The only subject showing no effect also proved insufficient engagement in the tasks. diverted) was observed in 19/20 subjects, of whom 18 showed the expected P300 effect and 1 showed an effect restricted to the N2 component. An effect of attention manipulation (oriented vs. Mental imagery proved to be more efficient than passive listening to lessen P300 response to deviant tones as compared with the active counting condition. Twenty healthy subjects were presented with a two-tone oddball paradigm in the three following condition: (a) passive listening, (b) mental imagery, (c) silent counting of deviant stimuli. To improve test sensitivity, we propose as a control condition to actively divert the subject's attention from the auditory stimuli with a mental imagery task that has been demonstrated to be within the grasp of the targeted patients: navigate in one's home. However, contrast between these two conditions is usually too weak to be detected at the individual level.
In comparison with passive listening, larger P300 in the active condition identifies voluntary processes. Using auditory ERPs, the active condition consists in orienting patient's attention toward oddball stimuli. Morlet, Dominique Ruby, Perrine André-Obadia, Nathalie Fischer, CatherineĪctive paradigms requiring subjects to engage in a mental task on request have been developed to detect consciousness in behaviorally unresponsive patients. The auditory oddball paradigm revised to improve bedside detection of consciousness in behaviorally unresponsive patients.
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