bluuebunny/crossref_metadata_2025_split huggingface dataset:
A cell adhesion molecule mimetic, FGL peptide, induces alterations in synapse and dendritic spine structure in the dentate gyrus of aged rats: a three‐dimensional ultrastructural study
Authors: Popov Victor I. , Medvedev Nikolay I. , Kraev Igor V. , Gabbott Paul L. , Davies Heather A. , Lynch Marina , Cowley Thelma R. , Berezin Vladimir , Bock Elisabeth , Stewart Michael G. 
Published: July 2010

AbstractThe FGL peptide is a neural cell adhesion molecule (NCAM) mimetic comprising a 15‐amino‐acid‐long sequence of the FG loop region of the second fibronectin type III module of NCAM. It corresponds to the binding site of NCAM for the fibroblast growth factor receptor 1. FGL improves cognitive function through enhancement of synaptic function. We examined the effect of FGL on synaptic and dendritic structure in the brains of aged (22‐month‐old) rats that were injected subcutaneously (8 mg/kg) at 2‐day intervals until 19 days after the start of the experiment. Animals were perfused with fixative, brains removed and coronal sections cut at 50 µm. The hippocampal volume was measured, tissue embedded and ultrathin sections viewed in a JEOL 1010 electron microscope. Analyses were made of synaptic and dendritic parameters following three‐dimensional reconstruction via images from a series of ∼100 serial ultrathin sections. FGL affected neither hippocampal volume nor spine or synaptic density in the middle molecular layer of the dentate gyrus. However, it increased the ratio of mushroom to thin spines, number of multivesicular bodies and also increased the frequency of appearance of coated pits. Three‐dimensional analysis showed a significant decrease in both post‐synaptic density and apposition zone curvature of mushroom spines following FGL treatment, whereas for thin spines the convexity of the apposition zone increased. These data indicate that FGL induces large changes in the fine structure of synapses and dendritic spines in hippocampus of aged rats, complementing data showing its effect on cognitive processes.
The glutamate receptor 2 subunit controls post‐synaptic density complexity and spine shape in the dentate gyrus
Authors: Medvedev Nikolay I. , Rodríguez‐Arellano José J. , Popov Victor I. , Davies Heather A. , Tigaret Cezar M. , Schoepfer Ralf , Stewart Michael G. 
Published: July 2010

AbstractIn adult brain the majority of AMPA glutamate receptor (GluR) subunits contain GluR2. In knock‐out (KO) mice the absence of GluR2 results in consequences for synaptic plasticity including cognitive impairments. Here the morphology of dendritic spines and their synaptic contacts was analysed via three‐dimensional reconstruction of serial electron micrographs from dentate gyrus (DG) of adult wild type (WT) and GluR2 KO mice. Pre‐embedding immunocytochemical staining was used to examine the distribution and subcellular localization of AMPA receptor GluR1 and N‐methyl‐d‐aspartate receptor NR1 subunits. There were no significant changes in synapse density in the DG of GluR2 KO compared with WT mice. However, in GluR2 KO mice there was a significant decrease in the percentage of synapses on mushroom spines but an increase in synapses on thin spines. There was also a large decrease in the proportion of synapses with complex perforated/segmented post‐synaptic densities (PSDs) (25 vs. 78% in WT) but an increase in synapses with macular PSDs (75 vs. 22%). These data were coupled in GluR2 KO mice with significant decreases in volume and surface area of mushroom spines and their PSDs. In both GluR2 KO and WT mice, NR1 and GluR1 receptors were present in dendrites and spines but there was a significant reduction in NR1 labelling of spine membranes and cytoplasm in GluR2 KO mice, and a small decrease in GluR1 immunolabelling in membranes and cytoplasm of spines in GluR2 KO compared with WT mice. Our data demonstrate that the absence of GluR2 has a significant effect on both DG synapse and spine cytoarchitecture and the expression of NR1 receptors.
PPARγ agonist pioglitazone rescues neuronal cell damage after transient global cerebral ischemia through matrix metalloproteinase inhibition
Authors: Lee Kyung‐Jae , Jang Young‐Ho , Lee Hyung , Yoo Ho‐Sang , Lee Seong‐Ryong 
Published: July 2010

