Volume 14, Issue 20, Pages 1842-1846 (October 2004) Nonvisual Responses to Light Exposure in the Human Brain during the Circadian Night  Fabien Perrin, Philippe Peigneux, Sonia Fuchs, Stéphane Verhaeghe, Steven Laureys, Benita Middleton, Christian Degueldre, Guy Del Fiore, Gilles Vandewalle, Evelyne Balteau, Robert Poirrier, Vincent Moreau, André Luxen, Pierre Maquet, Derk-Jan Dijk  Current Biology  Volume 14, Issue 20, Pages 1842-1846 (October 2004) DOI: 10.1016/j.cub.2004.09.082

Figure 1 Experimental Design, Neuroendocrine Results, and Behavioral Results (A) Top panel: the three blocks of four scans with their respective light exposure. (B) Middle: plasma melatonin samples were obtained after exposure to darkness (four samples) or light (three samples) and were expressed relative to the last sample obtained before scanning (they were analyzed using radioimmunoassay [Stockgrand Ltd, UK]). Melatonin levels decreased during light exposure and increased during darkness (F[1] = 11.83, p = 0.0055). (C) Bottom: alertness of the subjects as assessed by the Karolinska Sleepiness Scale, every 20 min, expressed as changes from the average score of the baseline period (arbitrary units). The alertness decreases along the night (F[2] = 15.35, p = 0.00005). This decrease is significantly attenuated by light exposure (F[3] = 5.36, p = 0.0037). Current Biology 2004 14, 1842-1846DOI: (10.1016/j.cub.2004.09.082)

Figure 2 Cortical Areas where the rCBF Is Significantly Increased in Proportion to the Duration of the Previous Exposure to Light Left panels: functional data displayed at p < 0.05 (voxel level), superimposed on the mean normalized MR scan. The relevant coordinates are in mm within the stereotactic space. Right panels: plots of the adjusted rCBF at the coordinates displayed in Table 1 (error bars = SEM) for the four scans of the blocks. For display, the adjusted rCBF were normalized to the maximum rCBF. (A) The right intraparietal sulcus (IPS, frontal and transverse views). The activated area lies in the depth of the anterior part of the IPS. (B) The striate cortex and extrastriate areas (sagittal and transverse views). (Ba) striate cortex; (Bb) left extrastriate cortex; (Bc) right extrastriate cortex. Current Biology 2004 14, 1842-1846DOI: (10.1016/j.cub.2004.09.082)

Figure 3 Suprachiasmatic Area where the rCBF Is Significantly Decreased in Proportion to the Duration of the Previous Exposure to Light Left panel: functional data displayed at p < 0.001 (uncorrected), superimposed on a parasagittal view of the mean normalized MR scan (x coordinate: 2 mm). Inset: blow up of the hypothalamic area. Right panel: adjusted rCBF (error bars = SEM) for the four scans of the blocks at 8 0 −10 mm. For display, the adjusted rCBF were normalized to the maximum rCBF. Current Biology 2004 14, 1842-1846DOI: (10.1016/j.cub.2004.09.082)