Poster B93, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
No-movement awareness induces ERP modulations after long-term limb immobilization in a Go/Nogo task
Valentina Bruno1, Irene Ronga1, Carlotta Fossataro1, Francesca Garbarini1; 1SAMBA – SpAtial, Motor & Bodily Awareness – Research Group, Psychology Department, University of Turin, Turin, Italy
This EEG study focused on electrophysiological processes underlying no-movement awareness (the conscious detection of the impossibility of accomplishing self-generated actions). We contrasted conditions in which participants were free to perform a Go/Nogo task with conditions in which left-hand movements were prevented by a cast. Immobilization effects were tested after the cast-positioning and after one week of immobilization. We predicted a modulation of event-related potentials in blocked-conditions, when subjects tried to perform the task, but movements were precluded. In nogo trials, a modulation of the inhibition-related P300 was found. Only in left (manipulated) side, P300 was reduced in blocked-conditions, suggesting that, when the system “knows” that no-movement can be performed, inhibitory responses are not implemented. In go trials, a modulation of N400, related to semantic/conceptual violations, was found. In our study, the motor-monitoring system could detect a violation when, according to go-signals, motor response was planned but no-movement was performed (due to immobilization). In left side, N400 was oppositely modulated by blocked- and free-conditions, depending on the day. In blocked-conditions, an enhanced N400 at day1 suggests that motor-monitoring system suddenly detects a mismatch between intended but not executed response. At day2, when motor-monitoring system changed its predictions about the “learned block”, no incongruence is detected. Contrariwise, in free-conditions, a larger N400 at day2 was elicited by the detection of new incongruence between no-movement predictions and the evidence of being able to move again. These findings show that mechanical limb-immobilization is a good model to investigate EEG-activity changes related to no-movement awareness.
Topic Area: PERCEPTION & ACTION: Motor control