AbstractPrevious studies have demonstrated that pioglitazone, a peroxisome proliferator‐activated receptor gamma (PPARγ) agonist, inhibits ischemia‐induced injury in various tissues including neural tissue. Pioglitazone has also been shown to reduce matrix metalloproteinase (MMP) activity. Because MMP is known to play a major role in the pathophysiology of brain ischemia, the present study was undertaken to test whether pioglitazone attenuates ischemic neuronal damage through MMP inhibition. C57BL/6 mice were subjected to global brain ischemia for 20 min. Animals were killed 72 h after ischemia. Oral pioglitazone (40 mg/kg/day, as a suspension in 0.5% carboxymethylcellulose) was administered to mice twice daily for 3 days before ischemia and twice daily after ischemia until the animals were killed. We investigated gelatinase activity by zymography and laminin immunohistochemistry. Histological analysis was also performed to test the protective effect of pioglitazone on neuronal damage. Mice treated with pioglitazone had attenuated gelatinase activity. Gelatin gel and in situ zymography showed up‐regulation of gelatinase activity after ischemia. Pioglitazone significantly inhibited ischemia‐induced elevation of the active form of MMP‐9. Pioglitazone also reduced up‐regulation of in situ gelatinase activity and laminin breakdown induced by ischemia in the hippocampus. There was marked neuronal damage in the CA1 and CA2 areas after ischemia. Neuronal damage in mice was significantly decreased by pioglitazone treatment, compared with vehicle‐treated mice. Pioglitazone also inhibited TdT‐mediated dUTP nick end labeling staining in CA1 and CA2 areas. Pioglitazone, a PPARγ agonist, reduces delayed neuronal damage induced by global ischemia through inhibition of MMP‐9 activity.
Interaction of visual hemifield and body view in biological motion perception
Authors: De Lussanet Marc H. E. , Fadiga Luciano , Michels Lars , Seitz Rüdiger J. , Kleiser Raimund , Lappe Markus 
Published: July 2010

AbstractThe brain network for the recognition of biological motion includes visual areas and structures of the mirror‐neuron system. The latter respond during action execution as well as during action recognition. As motor and somatosensory areas predominantly represent the contralateral side of the body and visual areas predominantly process stimuli from the contralateral hemifield, we were interested in interactions between visual hemifield and action recognition. In the present study, human participants detected the facing direction of profile views of biological motion stimuli presented in the visual periphery. They recognized a right‐facing body view of human motion better in the right visual hemifield than in the left; and a left‐facing body view better in the left visual hemifield than in the right. In a subsequent fMRI experiment, performed with a similar task, two cortical areas in the left and right hemispheres were significantly correlated with the behavioural facing effect: primary somatosensory cortex (BA 2) and inferior frontal gyrus (BA 44). These areas were activated specifically when point‐light stimuli presented in the contralateral visual hemifield displayed the side view of their contralateral body side. Our results indicate that the hemispheric specialization of one's own body map extends to the visual representation of the bodies of others.
The axon‐guidance roundabout gene alters the pace of the Drosophila circadian clock
Authors: Berni Jimena , Beckwith Esteban J. , Fernández María Paz , Ceriani María Fernanda 
Published: July 2010

AbstractGreat efforts have been directed to the dissection of the cell‐autonomous circadian oscillator in Drosophila. However, less information is available regarding how this oscillator controls rhythmic rest–activity cycles. We have identified a viable allele of roundabout, robohy, where the period of locomotor activity is shortened. From its role in axon‐pathfinding, we anticipated developmental defects in clock‐relevant structures. However, robohy produced minor defects in the architecture of the circuits essential for rhythmic behaviour. ROBO's presence within the circadian circuit strengthened the possibility of a novel role for ROBO at this postdevelopmental stage. Genetic interactions between pdf 01 and robohy suggest that ROBO could alter the communication within different clusters of the circadian network, thus impinging on two basic properties, periodicity and/or rhythmicity. Early translocation of PERIOD to the nucleus in robohy pacemaker cells indicated that shortened activity rhythms were derived from alterations in the molecular oscillator. Herein we present a mutation affecting clock function associated with a molecule involved in circuit assembly and maintenance.
Depolarization promotes GAD 65‐mediated GABA synthesis by a post‐translational mechanism in neural stem cell‐derived neurons
Authors: Gakhar‐Koppole Nidhi , Bengtson C. Peter , Parlato Rosanna , Horsch Kerstin , Eckstein Volker , Ciccolini Francesca 
Published: July 2010

