engleski

TRANSCRANIAL DOPPLER SONOGRAPHY DURING COLOR STIMULATION

OBJECTIVE: The objective of this study was to determine the changes in mean blood flow velocities (MBFV) using transcranial Doppler (TCD) in both posterior cerebral arteries (PCA) in healthy volunteers while they were watching colored light. BACKGROUND: It is well known that visual stimulation has influence on MBFV in posterior cerebral arteries. But, most often opening and closing of the eyes and stimulation with white light i were used as visual stimuli, while stimulation with colors was used very seldom. DESIGN/METHODS: Fifty one healthy, right-handed volunteers (27 males and 24 females) aged from 20 to 59 years (mean age 36, 98 years) were watching rectangular source of light with G colored filter for one minute while MBFV were measured in PCA using hand-held 2 MHz TCD probe. The filters (and color of light) were changed so every volunteer had measurement made while watching red, yellow, green and blue light. In half of volunteers measurements started on right-sided PCA, and continued on left-sided PCA, while in other half measurements started on left-sided PCA and continued on right-sided PCA. Results were compared using Wilcoxon Matched-pairs Signed-ranks Test. RESULTS: Results are presented as mean valueątwo standard deviations. MBFV mean values in left PCA during watching t red light were 31, 4ą7, 1 cm/s, during watching yellow light 31, 4ą7, 2 cm/s, during watching green light 32, 0ą8, 3 cm/s, and during watching blue light 33, 0ą7, 6 cm/s. There was no statistical signifficant difference between MBFV mean values in left PCA while volunteers were watching different colors. MBFV mean values in right PCA during watching red light were 39, 4ą8, 4 cm/s, during watching yellow light 38, 9ą9, 2 cm/s, during watching green light 37, 8ą9, 4 cm/s and during watching blue light 38, 0ą8, 8 cm/s. There was no statistical significant difference between MBF'V mean values in right PCA while volunteers were watching different colors. But, MBFV mean values were significantly higher in right PCA during watching every color (red, yellow, green and blue) than corresponding MBFV mean values in left PCA. CONCLUSIONS: Posterior cerebral arteries supply visual cortex in occipital lobes with arterial blood. Since it is well known that there is a coupling of brain metabolism and cerebral blood flow, our findings could indicate the greater metabolism of visual cortex in right occipital lobe during receiving and processing information about colors. Therefore, visual cortex of right occipital lobe could have greater importance in color perception than visual cortex of left occipital lobe. As many other higher cerebral functions (language, spatial orientation etc.) the perception of colors could be predominantly localized in one (in this case right) cerebral hemisphere.

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