bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short‐term synaptic plasticity during development of rat mossy fibre to granule cell synapses
Authors: Wall Mark J. 
Published: May 2005

AbstractChanges occur during the postnatal development of the rat glutamatergic mossy fibre to granule cell synapse: to the morphology of synapses, glutamate transporter expression, AMPA receptor expression and the kinetics of AMPA receptor‐mediated synaptic transmission. For example, both the rise and decay times of AMPA receptor‐mediated excitatory postsynaptic currents significantly shorten. To further define the development of mossy fibre to granule cell synaptic transmission, the properties and mechanisms of short‐term plasticity have been described. The characterization of short‐term plasticity will aid our understanding of the mechanisms that define the parameters of synaptic transmission during development and furthermore short‐term plasticity may play an important role in determining information transfer between mossy fibres and granule cells. In response to pairs of stimuli (2–100‐ms interval), depression (second excitatory postsynaptic current amplitude smaller than the first) was observed at both mature (older than 40 postnatal days) and immature (between 8 and 12 postnatal days) synapses. The degree of depression was similar at both stages of development, although recovery from depression was slower at mature synapses (τ 22 vs 12.5 ms). Several experimental approaches (coefficient of variation, low‐affinity antagonists and cyclothiazide) suggest that depression at immature synapses results from multiple mechanisms. At mature synapses, postsynaptic receptor desensitization appears to be the major cause of depression.
Nitric oxide release is induced by dopamine during illumination of the carp retina: serial neurochemical control of light adaptation
Authors: Sekaran S. , Cunningham J. , Neal M. J. , Hartell N. A. , Djamgoz M. B. A. 
Published: May 2005

AbstractSeveral lines of indirect evidence have suggested that nitric oxide may play an important role during light adaptation of the vertebrate retina. We aimed to verify directly the effect of light on nitric oxide release in the isolated carp retina and to investigate the relationship between nitric oxide and dopamine, an established neuromodulator of retinal light adaptation. Using a biochemical nitric oxide assay, we found that steady or flicker light stimulation enhanced retinal nitric oxide production from a basal level. The metabotropic glutamate receptor agonist l‐amino‐4‐phosphonobutyric acid, inhibited the light adaptation‐induced nitric oxide production suggesting that the underlying cellular pathway involved centre‐depolarizing bipolar cell activity. Application of exogenous dopamine to retinas in the dark significantly enhanced the basal production of nitric oxide and importantly, inhibition of endogenous dopaminergic activity completely suppressed the light‐evoked nitric oxide release. The effect of dopamine was mediated through the D1 receptor subtype. Imaging of the nitric oxide‐sensitive fluorescent indicator 4,5‐diaminofluorescein di‐acetate in retinal slices revealed that activation of D1 receptors resulted in nitric oxide production from two main spatial sources corresponding to the photoreceptor inner segment region and the inner nuclear layer. The results taken together would suggest that during the progression of retinal light adaptation there is a switch from dopaminergic to nitrergic control, probably to induce further neuromodulatory effects at higher levels of illumination and to enable more efficient spreading of the light adaptive signal.
Daily number and lengths of activity bursts in rabbit jaw muscles
Authors: Van Wessel Tim , Langenbach Geerling E. J. , Van Ruijven Leo J. , Brugman Peter , Van Eijden Theo M. G. J. 
Published: May 2005

AbstractMuscle activity has predominantly been studied for specific motor tasks not necessarily representative of normal daily behaviour. The few studies that have examined daily muscle use have quantified this by duty time, merging all levels of muscle activity. Muscle activity can also be characterized by the number, duration and level of bursts. The purpose of this study was to characterize, for various levels of muscle activity, the daily masseter and digastric actions in the rabbit. Characterization was realized by quantification of duty time (summed length of all bursts as a percentage of total time), number of bursts and distribution of burst lengths. A telemetric device was implanted in the two muscles of six rabbits, ensuring the recording of their jaw muscle activities while they moved freely. The continuously transmitted signals over 1 day were analysed. The results showed that (i) more than 100 000 bursts per day exceeded the 2% level of the maximum muscle activity in both muscles, whereas fewer than 100 bursts per day exceeded the 90% level; and (ii) the digastric muscle exhibited a significantly higher duty time than the masseter (respectively, 23% and 14% for activities exceeding the 2% level), which was mainly caused by the on average longer burst lengths at the lowest levels. The characterization of muscle activity in daily burst number and distribution of burst lengths exceeding various activity levels provides valuable information on motor control and enables further investigation of the adaptive capacity of muscles.
Removal of cholinergic input to perirhinal cortex disrupts object recognition but not spatial working memory in the rat
Authors: Winters Boyer D. , Bussey Timothy J. 
Published: May 2005

