to characterize transcripts induced by global ischemia after 1 day in Mongolian gerbils, when the cells in the CA1 region are still viable, but initiating the cell death pathway. One of the cloned transcripts turned out to be a repeat sequence termed SINE B2. We also cloned the other member of the SINE family, SINE B1, and found it also to be slightly induced by ischemia in the CA1 region. The SINE repeat regions are not translated and their role in ischemia may be related the neurons' attempt to cope with decreased translational levels and/or genomic reorganization. Together with the previous data demonstrating the inducibility of the SINE transcripts using in vitro stress models, the present study shows that SINE transcripts are stress‐inducible factors in the central nervous system.
Short‐term plasticity visualized with flavoprotein autofluorescence in the somatosensory cortex of anaesthetized rats
Authors: Murakami Hiroatsu , Kamatani Daiki , Hishida Ryuichi , Takao Tetsuro , Kudoh Masaharu , Kawaguchi Tadashi , Tanaka Ryuichi , Shibuki Katsuei 
Published: March 2004

AbstractIn the present study, short‐term plasticity of somatosensory neural responses was investigated using flavoprotein autofluorescence imaging in rats anaesthetized with urethane (1.5 g/kg, i.p.) Somatosensory neural activity was elicited by vibratory skin stimulation (50 Hz for 1 s) applied on the surface of the left plantar hindpaw. Changes in green autofluorescence (λ = 500–550 nm) in blue light (λ = 450–490 nm) were elicited in the right somatosensory cortex. The normalised maximal fluorescence responses (ΔF/F) was 2.0 ± 0.1% (n = 40). After tetanic cortical stimulation (TS), applied at a depth of 1.5–2.0 mm from the cortical surface, the responses elicited by peripheral stimulation were significantly potentiated in both peak amplitude and size of the responsive area (both P < 0.02; Wilcoxon signed rank test). This potentiation was clearly observed in the recording session started 5 min after the cessation of TS, and returned to the control level within 30 min. However, depression of the responses was observed after TS applied at a depth of 0.5 mm. TS‐induced changes in supragranular field potentials in cortical slices showed a similar dependence on the depth of the stimulated sites. When TS was applied on the ipsilateral somatosensory cortex, marked potentiation of the ipsilateral responses and slight potentiation of the contralateral responses to peripheral stimulation were observed after TS, suggesting the involvement of commissural fibers in the changes in the somatosensory brain maps. The present study clearly demonstrates that functional brain imaging using flavoprotein autofluorescence is a useful technique for investigating neural plasticity in vivo.
The developmental dynamics of the brain is reflected by a regionally specific rise and fall of molecular complexity
Authors: Illing Robert‐Benjamin , Jung Christian , Hirschmüller‐Ohmes Ingeborg 
Published: March 2004

AbstractTissue samples of inferior colliculus and cerebellar cortex were obtained from rat brains at various postnatal developmental stages. Samples were analysed by two‐dimensional SDS gel electrophoresis. Spots of proteins and their variants were visualized with automated silver staining, the number of spots was determined with a computer‐based image analysis system, and age groups were statistically compared. Judging from the waxing and waning of protein spot numbers, colliculus and cerebellum take distinctly different routes through postnatal development. Whereas molecular complexity in the colliculus was initially high, it decreased soon after the onset of hearing and settled on a significantly lower adult level. By contrast, the cerebellum initially showed low molecular complexity, rose sharply in complexity to reach highest values at late juvenile stages corresponding to peak scores of explorative behaviour, and fell off again to an adult level that remained, however, significantly higher than that of the colliculus. We conclude that the changing diversity of proteins may be used to identify landmarks in brain development.
The actions of monoamines and distribution of noradrenergic and serotoninergic contacts on different subpopulations of commissural interneurons in the cat spinal cord
Authors: Hammar Ingela , Bannatyne B. Anne , Maxwell David J. , Edgley Stephen A. , Jankowska Elzbieta 
Published: March 2004

