Endogenous BDNF is required for long-term memory formation in the rat parietal cortex

Information storage in the brain is a temporally graded process involving different memory phases as well as different structures in the mammalian brain. Cortical plasticity seems to be essential to store stable long-term memories, although little information is available at the moment regarding molecular and cellular events supporting memory consolidation in the neocortex. Brain-derived neurotrophic factor (BDNF) modulates both short-term synaptic function and activity-dependent synaptic plasticity in hippocampal and cortical neurons. We have recently demonstrated that endogenous BDNF in the hippocampus is involved in memory formation. Here we examined the role of BDNF in the parietal cortex (PCx) in short-term (STM) and long-term memory (LTM) formation of a one-trial fear-motivated learning task in rats. Bilateral infusions of function-blocking anti-BDNF antibody into the PCx impaired both STM and LTM retention scores and decreased the phosphorylation state of cAMP response element-binding protein (CREB). In contrast, intracortical administration of recombinant human BDNF facilitated LTM and increased CREB activation. Moreover, inhibitory avoidance training is associated with a rapid and transient increase in phospho-CREB/total CREB ratio in the PCx. Thus, our results indicate that endogenous BDNF is required for both STM and LTM formation of inhibitory avoidance learning, possibly involving CREB activation-dependent mechanisms. The present data support the idea that early sensory areas constitute important components of the networks subserving memory formation and that information processing in neocortex plays an important role in memory formation.     

Associative and causal reasoning accounts of causal induction: Symmetries and asymmetries in predictive and diagnostic inferences

Associative and causal reasoning accounts are probably the two most influential types of accounts of causal reasoning processes. Only causal reasoning accounts predict certain asymmetries between predictive (i.e., reasoning from causes to effects) and diagnostic (i.e., reasoning from effects to causes) inferences regarding cue-interaction phenomena (e.g., the overshadowing effect). In the experiments reported here, we attempted to delimit the conditions under which these asymmetries occur. The results show that unless participants perceived the relevance of causal information to solving the task, predictive and diagnostic inferences were symmetrical. Specifically, Experiments 1A and 1B showed that implicitly stressing the relevance of causal information by having participants review the instructions favored the presence of asymmetries between predictive and diagnostic situations. In addition, Experiment 2 showed that explicitly stressing the relevance of causal information by stating the importance of the causal role of events after the instructions were given also favored the asymmetry.     

Motivational versus volitional mediation of passivity in institutionalized older people

The relationship between perceived loss of control and passivity in social activities in a non-handicapped institutionalized elderly population was assessed. Perceived loss of control was assessed from three different types of expectancies: low action-outcome expectancies, high situation-outcome expectancies, and low efficacy expectancies. Passivity scores were reported by the staff. The effect of these three types of expectancies on passivity was analyzed in terms of motivation and volition, which were treated as mediating variables. Overall analysis of the structural equations, as well as partial hierarchical regression analyses, showed that efficacy expectancies were good predictors of passivity, but this was not the case for the action-outcome and situation-outcome expectancies. These results lend more support to a volitional rather than to a motivational interpretation of the effect of control on passivity. The implications of these results for intervention and for a differentiated conception of expectancies are discussed.     

The influence of the visual surrounding environment in older adults and young adults’ cognitive performance: an alternative paradigm

ABSTRACT

This study investigated how the characteristics of the visual surrounding environment influence older- and young-adults’ cognitive performance. Sixty-four older adults and 64 young adults performed four visual cognitive tasks (attention and memory tasks) in two independent sessions while being exposed to a high-load and a low-load visual surrounding environment. We expected that the high-load environment would hurt the older-adults performance due to typical difficulties in ignoring irrelevant stimuli, whereas no such effect would likely occur for the young-adults whose cognitive abilities are at their best. Overall, our results were consistent with our prediction in three tasks (go/no-go, choice reaction time, and Corsi block-tapping). Additionally, the older adults performed worse than the young adults in all tasks, thus confirming expected age-related differences. Our results are consistent with those obtained when distractors and targets are presented in the same display, now using a paradigm which locates the distractors in the surrounding environment.