AbstractThe perirhinal cortex of the temporal lobe has a crucial role in object recognition memory. Cholinergic transmission within perirhinal cortex also seems to be important for this function, as the muscarinic receptor antagonist scopolamine disrupts object recognition performance when administered systemically or directly into perirhinal cortex. In the present study, we directly assessed the contribution of cholinergic basal forebrain input to perirhinal cortex in object recognition. Selective bilateral removal of the cholinergic basal forebrain inputs to perirhinal cortex was accomplished by injecting the immunotoxin 192 IgG‐saporin directly into perirhinal cortex in rats. These animals were significantly impaired relative to vehicle‐injected controls in a spontaneous object recognition task despite intact spatial alternation performance. These results are consistent with recent reports of object recognition impairment following acute cholinergic receptor blockade and extend these findings by demonstrating that chronic removal of cholinergic basal forebrain input to an otherwise intact perirhinal cortex causes a severe object recognition deficit similar to that associated with more extensive cell body lesions of perirhinal cortex.
Cannabinoid CB1 receptor antagonism reduces conditioned reinstatement of ethanol‐seeking behavior in rats
Authors: Cippitelli Andrea , Bilbao Ainhoa , Hansson Anita C. , Del Arco Ignacio , Sommer Wolfgang , Heilig Markus , Massi Mauricio , Bermúdez‐Silva Francisco Javier , Navarro Miguel , Ciccocioppo Roberto , De Fonseca Fernando Rodríguez 
Published: May 2005

AbstractThe endocannabinoid system is involved in a variety of effects of drugs of misuse, and blockade of the cannabinoid CB1 receptor by selective antagonists elicits marked reductions in opioid and alcohol self‐administration. The present study was designed to extend our knowledge of the role of the cannabinoid CB1 receptor in the modulation of alcohol misuse vulnerability in rats. Accordingly, using nonselected Wistar rats and genetically selected Marchigian Sardinian alcohol‐preferring (msP) rats, we investigated the effect of the CB1 antagonist SR141716A on operant alcohol self‐administration and on reinstatement of alcohol‐seeking behavior by environmental conditioning factors. In addition, in situ hybridization studies in both strains were performed to measure cannabinoid CB1 receptor mRNA in different brain areas of these animals. Results showed that intraperitoneal administration of SR141716A (0.03, 1.0 and 3.0 mg/kg) markedly inhibits ethanol self‐administration and conditioned reinstatement of ethanol‐seeking behavior in both strains of rats. ED50 analysis showed significantly higher sensitivity (P < 0.05) to the effect of SR141716A in msP rats than in heterogeneous Wistar rats. In situ hybridization studies revealed that, compared with Wistar rats, msP animals have consistently greater cannabinoid CB1 receptor mRNA expression in a number of brain areas, including the frontoparietal cortex, caudate‐putamen and hippocampus (CA1 and dentate gyrus areas). In conclusion, we provide clear evidence that blockade of CB1 receptors reduces both ethanol self‐administration and conditioned reinstatement of alcohol‐seeking behavior in rats. In addition, current pharmacological and neuroanatomical data suggest that an altered function of the CB1 receptor system exists between genetically selected alcohol‐preferring msP rats and a heterogeneous animal population.
Candidate pheromone receptors of the silkmoth Bombyx mori
Authors: Krieger Jürgen , Große‐Wilde Ewald , Gohl Thomas , Breer Heinz 
Published: May 2005

