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241.
242.
NMDA and muscarinic receptors of the nucleus accumbens have differential effects on taste memory formation
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Ramírez-Lugo L Zavala-Vega S Bermúdez-Rattoni F 《Learning & memory (Cold Spring Harbor, N.Y.)》2006,13(1):45-51
Animals recognize a taste cue as aversive when it has been associated with post-ingestive malaise; this associative learning is known as conditioned taste aversion (CTA). When an animal consumes a new taste and no negative consequences follow, it becomes recognized as a safe signal, leading to an increase in its consumption in subsequent presentations (attenuation of neophobia, AN). It has been shown that the nucleus accumbens (NAcc) has an important role in taste learning. To elucidate the involvement of N-methyl-D-aspartate (NMDA) and muscarinic receptors in the NAcc during safe and aversive taste memory formation, we administrated bilateral infusions of DL-2-amino-5-phosphonopentanoic acid (APV) or scopolamine in the NAcc shell or core respectively. Our results showed that pre-training injections of APV in the NAcc core and shell disrupted aversive but not safe taste memory formation, whereas pre-training injections of scopolamine in the NAcc shell, but not core, disrupted both CTA and AN. These results suggest that muscarinic receptors seem to be necessary for processing taste stimuli for either safe or aversive taste memory, whereas NMDA receptors are only involved in the aversive taste memory trace formation. 相似文献
243.
Vidal-Gonzalez I Vidal-Gonzalez B Rauch SL Quirk GJ 《Learning & memory (Cold Spring Harbor, N.Y.)》2006,13(6):728-733
Recent studies using lesion, infusion, and unit-recording techniques suggest that the infralimbic (IL) subregion of medial prefrontal cortex (mPFC) is necessary for the inhibition of conditioned fear following extinction. Brief microstimulation of IL paired with conditioned tones, designed to mimic neuronal tone responses, reduces the expression of conditioned fear to the tone. In the present study we used microstimulation to investigate the role of additional mPFC subregions: the prelimbic (PL), dorsal anterior cingulate (ACd), and medial precentral (PrCm) cortices in the expression and extinction of conditioned fear. These are tone-responsive areas that have been implicated in both acquisition and extinction of conditioned fear. In contrast to IL, microstimulation of PL increased the expression of conditioned fear and prevented extinction. Microstimulation of ACd and PrCm had no effect. Under low-footshock conditions (to avoid ceiling levels of freezing), microstimulation of PL and IL had opposite effects, respectively increasing and decreasing freezing to the conditioned tone. We suggest that PL excites amygdala output and IL inhibits amygdala output, providing a mechanism for bidirectional modulation of fear expression. 相似文献
244.
Prado-Alcalá RA Díaz del Guante MA Garín-Aguilar ME Díaz-Trujillo A Quirarte GL McGaugh JL 《Neurobiology of learning and memory》2006,86(2):144-149
The hypothesis that memory is stored through a single stage of consolidation that results in a stable and lasting long-term memory has been challenged by the proposition that reactivation of a memory induces reconsolidation of the memory. The reconsolidation hypothesis is supported by evidence that, under some conditions, post-retrieval treatments affecting amygdala and hippocampus functioning impair subsequent retention performance. We now report that repeated retention testing attenuates the performance impairment induced by post-retrieval reversible inactivation of the amygdala and hippocampus of rats induced by tetrodotoxin. These findings challenge the reconsolidation hypothesis and suggest that the post-retrieval retention performance impairment is best explained as due to temporary retrieval failure. 相似文献
245.
Taste aversion learning (TAL) is a type of learning characterized by rejection of a gustatory/flavor stimulus as a consequence of its pairing with visceral discomfort and malaise. TAL can be established in the laboratory by two different behavioral procedures, concurrent or sequential. Neural mechanisms of these learning modalities remain to be elucidated, but several studies have discussed the implication of various anatomical structures, including the vagus nerve. The aim of this study was to examine the role of capsaicin-sensitive vagal afferent fibers in concurrent (Experiment 1) and sequential (Experiment 2) TAL in Wistar rats. Results showed that perivagal administration of capsaicin (1mg of capsaicin dissolved in 1ml of vehicle (10% Tween 80 in oil)) blocked acquisition of concurrent but not sequential TAL. These data support the hypothesis of two different modalities of TAL mediated by distinct neurobiological systems, with vagal nerve participation only being essential in concurrent TAL. 相似文献
246.
