Flicker-evoked responses of human optic nerve head blood flow: luminance versus chromatic modulation.

摘要: PURPOSE: To determine the response of human optic nerve head blood flow (R:F(onh)) to heterochromatic equiluminant flicker modulation and compare it induced by pure luminance flicker. METHODS: In five normal volunteers, F(onh) measured at neuroretinal rim was monitored continuously laser Doppler flowmetry. Stimuli were generated green red light emitting diodes delivered fundus in Maxwellian view (field 25(o)). Both (G:) (R:) illuminances square-wave modulated, 180(o) out phase, with a maximum value 10.4 for G: 2.64 lux R: Flicker frequency varied from 2 Hz 40 Hz. R:F(onh) defined as change during stimulation relative prestimulus F(onh). RESULTS: Defining color ratio r R:/(R: + G:), R:F(onh), 15-Hz flicker, largest (r = 0 1), declined mixed chromatic modulations, reached secondary 0.45, psychophysical equiluminance. versus displayed characteristics low-pass function equiluminance stimulus band-pass function, intermediate frequencies, stimulus. CONCLUSIONS: humans can be evoked modulated either or conditions. may specific similar neural responses dominated magno- parvocellular activity, respectively. These findings offer new approach study neurovascular coupling both physiological diseased conditions involving predominantly selectively pathways.