AbstractCommunication via specific chemical signals is vitally important for the reproductive behaviour of many species. The first identified sex‐attractant pheromone was bombykol from the silkmoth Bombyx mori. This female‐released signalling compound is perceived by the male moth with extreme sensitivity and specificity. Antennal sensory cells supposedly respond to individual bombykol molecules and can efficiently distinguish bombykol from highly related structural analogues like bombykal, a second female‐released pheromone component. In the four decades since the discovery of bombykol, the Bombyx mori system has continued to serve as an invaluable model system for unraveling the intricacies of chemical communication. The molecular basis for this extraordinary specific recognition of an extraneous compound is still elusive but probably based on specific receptors of the pheromone‐responsive cells. In this study, molecular and bioinformatic approaches were employed to search for candidate pheromone receptors of Bombyx mori. A few receptor types were identified that are related to Heliothis candidate pheromone receptors. They were found to be almost exclusively expressed in male antennae, and double in situ hybridization experiments disclosed a characteristic topographic expression pattern that was reminiscent of pheromone‐responsive cells. Furthermore, the receptor‐expressing cells were closely associated with cells expressing the pheromone‐binding protein. Together, the data support the view that the identified receptor types of Bombyx mori are candidate receptors for pheromone components.
Over‐expression of the human EAAT2 glutamate transporter within neurons of mouse organotypic hippocampal slice cultures leads to increased vulnerability of CA1 pyramidal cells
Authors: Selkirk Julie V. , Stiefel Theodore H. , Stone Ida M. , Naeve Greg S. , Foster Alan C. , Poulsen David J. 
Published: May 2005

AbstractExcitatory amino acid transporters (EAATs) maintain the balance between pathological and physiological conditions by limiting the extracellular concentration of glutamate within the CNS and thus preventing excitotoxic injury. The loss of EAAT2 has been associated with the development of neurological diseases such as amyotrophic lateral sclerosis. It has therefore been suggested that the over‐expression of specific EAATs may provide some degree of neuroprotection. However, the inability to isolate and study the function of the different EAAT isoforms in a cell type‐specific manner has made it difficult to determine the exact contribution of individual EAATs toward neuroprotection or neurodegeneration in the context of excitotoxic injury. To address this question, we transduced hippocampal slice cultures from 1‐week‐old C57B/6 mice with recombinant adeno‐associated virus carrying an EAAT2 gene expression cassette. EAAT2 gene expression was driven in neurons with the neuron‐specific enolase promoter. Using this model system, we were able to induce a significant increase in the expression of functional EAAT2. Consequently, a significant increase in CA1 neuronal damage was observed in slices over‐expressing EAAT2 in neurons following an acute exposure to exogenous glutamate. These data suggest that the increased expression of EAAT2 within neurons may contribute to neurodegeneration.
Pathological implications of iNOS expression in central white matter: an ex vivo study of optic nerves from rats with experimental allergic encephalomyelitis
Authors: Garthwaite G. , Batchelor A. M. , Goodwin D. A. , Hewson A. K. , Leeming K. , Ahmed Z. , Cuzner M. L. , Garthwaite J. 
Published: May 2005

AbstractExcessive nitric oxide (NO) production from the inducible isoform of nitric oxide synthase (iNOS) has been invoked as a causative factor in many neurodegenerative disorders, including multiple sclerosis. This hypothesis has been supported by in vitro studies showing that glial iNOS expression results in toxic NO concentrations (near 1 µm). To investigate the relevance of such findings, experiments were carried out ex vivo on optic nerves from rats with exacerbated experimental allergic encephalomyelitis, a model of multiple sclerosis. The nerves displayed characteristic immunopathology and expression of iNOS in macrophages and/or microglia and there was overt axonal damage in localized regions of the optic chiasm. The resulting NO levels in the optic nerve were sufficient to cause activation of guanylyl cyclase‐coupled NO receptors, resulting in marked cGMP accumulation in axons throughout the nerve. Nevertheless, calibration of cGMP levels against those evoked by exogenous NO indicated that the nerves were not compromised metabolically and that their ambient NO concentration was only ≈ 1 nm. Consistent with this observation, electrophysiological tests indicated that there was no ongoing malfunctioning of the type that can be elicited by high exogenous NO concentrations. It is concluded that, with iNOS expressed in physiological locations and levels, the tissue levels of NO remain at concentrations far lower than those shown to have toxic effects, despite continuous NO synthesis. The fact that NO can rise to much higher levels in dispersed cultures in vitro may be attributable to a deficiency in NO inactivation in such preparations.
Lasting accelerative effects of 1 Hz and 20 Hz electrical stimulation on cortical spreading depression: relevance for clinical applications of brain stimulation
Authors: Fregni Felipe , Monte‐Silva Katia K. , Oliveira Manuella B. , Freedman Steven D. , Pascual‐Leone Alvaro , Guedes Rubem C. A. 
Published: May 2005

