Balda Aizpurua, J. F. | Search bioRxiv

bioRxiv2023

Light modulates task-dependent thalamo-cortical connectivity during an auditory attentional task

Exposure to blue wavelength light stimulates alertness and performance by modulating a widespread set of task-dependent cortical and subcortical areas. How light affects the crosstalk between brain areas to trigger this stimulating effect is not established. We recorded the brain activity of 19 healthy young participants (24.05{+/-}2.63; 12 women) while they completed an auditory attentional task in darkness or under an active (blue-enriched) or a control (orange) light, in an ultra-high-field 7 Tesla MRI scanner. We tested if light modulated the effective connectivity between an area of the posterior associative thalamus, encompassing the pulvinar, and the intraparietal sulcus (IPS), key areas in the regulation of attention. We found that only the blue-enriched light strengthened the connection from the posterior thalamus to the IPS. Our results provide the first empirical data supporting that blue wavelength light affects ongoing non-visual cognitive activity by modulating task-dependent information flow from subcortical to cortical areas.

neuroscience↗

bioRxiv2023

Impact of light on task-evoked pupil responses during cognitive tasks.

Light has many non-image-forming functions including modulation of pupil size and stimulation of alertness and cognition. Part of these non-image-forming effects may be mediated by the brainstem locus coeruleus. The processing of sensory inputs can be associated with a transient pupil dilation that is likely driven in part by the phasic activity of the locus coeruleus. Here, we aimed to characterise the task-evoked pupil response associated with auditory inputs under different light levels and across two cognitive tasks. We continuously monitored the pupil of 20 young healthy participants (24.05y {+/-}4.0; 14 women) while they completed an attentional and an emotional auditory task whilst exposed to repeated 30-to-40s-blocks of light interleaved with darkness periods. Blocks could either consist of monochromatic orange light [0.16 melanopic Equivalent Daylight Illuminance (EDI) lux] or blue-enriched white light of three different levels [37, 92, 190 melanopic EDI lux; 6500K]. For the analysis 15 and then 14 participants were included in the attentional and emotional tasks respectively. Generalized Linear Mixed Models showed a significant main effect of light level on the task-evoked pupil responses triggered by the attentional and emotional tasks (p[≤].0001). The impact of light was different for the target vs. non-target stimulus of the attentional task but was not different for the emotional and neutral stimulus of the emotional task. Despite a smaller sustained pupil size during brighter light blocks, a higher light level triggers a stronger task-evoked pupil response to auditory stimulation, presumably through the recruitment of the locus coeruleus.

neuroscience↗