Spectral analysis of P300 paradigm using High Density EEG in patients with schizophrenia undergoing TMS treatment

This thesis is the result of my contribution to the ongoing "AVH TMS project" at Reykjavik University, Iceland. This exploratory work aims to hypothesize a methodological tool and electroencephalogram (EEG) biomarkers for the effect of repetitive Transcranial Magnetic Stimulation (rTMS) on patients with schizophrenia and auditory and verbal hallucinations (AVH). Ten patients diagnosed with schizophrenia and pharmacological persistent AVH were divided into two groups: the first group (TG) received 1Hz frequency rTMS treatment during 10 daily sessions (900 pulses/session) over the left T3-P3 International 10-20 location. The second group (CG) received rTMS treatment over the Cz (vertex) EEG location. Data from the patients were acquired before the rTMS treatment (pre) and 10 days after the treatment (post), and they were compared with the results obtained from a third group of healthy subjects (HS), who did not receive rTMS treatment. A P300 experiment (oddball auditory paradigm) was done and recorded with a highdensity electroencephalogram (HD EEG). The data were analyzed in the frequency domain, focusing on the alpha (8-13 Hz), low beta (13-18 Hz) and high beta (18-30 Hz) frequency bands and the power distribution was computed to show the differences of cortical response between groups. Despite the limited number of subjects enrolled in our study, this work is a first step towards defining biomarkers assessing the effect of left temporoparietal TMS treatment.