AbstractModulatory actions of monoamines were investigated on spinal commissural interneurons which coordinate left–right hindlimb muscle activity through direct projections to the contralateral motor nuclei. Commissural interneurons located in Rexed lamina VIII, with identified projections to the contralateral gastrocnemius–soleus motor nuclei, were investigated in deeply anaesthetized cats. Most interneurons had dominant input from either the reticular formation or from group II muscle afferents; a small proportion of neurons had input from both. Actions of ionophoretically applied serotonin and noradrenaline were examined on extracellularly recorded spikes evoked monosynaptically by group II muscle afferents or reticulospinal tract fibres. Activation by reticulospinal fibres was facilitated by both serotonin and noradrenaline. Activation by group II afferents was also facilitated by serotonin but was strongly depressed by noradrenaline. To investigate the possible morphological substrates of this differential modulation, seven representative commissural interneurons were labelled intracellularly with tetramethylrhodamine–dextran and neurobiotin. Contacts from noradrenergic and serotoninergic fibres were revealed by immunohistochemistry and analysed with confocal microscopy. There were no major differences in the numbers and distributions of contacts among the interneurons studied. The findings suggest that differences in modulatory actions of monoamines, and subsequent changes in the recruitment of subpopulations of commissural interneurons in various behavioural situations, depend on intrinsic interneuron properties rather than on the patterns of innervation by monoaminergic fibres. The different actions of noradrenaline on different populations of interneurons might permit reconfiguration of the actions of the commissural neurons according to behavioural context.
Calcium‐dependent subthreshold oscillations determine bursting activity induced by N‐methyl‐d‐aspartate in rat subthalamic neurons in vitro
Authors: Zhu Zi‐Tao , Munhall Adam , Shen Ke‐Zhong , Johnson Steven W. 
Published: March 2004

AbstractWe used whole‐cell patch recordings in current clamp to investigate the ionic dependence of burst firing induced by N‐methyl‐d‐aspartate (NMDA) in neurons of the subthalamic nucleus (STN) in slices of rat brain. NMDA (20 µm) converted single‐spike firing to burst firing in 87% of STN neurons tested. NMDA‐induced bursting was blocked by AP5 (50 µm), and was not mimicked by the non‐NMDA receptor agonist AMPA (0.6 µm). Tetrodotoxin (1 µm) converted bursts to oscillations of membrane potential, which were most robust when oscillations ranged between −50 and −70 mV. The NMDA bursts were blocked by an elevated extracellular concentration of Mg2+, but superfusate containing no added Mg2+ either reduced or increased burst firing, depending upon the amount of intracellular current injection. Block of K+ conductances by apamin and tetraethylammonium prolonged burst duration, but iberiotoxin had no effect. NMDA‐induced burst firing and membrane oscillations were completely blocked by superfusate containing no added Ca2+, and they were significantly reduced when patch pipettes contained BAPTA. Selective antagonists for T‐type (mibefradil, 10 µm), L‐type (nifedipine, 3 µm), and N‐type (ω‐conotoxin GVIA, 1 µm) Ca2+ channels had no effect on NMDA burst firing. Superfusate containing a low concentration of Na+ (20 mm) completely abolished NMDA‐induced burst firing. Flufenamic acid (10 µm), which blocks current mediated by Ca2+‐activated nonselective cation channels (ICAN), reversibly abolished NMDA‐depended bursting. These results are consistent with the hypothesis that NMDA‐induced burst firing in STN neurons requires activation of either an ICAN or a Na+–Ca2+ exchanger.
Orexin (hypocretin)/dynorphin neurons control GABAergic inputs to tuberomammillary neurons
Authors: Eriksson Krister S. , Sergeeva Olga A. , Selbach Oliver , Haas Helmut L. 
Published: March 2004