AbstractNeuronal activity regulates neurogenesis and neuronal differentiation in the mammalian brain. The commencement of neurotransmitter expression establishes the neuronal phenotype and enables the formation of functional connectivity between neurons. In addition, release of neurotransmitters from differentiating neurons may modulate the behaviour of neural precursors. Here, we show that neuronal activity regulates γ‐aminobutyric acid (GABA) expression in neurons generated from stem cells of the striatum and adult subventricular zone (SVZ). Differentiating neurons display spontaneous Ca2+ events, which are voltage‐gated calcium channel (VGCC) dependent. Depolarization increases both the frequency of Ca2+ transients and the amount of Ca2+ influx in differentiating neurons. We show that depolarization‐dependent GABA expression is regulated by the amplitude and not by the frequency of Ca2+ influx. Brief activation of VGCCs leads to Ca2+ influx that in turn promotes a rapid expression of GABA. Depolarization‐dependent GABA expression does not require changes in gene expression. Instead, it involves cAMP‐dependent protein kinase (PKA) and Ca2+ and phospholipid‐dependent protein kinase (PKC) signalling. Activity increases the number of glutamic acid decarboxylase (GAD) 65‐immunoreactive neurons in a PKA‐dependent manner, without altering the expression of GAD 65, suggesting that depolarization promotes recruitment of GAD 65 by a post‐translational mechanism. In line with this, depolarization does not permanently increase the expression of GABA in neurons derived from neural stem cells of the embryonic striatum, cortex and adult SVZ. Thus, neuronal activity does not merely accelerate neuronal differentiation but it may alter the mechanism of GABA synthesis in newly generated neurons.
A neuroanatomically grounded Hebbian‐learning model of attention–language interactions in the human brain
Authors: Garagnani Max , Wennekers Thomas , Pulvermüller Friedemann 
Published: July 2010

AbstractMeaningful familiar stimuli and senseless unknown materials lead to different patterns of brain activation. A late major neurophysiological response indexing ‘sense’ is the negative component of event‐related potential peaking at around 400 ms (N400), an event‐related potential that emerges in attention‐demanding tasks and is larger for senseless materials (e.g. meaningless pseudowords) than for matched meaningful stimuli (words). However, the mismatch negativity (latency 100–250 ms), an early automatic brain response elicited under distraction, is larger to words than to pseudowords, thus exhibiting the opposite pattern to that seen for the N400. So far, no theoretical account has been able to reconcile and explain these findings by means of a single, mechanistic neural model. We implemented a neuroanatomically grounded neural network model of the left perisylvian language cortex and simulated: (i) brain processes of early language acquisition and (ii) cortical responses to familiar word and senseless pseudoword stimuli. We found that variation of the area‐specific inhibition (the model correlate of attention) modulated the simulated brain response to words and pseudowords, producing either an N400‐ or a mismatch negativity‐like response depending on the amount of inhibition (i.e. available attentional resources). Our model: (i) provides a unifying explanatory account, at cortical level, of experimental observations that, so far, had not been given a coherent interpretation within a single framework; (ii) demonstrates the viability of purely Hebbian, associative learning in a multilayered neural network architecture; and (iii) makes clear predictions on the effects of attention on latency and magnitude of event‐related potentials to lexical items. Such predictions have been confirmed by recent experimental evidence.
Nature's food anticipatory experiment: entrainment of locomotor behavior, suprachiasmatic and dorsomedial hypothalamic nuclei by suckling in rabbit pups
Authors: Caba Mario , Tovar Anibal , Silver Rae , Mogado Elvira , Meza Enrique , Zavaleta Yael , Juárez Claudia 
Published: July 2010

