Spectral analysis of the electroencephalographic response to motion sickness.

Ten subjects participated in a laboratory experiment using cross-coupled angular stimulation to induce motion sickness symptoms. A 14-channel montage using subdermal electrodes was employed to record the electroencephalogram during a pre-Coriolis stimulation baseline through to imminent emesis. Spectral analyses of the EEG were performed upon the recorded data and individual band energies were quantified to attempt to characterize the cortical electrical response to motion sickness. Power spectral analysis was performed upon the temporo-frontal signals through the entire period over the delta, theta, and alpha EEG bands. The power in each of these bands was integrated and the baseline periods compared with that during frank sickness. Mean power spectral energy in the delta band during frank sickness increased by a factor of 13.7 over baseline. Mean theta band energy increased by a factor of 2.2. Mean alpha band energy was not significantly different. EEG power spectral levels in the delta and theta bands increased along with the level of motion sickness symptoms. These changes, particularly those in the delta band, suggest that intense low frequency oscillatory stimulation is being diffusely projected about the central nervous system. These EEG changes, similar to those sometimes seen in partial seizures, and the similarity of the symptom/sign complex in the two disorders, provide evidence that the pathophysiology and electrophysiology of motion sickness may be a variant of seizure activity.