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Modelo de Aceitação da Tecnologia adaptado às compras online

Vilar, Márcio Alberto da Silva
Fonte: [s.n.] Publicador: [s.n.]
Tipo: Dissertação de Mestrado
Publicado em //2013 Português
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26.03%
Dissertação apresentada à Universidade Fernando Pessoa como parte dos requisitos de obtenção do grau de Mestre em Ciências da Comunicação, ramo de Marketing e Publicidade; O tema abordado neste trabalho é o da Modelo de Aceitação Tecnológica, TAM (do inglês Technology Acceptance Model) aplicada às compras realizadas através da internet. O aumento das necessidades tecnológicas e as falhas na adopção de novos sistemas nas empresas nos anos 70 despertou o interesse dos investigadores no campo da aceitação de modelos tecnológicos. Davis em 1989 propôs que a utilização do sistema é uma resposta que pode ser explicada por um estímulo externo constituído pelos recursos e capacidades do sistema actual. Em Portugal, as compras online têm crescido exponencialmente atingindo no ano de 2011 1.2% do total das compras pagas com cartão bancário, alcançando a quantia de 678 milhões de euros. Deste modo, o presente estudo teve como objectivo medir a intenção comportamental dos portugueses em relação às compras online. A metodologia utilizada teve por base uma análise descritiva com a aplicação de um questionário a uma amostra não probabilística por conveniência a 260 indivíduos. A análise dos dados foi realizada através do SPSS (Statistical Package for Social Sciences) e do PLS (Partial Least Squares). Os resultados do trabalho confirmaram a validade do modelo conceptual e permitiram analisar a intenção dos consumidores portugueses relativamente às compras online...

Efeitos da estimulação magnética transcraniana sobre a cognição no comprometimento cognitivo leve: estudo duplo-cego, randomizado controlado; Effects of transcranial magnetic stimulation on cognition in mild cognitive impairment. Double-blind, randomized controlled trial

Marra, Hellen Livia Drumond
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/11/2012 Português
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INTRODUÇÃO: O envelhecimento está associado, muitas vezes, a um declínio cognitivo frequentemente negligenciado, especialmente quando em formas brandas e/ou iniciais, com importante repercussão na vida das pessoas. Tais declínios podem regredir para a normalidade, estabilizar ou mesmo evoluir para quadro demenciais. O comprometimento cognitivo leve (CCL) é uma síndrome clínica de associada a um risco aumentado de demência, podendo ter várias etiologias e patologias. Até o momento, não existe ainda uma abordagem terapêutica, deixando uma lacuna no arsenal terapêutico tanto do especialista quanto do clínico geral. A estimulação magnética transcraniana é uma técnica não invasiva e promissora. Tem potencial para melhorar a memória e a cognição de idosos ativando redes neurais. OBJETIVOS: Este trabalho visa verificar os efeitos da estimulação magnética transcraniana repetitiva (EMTr) de alta frequência primeiramente sobre a memória e, secundariamente, sobre a cognição global de idosos com CCL. MÉTODOS: Trata-se de um estudo duplo cego, randomizado sham-controlado. Foram estimulados 32 idosos com idades entre 60-74 anos, totalmente independentes para as atividades instrumentais de vida diária (AIVDs), com queixas subjetivas de memória e evidência de algum prejuízo na avaliação neuropsicológica...

Effects of imidacloprid exposure on Chironomus riparius Meigen larvae: Linking acetylcholinesterase activity to behaviour

Azevedo-Pereira, HMVS; Lemos, MFL; Soares, AMVM
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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Imidacloprid (IMI) is an insecticide that interferes with the transmission of stimuli in the nervous system of insects. It is neurotoxic by mimicking nicotine through its binding to the nicotinic acetylcholine receptor. In this work, experiments comprising 96 h exposure followed by 48 h in clean medium were conducted to evaluate the toxicity of IMI to Chironomus riparius and its potential recovery. Behavioural parameters and AChE activity were assessed. After 96 h exposure to IMI, AChE activity, and the behaviour parameters ventilation and locomotion were reduced. There were no signs of recovery after removal to clean water for 48 h. Ventilation behaviour was the most sensitive parameter and the one with the highest correlation to AChE activity. Despite the possibility that IMI might be having an indirect effect on AChE activity, the behavioural endpoint showed a higher sensitivity than the biochemical response itself. This work highlights the importance of linking parameters with ecological relevance at individual level (behavioural parameters) with biochemical responses, to unravel xenobiotics mode of action. (C) 2011 Elsevier Inc. All rights reserved.

