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
- 221 Downloads
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.
KeywordsLORETA Obstructive sleep apnea syndrome Omega complexity Quantitative EEG Posterior cingulate cortex Precuneus Posterior parietal cortex
This work was supported by grant from the Hungarian Science Found (OTKA T048338). The authors thank Dr. Pascual-Marqui at the KEY Institute for Brain-Mind Research, Zurich, Switzerland for making available the LORETA-Key software and his help in the use of this program.
- Broyd SJ, Demanuele C, Debener S, Helps SK, James CJ, Sonuga-Barke EJS (2008) Default-mode brain dysfunction in mental disorders: a systematic review. Neurosci Biobehav Rev. Epub ahead print. doi: 10.1016/j.neubiorev.2008.09.002
- Chesson AL Jr, Berry RB, Pack A (2003) Practice parameters for the use of portable monitoring devices in the investigation of suspected obstructive sleep apnea in adults. A joint project sponsored by the American Academy of Sleep Medicine, the American Thoracic Society, and the American College of Chest Physicians. Sleep 26(7):907–913PubMedGoogle Scholar
- Pascual-Marqui RD (1999) A review of methods for solving the EEG inverse problem. Int J Bioelectromagnet 1:75–86Google Scholar
- Smejkal V, Druga R, Tintera J (1999) Control of breathing and brain activation in human subjects seen by functional magnetic resonance imaging. Physiol Res 1999(48):21–25Google Scholar
- Talairach J, Tournoux P (1988) Co-planar stereotaxic atlas of the human brain. Thieme, StuttgartGoogle Scholar
- Wackermann J (1996) Beyond mapping: estimating complexity of multichannel EEG recordings. Acta Neurobiol Exp 56:197–208Google Scholar