Reduced information processing speed and event-related EEG synchronization in traumatic brain injury (P6.149)

Objective: To examine electroencephalography (EEG) –derived changes in event-related synchronization associated with reduced processing speed in traumatic brain injury (TBI). Background: Reduced processing speed is common following TBI and it is associated with executive dysfunction and disability. Task-related alterations in neural synchronization as indexed by EEG during target detection and speeded responding may reflect modulation in the strength of communication within and between cortical areas, which in turn may determine information processing speed. Design/Methods: 30 subjects, including 16 moderate-severe TBI patients and 14 age-matched healthy controls took part in the study. Participants performed a choice reaction time task (CRT) during 32-channel EEG acquisition. Time-frequency analysis of the EEG signal was carried out both time-locked to the stimulus and to the response for correct trials. Event-related potential (ERP) P300 was also computed. Results: Reaction times (RT) were significantly slower in TBI patients than in healthy controls (U=53, P=0.013). Compared to controls, TBI patients showed significantly reduced event-related synchronisation and phase coherence in the theta band in frontal channels from 200 ms to 50 ms before the stimulus onset and 600 ms before the response. In addition, P300 amplitude was significantly reduced in TBI patients (U=160, P=0.047). Higher P300 amplitude was associated with faster RT in both patients and controls, but there was no interaction by group. Conclusions: Reduced frontal theta event-related synchronisation preceding target detection in a speeded choice reaction time task may be a surrogate marker of slowed information processing following TBI. Study Supported by: Academy of Medical Sciences, National Institute of Health Research (NIHR), Agence regionale de Sante Basse-Normandie (bourse Annee-Recherche) Disclosure: Dr. Dautricourt has nothing to disclose. Dr. Violante has nothing to disclose. Dr. Mallas has nothing to disclose. Dr. Daws has nothing to disclose. Dr. Ross has nothing to disclose. Dr. Jolly has nothing to disclose. Dr. Lorenz has nothing to disclose. Dr. Sharp has nothing to disclose. Dr. Gorgoraptis has nothing to disclose.