Amygdala upregulation of NCAM polysialylation induced by auditory fear conditioning is not required for memory formation, but plays a role in fear extinction

There is much interest to understand the mechanisms leading to the establishment, maintenance, and extinction of fear memories. The amygdala has been critically involved in the processing of fear memories and a number of molecular changes have been implicated in this brain region in relation to fear learning. Although neural cell adhesion molecules (NCAMs) have been hypothesized to play a role, information available about their contribution to fear memories is scarce. We investigate here whether polysialylated NCAM (PSA-NCAM) contributes to auditory fear conditioning in the amygdala. First, PSA-NCAM expression was evaluated in different amygdala nuclei after auditory fear conditioning at two different shock intensities. Results showed that PSA-NCAM expression was increased 24 h post-training only in animals subjected to the highest shock intensity (1mA). Second, PSA-NCAM was cleaved in the basolateral amygdaloid complex through micro-infusions of the enzyme endoneuraminidase N, and the consequences of such treatment were investigated on the acquisition, consolidation, remote memory expression, and extinction of conditioned fear memories. Intra-amygdaloid cleavage of PSA-NCAM did not affect acquisition, consolidation or expression of remote fear memories. However, intra-amygdaloid PSA-NCAM cleavage enhanced fear extinction processes. These results suggest that upregulation of PSA-NCAM is a correlate of fear conditioning that is not necessary for the establishment of fear memory in the amygdala, but participates in mechanisms precluding fear extinction. These findings point out PSA-NCAM as a potential target for the treatment of psychopathologies that involve impairment in fear extinction.     

Personality and creativity

Previous research has provided conflicting accounts of the effects of personality on creative behaviour. This study examines the issue by means of factor analysis and multivariate analysis of variance. Different measures of creative behaviour and cognitive abilities are correlated with personal characteristics such as psychoticism, extraversion and other measures of personality. The results are consistent with the idea that different forms of creative behaviour are related to distinct characteristics of personality.     

Procesos de aprendizaje y terapia de conducta en la adicción a la heroína

Resumen

Múltiples principios de condicionamiento clásico y operante interaccionan en la adición a la heroína. Destacan la presencia de RC Compensatorias en forma de Síndrome de Abstinencia Condicionado (SAC) y distintos programas de reforzamiento en el estilo de vida, argot y efectos de la heroína. En evaluación conductual se estudian los correlatos subjetivos y psicofisiológicos del SAC; la validez externa de los autorregistros se logra mediante análisis de orina. En terapia de conducta los programas de amplio espectro se combinan con la intervención comunitaria y apoyo médico. A nivel metodológico se resalta la necesidad de usar múltiples criterios de medición, introducción del análisis multivariado y uso de diseños estadísticos, realización de seguimientos a largo plazo.     

Age differences in the rejection of false memories: The effects of giving warning instructions and slowing the presentation rate

Two experiments were conducted to examine whether children of different ages differ in their ability to reject associative false memories with the Deese–Roediger–McDermott (DRM) paradigm. Two different types of manipulations that are thought to facilitate false memory rejection in adults—slowing the presentation rate and issuing explicit warnings—were analyzed in younger and older children. The results showed that older children were more able than younger children to reject associative false memories through warnings and by slowing the presentation rate. We conclude that although older children are, in general, more prone to produce false memories with the DRM paradigm, they are also more able to reject them when certain conditions facilitate the editing process.     

“Identify-to-reject”: A specific strategy to avoid false memories in the DRM paradigm

Previous research using the Deese–Roediger–McDermott (DRM) paradigm has shown that lists of associates in which the critical words were easily identified as the themes of the lists produce lower levels of false memories in adults. In an attempt to analyze whether this effect is due to the application of a specific memory-editing process (the identify-to-reject strategy), two experiments manipulated variables that are likely to disrupt this strategy either at encoding or at retrieval. In Experiment 1, lists were presented at a very fast presentation rate to reduce the possibility of identifying the missing critical word as the theme of the list, and in Experiment 2, participants were pressed to give yes/no recognition answers within a very short time. The results showed that both of these manipulations disrupted the identifiability effect, indicating that the identify-to-reject strategy and theme identifiability play a major role in the rejection of false memories in the DRM paradigm.