Sustained attention during priming effect: a Contingent Negative Variation and Transcranial Magnetic Stimulation study

Question: Alertness improves behavioural responses and induces a priming effect on the target stimulus. We investigated the functional characteristics of sustained phasic alertness associated with the priming effect and examined the role of a specific brain area, i.e. the right dorso-lateral prefrontal cortex (DLPFC), during attentional processing of the stimulus related to primitive priming learning. Methods: The study consisted of two experiments. In the Experiment I, ten subjects performed a Contingent Negative Variation (CNV) ERP motor task, for three consecutive times, each one after 30 min interval. In experiment II, the CNV was evaluated in basal, and after 30 min of real or sham 1-Hz rTMS stimulation of the right DLPFC in twelve subjects. Results: Repetition of a CNV motor task resulted in a reduction of the reaction times (RT) and was associated with the stability of the CNV phenomenon. Transient virtual inhibition of the right DLPFC induced by real 1-Hz rTMS stimulation was associated with a significant decrease in total CNV and W1-CNV areas if compared with the basal and post-sham rTMS conditions. RTs did not decrease after inhibitory rTMS, but they did improve after sham stimulation. Conclusions: These results suggest that the continuous recruitment of attentional resources without any attenuation phenomenon in the presence of repetitions of a behavioural task is critical for the learning of a motor task. Moreover, the right DLPFC appears to play a crucial role in the genesis and maintenance of the alerting state and the learning processes.