AbstractClinical applications of brain stimulation have been increasing during the last decade; however, the mechanisms of action remain unknown. One proposed mechanism of action is that repetitive stimulation modulates cortical excitability. Herein, we explore the question of whether repetitive electric stimulation increases cortical excitability as indexed by the cortical spreading depression. Twenty‐four Wistar rats were divided into three groups according to the treatment: sham, 1‐Hz and 20‐Hz stimulation. Stimulation was applied to the left frontal cortex through a pair of epidurally implanted silver‐wire electrodes. The cortical spreading depression‐features were analysed at three time points (one day before, one day after and 2 weeks after treatment) in both the stimulated and unstimulated hemisphere. A 3 × 2 × 3 factorial anova with repeated measures showed significant differences in the main effect of time (P < 0.0001), hemisphere (P = 0.0002) and stimulation group (P = 0.008). The interaction between time vs. hemisphere vs. stimulation group was also significant (P < 0.0001). Posthoc analysis demonstrated that 1‐Hz and 20‐Hz repetitive electrical stimulation significantly increased the velocity of cortical spreading depression in the stimulated hemisphere. Furthermore, 20‐Hz stimulation showed a greater effect on cortical spreading depression compared to 1‐Hz stimulation. The results show that 1‐Hz and 20‐Hz repetitive electrical stimulation results in an increase in cortical spreading depression velocity that is associated with the frequency and the hemisphere of stimulation. Furthermore, the effects are found to be long lasting. We believe that these findings have strong relevance to support the clinical application of therapies involving electrical stimulation for diseases of reduced cortical excitability.
Real Options Effects on Employment: Does Exchange Rate Uncertainty Matter for Aggregation?
Authors: Belke Ansgar , Göcke Matthias 
Published: May 2005

Abstract
In a baseline micro model a band of inaction due to hiring and firing costs is widened by option value effects of exchange rate uncertainty. Based on this micro foundation, an aggregation approach is presented. Under uncertainty, intervals of weak response to exchange rate reversals (called ‘play’ areas) are introduced on the macro level. ‘Spurts’ in new employment or firing may occur after an initially weak response. Since these mechanisms may apply to other ‘investment’ cases where the aggregation of microeconomic real options effects under uncertainty are relevant, they may even be of a more general interest.
The Promise and Pitfalls of Restructuring Network Industries
Authors: Buehler Stefan 
Published: May 2005

Abstract
This paper examines the competitive effects of reorganizing a network industry’s vertical structure. In this industry, an upstream monopolist operates a network used as an input to produce horizontally differentiated final products that are imperfect substitutes. Three potential pitfalls of restructuring integrated network industries are analyzed: (i) double marginalization, (ii) underinvestment and (iii) vertical foreclosure. The paper studies the net effect of restructuring on retail prices and cost-reducing investment and discusses policy implications.
Design of the 3G Spectrum Auctions in the UK and Germany: An Experimental Investigation
Authors: Seifert Stefan , Ehrhart Karl-Martin 
Published: May 2005

