P56-F Auditory-motor task triggers gamma and beta oscillations in patients with schizophrenia and auditory verbal hallucinations

Abstract

Background In a study with intracranial recordings, auditory-verbal stimuli elicited augmented gamma-oscillations in the posterior portion of the superior temporal gyrus, whereas hand-motor responses elicited gamma-augmentation in the pre- and postcentral gyri (Nagasawa et al., 2010). We aimed to investigate if motor cortical activation (MCA) during an auditory-motor (AM) task is affected by laterality of hand motor responses in healthy subjects (HS) and in patients with auditory verbal hallucinations (AVH). Methods Eight HS and ten patients were asked to press a button using the thumb of both hands independently, during two sessions of 3 min. Each session contained 40 trials; 20 auditory-verbal commands saying “Press” and 20 commands saying “Do not press” (Nagasawa et al., 2010). MCA analysis epochs had duration of 500 ms following the button “press”. We used high-density 256 EEG ANT Neuro. Here we show preliminary results of MCA in HS and AVH patients using power spectral density (PSD) and topographical frequency maps including both hands sensory-motor regions. Results The preliminary data show that the laterality of the cortical activation related to the AM task may not be affected to a large degree by the motor reaction. Resting state EEG and AM task brain maps showed fragmented EEG topography in patients with schizophrenia for all analyzed band frequencies. Conclusions With this method we were able to trigger high beta and gamma bands activity in regions related to sensory-motor cortex. The topography of these frequencies remained stable when the participant used the right or the left hand.