RESUMO
In this study, we employed a visuo-motor imagery task of alertness as a mental training to examine temporal processing of motor responses within healthy young adults. Participants were divided into two groups (group 1; n = 20 who performed the mental training before the real physical task and a control group who performed the physical task without mental training). We vary the time interval between the imperative stimulus and the preceding one (fore-period) in which temporal preparation and arousal increase briefly. Our behavioural results provide clear evidence that mental training reinforces both temporal preparation and arousal, by shortening reaction time (RT), especially for the shortest fore-periods (FP) within exogenous "FP 250 ms" (p = 0.008) and endogenous alertness "FP 650 ms" (p = 0.001). We investigated how the brain controls such small temporal changes. We focus our neural hypothesis on three brain regions: anterior insula, dorsolateral prefrontal cortex, and anterior cingulate cortex and three putative circuits: one top-down (from dorsolateral prefrontal cortex to anterior cingulate cortex) and two bottom-up (from anterior insula to dorsolateral prefrontal cortex and anterior cingulate cortex). In fMRI, effective connectivity is strengthened during exogenous alertness between anterior insula and dorsolateral prefrontal cortex (p = 0.001), between anterior insula and cingulate cortex (p = 0.01), and during endogenous alertness between dorsolateral prefrontal cortex and anterior cingulate cortex (p = 0.05). We suggest that attentional reinforcement induced by an intensive and short session of mental training induces a temporal deployment of attention and allow optimizing the time pressure by maintaining a high state of arousal and ameliorating temporal preparation.