Functional Magnetic Resonance Imaging Activation Of Brain Areas For Simple Flicker Stimulation

Abstract

Abstract: : Purpose: We sometimes use special perimetry techniques to detect glaucoma and other conditions. One technique is frequency doubling technology perimetry and another is flicker perimetry. These techniques are believed to activate the magnocellular pathway, although direct evidence of activation in humans is lacking. We recently reported functional magnetic resonance imaging activation for frequency doubling technology in human MT+. In this study, we investigated cerebral areas that are assciated with viewing a simple flickering disk, similar to the stimuli used for flicker perimetry. Methods: Four healthy volunteers viewed the visual stimuli consisting of a small disc and a fixation cross(Figure). A 17–Hz flickering disc and a static disc were each presented for 10 seconds. A fixation cross was presented as a control for 20 seconds between presentation of the two stimuli. The luminance of the static disc was adjusted to equal to that of the flickering disc. Subjects were required to execute passive viewing. Results: MT+ and other activations were observed in each subject. Conclusions: Both the frequency doubling illusion and simple flicker stimuli activate the magnocellular pathway in humans.  

Keywords: motion–D • neuro–ophthalmology: cortical function/rehabilitation • perimetry