Cross-continental differences in patterns of predation: will naive moose in Scandinavia ever learn?

Sand, Håkan; Wikenros, Camilla; Wabakken, Petter; Liberg, Olof
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
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Predation has been recognized as a major selective force in the evolution of behavioural characteristics of mammals. As a consequence of local predator extinction, prey may lose knowledge about natural predators but usually express behavioural adjustments after return of predators. Human harvest may replace natural predation but prey selection may differ from that of natural predators leading to a change in the behavioural response of prey. We show that hunting success (HS) of re-colonizing wolves (Canis lupus) on moose (Alces alces) in Scandinavia was higher than reported in North America, where moose have been continuously exposed to wolves and grizzly bears. We found no evidence that moose expressed behavioural adjustments that lowered the HS of wolves in territories that had been occupied by wolves for up to 21 years. Moose behaviour towards wolves and humans typically differs in Scandinavia compared to North America. We explain the differences found to be caused by variation in predation pressure by large carnivores and the rate, and mode, of human harvest during the twentieth century.

Olfactory bulb ablation in the rat: behavioural changes and their reversal by antidepressant drugs.

van Riezen, H; Schnieden, H; Wren, A F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1977 Português
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1. The effects of bilateral olfactory bulbectomy, sham-operation and inducement of peripheral anosmia were studied on locomotor activity, passive avoidance acquisition and irritability. 2. Bulbectomized rats were hyperactive, deficient at learning a step-down passive avoidance response and hyperirritable. Peripheral anosmia, induced by intranasal infusion of ZnSO4 solution resulted in no behavioural changes. 3. Chronic pretreatment with amitriptyline (3 and 10 mg/kg) and a tetracyclic antidepressant mianserin (Org GB 94, 5 and 15 mg/kg) reversed the hyperactivity and reduced the learning deficit of bulbectomized rats. These drugs had no significant effects on sham-operated animals. 4. Neither amitriptyline nor mianserin reduced the exaggerated responses of bulbectomized rats to external stimuli. 5. (+)-Amphetamine (1 and 3 mg/kg) accelerated the acquisition of the passive avoidance response, greatly enhanced the locomotor activity and slightly increased the irritability score of both sham-operated and bulbectomized rats. 6. Chlorpromazine (1 and 3 mg/kg) and chlordiazepoxide (10 mg/kg) significantly reduced the acquisition, locomotor activity and irritability of experimental and control rats. 7. Lithium sulphate (1 and 3 mg/kg) had no effect on activity or irritability but produced a small impairment in acquistion of bulbectomized rats. 8. It is concluded that the reversal by antidepressant drugs of the behavioural syndrome seen after olfactory bulb ablation could constitute a new model for the detection of this group of centrally acting compounds.

beta-Adrenoceptor antagonists inhibit the behavioural responses of rats to increased brain 5-hydroxytryptamine.