AbstractHigh activity of the histaminergic neurons in the tuberomammillary (TM) nucleus increases wakefulness, and their firing rate is highest during waking and lowest during rapid eye movement sleep. The TM neurons receive a prominent innervation from sleep‐active γ‐aminobutyric acidergic (GABAergic) neurons in the ventrolateral preoptic nucleus, which inhibits them during sleep. They also receive an excitatory input from the orexin‐ and dynorphin‐containing neurons in the lateral hypothalamus, which are critically involved in sleep regulation and whose dysfunction causes narcolepsy. We have used intracellular recordings and immunohistochemistry to study if orexin neurons exert control over the GABAergic inputs to TM neurons in rat hypothalamic slices. Dynorphin suppressed GABAergic inputs and thus disinhibits the TM neurons, acting in concert with orexin to increase the excitability of these neurons. In contrast, both orexin‐A and orexin‐B markedly increased the frequency of GABAergic potentials, while co‐application of orexin and dynorphin produced responses similar to dynorphin alone. Thus, orexins excite TM neurons directly and by disinhibition, gated by dynorphin. These data might explain some of the neuropathology of narcolepsy.
Thalamic innervation of striatal and subthalamic neurons projecting to the rat entopeduncular nucleus
Authors: Lanciego José L. , Gonzalo Nancy , Castle Maria , Sanchez‐Escobar Carlos , Aymerich Maria S. , Obeso Jose A. 
Published: March 2004

AbstractThe present study analyses the anatomical arrangement of the projections linking the Wistar rat parafascicular thalamic nucleus (PF) and basal ganglia structures, such as the striatum and the subthalamic nucleus (STN), by using neuroanatomical tract‐tracing techniques. Both the thalamostriatal and the striato‐entopeduncular projections were topographically organized, and several areas of overlap between identified circuits were noticed, sustaining the existence of up to three separated channels within the Nauta–Mehler loop. Thalamic afferents arising from dorsolateral PF territories are in register with striatofugal neurons located in dorsolateral striatal areas, which in turn project to dorsolateral regions of the entopeduncular nucleus (ENT). Medial ENT regions are innervated by striatal neurons located within medial striatal territories, these neurons being the target for thalamic afferents coming from medial PF areas. Finally, afferents from neurons located in ventrolateral PF areas approached striatal neurons in ventral and lateral striatal territories, which in turn project towards ventral and lateral ENT regions. Efferent STN neurons projecting to ENT were found to be the apparent postsynaptic target for thalamo‐subthalamic axons. The thalamo‐subthalamic projection was also topographically organized. Medial, central and lateral STN territories are innervated by thalamic neurons located within medial, ventrolateral and dorsolateral PF areas, respectively. Thus, each individual PF subregion projects in a segregated fashion to specific parts of the striato‐entopeduncular and subthalamo‐entopeduncular systems. These circuits enabled the caudal intralaminar nuclei to modulate basal ganglia output.
Ultrastructural study of depolarization‐induced translocation of NRF‐2 transcription factor in cultured rat visual cortical neurons
Authors: Yang Shou Jing , Liang Huan Ling , Ning Gang , Wong‐Riley Margaret T. T. 
Published: March 2004

AbstractNuclear respiratory factor (NRF)‐2 or GA‐binding protein is a potential transcriptional, bigenomic coordinator of mitochondrial and nuclear‐encoded subunits of cytochrome oxidase genes. It is composed of an α subunit that binds DNA and a β subunit that has the transactivating domain. Previously, we found that the level of NRF‐2 paralleled that of cytochrome oxidase under normal and functionally altered states. The goal of our present study was to increase the resolution to the ultrastructural level and to quantify changes before and after depolarizing stimulation. We used a pre‐embedding immunogold–silver method for the two subunits of NRF‐2 in cultured rat visual cortical neurons. NRF‐2α and β were normally located in both the nucleus and the cytoplasm. In the nucleus, both subunits were associated primarily with euchromatin rather than heterochromatin, consistent with active involvement in transcription. In the cytoplasm, they were associated mainly with free ribosomes and occasionally with the Golgi apparatus and the outer membrane of the nuclear envelope. Labelling was not found in the mitochondria, confirming the specificity of the antibodies. Neuronal depolarization by KCl for 5 h induced a six‐ to seven‐fold increase in the nuclear‐to‐cytoplasmic ratio of both subunits (P < 0.001) without increases in total labelling densities. These results strongly indicate that both NRF‐2α and NRF‐2β respond to increased neuronal activity by translocating from the cytoplasm to the nucleus, where they engage in transcriptional activation of target genes. Our results also indicate that the cytoplasmic to nuclear movement of transcription factors is a dynamic process induced by neuronal activity.
Dynamic changes in glypican‐1 expression in dorsal root ganglion neurons after peripheral and central axonal injury
Authors: Bloechlinger Stefan , Karchewski Laurie A. , Woolf Clifford J. 
Published: March 2004

