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Id: lil-604520
Autor: Guerra, Luiz Guilherme Gomes Cardim; Silva, Maria Teresa Araujo.
Título: Learning processes and the neural analysis of conditioning
Fonte: Psychol. neurosci. (Impr.);3(2):195-208, July-Dec. 2010.
Idioma: en.
Resumo: Classical and operant conditioning principles, such as the behavioral discrepancy-derived assumption that reinforcement always selects antecedent stimulus and response relations, have been studied at the neural level, mainly by observing the strengthening of neuronal responses or synaptic connections. A review of the literature on the neural basis of behavior provided extensive scientific data that indicate a synthesis between the two conditioning processes based mainly on stimulus control in learning tasks. The resulting analysis revealed the following aspects. Dopamine acts as a behavioral discrepancy signal in the midbrain pathway of positive reinforcement, leading toward the nucleus accumbens. Dopamine modulates both types of conditioning in the Aplysia mollusk and in mammals. In vivo and in vitro mollusk preparations show convergence of both types of conditioning in the same motor neuron. Frontal cortical neurons are involved in behavioral discrimination in reversal and extinction procedures, and these neurons preferentially deliver glutamate through conditioned stimulus or discriminative stimulus pathways. Discriminative neural responses can reliably precede operant movements and can also be common to stimuli that share complex symbolic relations. The present article discusses convergent and divergent points between conditioning paradigms at the neural level of analysis to advance our knowledge on reinforcement
Responsável: BR85.1 - Biblioteca Dante Moreira Leite


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Id: lil-655483
Autor: Kunicki, Ana Carolina Bione.
Título: Dinâmica do sistema córtico-hipocampal durante o condicionamento contextual de medo / Cortico-hippocampal system dynamics during contextual fear conditioning.
Fonte: São Paulo; s.n; 2011. 119 p. ilus, tab, graf.
Idioma: pt.
Tese: Apresentada a Universidade de São Paulo. Faculdade de Medicina para obtenção do grau de Doutor.
Resumo: O estabelecimento das memórias de longo prazo requer uma efetiva comunicação do hipocampo com o neocortex. Um mecanismo plausível envolvido na comunicação neuronal e na plasticidade sináptica é a sincronização da atividade elétrica cerebral na frequência teta. Estudos recentes mostraram que a sincronização entre os ritmos teta do hipocampo e do córtex pré-frontal aumenta durante a evocação das memórias aversivas e diminui após a extinção do aprendizado. Entretanto, outros ritmos cerebrais, como as ondas delta, também estão envolvidos nas respostas comportamentais do medo e nos processos de memória. Desta forma, o ritmo teta, que já foi bastante estudado pelo seu papel no aprendizado e na memória, e o ritmo delta, por seu envolvimento no ciclo sono-vigília, foram investigados considerando a relação causal entre eles. Ainda não está bem estabelecido como os ritmos delta e teta podem juntos contribuir nos processos cognitivos ou como os ritmos do hipocampo podem influenciar ou receber influencias da atividade cortical. Neste trabalho foi investigada a contribuição dos ritmos delta e teta em função do estado comportamental (vigília ativa ou congelamento) e do tipo de memória evocada (recente ou remota). Além disso, foi realizada uma análise de sincronia de fase para inferir a dinâmica da atividade elétrica entre o córtex pré-frontal medial, o hipocampo e o córtex visual durante a evocação das memórias de medo. Para tanto, os animais foram treinados e testados numa tarefa de condicionamento de medo ao contexto. Neste tipo de condicionamento, o animal aprende a estabelecer uma associação entre um determinado contexto (caixa de condicionamento) e um evento aversivo (choque elétrico nas patas) que ocorreu neste contexto...

The establishment of long-term memories requires effective communication of the hippocampus to the neocortex. Electrophysiological activities between hippocampus and prefrontal cortex have shown higher theta synchronization during retrieval of aversive memories and lower during extinction learning. While theta activity is more differently related to learning and memory, delta waves have been more discussed in the context of sleep or "offline" states. Few studies have investigated delta waves during "on-line" states (such as task-relevant situations) and the contribution of these rhythms to memory storage remains unclear. We recorded electrophysiological data to study the contributions of delta and theta waves in cortico-hippocampal system of rats underwent to contextual fear conditioning. Our experiment consisted of environmental pre-exposition, training with electrical footshocks, and recent/remote memory tests. Two groups of rats were tested one or eighteen days post training for recent or remote memory, respectively. Local field potential time series of two behavioral states were sampled: active exploration and freezing. The results showed that theta and delta rhythms play an important role in behavioral responses and memory processing. They are related to fear recall and their contribution depend on the recent or remote memory. Additionally, using an order parameter we show that theta contribution is strongly pronounced in active exploration, decreasing during freezing. In the latter, the rats presented pronounced delta waves in freezing. Moreover, a behavioral-dependent causality measure showed an increase of theta influence in delta rhythms, resulting in a theta slowing in aversive memory retrieval. Finally, we show an increased synchrony between hippocampus and prefrontal cortex during recall of recent memory, but a decreased synchrony in remote memory...
Responsável: BR66.1 - Divisão de Biblioteca e Documentação
BR66.1; W4.DB8, C177es, FM-2, 2011


