Investigação da relação entre impulsividade e componentes inibitórios: um estudo comportamental e eletromiográfico

Abstract

Inhibitory control is an executive component that enables appropriate and goal-directed behavior. It is known that inhibition is not a unitary function, and that, in fact, it can be separated into different inhibitory processes which have unique properties. Stroop-like and stop-signal tasks are among those commonly used to evaluate the inhibitory capacity. Some researches have investigated which types of inhibition are involved in Stroop-like tasks and stop-signal tasks and how they interact; however, there is no consensus about this issue. Inhibitory functions have also a central role in disorders characterized by impulsive behaviors, such as ADHD. The current study investigated, initially, for interactions between the behavioral variables obtained in the Stroop-matching and stop-signal tasks, i.e., the reaction time (RT) of the Stroop task and the latency of response inhibition of the stop-signal task – stop-signal reaction time (SSRT). Moreover, Spearman correlations were made between the behavioral data (RT, SSRT and error rates), the scores obtained in self-report instruments used to assess impulsivity (BIS-11 and UPPS) and ADHD symptoms (ASRS). Finally, we also verified how electromyographic measures (EMG) varied according to the behavioral tasks. Thus, we analyzed how the percentage of bilateral myoelectric activities (those obtained in both hands – double activations) and subliminal activities, both representing conflicts at motor level, varied as a function of the different Stroop conditions adopted. The results indicated that RTs, SSRTs and EMG measures differed significantly among different Stroop conditions, being longer in those conditions with higher levels of conflict. Furthermore, SSRT and both EMG parameters were sensitive to the difficulty level of the Stroop-task condition. Finally, the correlations indicated that in general terms, participants with higher scores in the scales showed lower RTs, lower SSRT and higher number of errors. These results suggested that the inhibitory mechanisms involved in the Stroop-matching and stop-signal tasks do interact. The finding that inhibitory processes are faster in non-clinical adults with higher scores in impulsivity scales gives support to the so-called “functional view of impulsivity”, as proposed by Dickman (1990). Other studies are necessary to know if these results would also be found in clinical population with impulsivity disorders