Abstract
It has been shown that exposure to blue light affects our executive functions, alertness, and circadian rhythm. Recent studies also showed that brain regions related to eye movements such as frontal eye field (Hung et al., 2017) were activated by intrinsically photosensitive retinal ganglion cells (ipRGCs), which contain photoreceptors that are especially sensitive to blue light. We used the saccadic and manual gap paradigm to investigate whether blue light affects the gap effect, a facilitated saccadic or manual response to a peripherally presented target by extinguishing the fixation shortly before the target onset. Participants were exposed to blue and orange light in two consecutive days, and they were instructed to respond to peripherally presented targets in one of four directions (left, right, up, and down) either through saccade or manual response as quickly and accurately as possible. Robust gap effects were found in both saccadic and manual response under both light exposures, and downward direction led to the slowest response. In addition, the saccade latency was significantly shorter under blue light compared to orange light; however, the manual response times were not different between the two light conditions. A significant interaction between gap/overlap condition and colors of light was found in saccade latency: saccade latency in the overlap condition under orange light was significantly longer than the one under blue light. This indicated that the larger gap effect under orange light was mainly driven by the delay in the overlap condition. Among the three explanations of the gap effect (general warning, attentional disengagement, and oculomotor systems), attentional release and oculomotor response were affected under blue light, which resulted in a smaller saccadic gap effect. This study has bridged up the connection between neuroimaging and behavioral studies, showing how blue light affects our attention and eye movements.
Acknowledgement: Taiwan’s Ministry of Science and Technology, MOST 104-2410-H-002 -061 -MY3