AbstractIn nature and under laboratory conditions, dams nurse rabbit pups once daily for a duration of fewer than 5 min. The present study explored neural mechanisms mediating the timing of nursing in this natural model of food anticipatory activity, focussing on the suprachiasmatic nucleus (SCN), the locus of the master circadian clock and on the dorsomedial hypothalamic nucleus (DMH), a region implicated in timing of food‐entrained behavior. Rabbit pups are born in the dark, with eyelids closed. Nursing visits to the litters also occurs during the dark phase. To explore the effect of the timing of feeding, pups were maintained in constant darkness, while females housed in a light–dark cycle were permitted to nurse their pups either during the night (night‐fed group) or day (day‐fed group). All pups exhibited anticipatory locomotor activity before daily nursing. In the SCN, PER1 and FOS peaked during the night in both groups, with a longer duration of elevated protein expression in the night‐fed group. In contrast, DMH peak PER1 expression occurred 8 h after pups were fed, corresponding to the shift in timing of nursing. Comparison of nursed and 48 h fasted pups indicates that the timing of PER1 expression was similar in the SCN and DMH, with fewer PER1‐positive cells in the latter group. The results indicate that rabbit pups show food anticipatory activity, and that timing of nursing differentially affects PER1 expression in the SCN and DMH.
Prior pallidotomy reduces and modifies neuronal activity in the subthalamic nucleus of Parkinson's disease patients
Authors: Zaidel A. , Moran A. , Marjan G. , Bergman H. , Israel Z. 
Published: July 2010

AbstractParkinson's disease (PD) patients with prior radio‐frequency lesions in the internal segment of the globus pallidus (GPi, pallidotomy), whose symptoms have deteriorated, may be candidates for further invasive treatment such as subthalamic deep brain stimulation (STN DBS). Six patients with prior pallidotomy (five unilaterally; one bilaterally) underwent bilateral STN DBS. The microelectrode recordings (MERs, used intraoperatively for STN verification), ipsilateral and contralateral to pallidotomy, and MERs from 11 matched PD patients who underwent bilateral STN DBS without prior pallidotomy were compared. For each trajectory, average, variance and mean successive difference (MSD, a measure of irregularity) of the root mean square (RMS) of the STN MER were calculated. The RMS in trajectories ipsilateral to pallidotomy showed significant reduction of the mean average and MSD of STN activity when compared with trajectories from patients without prior pallidotomy. The RMS parameters contralateral to pallidotomy tend to lie between those ipsilateral to pallidotomy and those without prior pallidotomy. The average STN power spectral density of oscillatory activity was notably lower ipsilateral to pallidotomy than contralateral, or without prior pallidotomy. The finding that pallidotomy reduces STN activity and changes firing characteristics, in conjunction with the effectiveness of STN DBS despite prior pallidotomy, calls for reappraisal and modification of the current model of the basal ganglia (BG) cortical network. It highlights the critical role of direct projections from the BG to brain‐stem structures and suggests a possible GPi–STN reciprocal positive‐feedback mechanism.
Variations in tissue resistivity and in the extension of activated neuron domains shape the voltage signal during spreading depression in the CA1 in vivo
Authors: Makarova Julia , Gómez‐Galán Marta , Herreras Oscar 
Published: July 2010

AbstractSpreading depression (SD), a wave of neuron activity related to migraine and the ischaemic penumbra, features a moving shell of extracellular negative potential shift (Vo) whose generators are poorly understood. We investigated its subcellular correlates in the hippocampal CA1 in vivo by localizing the neuron domains that generate transmembrane current (Im) using field analysis, and the local changes of tissue resistivity, a major determinant of extracellular current flow. A large increase of tissue resistivity occurred in times and dendritic strata displaying large Vo, albeit with different rates. Typically, SD is composed of basal and apical dendritic components. The apical SD lasts much longer, while it becomes gradually restricted to a narrow dendritic region. Strikingly, pyramidal cells displayed a strong surge of inward current only when SD affected a small dendritic region. However, when the Vo signal covered most of the main neuron axis, only smaller surges of inward current developed at the outer dendritic rims of a wide null current zone. Computational reconstruction showed that this effect was due to strong spatial cancellation of the inward and outward currents in SD‐activated isopotential and shunted regions of individual neurons. Consequently, despite former accounts of large conductance increase, the net Im is small and the large ΔVo amplitude mostly due to increased tissue resistivity. The particular subcellular evolution indicates an initial explosive opening of conductance along most of the pyramidal neuron followed by a wave‐like centripetal closure towards the apical dendrites. The applicability of these mechanisms to SD in other brain regions is discussed.
Visualization of Large‐Scale Urban Models through Multi‐Level Relief Impostors
Authors: Andujar C. , Brunet P. , Chica A. , Navazo I. 
Published: July 2010

