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EEG Coherence in Pathological Conditions

Leocani, Letizia; Comi, Giancarlo

Journal of Clinical Neurophysiology: November 1999 - Volume 16 - Issue 6 - p 548
Review Article

Summary Coherence analysis of the electroencephalogram is considered an indicator of functional cortico-cortical connections, which makes it suitable for the neurophysiologic investigation of brain connectivity in normal and pathological conditions. In the clinical environment, coherence analysis has been applied in the study of brain development and in the assessment of diseases potentially involving brain connectivity, such as cortical and subcortical dementia, schizophrenia, and corpus callosum lesions. Whereas coherence decrease, at least for the high-frequency bands, is considered the expression of decreased functional cortico-cortical connections, more work needs to be performed in interpreting coherence increases. A special consideration is also required by technical aspects, such as the recording conditions and the reference used, which may greatly influence the results and need to be accounted for when drawing physiopathological interpretations. At present, whereas coherence analysis resulted successful in differentiating patients groups from the normal population, the specificity of coherence changes in various pathological conditions is questionable at the best. The same limits apply to the diagnostic value of the technique in individual patients.

Department of Clinical Neurophysiology, University of Milan, Scientific Institute Hospital San Raffaele, Milan, Italy

Address correspondence and reprint requests to Prof. Giancarlo Comi, Department of Clinical Neurophysiology, Scientific Institute H. San Raffaele, via Olgettina 60, 20132 Milan, Italy.

This work was partly supported by a grant from the Istituto Superiore di Sanità (National Ministry of Health, Rome, Italy; protocol number 96/J/T44).

Copyright © 1999 American Clinical Neurophysiology Society