Comparison of TMS-evoked EEG potentials between waking and NREM sleep states
We experience the sleep-wake cycle on a daily basis, but what related underlying processes change in the brain? Using electroencephalography (EEG), the spread of the evoked potentials of non-sensory task-independent transcranial magnetic stimulation (TMS) to the occipital areas V1 or lateral occipital cortex in waking and non-rapid eye movement (NREM) sleep was compared in the study. We hypothesized that a) right-hemisphere slow negative potentials evoked by V1 TMS are reduced in NREM sleep, and b) stimulating different target sites leads to different activation patterns. Results showed significant interactions between different regions and states of consciousness in influencing the evoked EEG activity, suggesting different activation patterns in response to TMS when sleeping or awake. The data confirms and extends previous results.