Studio comportamentale e neurofunzionale degli effetti della presentazione di un segnale d'avvertimento sui tempi di reazione semplici: allerta o controllo inibitorio degli automatismi visuomotori?

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Questions about attention are usually addressed by cueing tasks assessing whether knowledge of stimulus related information provided in advance will improve target processing. Most current interpretations suggest that a warning stimulus provokes an alerting on the organism resulting in a faster processing of either the sensory or the motor aspects of the task. However, as shown in chapeter III, warning signals trigger automatic motor activations (observed on EMG) which are likely to cause false alarms. Chapter IV provides converging behavioral and fMRI evidences that classical cueing methods entail competing processes of automatic motor activation triggered by the cue and the proactive response inhibition intended to counteract these automatic responses to the cue. It is concluded that some classical protocols generally used in attention research are likely to be biased and to reveal behavioral effects that are not attentional in origin. The paradoxical warning signal effect (proactive inhibition) was found to be mediated with a role in volitional inhibition (Chapter V). This inhibition would act on motor structures which are critical for connecting the basal ganglia and appealing the neuronal processes underlying movement initiation (M1, SMA, putamen). This premotor hypotesis was further reinforced in chapter VI by the electroencephalographic analysis of this effect. It is concluded that strong interactions (even confusions) are observed within attentional, sensorimotor and executive functions.