Brain responses to sine wave modulated light (SML): reliability and relationship to spontaneous EEG

Brain activity elicited by sine wave modulated light and spontaneous EEGs were obtained from 11 healthy adult males on two separate occasions. Within-subject correlations (test-retest correlation coefficients) for SML responses were high, and comparable to reliability estimates of spontaneous EEG activity in this sample. Reliability of the spontaneous EEG was evaluated using two measures: absolute and relative power. Although their magnitudes were comparable, the test-retest correlation coefficients for the right occipital were consistently higher than those of the left using absolute measures; this pattern was not reflected by test-retest correlations based on relative EEG measures. Finally, the SML responses to 5, 15, 18 and 24 Hz stimulation frequency rates correlated most highly with absolute measures of spontaneous EEG beta, whereas the SML response to 10 Hz stimulation yielded the highest correlations with spontaneous alpha activity.