Jose Fernandez-Rey

External validation of the computerized, group administrable adaptation of the “operation span task”

One of the most widely used tasks for measuring working memory capacity is the operation span task (OSPAN; Turner & Engle, 1989). This task has almost always been applied individually, and stimuli presentation is controlled by the experimenter. Recently, De Neys, d’Ydewalle, Schaeken, and Vos (2002) improved the administration procedure by designing an automated, group-administrable version of the task (GOSPAN). They found GOSPAN to be reliable, and they also provided evidence on its validity (a significant positive correlation between GOSPAN and OSPAN scores). However, an external test of GOSPAN validity is still lacking. In this work, we present such a validation for the automated version, when the task is administered both individually (Experiment 1) and to groups (Experiment 2). There are abundant previous data on the relation between working memory capacity and reading comprehension. In this work, this relation is studied using an automated OSPAN version to measure working memory capacity. Given that our results are similar to those found using the original OSPAN, our data support the external validity of the automated version of the task. We also tested the reliability of the task and found high internal consistency in both experiments.

Decision-Making in the Ventral Premotor Cortex Harbinger of Action

Although the premotor (PM) cortex was once viewed as the substrate of pure motor functions, soon it was realized that it was involved in higher brain functions. By this it is meant that the PM cortex functions would better be explained as motor set, preparation for limb movement, or sensory guidance of movement rather than solely by a fixed link to motor performance. These findings, together with a better knowledge of the PM cortex histology and hodology in human and non-human primates prompted quantitative studies of this area combining behavioral tasks with electrophysiological recordings. In addition, the exploration of the PM cortex neurons with qualitative methods also suggested its participation in higher functions. Behavioral choices frequently depend on temporal cues, which together with knowledge of previous outcomes and expectancies are combined to decide and choose a behavioral action. In decision-making the knowledge about the consequences of decisions, either correct or incorrect, is fundamental because they can be used to adapt future behavior. The neuronal correlates of a decision process have been described in several cortical areas of primates. Among them, there is evidence that the monkey ventral premotor (PMv) cortex, an anatomical and physiological well-differentiated area of the PM cortex, supports both perceptual decisions and performance monitoring. Here we review the evidence that the steps in a decision-making process are encoded in the firing rate of the PMv neurons. This provides compelling evidence suggesting that the PMv is involved in the use of recent and long-term sensory memory to decide, execute, and evaluate the outcomes of the subjects’ choices.

EEG activity represents the correctness of perceptual decisions trial-by-trial

Performance monitoring is an executive function, which we depend on for detecting and evaluating the consequences of our behavior. Although event related potentials (ERPs) have revealed the existence of differences after correct and incorrect decisions, it is not known whether there is a trial-by-trial representation of the accuracy of the decision. We recorded the electroencephalographic activity (EEG) while participants performed a perceptual discrimination task, with two levels of difficulty, in which they received immediate feedback. Receiver Operating Characteristic (ROC) analyses were used to reveal two components that convey trial-by-trial representations of the correctness of the decisions. Firstly, the performance monitoring-related negativity (PM-N), a negative deflection whose amplitude is higher (more negative) after incorrect trials. Secondly, the performance monitoring-related positivity (PM-P), a positive deflection whose amplitude is higher after incorrect trials. During the time periods corresponding to these components, trials can be accurately categorized as correct or incorrect by looking at the EEG activity; this categorization is more accurate when based on the PM-P. We further show that the difficulty of the discrimination task has a different effect on each component: after easy trials the latency of the PM-N is shorter and the amplitude of the PM-P is higher than after difficult trials. Consistent with previous interpretations of performance-related ERPs, these results suggest a functional differentiation between these components. The PM-N could be related to an automatic error detection system, responsible for fast behavioral corrections of ongoing actions, while the PM-P could reflect the difference between expected and actual outcomes and be related to long-term changes in the decision process.

Is it possible to modify fear memories in humans with extinction training within a single day

Extinction procedures have been used widely in the study of fear memories, and different positions have been adopted regarding the efficacy of such procedures and the mechanisms involved. It has been argued that extinction may interfere with the consolidation of the fear memory if the procedure is applied with the appropriate timing after acquisition. However, the opposite position is also held, that is, that the extinction does not achieve an elimination of the fear response. The aim of the present study is to test the short-term effects of immediate extinction in fear reduction when this extinction is preceded by a retrieval trial. For this, a procedure similar to that employed by Schiller et al. (Nature 463(7277): 49–53, 2010) was used, but in a single day and with white noise as an aversive unconditioned stimulus. The results indicate that a CS+ single retrieval trial before the extinction procedure after acquisition was more effective in fear reduction than standard immediate extinction.

Preventing the return of fear memories with postretrieval extinction: A human study using a burst of white noise as an aversive stimulus.

Standard extinction procedures seem to imply an inhibition of the fear response, but not a modification of the original fear-memory trace, which remains intact (Bouton, 2002, 2004). Typically, the behavioral procedure used to modify this trace is the so-called postretrieval extinction, consisting of fear-memory reactivation followed by extinction applied within the reconsolidation window. However, the application of this technique yields mixed results, probably due to a series of boundary conditions that limit the effectiveness of postretrieval-extinction effects. In this study a number of potential, and hitherto unexplored, moderators of such effects are considered. Using an interval of 48 hr between extinction and re-extinction, the findings show a spontaneous recovery similar to that found in studies that use a 24-hr interval. Also, the use of intervals of 10 and 20 min between reactivation and extinction led to a similar fear return. Finally, the burst of white noise used as an unconditioned stimulus (US) here was shown to be as effective as the electric shock normally used in the study of fear-memory reconsolidation. These findings suggest that postretrieval extinction is an effective behavioral technique for modifying the original fear memory and for the elimination of the fear return.