The “simulation” of the facial expression of emotions in case of short and long stimulus duration. The effect of pre-motor cortex inhibition by rTMS

Embodied cognition model states that the “simulation process” is necessary to the recognition of emotional significance of face. The present research explored the contribution of frontal motor brain components (i.e. mainly premotor area) to embodied cognition by using rTMS stimulation, to produce a temporary disruption of this specific cortical site. Secondly, short and long stimulus duration conditions were included to verify the contribution of the “simulation process” in response to overt and covert emotional stimulus comprehension. Nineteen subjects were asked to detect emotion/no emotion (anger, fear, happiness, neutral) in these two experimental conditions, by using a backward masking procedure. Five-second rTMS (1 Hz) was delivered before the stimulus onset. False alarms (Fa) and RTs increased and Hits decreased when frontal premotor brain activity was disrupted, specifically in response to anger and fear, for both long and shortduration condition. Thus, the present results highlight the main role of the frontal motor system for emotion facial expression processing.     

Impaired discriminative fear-conditioning resulting from elevated fear responding to learned safety cues among individuals with panic disorder

Classical fear-conditioning is central to many etiologic accounts of panic disorder (PD), but few lab-based conditioning studies in PD have been conducted. One conditioning perspective proposes associative-learning deficits characterized by deficient safety learning among PD patients. The current study of PD assesses acquisition and retention of discriminative aversive conditioning using a fear-potentiated startle paradigm. This paradigm was chosen for its specific capacity to independently assess safety- and danger learning in the service of characterizing putative anomalies in each type of learning among those with PD. Though no group difference in fear-potentiated startle was found at retention, acquisition results demonstrate impaired discriminative learning among PD patients as indexed by measures of conditioned startle-potentiation to learned safety and danger cues. Importantly, this discrimination deficit was driven by enhanced startle-potentiation to the learned safety cue rather than aberrant reactivity to the danger cue. Consistent with this finding, PD patients relative to healthy individuals reported higher expectancies of dangerous outcomes in the presence of the safety cue, but equal danger expectancies during exposure to the danger cue. Such results link PD to impaired discrimination learning, reflecting elevated fear responding to learned safety cues.     

Single and double alternation learning in rats: The role of set size and correction

In many experiments, rats have evidenced extreme difficulty mastering alternation patterns. In three experiments, we explored rats’ ability to learn double alternation patterns and possible reasons behind their past difficulties with such patterns. In Experiment 1, rats learned single and double alternation patterns. In the second and third experiment, we explored the role of correction and interference from stimulus set size on rats’ learning of double alternation patterns. Our results showed that rats easily learned both single and double alternation patterns and that stimulus set size had no noticeable effect on learning double alternation patterns. Findings additionally evidenced that correction played an important role in rats’ learning double alternation patterns.     

The equivalence of two ways of computing distances from dissimilarities for arbitrary sets of stimuli

Given a set endowed with pairwise dissimilarities, the Dissimilarity Cumulation procedure computes the (quasi)distance between any two elements of the set as the infimum of the sums of dissimilarities across all finite chains of elements connecting the two elements. For finite sets, this procedure is known to be equivalent to recursive corrections for violations of the triangle inequality in any sequence of ordered triads of points which contains every triad a sufficient number of times. This paper extends this equivalence to infinite set.     

Stimulus–response correspondence effect as a function of temporal overlap between relevant and irrelevant information processing

The stimulus–response correspondence (SRC) effect refers to advantages in performance when stimulus and response correspond in dimensions or features, even if the common features are irrelevant to the task. Previous research indicated that the SRC effect depends on the temporal course of stimulus information processing. The current study investigated how the temporal overlap between relevant and irrelevant stimulus processing influences the SRC effect. In this experiment, the irrelevant stimulus (a previously associated tone) preceded the relevant stimulus (a coloured rectangle). The irrelevant and relevant stimuli onset asynchrony was varied to manipulate the temporal overlap between the irrelevant and relevant stimuli processing. Results indicated that the SRC effect size varied as a quadratic function of the temporal overlap between the relevant stimulus and irrelevant stimulus. This finding extends previous experimental observations that the SRC effect size varies in an increasing or decreasing function with reaction time. The current study demonstrated a quadratic function between effect size and the temporal overlap.