Costain, D W; Green, A R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1978 Português
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1 The effect of various beta-adrenoceptor blocking agents on the 5-hydroxytryptamine (5-HT)-induced hyperactivity response produced in rats by administration of tranylcypromine (10 mg/kg i.p.) followed by L-tryptophan (50 mg/kg i.p.) has been investigated. 2 (+/-)-Alprenolol, (+/-)-timolol, (+/-)-sotalol, (+/-)-pindolol (all at 40 mg/kg) all inhibited the hyperactivity response to some degree when given 45 min before the tranylcypromine, as did (+/-)-oxprenolol when given after the L-tryptophan. 3 beta-Adrenoceptor antagonists that are not found in the brain appreciable amount after peripheral injection, (+/-)-atenolol, (+/-)-practolol, (+/-)-labetalol and (+/-)-acebutalol, did not inhibit the 5-HT-mediated behaviour. 4 Neither the beta1-selective drug (+/-)-metoprolol, nor the beta2-selective drug (+/-)-butoxamine inhibited the behavioral response. 5 The drugs that blocked the 5-HT-mediated behaviour did not alter brain 5-HT concentrations, synthesis rate or the accumulation of 5-HT following tranylcypromine/L-tryptophan. However, they did inhibit the hyperactivity produced by the suggested 5-HT agonist, 5-methoxy N,N-dimethyltryptamine, indicating that the beta-adrenoceptor blocking drugs were inhibiting the post-synaptic 5-HT-mediated response. 6 Circling produced by methamphetamine (3 mg/kg) in unilateral nigro-striatal lesioned rats was not altered by alprenolol...

Gut focused behavioural treatment (biofeedback) for constipation and faecal incontinence in multiple sclerosis

Wiesel, P.; Norton, C.; Roy, A.; Storrie, J.; Bowers, J.; Kamm, M.
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /08/2000 Português
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OBJECTIVES—To determine whether gut focused behavioural treatment (biofeedback) is a useful therapy in multiple sclerosis patients referred for constipation, incontinence, or a combination of these symptoms. Most patients with multiple sclerosis complain of constipation, faecal incontinence, or a combination of the two. Patients rate these bowel symptoms as having a major impact on their life. Until now the management of these problems has been empirical, with a lack of evaluated therapeutic regimes.
METHODS—Thirteen patients (eight women, median age 38 years, median duration of multiple sclerosis 10 years) complaining of constipation, with or without faecal incontinence underwent a median of four sessions of behavioural treatment. Anorectal physiological tests were performed before therapy. Impairment and disability were rated with the Kurtzke score and the Cambridge multiple sclerosis basic score (CAMBS). Patients were contacted a median of 14 months after completion of treatment.
RESULTS—A beneficial effect was attributed to biofeedback in five patients. Mild to moderate disability, quiescent and non-relapsing disease, and absence of progression of multiple sclerosis over the year before biofeedback were predictive of symptom improvement. No physiological test predicted the response to therapy.
CONCLUSION—Biofeedback retraining is an effective treatment in some patients with multiple sclerosis complaining of constipation or faecal incontinence. A response is more likely in patients with limited disability and a non-progressive disease course.



Behavioural pharmacology: 40+ years of progress, with a focus on glutamate receptors and cognition

Robbins, Trevor W.; Murphy, Emily R.
Fonte: Published By Elsevier In Association With The International Union Of Pharmacology Publicador: Published By Elsevier In Association With The International Union Of Pharmacology
Tipo: Artigo de Revista Científica
Publicado em /03/2006 Português
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Behavioural pharmacology is an interdisciplinary field at the intersection of several research areas that ultimately lead to the development of drugs for clinical use and build understanding of how brain functions enable cognition and behaviour. In this article, the development of behavioural pharmacology in the UK is briefly surveyed, and the current status and success of the field is highlighted by the progress in our understanding of learning and memory that has resulted from discoveries in glutamate receptor pharmacology allied to theoretical and methodological advances in behavioural neuroscience. We describe the original breakthrough in terms of the role of NMDA receptors in hippocampal-mediated spatial learning and long-term potentiation, and review recent advances that demonstrate the involvement of glutamate receptor in working memory, recognition memory, stimulus–response learning and memory, and higher cognitive functions. We also discuss the unique functions of NMDA receptors and the fundamental role of AMPA receptors in processes that are common to some of these forms of memory, including encoding, consolidation and retrieval.

