Influence of moving sight by turning over frequency

In late years, f-MRI (functional Magnetic Resonance Imaging) are used for analysis of a visual function. In case of the study for a visual function, the checker flag pattern consists of white square and black square is usually used for sight stimulation. In sight stimulation using this pattern, a color of square (black and white) changes alternately at constant frequency. It is usually called pattern reversal stimulation. When this pattern is used for stimulation, the subject sometimes feels movement for the shown stimulation pattern. We think that this sensation of movement relates to spatial frequency (that means the size of a square of a stimulation pattern) of a stimulation image and a turning over frequency of a stimulation pattern strongly. Our objectives of this study are the following. 1) Clarify a part of the brain that is a cause of this moving sensation. 2) Investigate the relationship among the magnitude ofthis sensation, spatial frequency and turning over frequency. Three normal adults were used for the subject. This time, turning over frequency was changed from 0Hz to 8 Hz by 1Hz step under fixed spatial frequency. Under this condition, we examined the state of activation of a V1 area. In addition, we examined whether BOLD effect varied with a change of a stimulation color. In this experiment, we used blue and yellow color instead of black and white for stimulation, and the reaction was examined. Key word—fMRI visual cortex color V1 field MT field