AbstractGlypican‐1, a glycosyl phosphatidyl inositol (GPI)‐anchored heparan sulphate proteoglycan expressed in the developing and mature cells of the central nervous system, acts as a coreceptor for diverse ligands, including slit axonal guidance proteins, fibroblast growth factors and laminin. We have examined its expression in primary sensory dorsal root ganglion (DRG) neurons and spinal cord after axonal injury. In noninjured rats, glypican‐1 mRNA and protein are constitutively expressed at low levels in lumbar DRGs. Sciatic nerve transection results in a two‐fold increase in mRNA and protein expression. High glypican‐1 expression persists until the injured axons reinnervate their peripheral targets, as in the case of a crushed nerve. Injury to the central axons of DRG neurons by either a dorsal column injury or a dorsal root transection also up‐regulates glypican‐1, a feature that differs from most DRG axonal injury‐induced genes, whose regulation changes only after peripheral and not central axonal injury. After axonal injury, the cellular localization of glypican‐1 changes from a nuclear pattern restricted to neurons in noninjured DRGs, to the cytoplasm and membrane of injured neurons, as well as neighbouring non‐neuronal cells. Sciatic nerve transection also leads to an accumulation of glypican‐1 in the proximal nerve segment of injured axons. Glypican‐1 is coexpressed with robo 2 and its up‐regulation after axonal injury may contribute to an altered sensitivity to axonal growth or guidance cues.
Book Reviews
Authors: Ho Samuel M. Y. 
Published: March 2004

The Spiritual Recovery Manual. Vedic Knowledge and Yogic Techniques to Accelerate Recovery for Addicts, Codependents and Adult Children of Dysfunctional Families. Patrick Gresham Williams (Ed). Incandescent Press, Palo Alto, CA, 2002. 272 pp.ISBN 0‐9709078‐1‐8. Price US $35.00, paperback.
Idealism and Williams's Semantic Paradox
Authors: Jacquette Dale 
Published: March 2004

AbstractBernard Williams's essay ‘Wittgenstein and Idealism’ argues that that the conventionality of language entails the dependence of the truth of sentences and ultimately of corresponding states of affairs as truth‐makers on the existence of thinking subjects. Peter Winch and Colin Lyas try to avoid William's paradox by distinguishing between the existence conditions of a sentence and its assertion. The Winch‐Lyas solution is criticized and a stronger Winch‐Lays resistant version of Williams's paradox is proposed. A more satisfactory countercriticism is given, involving an ineliminable modal fallacy occurring in the paradox inference, that arises because of the argument's invalid combination of categorical and counterfactual assumptions and conclusions.
A Religious Point of View
Authors: Wolgast Elizabeth 
Published: March 2004

AbstractThe purpose of this paper is to show connections between Wittgenstein's approach to philosophy and the writings on religion of two authors whom we know Wittgenstein read and admired: William James and Leo Tolstoy. Wittgenstein stresses certain attitudes toward philosophical ‘problems’ which resemble the attitudes that James and Tolstoy connect with religious faith. There are also similarities of phrases and expressions.It is not possible to say that these writers influenced the way Wittgenstein regarded philosophy, but it suggests that he recognized the similarities between their approaches and his despite the differences in subject. Consequently it helps to clarify why he would speak of his approach to problems as being from ‘a religious point of view’ even though its orientation is not specifically religious.
Kinds of Context: A Wittgensteinian Approach to Proper Names and Indexicals
Authors: Corazza Eros 
Published: March 2004

AbstractIn focusing on indexicals and proper names and on the different ways in which their references are fixed, I illustrate how our linguistic practice rests on context, broadly construed. The following theses are discussed and defended:

There are two main kinds of information: (i) anchored information, i.e. the information one gathers in using and entertaining indexical expressions and (ii) unanchored information, i.e. the information one may gain in hearing a proper name.
Indexical expressions differ from proper names; this difference relies on the differing ways in which extra‐linguistic context enters the scene.
The Kaplanian framework in particular, and the framework of direct reference in general, are best understood and appreciated against the background of a Wittgensteinian conception of language.