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Id: lil-654438
Autor: Nascimento, Gabriela Souza do; Monteiro, Patrícia Caroline Madeira; Gouveia Jr, Amauri; Carvalho Neto, Marcus Bentes de.
Título: Subchronic effects of fluoxetine on conditioned suppression produced by a hot air blast
Fonte: Psychol. neurosci. (Impr.);5(1):117-122, Jan.-June 2012. graf.
Idioma: en.
Resumo: Conditioned suppression is an animal model of anxiety disorders that has been broadly used to investigate the behavioral effects of different drugs. However, various methodological variables (e.g., the type of aversive stimulus) that supposedly interfere with the acquisition of conditioned suppression may also contribute to conflicting results among the studied drugs. Additionally, few studies have sought to investigate the effects of selective serotonin reuptake inhibitors (SSRIs). The present study investigated the effect of subchronic 5-day administration of 5 mg/kg fluoxetine in the retention of conditioned suppression produced by a hot air blast (HAB). The subjects were 12 albino Wistar rats distributed into an Experimental Group (EG) and Control Group (CG). After sessions were conducted to pair two stimuli, a sound and HAB, fluoxetine (EG) or saline (CG) was administered. Twenty-four hours after the last injection, a test session was conducted. The results showed no difference between groups. Fluoxetine (5 mg/kg) did not exert anxiolytic effects in this model of conditioned suppression produced by a HAB.
Responsável: BR85.1 - Biblioteca Dante Moreira Leite


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Id: lil-635142
Autor: Rozo, Jairo A; Acosta, Andrés M.
Título: Condicionamiento clásico y cognición implícita / Classical conditioning and implicit cognition
Fonte: Acta colomb. psicol;9(1):63-76, mayo 2006. ilus.
Idioma: es.
Resumo: En su conjunto, las evidencias experimentales conductuales y psicobiológicas revisadas en este artículo muestran que el condicionamiento clásico humano tiene una justificación evolutiva, se desarrolla mediante un procesamiento cognitivo diferente del procesamiento consciente y se sustenta en estructuras cerebrales diferentes. Dichas estructuras no suelen funcionar desligadas y por ello la combinación de ambas formas de procesamiento, explícito e implícito, es el patrón general en condiciones naturales. De hecho, debido a la organización jerárquica del sistema nervioso, suele existir un proceso de control de arriba hacia abajo (cortical-subcortical) pero, bajo condiciones especiales de laboratorio, puede hacerse evidente en la conducta, por ejemplo mediante los paradigmas de miedo condicionado, la estrecha relación entre procesamiento implícito y el condicionamiento clásico en nuestra especie.

Experimental data, behavioral and psychobiological, reviewed in this paper show that human classical conditioning has an evolutionary purpose, it is developed by means of a cognitive processing different from the conscious processing, and sustained by different cerebral structures. These structures usually do not work isolated. For that reason, combination of both forms of processing, explicit/implicit, is the general pattern in natural conditions. In fact, due to the hierarchical organization of the nervous system, usually it exists a top-down control process (cortical-subcortical) but, under special conditions of laboratory, can be behaviorally evident, for example by means of the fear conditioning, close relationship between implicit processing and Pavlovian conditioning in humans.
Responsável: CO332 - Facultad de Medicina


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Id: lil-626748
Autor: Vogel, Edgar H.
Título: Reinstatement of short-latency responses after asymptotic Pavlovian conditioning training by the presentation of an extraneous stimulus
Fonte: Biol. Res;45(1):61-65, 2012. ilus.
Idioma: en.
Projeto: National Science Foundation.
Resumo: The purpose of this study was to examine whether the progressive disappearance of short-latency conditioned responses, or inhibition of delay, observed in Pavlovian conditioning with long inter-stimulus intervals, could be reverted by the presentation of a novel stimulus. In one experiment, two groups of rabbits received extensive training with a short (250 ms) or a long (1500 ms) tone that overlapped and terminated with a periorbital shock unconditioned stimulus. After training, the presentation of an extraneous stimulus prior to tone onset produced a reinstatement of short latency CRs in the group trained with the long CS, but did not affect CR latency in the group trained with the short CS. This finding is consistent with Pavlov's (1927) view that conditioning with long conditioned stimuli involves the acquisition of response tendencies in the early portion of the stimulus that are subsequently suppressed by the development of an inhibitory process.
Responsável: CL1.1 - Biblioteca Central


