Electrophysiological Correlates of Emotional and Crossmodal Stimuli Processing Among Alcohol-dependent Participants : Exploration of the Peripheral Presentation Effect

Methodology: Evaluation the event-related potentials elicited among alcohol-dependent and healthy participants while performing an emotion-detection task on unimodal (visual or auditory) or crossmodal (visuo-auditory) stimulations presented centrally or peripherally. Event-related potentials allow to monitor the electrical activity of the brain with high temporal resolution and to detect even minor neurocognitive restrictions. This cerebral measures will be completed by behavioral (reaction times and accuracy) and psychopathological measures.

No specific interventions assigned to the subjects of the study.

Evaluations: The room contains a panoramic screen (2.4 X 4 meters) covering a 180 degrees of visual angle. Participants will seat in a chair situated two meters away from the screen, in front of a table on which the response pad will be placed. Three projectors will display the visual stimulations, either centrally or lateralized (-12°, -24°on the left or +12°, +24° on the right). Headphones will be placed on participants' ears in order to display the auditory stimulations, either on both ears or lateralized (left or right ear), and presented separately (unimodal conditions) or simultaneously (crossmodal condition) with the visual stimuli. Visual stimuli, constructed using FaceGen 3.4 program, will be emotional faces (two males, two females) depicting happiness, anger or a neutral expression. Auditory stimuli (two males, two females), from a validated battery, will be emotional voices depicting happiness, anger or a neutral prosody and presented at a 70 decibels level. Crossmodal stimulations will be a combination of visual and auditory stimuli, congruent for gender and emotion. Experiment will be composed of 39 conditions: 3 stimulations (visual, auditory, visuo-auditory) X 3 emotions (anger, happiness, neutral) X 3/5 lateralisation (-24°, -12°, 0°, 12°, 24°). Each condition will be evaluated on the basis of 50 stimulations. Event-related potentials will be recorded during the whole experiment by means of a 128 electrodes cap placed on participant's head and connected with an amplifier (Advanced Neuro Technology, ANT) and a recording computer, synchronised with the stimulation system. Behavioral responses will be recorded by means of a response pad. Psychopathological measures will be conducted using validated questionnaires: State and trait anxiety (STAI A and B, Spielberger et al., 1983), depression (BDI, Beck et al., 1987), interpersonal problems (Horowitz et al. (1988)), evaluating the quantity and quality of the social interactions, and the integration in the family and relationship background and alexithymia (Bagby et al., 1994).