0038 Acute Blue Light Exposure Increases Activation in the Pulvinar Nucleus

Abstract Introduction Blue-wavelength light can produce phase-shifts in the circadian rhythm. We have previously shown that morning blue exposure was associated with advanced onset of sleep time and diminished daytime sleepiness. These changes were increased gray matter volume left pulvinar nucleus thalamus, a key hub visual attention network. However, very little is known about underlying mechanisms these activations. hypothesized may be affected more by acute activating effects rather than its on melatonin. Therefore, we exposed individuals to or amber while undergoing functional neuroimaging at day when melatonin levels are almost non-existent. Methods Twenty-six healthy (15 male; 11 female; age=24.27, SD=6.27) completed counterbalanced cross-over study involving two 3T MRI sessions separated one week. During scanning, participants acutely either continuous (470 nm; active condition) (580 placebo) completing an N-Back working memory task. contrasted 2-back versus 0-back condition compared using paired t-test SPM12. Results Acute (versus during task significantly greater activation (p<.05) within (k=47 voxels; MNI: x=-14, y=-34, z=8), region nearly identical found our previous work where six-weeks daily exposure. Salivary unchanged condition. Conclusion blue-wavelength placebo light) activated network demonstrated enlarged 6-weeks As remained this study, findings point neural mechanism lead specifically pulvinar, which over enhance structure. suggest concordance structural induced exposure, been shifts rhythms. Support (If Any)