Ultra high-field MRI indications that exposure to blue enriched light increases attention brain responses during an oddball task

With the discovery of a new, non-rod, non-cone, photoreceptor, new research shows that natural and artificial light regimes have the potential to weaken and strengthen cognition, attention and perception. These effects are mediated in part by melanopsin-expressing light-sensitive ganglion cells that, in contrast to the classical photopic system that is maximally sensitive to green light (550 nm), is very sensitive to blue light (470--480 nm). These photoreceptors not only stimulate alertness, attention, vitality, and cognitive performance, but they also influence our biological clock, sleep, thermoregulation and hormonal processes.

Using high resolution ultra-high field (7T) functional magnetic resonance imaging (fMRI), we characterized the neural correlates of the alerting effect of light by assessing the reposes to an auditory oddball task. Twenty healthy young subjects (22.95y ± 2.1 women) were requested to detect rare (20%) deviant tones (100Hz) among more frequent (80%) standard (500 Hz) ones by pressing a button with their right index. In this task, participants were exposed to 30s blocks of blue enriched light (4,000K; 3 intensities: 63, 155, 308 melanopic EDI lux) and orange monochromatic light (589nm; .2 melanopic EDI lux) interleaved by ~15s dark periods.

Like many previous studies have reported, there have been activations of temporal, parietal, thalamus, intraparietal sulcus (IPS) and occipital lobes (uncorrected p<.001) during oddball task. There was increased activation in the left IPS and thalamus, under blue light in comparison to orange light (p=0.001 uncorrected). This is in line with other studies that report increased activation in cortical and subcortical regions related to attention as thalamus and IPS under blue light. These preliminary results will be confirmed in a larger sample.