Social interaction modifies neural response to gaze shifts

Bristow, Davina; Rees, Geraint; Frith, Christopher D.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em /03/2007 Português
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Monitoring gaze shifts is important for social interactions. The direction of gaze can reveal intentions and help to predict future actions. Here we examined whether behavioural and neural responses to gaze shifts were modulated by the social context of the gaze shift in two linked experiments. Two faces were presented, one gazing directly at the subject (the ‘social’ face) and one with averted gaze (the ’unsocial’ face). One face then made a gaze shift that was either towards a visible target (’correct’) or towards another location in space (’incorrect’). Both behavioural and neural responses to gaze shifts were modulated by the social context and the goal directedness of the gaze shift. Reaction times were significantly faster in response to ’correct’ and ‘social’ compared with ’incorrect’ and ’unsocial’ gaze shifts, respectively. Using functional magnetic resonance imaging, we found significantly greater activation in the parieto-frontal attentional network, and in some parts of the posterior superior temporal sulcus, in response to ‘incorrect’ and ’unsocial’ compared with ’incorrect’ and ‘social’ gaze shifts, respectively. Conversely, we found greater activation in the medial prefrontal cortex and precuneus in response to ’correct’ and ‘social’ compared with ’incorrect’ and ’unsocial’ gaze shifts. This activity may reflect the experience of joint attention associated with these gaze shifts.

Searching for anatomical correlates of olfactory lateralization in the honeybee antennal lobes: A morphological and behavioural study

Rigosi, Elisa; Frasnelli, Elisa; Vinegoni, Claudio; Antolini, Renzo; Anfora, Gianfranco; Vallortigara, Giorgio; Haase, Albrecht
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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The honeybee, Apis mellifera L. (Hymenoptera: Apidae), has recently become a model for studying brain asymmetry among invertebrates. A strong lateralization favouring the right antenna was discovered in odour learning and short-term memory recall experiments, and a lateral shift favouring the left antenna for long-term memory recall. Corresponding morphological asymmetries have been found in the distribution of olfactory sensilla between the antennae and confirmed by electrophysiological odour response measurements in isolated right and left antennae. The aim of this study was to investigate whether a morphological asymmetry can be observed in the volume of the primary olfactory centres of the central nervous system, the antennal lobes (ALs). Precise volume measurements of a subset of their functional units, the glomeruli, were performed in both sides of the brain, exploiting the advantages of two-photon microscopy. This novel method allowed minimal invasive acquisition of volume images of the ALs, avoiding artefacts from brain extraction and dehydration. The study was completed by a series of behavioural experiments in which response asymmetry in odour recall following proboscis extension reflex conditioning was assessed for odours...

Are Olfactory Cues Involved in Nest Recognition in Two Social Species of Estrildid Finches?

Krause, E. Tobias; Caspers, Barbara A.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/05/2012 Português
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Reliably recognizing their own nest provides parents with a necessary skill to invest time and resources efficiently in raising their offspring and thereby maximising their own reproductive success. Studies investigating nest recognition in adult birds have focused mainly on visual cues of the nest or the nest site and acoustic cues of the nestlings. To determine whether adult songbirds also use olfaction for nest recognition, we investigated the use of olfactory nest cues for two estrildid finch species, zebra finches (Taeniopygia guttata) and Bengalese finches (Lonchura striata var. domestica) during the nestling and fledgling phase of their offspring. We found similar behavioural responses to nest odours in both songbird species. Females preferred the odour of their own nest over a control and avoided the foreign conspecific nest scent over a control during the nestling phase of their offspring, but when given the own odour and the foreign conspecific odour simultaneously we did not find a preference for the own nest odour. Males of both species did not show any preferences at all. The behavioural reaction to any nest odour decreased after fledging of the offspring. Our results show that only females show a behavioural response to olfactory nest cues...

