ENERGY ERP ANALYSIS OF READING RELATED COGNITIVE FUNCTION

Richard W. Montgomery, Ph.D., *Leslie D. Montgomery, Ph.D., Raul Guisado, M.D., Alvirda Farmer, Ph.D.

ABSTRACT

Three stages of reading-related cognitive processing were analyzed in a cross-subject study of four dyslexic and four normal readers, using EEG based data. Conventional ERPs for a synonym-antonym discrimination task were mathematically converted to time integrals of scalp electrical energy density. Comparing the quantitative values of these integrals for selected cortical regions during specific periods of the ERP permitted dynamic localization of task-related cognitive processing. Comparisons with subjects' task performance scores permitted evaluation of the role of successive phases of cognitive processing in determining performance. It was found that the four dyslexics were distinguished by a very low level of activation in the left occipital cortex during the first 180 msec of the task but that some dyslexic subjects compensated through a high degree of interhemispheric interaction during the period 200-500 msec. The method of this study demonstrates the possibility of clinically classifying individuals along a quantitative continuum instead of merely in terms of dyslexic/non-dyslexic. It also demonstrates a procedure which may be used to investigate disorders of other cortical functions.

Keywords: EEG, ERP.