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Id: lil-619665
Autor: Bernal-Gamboa, Rodolfo; Carranza-Jasso, Rodrigo; González-Martín, Gabriela; Juárez, Yectivani; Nieto, Javier; Sánchez-Carrasco, Livia.
Título: Modulación contextual en la extinción: recuperación de una aversión condicionada al sabor en un tercer contexto / Modulação contextual na extinção: recuperação de uma aversão condicionada ao sabor em um terceiro contexto / Contextual modulation of extinction: recovery of taste-aversion conditioning in a third context
Fonte: Rev. colomb. psicol;20(2):209-218, jul.-dic. 2011.
Idioma: es.
Projeto: DGAPA-PAPIIT. Recuperación de recuerdos en función de claves contextuales.
Resumo: Este experimento se diseñó para evaluar la renovación ABC con un procedimiento de condicionamiento de aversión al sabor (CAS) en tres fases: adquisición, extinción y prueba. Durante la adquisición, 15 ratas Wistar, asignadas a los grupos ABC y ABB, tuvieron acceso a una solución con sacarosa y posteriormente recibieron una inyección de cloruro de litio (liCl) en el Contexto A. En la extinción, ambos grupos bebieron la solución con sacarosa sin la administración del liCl en el Contexto B. En la prueba, los grupos tuvieron acceso a la solución con sacarosa sin administrarles liCl en el contexto de extinción para el grupo ABB, y en un tercer contexto para el grupo ABC. Los resultados mostraron la recuperación de la aversión condicionada al sabor únicamente en el grupo ABC.

This experiment was designed to evaluate ABC renewal in a conditioned taste aversion (CTA) procedure consisting of three phases: acquisition, extinction and test. During the acquisition phase, 15 Wistar rats assigned to groups ABC and ABB had access to a sucrose solution, after which they were injected with lithium chloride (liCl) in Context A. In the extinction phase, both groups of rats had access to the sucrose solution in Context B, but no liCl was administered. Finally, during the test, group ABB received sucrose solution without liCl in the extinction context, while group ABC was tested in a third context. Results showed renewal of conditioned taste aversion only in the ABC group.

Este experimento foi elaborado para avaliar a renovação ABC com um procedimento de condicionamento de aversão ao sabor (CAS) em três fases: aquisição, extinção e prova. Durante a aquisição, 15 ratos Wistar, designados aos grupos ABC e ABB, tiveram acesso a uma solução com sacarose e posteriormente receberam uma injeção de cloreto de lítio (liCl) em Contexto a. Na extinção, ambos grupos beberam a solução com sacarose sem a administração do liCl em Contexto B. Na prova, os grupos tiveram acesso à solução com sacarose sem administrar-lhes liCl num contexto de extinção para o grupo ABB, e num terceiro contexto para o grupo ABC. Os resultados mostraram a recuperação da aversão condicionada ao sabor unicamente no grupo ABC.
Responsável: CO136.3 - Biblioteca Central


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Id: lil-604501
Autor: Leão, Rodrigo M; Cruz, Fábio C; Planeta, Cleopatra S.
Título: Prior exposure to stress delays extinction but does not modify reinstatement of nicotine-induced conditioned place preference
Fonte: Psychol. neurosci. (Impr.);3(1):53-57, Jan.-June 2010. ilus, tab.
Idioma: en.
Projeto: Fundação de Amparo à Pesquisa do Estado de São Paulo; . CNPq.
Resumo: Studies in humans suggest that exposure to stress is related to relapse to tobacco use. The reinstatement of conditioned place preference (CPP) provides a simple, noninvasive and easy approach to investigate the mechanisms for drug relapse. The present study investigated whether repeated exposure to stress could change the extinction and reinstatement of nicotine-induced CPP. Adult male Wistar were exposed to restraint-stress for 2 hours/daily for 7 days, while the control-group was left undisturbed during this period. One day after the last stress session the CPP protocol was carried out. Nicotine produced a place preference to the compartment paired with its injections during conditioning (.16 mg/kg, s.c.; four drug sessions). Once established, nicotine place preference was extinguished by alternate exposure to each compartment after a saline injection (four exposures to each compartment). The animals that did not show extinction of CPP were submitted to two other extinction sessions. Following this extinction phase, the reinstatement of place conditioning was investigated following a priming injection of nicotine. Both control and stress groups showed reinstatement of CPP. The percentage of rats from the stress group that extinguished nicotine-CPP in the first and second test was lower as compared to the control group. In conclusion, stress delayed the extinction of the nicotine-induced CPP, but did not modify the reinstatement.
Responsável: BR85.1 - Biblioteca Dante Moreira Leite


