1 Modeling Brain Electrical Activity Involving Vagus Nerve Stimulation

Experiments involving electroencephalographic (EEG) analysis of spatiotemporal structures identified various characteristic features in the measured brain activity of human subjects, while awake, at rest, in sleep, and preceding and during epileptic seizure. Gamma power of EEG signals (20Hz to 80 Hz) varies with changes in the cognitive activity and medical conditions of the subject. Qualitative characterization of the measured effects involves the Lyapunov analysis in time domain and power spectral analysis in frequency domain. Positive Lyapunov exponents and scale free behavior in spectra are indications of nonlinear chaotic dynamics underlying brains behavior. The present work introduces results obtained by the KIV model, which represents a hierarchical approach to the spatio-temporal dynamic of the limbic system. Our approach models some aspects of the neurosurgical treatment of medically intractable epilepsy using Vagus Nerve Stimulation (VNS). Several properties of brain dynamics during VNS treatment has been reproduced by KIV simulations, which indicates a potential for future interpretation of VNS experimental data.