Using Activity-Related Behavioural Features towards More Effective Automatic Stress Detection

Giakoumis, Dimitris; Drosou, Anastasios; Cipresso, Pietro; Tzovaras, Dimitrios; Hassapis, George; Gaggioli, Andrea; Riva, Giuseppe
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 19/09/2012 Português
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This paper introduces activity-related behavioural features that can be automatically extracted from a computer system, with the aim to increase the effectiveness of automatic stress detection. The proposed features are based on processing of appropriate video and accelerometer recordings taken from the monitored subjects. For the purposes of the present study, an experiment was conducted that utilized a stress-induction protocol based on the stroop colour word test. Video, accelerometer and biosignal (Electrocardiogram and Galvanic Skin Response) recordings were collected from nineteen participants. Then, an explorative study was conducted by following a methodology mainly based on spatiotemporal descriptors (Motion History Images) that are extracted from video sequences. A large set of activity-related behavioural features, potentially useful for automatic stress detection, were proposed and examined. Experimental evaluation showed that several of these behavioural features significantly correlate to self-reported stress. Moreover, it was found that the use of the proposed features can significantly enhance the performance of typical automatic stress detection systems, commonly based on biosignal processing.

The modality-specific contribution of peptidergic and non-peptidergic nociceptors is manifest at the level of dorsal horn nociresponsive neurons

Zhang, Jie; Cavanaugh, Daniel J; Nemenov, Michael I; Basbaum, Allan I
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
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We previously demonstrated that genetic and/or pharmacological ablation of the TRPV1+/peptidergic or the MrgprD+/non-peptidergic subset of nociceptors produced selective, modality-specific deficits in the behavioural responses to heat and mechanical stimuli, respectively. To assess whether this modality-specific contribution is also manifest at the level of spinal cord neuron responsiveness, here we made extracellular recordings from lumbar dorsal horn neurons of the mouse in response to graded thermal and mechanical stimulation. We found that, following intrathecal injection of capsaicin to eliminate the central terminals of TRPV1+ nociceptors, neurons in the region of laminae I and V of the spinal cord lost responsiveness to noxious heat (whether generated by a contact heat probe or diode laser), with no change in their response to noxious mechanical stimulation. In contrast, ablation of MrgprD+ afferents did not alter the response to noxious heat, but reduced the firing of superficial dorsal horn nociceptive-specific neurons in response to graded mechanical stimulation and decreased the relative number of wide dynamic range neurons that were exclusively mechanosensitive. Neither ablation procedure reduced the number of dorsal horn neurons that responded to noxious cold. These findings support the conclusion that TRPV1+ nociceptors are necessary and probably sufficient for noxious heat activation of dorsal horn neurons and that...

The effects of brain serotonin deficiency on behavioural disinhibition and anxiety-like behaviour following mild early life stress

Sachs, Benjamin D.; Rodriguiz, Ramona M.; Siesser, William B.; Kenan, Alexander; Royer, Elizabeth L.; Jacobsen, Jacob P. R.; Wetsel, William C.; Caron, Marc G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Aberrant serotonin (5-HT) signalling and exposure to early life stress have both been suggested to play a role in anxiety- and impulsivity-related behaviours. However, whether congenital 5-HT deficiency×early life stress interactions influence the development of anxiety- or impulsivity-like behaviour has not been established. Here, we examined the effects of early life maternal separation (MS) stress on anxiety-like behaviour and behavioural disinhibition, a type of impulsivity-like behaviour, in wild-type (WT) and tryptophan hydroxylase 2 (Tph2) knock-in (Tph2KI) mice, which exhibit ~60–80% reductions in the levels of brain 5-HT due to a R439H mutation in Tph2. We also investigated the effects of 5-HT deficiency and early life stress on adult hippocampal neurogenesis, plasma corticosterone levels and several signal transduction pathways in the amygdala. We demonstrate that MS slightly increases anxiety-like behaviour in WT mice and induces behavioural disinhibition in Tph2KI animals. We also demonstrate that MS leads to a slight decrease in cell proliferation within the hippocampus and potentiates corticosterone responses to acute stress, but these effects are not affected by brain 5-HT deficiency. However, we show that 5-HT deficiency leads to significant alterations in SGK-1 and GSK3β signalling and NMDA receptor expression in the amygdala in response to MS. Together...

