Exposure to different light wavelengths impacts cortical areas associated with oculomotor and attentional control.

Light stimulation has been used in research to treat health-related problems. However, the impact of different wavelengths in cortical areas related to vision remains unknown. In this study, we aim to investigate the effects of light exposure to three different monochromatic wavelengths on brain areas involved in vergence and oculomotor control. Participants underwent resting-state functional magnetic resonance imaging before and after one-minute exposure to monochromatic light, on three separate days for three different wavelengths corresponding to blue, green, and red light. Fractional amplitude of low-frequency fluctuations and regional homogeneity were used to investigate the changes in the regional intensity of spontaneous fluctuations after each passive light stimulation, for cortical regions involving vergence and eye movements, but also for the whole brain. We observed that green light exposure compared with the red and blue light increases the intensity on: i) the intersection of the intraparietal sulcus with the postcentral sulcus (bilaterally), and ii) the intersection of the left middle frontal gyrus with the precentral sulci, measured with fractional amplitude of low-frequency fluctuations and regional homogeneity. This study shows the potential impact of light exposure on brain areas involved in attentional control tasks such as oculomotor control, especially when comparing the effects of green and blue light. Future research can further explore the impact of light stimulation in cortical regions involving the visual and oculomotor systems.