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Britto, L. R. G
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Id: lil-595720
Autor: Brito, I; Britto, L. R. G; Ferrari, E. A. M.
Título: Induction of Zenk protein expression within the nucleus taeniae of the amygdala of pigeons following tone and shock stimulation
Fonte: Braz. j. med. biol. res = Rev. bras. pesqui. méd. biol;44(8):762-766, Aug. 2011. ilus.
Idioma: en.
Resumo: In this study, we evaluated the expression of the Zenk protein within the nucleus taeniae of the pigeon’s amygdala (TnA) after training in a classical aversive conditioning, in order to improve our understanding of its functional role in birds. Thirty-two 18-month-old adult male pigeons (Columba livia), weighing on average 350 g, were trained under different conditions: with tone-shock associations (experimental group; EG); with shock-alone presentations (shock group; SG); with tone-alone presentations (tone group; TG); with exposure to the training chamber without stimulation (context group; CG), and with daily handling (naive group; NG). The number of immunoreactive nuclei was counted in the whole TnA region and is reported as density of Zenk-positive nuclei. This density of Zenk-positive cells in the TnA was significantly greater for the EG, SG and TG than for the CG and NG (P < 0.05). The data indicate an expression of Zenk in the TnA that was driven by experience, supporting the role of this brain area as a critical element for neural processing of aversive stimuli as well as meaningful novel stimuli.
Responsável: BR1.1 - BIREME


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Id: lil-574101
Autor: Graham, Lauren K; Yoon, Taejib; Lee, Hongjoo J; Kim, Jeansok J.
Título: Strain and sex differences in fear conditioning: 22 kHz ultrasonic vocalizations and freezing in rats
Fonte: Psychol. neurosci. (Impr.);2(2):219-225, Dec. 2009. graf.
Idioma: en.
Projeto: Whitehall Foundation; . NIMH.
Resumo: Strain and sex differences in fear conditioning were investigated in two commonly used laboratory rats: Sprague Dawleys and Long-Evans. Twenty-two kHz ultrasonic vocalization (USV) distress calls and freezing behavior were used to measure fear responses to contextual and auditory conditioned stimuli (CSs), which were previously paired with a footshock unconditioned stimulus (US). Both strain and sex had significant effects on USVs and freezing during training and subsequent context and tone tests. Overall, the male Sprague Dawley rats froze and emitted USVs more than the other groups. Additionally, levels of freezing and USVs were differentially influenced by the type of CS (context or tone). These results suggest that species-specific defense responses in laboratory rats are highly influenced by the strain and sex of the subject, and that these factors should be considered in future fear conditioning studies.
Responsável: BR85.1 - Biblioteca Dante Moreira Leite


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Andery, Maria Amalia Pie Abib
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Id: lil-520243
Autor: Montans, Maria Paula Soares; Andery, Maria Amalia Pie Abib.
Título: A emergência de relações condicionais entre estímulos como resultado de treino de série de discriminações simples simultâneas / The emergence of conditional relationships among stimuli resulting from serial training of simple, simultaneous discriminations
Fonte: Estud. psicol. (Campinas);26(2):133-146, abr.-jun. 2009. graf.
Idioma: pt.
Resumo: O procedimento de emparelhamento de acordo com o modelo tem sido privilegiado para o estabelecimento de discriminações condicionais entre estímulos e para testar a emergência de classes de estímulos equivalentes. No entanto, outros procedimentos de treino discriminativo também têm sido efetivos para o estabelecimento destas classes. Este trabalho teve por objetivo estudar um procedimento de discriminação simples que, com base em discriminações simples já existentes, promoveria a emergência de relações condicionais entre estímulos. Participaram do estudo seis crianças (de seis e sete anos de idade) que trabalharam em computador. Depois de estabelecida uma discriminação simples entre dois estímulos, estes foram sobrepostos a novos estímulos, até a formação de nova discriminação. O mesmo procedimento foi repetido com outros estímulos. Depois de treino discriminativo no qual um participante apresentou apenas seis erros e os demais apresentaram três ou menos erros, testou-se a emergência de relações entre estímulos. Os testes revelaram que houve formação de classes de estímulos equivalentes para três participantes e sugeriram esta possibilidade para outros dois.

A number of studies have shown the possibility of using series of simple discriminations and multiple reversals to establish equivalent stimulus classes. The current study aimed to test the possibility of establishing equivalence classes through a training procedure that established simple discriminations on the basis of previously established ones, without reversals. Participants consisted of 6 children, aged 6 and 7. After the initial discrimination training of a pair of stimuli, two new, simple discriminations were established, one at a time, using the superimposition of stimuli. Following training, conditional relations between stimuli were tested. Results showed that all participants learned the discriminations almost without error: one participant had 6 errors and all the others had three errors or fewer. Tests for the emergence of classes of equivalent stimuli were positive for 3 participants and suggested the possibility of such emergence for 2 other participants.
Responsável: BR27.1 - Biblioteca do Campus II



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