Seasonal changes in behavioural and thermoregulatory responses to hypoxia in the Eastern Chipmunk (Tamias striatus) /

Levesque, Danielle L.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
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Mammalian heterotherms, such as hibemators, are known to be more tolerant of low oxygen tensions than their homeothermic counterparts. It has been suggested that this relative hypoxia tolerance is related to their ability to deal with dramatic changes in body temperature during entry to and arousal from torpor. However, hibemators demonstrate dramatic seasonality in both daily heterothermy and overall torpor expression. It was of interest to test if seasonal comparisons of normothermic individuals within a single species with the capacity to hibernate produce changes in the response to hypoxia that would reflect a seasonal change in tolerance to low oxygen. In particular, the species studied, the Eastern chipmunk {Tamias striatus), is known to enter into torpor exclusively in the winter. To test for seasonal differences in the metabolic and thermoregulatory responses to hypoxia, flow-through respirometry was used to compare metabolic rate, minimum thermal conductance, body temperature, and a thermal gradient used to assess selected ambient temperature in response to hypoxia in both summer and winter acclimated animals. Although the animals periodically expressed torpor throughout the winter, no differences between season in resting metabolic rate...

COUNTERMANDING IN RATS AS AN ANIMAL MODEL OF INHIBITION OF ACTION: VALIDATION OF THE RACE MODEL

BEUK, JONATHAN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 712514 bytes; application/pdf
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Executive function, the cognitive processes that allow the voluntary control of goal-directed behaviour, can be studied through the examination of inhibition of action. The countermanding paradigm has been shown to be a powerful tool to examine a subject’s ability to withhold responses to a go stimulus when a stop signal is presented occasionally. Logan and Cowan (1984) developed a race model to account for countermanding performance in humans, proposing that independent go and stop process initiated by the go and stop signals respectively, race toward a finish line whereby the first process to cross its finish line determines the behavioural outcome. The model allows estimation of the stop signal response time, a variable that is not directly observable. The race model has yet to be validated for countermanding performance in rats. Using a new rodent countermanding task inspired directly from human studies, male Wistar rats were trained to respond to a visual stimulus (go signal) by pressing a lever below an illuminated light for food reward, but to countermand lever the press (25% of trials) subsequent to an auditory tone (stop signal) presented after a variable delay. The ability to cancel a response decreased as stop signal delay increased. The stop signal response time for rats was estimated to be 157 ms...

Effects of ZNF804A on auditory P300 response in schizophrenia

O'Donoghue, T; Morris, D W; Fahey, C; Da Costa, A; Moore, S; Cummings, E; Leicht, G; Karch, S; Hoerold, D; Tropea, D; Foxe, J J; Gill, M; Corvin, A; Donohoe, G
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
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The common variant rs1344706 within the zinc-finger protein gene ZNF804A has been strongly implicated in schizophrenia (SZ) susceptibility by a series of recent genetic association studies. Although associated with a pattern of altered neural connectivity, evidence that increased risk is mediated by an effect on cognitive deficits associated with the disorder has been equivocal. This study investigated whether the same ZNF804A risk allele was associated with variation in the P300 auditory-evoked response, a cognitively relevant putative endophenotype for SZ. We compared P300 responses in carriers and noncarriers of the ZNF804A risk allele genotype groups in Irish patients and controls (n=97). P300 response was observed to vary according to genotype in this sample, such that risk allele carriers showed relatively higher P300 response compared with noncarriers. This finding accords with behavioural data reported by our group and others. It is also consistent with the idea that ZNF804A may have an impact on cortical efficiency, reflected in the higher levels of activations required to achieve comparable behavioural accuracy on the task used.

5-Hydroxytryptamine release in vivo from a cytoplasmic pool: studies on the 5-HT behavioural syndrome in reserpinized rats.

