The influence of brightness, colour and complexity on visual evoked doppler flow responses

Abstract The purpose of this study was to evaluate specific influence of colour, brightness and complexity on visual evoked flow responses (VEFRs). A total of 31 healthy subjects aged 35.1 ± 7.7 years participated in the study. Mean arterial velocity was measured in the right posterior cerebral artery (v pca ) and in the left middle cerebral artery (v mca ) by Multi-DopX4 (DWL). Simple-white (SW), red (R) and complex-checkerboard (C) stimuli were used. VEFRs were determined by the difference of the v pca :v mca ratio before and after stimulation. The VEFRs of SW with brightness of 21.4 cd/m 2 , 10.5 cd/m 2 and 2 cd/m 2 were 8.7 ± 3.4%, 9.1 ± 3.0% and 8.0 ± 3.7%, respectively ( p p p = 0.295) between VEFRs of SW of different brightness, but variances between VEFRs of SW, R and C stimuli were significant ( p p p = 0.008) as well as between VEFRs of C and of R stimuli (2.0 ± 2.5%, p = 0.010). We have concluded that SW, R and C stimuli have a specific influence on VEFRs. Brightness does not appear to affect VEFRs. (E-mail: marjan.zaletel@kclj.si)