title: Characteristic changes in brain electrical activity due to chronic hypoxia in patients with obstructive sleep apnea syndrome (OSAS): a combined EEG study using LORETA and omega complexity.
abstract: EEG background activity of patients with obstructive sleep apnea syndrome (OSAS, N = 25) was compared to that of normal controls (N = 14) to reflect alterations of brain electrical activity caused by chronic intermittent hypoxia in OSAS. Global and regional (left vs. right, anterior vs. posterior) measures of spatial complexity (Omega) were used to characterize the degree of spatial synchrony of EEG. Low resolution electromagnetic tomography (LORETA) was used to localize generators of EEG activity in separate frequency bands. Comparing patients to controls, lower Omega complexity was found globally and in the right hemisphere. Using LORETA, an increased medium frequency activity was seen bilaterally in the precuneus, paracentral and posterior cingulate cortex. These findings indicate that alterations caused by chronic hypoxia in brain electrical activity in regions associated with influencing emotional regulation, long-term memory and the default mode network. Global synchronization (lower Omega complexity) may indicate a significantly reduced number of relatively independent, parallel neural processes due to chronic global hypoxic state in apneic patients as well as over the right hemisphere.
authors.affiliation: Department of Neurology, Medical Center, University of Pécs, Pécs, Rét utca 2, Hungary. toth_martin@yahoo.com
authors.forename: Marton
authors.initials: M
authors.lastname: Toth
authors.forename: Bela
authors.initials: B
authors.lastname: Faludi
authors.forename: Jiri
authors.initials: J
authors.lastname: Wackermann
authors.forename: Jozsef
authors.initials: J
authors.lastname: Czopf
authors.forename: Istvan
authors.initials: I
authors.lastname: Kondakor
mesh_terms: D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002908:Chronic Disease; D004569:Electroencephalography; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014851:Wakefulness