da Silva WC Bonini JS Bevilaqua LR Izquierdo I Cammarota M 《Neurobiology of learning and memory》2006,86(1):100-106
Several evidences suggest that brain histamine is involved in memory consolidation but the actual contribution of the hippocampal histaminergic system to this process remains controversial. Here, we show that when infused into the CA1 region of the dorsal hippocampus immediately after training in an inhibitory avoidance task, but not later, histamine induced a dose-dependent promnesic effect without altering locomotor activity, exploratory behavior, anxiety state or retrieval of the avoidance response. The facilitatory effect of intra-CA1 histamine was mimicked by the histamine N-methyltransferase inhibitor SKF-91844 as well as by the H2 receptor agonist dimaprit and it was blocked completely by the H2 receptor antagonist ranitidine. Conversely, the promnesic action of histamine was unaffected by the H1 receptor antagonist pyrilamine, the H3 receptor antagonist, thioperamide, and the NMDAr polyamine-binding site antagonist ifenprodil. By themselves, ranitidine, pyrilamine, thioperamide, and ifenprodil did not affect IA memory consolidation. Our data indicate that, when given into CA1, histamine enhances memory consolidation through a mechanism that involves activation of H2 receptors; however, endogenous CA1 histamine does not seem to participate in the consolidation of IA memory at least at the post-training times analyzed. 相似文献
247.
- In this study, we deal with the existing debate related to the establishment of switching barriers retaining customers in the relationship with a provider. In particular, we demonstrate that ‘positive’ switching barriers (relational benefits) play a greater role that the ‘negative’ ones (switching costs and availability and attractiveness of other providers' offers) in determining customer satisfaction and retention. On the other hand, we include customers' need for variety in the proposed model, in order to demonstrate that a higher level of this psychological trait will lead to a lower perception of the existence of switching barriers. The hypotheses proposed have been tested for a services context on a sample of 800 individuals, using the technique ‘Partial Least Squares’ (PLS). Our findings lead to some interesting managerial implications.
248.
The primary objective of this study was to translate and validate Situational Inventory of Body-Image Dysphoria-Short form (SIBID-S) in a Spanish population. The scale consists of 20 items to assess the frequency of dysphoric body-image emotions in certain situational contexts, using a five-point rating scale. The questionnaire was administered to 214 women between the ages of 14 and 29 years, from primary and secondary schools and a university. Principal components analysis indicated a one-factor structure for the entire sample and both younger (<18) and older (≥18) participants. Internal consistency was high (0.94), and the test–retest reliability over 1 month ranged between 0.89 and 0.93. The SIBID-S showed good convergent validity in relation to other pertinent measures of body image, eating pathology, and self-esteem. Moreover, the SIBID-S was differentiated low-risk, subclinical eating disturbed, and clinical eating disordered patients. Results support the potential utility of the SIBID-S in the Spanish female population, including a younger group than previously studied, as well as its usefulness in the assessment of body image among females varying in degrees of eating pathology. 相似文献
249.
Gaertner L Iuzzini J Witt MG Oriña MM 《Journal of personality and social psychology》2006,90(3):426-439
Four experiments examined whether group formation and positive in-group regard require interaggregate comparison as the in-group-requires-an-out-group assumption of the metacontrast principle implies. The authors fostered novel social aggregates with or without a contrasting aggregate with which members could compare and varied intra-aggregate factors (interaction or interdependence). Regardless of whether interaggregate comparison was feasible, the intra-aggregate factors increased the perceived entitativity of the aggregate and positive regard toward the aggregate (i.e., social attraction and cooperation among members). Mediation analyses were consistent with the possibility that the intra-aggregate factors promoted entitativity, which in turn promoted in-group regard. These data suggest that group formation and in-group regard have intragroup origins and do not require comparison with a contrasting social aggregate. 相似文献
250.
The aim of the study was to provide a standardization of self-reported competences and emotional/behavioural problems in Spanish adolescents, using the Achenbach's Youth Self-Report (YSR), and to compare our results to those from other countries. The YSR was completed by 2822 adolescents aged 11-18 years, recruited from secondary schools in two regions of Spain. There were significant differences in Total behaviour problems and in most problem scales in boys and girls, scoring boys higher on externalizing syndromes, whereas girls score higher on internalizing syndromes . Males' mean scores were higher than females' scores for social competence. Age effects also showed significant differences with respect to internalizing problems, thought problems, social problems and depression. Cut-off points based on the 90th and 98th percentile developed from this sample are presented for the competences and the problem scales. To test the overall range of variations across cultures, comparisons were made between broad band and narrow band measures of the YSR in Spanish adolescents and those from other countries. Gender differences in the YSR were similar to those found across different cultures; there is a consistent trend to increase behavioural problems with age; and social competence seem to be a relevant protective factor against behavioural problems. 相似文献