AbstractThis paper analyses the auction designs chosen for awarding 3G licences in the UK and Germany and compares them with respect to revenues and bidders’ surplus using a laboratory experiment. In our study with a given number of bidders, the German design leads to higher revenues. However, bidder surplus in the German design is lower and bidders face a severe exposure problem. Because this might discourage participation, it will probably lead to less competitive bidding in real applications.
Money Illusion and the Double Dividend in the Short Run
Authors: Schleiniger Reto 
Published: May 2005

Abstract
In their seminal paper, Bovenberg and de Mooij (1994) elucidate why an ecological tax reform will not yield a double dividend, i.e. fails to increase the efficiency of the tax system. The present paper slightly modifies the Bovenberg and de Mooij model by introducing money illusion. With this modification, an environmental tax reform that raises the price level may generate a double dividend, since the additional tax on the dirty good does not reduce labor supply. A prerequisite for the double dividend to occur is a sufficiently small elasticity of substitution between clean and dirty consumption. Moreover, accounting for money illusion always reduces the intertemporal gross cost of the tax reform.
Uncertainty, Trust and Pensions: The Case of the Current UK Reforms
Authors: Taylor‐Gooby Peter 
Published: May 2005

Abstract Trust is valuable in facilitating social cooperation and is often thought to be helpful in the running of a complex modern welfare state. However, a number of sociologists, psychologists and political scientists have recently argued that trust in social institutions is in decline. One approach argues that the issue is compounded by a shift towards a more active and discriminating trust as part of a social transition towards a more reflexive society, and goes on to suggest that people often choose to place their active trust in non‐state provision. This paper examines recent quantitative and qualitative evidence on trust in state and non‐state pensions in the UK, as a context where current policy developments throw the general issues into sharp relief. It shows that patterns of trust in this setting can be understood in active terms, but that social divisions remain important in determining how active trust operates in practice. More vulnerable groups put their trust in the state, through lack of an alternative, while more confident and better‐off groups tend to pursue investment strategies which they believe will give them more individual control over their money. Social divisions remain important during current social transitions, and often receive less attention than they merit in theoretical writing.
To Retire or Not to Retire: Is There an Option for Older Workers in Hong Kong?
Authors: Chou Kee‐Lee , Chow Nelson W. S. 
Published: May 2005

Abstract Over the next thirty years, Hong Kong will have a rapidly ageing population. One possible consequence of this will be a labour shortage, which means that it will be essential to strike a proper balance between the amount of time spent in work and the amount spent in retirement in old age. The balance is determined by the interaction between the aspiration of workers, employers’ attitudes to older workers, as well as the productivity of the labour force. In this article, we examine the issue based on life‐course theory and we argue that the compartmentalization of education, work and retirement must be broken by changes in social policy. We identify three groups of future older adults in the coming three decades: those who may be forced to retire early in their fifties, those who plan to retire in their sixties, and those who will continue to work until they can no longer work. The current situations of these groups are described, and social policies that are related to retirement pension scheme, age discrimination, life‐long education, and flexible work arrangements are suggested to weaken the age structuring of education and employment institutions. Our ultimate objective is to create a societal environment in which older workers have a real option either to work or to retire in the coming decades.
Financial Incentives and Job‐search Training: Methods to Increase Labour Market Integration in Contemporary Welfare States?
Authors: Malmberg‐Heimonen Ira , Vuori Jukka 
Published: May 2005

AbstractIn their efforts to increase labour market integration, contemporary welfare states emphasize the importance of financial incentives, active job‐searching and participation in labour market programmes. However, the effects of these policies have been minor and in some cases even inconsistent. The aim of this study was to examine whether and how financial incentives and job‐search training programmes increase re‐employment and the quality of re‐employment. A total of 1,015 unemployed persons participated in a Finnish follow‐up study with a randomized experimental design. Although no overall impact of job‐search training on re‐employment emerged, a positive effect was found for those groups of the unemployed who had a financial incentive to participate in the programme. Nevertheless, among unemployed workers with benefits at a minimum level there were no positive effects on the quality of re‐employment, and the impact decreased when unemployment was prolonged. Financial incentives and job‐search training appear to increase re‐employment among those of the unemployed who generally have better chances on the labour market, whereas these measures are not sufficient for the more disadvantaged groups of the unemployed.