Excitability and susceptibility of the brain's electrical activity during sleep: An analysis of late components of aeps and veps

Abstract

We investigated ten healthy male subjects and measured late components of AEPs and VEPs during sleep. According to Rechtschaffen and Kales (1968) we performed an off-line scoring procedure of sleep-EEG and averaged the AEPs and VEPs of five different periods, corresponding to sleep stages I, II, III, IV and REM. From the averaged evoked potentials we computed the amplitude-frequency-characteristic (AFC) of the brain (Basar, 1980) during different sleep stages. These AFCs characterize transfer properties of an oscillating system. A comparison of different AFCs has shown that the excitability of the brain depicts a clear alpha resonance during stage I, a pronounced delta resonance during stages II, III and IV, and a theta resonance during REM sleep. A comparison of these results from linear system theory with the nonlinear dynamical behavior of the CNS was performed.

Key Words:

• sleep-EEG
• AEP
• VEP
• frequency analysis
• linear system theory
• correlation dimension
• nonlinear dynamics