Left-Right Information flow in the Brain during EEG arousals

In disorders such as sleep apnea, sleep is fragmented with frequent EEG-arousal (EEGA) as determined via changes in the sleep-electroencephalogram. EEGA is a poorly understood, complicated phenomenon which is critically important in studying the mysteries of sleep. In this paper we study the information flow between the left and right hemispheres of the brain during the EEGA as manifested through inter-hemispheric asynchrony (IHA) of the surface EEG. EEG data (using electrodes A1/C4 and A2/C3 of international 10-20 system) was collected from 5 subjects undergoing routine polysomnography (PSG). Spectral correlation coefficient (R) was computed between EEG data from two hemispheres for delta-delta(0.5-4 Hz), theta-thetas(4.1-8 Hz), alpha-alpha(8.1-12 Hz) & beta-beta(12.1-25 Hz) frequency bands, during EEGA events. EEGA were graded in 3 levels as (i) micro arousals (3-6 s), (ii) short arousals (6.1-10 s), & (iii) long arousals (10.1-15 s). Our results revealed that in beta band, IHA increases above the baseline after the onset of EEGA and returns to the baseline after the conclusion of event. Results indicated that the duration of EEGA events has a direct influence on the onset of IHA. The latency (L) between the onset of arousals and IHA were found to be L=2plusmn0.5 s (for micro arousals), 4plusmn2.2 s (short arousals) and 6.5plusmn3.6 s (long arousals)

[1]  J. C. Woestenburg,et al.  The removal of the eye-movement artifact from the EEG by regression analysis in the frequency domain , 1983, Biological Psychology.

[2]  M. J. Nichols,et al.  The assessment of two methods for removing eye movement artefact from the EEG. , 1985, Electroencephalography and clinical neurophysiology.

[3]  F Denoth,et al.  Changes in the interhemispheric correlation during sleep in normal subjects. , 1986, Electroencephalography and clinical neurophysiology.

[4]  C. Guilleminault,et al.  EEG arousals: scoring rules and examples: a preliminary report from the Sleep Disorders Atlas Task Force of the American Sleep Disorders Association. , 1992, Sleep.

[5]  C Guilleminault,et al.  EEG frequency changes during sleep apneas. , 1996, Sleep.

[6]  K. Bloch,et al.  Polysomnography: a systematic review. , 1997, Technology and health care : official journal of the European Society for Engineering and Medicine.

[7]  Peter Achermann,et al.  Frequency and state specific hemispheric asymmetries in the human sleep EEG , 1999, Neuroscience Letters.

[8]  I. Fietze,et al.  Electroencephalographic spectral analysis: detection of cortical activity changes in sleep apnoea patients , 2002, European Respiratory Journal.

[9]  Craig Hukins,et al.  Higher-order spectra for the estimation of total-airway-response (TAR) in snore-based diagnosis of apnoea , 2004, ICARCV 2004 8th Control, Automation, Robotics and Vision Conference, 2004..

[10]  V. Swarnkar,et al.  Statistical analysis of EEG arousals in sleep apnea syndrome , 2006 .