Abstract In this paper, we present an efficient approach for the interactive rendering of large‐scale urban models, which can be integrated seamlessly with virtual globe applications. Our scheme fills the gap between standard approaches for distant views of digital terrains and the polygonal models required for close‐up views. Our work is oriented towards city models with real photographic textures of the building facades. At the heart of our approach is a multi‐resolution tree of the scene defining multi‐level relief impostors. Key ingredients of our approach include the pre‐computation of a small set of zenithal and oblique relief maps that capture the geometry and appearance of the buildings inside each node, a rendering algorithm combining relief mapping with projective texture mapping which uses only a small subset of the pre‐computed relief maps, and the use of wavelet compression to simulate two additional levels of the tree. Our scheme runs considerably faster than polygonal‐based approaches while producing images with higher quality than competing relief‐mapping techniques. We show both analytically and empirically that multi‐level relief impostors are suitable for interactive navigation through large urban models.
Board Information and Strategic Tasks Performance
Authors: Zhang Pingying 
Published: July 2010

ABSTRACTManuscript Type: EmpiricalResearch Question/Issue: Examining how corporate boards can create a sustainable competitive advantage is an understudied area of research in corporate governance. This area of research is advanced in this study, which examines: How can boards improve the performance of their strategic tasks by using their information advantages?Research Findings/Insights: The study examines 318 responses of CEOs from survey data collected in the years 2003 and 2005 from Norway. We found differences between using diverse information and possessing diverse information. Using diverse information has a higher impact on the board's current strategic tasks performance than possessing diverse information. However, possessing diverse information is more likely to improve both the board's current and future strategic tasks performance than using diverse information.Theoretical/Academic Implications: First, this study has extended the analysis of board capital by including a dynamic dimension of using diverse information. Second, this study links a resource‐based view with a perspective of information biases in a diverse group. Diverse information is valuable for improving the quality of group decision‐making; however, improper use of diverse information due to information biases could reduce the quality. We thus suggest examining possible behavioral biases in using information in a diverse board, specifically through each of the three practices of open discussion, effective leadership, and active search.Practitioner/Policy Implications: Controlling sampling, repetition, and evaluation biases is necessary in a diverse board. It helps to reduce behavioral biases, and therefore ensure the quality of using diverse information. Consequently, it improves the board's current strategic tasks performance that may not necessarily be achieved by merely having a diverse board.
Introduction to the Special Issue on Leadership, Altruism, and Social Organization
Authors: CHANDER PARKASH , CONLEY JOHN P. , VESTERLUND LISE 
Published: July 2010

AbstractThe objective of the conference on “Leadership, Altruism, and Social Organization” was to bring researchers together who were interested in exploring the functioning of the nonprofit sector. The conference and this special issue focus on three themes. First, what causes social and volunteer‐based organizations to successfully compete against a private enterprise? Second, why do individuals or organizations take the lead in providing or securing provision of public goods? Third, what are the consequences of having altruistically motivated agents, and how can such motives be sustained?
Knowledge Market Design: A Field Experiment at Google Answers
Authors: CHEN YAN , HO TECK‐HUA , KIM YONG‐MI 
Published: July 2010

AbstractIn a field experiment at Google Answers, we investigate the performance of price‐based online knowledge markets by systematically manipulating prices. Specifically, we study the effects of price, tip, and a reputation system on both an answerer's effort and answer quality by posting real reference questions from the Internet Public Library on Google Answers under different pricing schemes. We find that a higher price leads to a significantly longer, but not better, answer, while an answerer with a higher reputation provides significantly better answers. Our results highlight the limitation of monetary incentives and the importance of reputation systems in knowledge market design.