Kuhn, D. M.; Wolf, W. A.; Youdim, M. B.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em /01/1985 Português
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Treatment of rats with reserpine in order to disrupt vesicular amine storage reduces 5-hydroxytryptamine (5-HT) levels throughout brain by 90-95%. Despite the drastic reduction in brain 5-HT content by reserpine, the 5-HT releasing drug p-chloramphetamine (PCA) produces a behavioural syndrome in reserpine-treated rats which is not different from that observed in normal animals given PCA. Prior treatment of reserpinized rats with p-chlorophenylalanine (PCPA), the irreversible tryptophan hydroxylase inhibitor which inhibits the synthesis of new 5-HT, prevents the PCA-induced behavioural syndrome. The 5-HT receptor antagonist methergoline, blocks the PCA effect in reserpine-treated rats. Treatment of reserpinized rats with pargyline, a non-selective inhibitor of monoamine oxidase, in order to increase cerebral 5-HT levels, shifts the PCA dose-response curve for inducing the 5-HT behavioural syndrome to the left. The specific 5-HT uptake blocker, fluoxetine, protects normal and reserpine-treated rats from the 5-HT depleting effects of PCA but does not always prevent the PCA-induced 5-HT behavioural syndrome. These results indicate that PCA releases 5-HT into the synapse from a small cytoplasmic pool which is resistant to reserpine and suggest that this newly synthesized compartment of 5-HT represents the 'functional' transmitter pool.

Behavioural correlates of combinatorial versus temporal features of odour codes

Saha, Debajit; Li, Chao; Peterson, Steven; Padovano, William; Katta, Nalin; Raman, Baranidharan
Fonte: Nature Pub. Group Publicador: Nature Pub. Group
Tipo: Artigo de Revista Científica
Publicado em 27/04/2015 Português
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Most sensory stimuli evoke spiking responses that are distributed across neurons and are temporally structured. Whether the temporal structure of ensemble activity is modulated to facilitate different neural computations is not known. Here, we investigated this issue in the insect olfactory system. We found that an odourant can generate synchronous or asynchronous spiking activity across a neural ensemble in the antennal lobe circuit depending on its relative novelty with respect to a preceding stimulus. Regardless of variations in temporal spiking patterns, the activated combinations of neurons robustly represented stimulus identity. Consistent with this interpretation, locusts reliably recognized both solitary and sequential introductions of trained odourants in a quantitative behavioural assay. However, predictable behavioural responses across locusts were observed only to novel stimuli that evoked synchronized spiking patterns across neural ensembles. Hence, our results indicate that the combinatorial ensemble response encodes for stimulus identity, whereas the temporal structure of the ensemble response selectively emphasizes novel stimuli.

Aberrant brain responses to emotionally valent words is normalised after cognitive behavioural therapy in female depressed adolescents

Chuang, Jie-Yu; Whitaker, Kirstie; Murray, Graham K.; Elliott, Rebecca; Hagan, Cindy C.; Graham, Julia M. E.; Ooi, Cinly; Tait, Roger; Holt, Rosemary J.; Nieuwenhuizen, Adrienne O. van; Reynolds, Shirley; Wilkinson, Paul O.; Bullmore, Edward T.; Lennox, B
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; published version
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This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.jad.2015.09.008; Background Depression in adolescence is debilitating with high recurrence in adulthood, yet its pathophysiological mechanism remains enigmatic. To examine the interaction between emotion, cognition and treatment, functional brain responses to sad and happy distractors in an affective go/no-go task were explored before and after Cognitive Behavioural Therapy (CBT) in depressed female adolescents, and healthy participants. Methods Eighty-two Depressed and 24 healthy female adolescents, aged 12?17 years, performed a functional magnetic resonance imaging (fMRI) affective go/no-go task at baseline. Participants were instructed to withhold their responses upon seeing happy or sad words. Among these participants, 13 patients had CBT over approximately 30 weeks. These participants and 20 matched controls then repeated the task. Results At baseline, increased activation in response to happy relative to neutral distractors was observed in the orbitofrontal cortex in depressed patients which was normalised after CBT. No significant group differences were found behaviourally or in brain activation in response to sad distractors. Improvements in symptoms (mean: 9.31...