title: Photic memory for executive brain responses.
abstract: Light is a powerful stimulant for human alertness and cognition, presumably acting through a photoreception system that heavily relies on the photopigment melanopsin. In humans, evidence for melanopsin involvement in light-driven cognitive stimulation remains indirect, due to the difficulty to selectively isolate its contribution. Therefore, a role for melanopsin in human cognitive regulation remains to be established. Here, sixteen participants underwent consecutive and identical functional MRI recordings, during which they performed a simple auditory detection task and a more difficult auditory working memory task, while continuously exposed to the same test light (515 nm). We show that the impact of test light on executive brain responses depends on the wavelength of the light to which individuals were exposed prior to each recording. Test-light impact on executive responses in widespread prefrontal areas and in the pulvinar increased when the participants had been exposed to longer (589 nm), but not shorter (461 nm), wavelength light, more than 1 h before. This wavelength-dependent impact of prior light exposure is consistent with recent theories of the light-driven melanopsin dual states. Our results emphasize the critical role of light for cognitive brain responses and are, to date, the strongest evidence in favor of a cognitive role for melanopsin, which may confer a form of "photic memory" to human cognitive brain function.
authors.affiliation: Cyclotron Research Center, University of Liège, 4000 Liège, Belgium.
authors.forename: Sarah Laxhmi
authors.initials: SL
authors.lastname: Chellappa
authors.forename: Julien Q M
authors.initials: JQ
authors.lastname: Ly
authors.forename: Christelle
authors.initials: C
authors.lastname: Meyer
authors.forename: Evelyne
authors.initials: E
authors.lastname: Balteau
authors.forename: Christian
authors.initials: C
authors.lastname: Degueldre
authors.forename: André
authors.initials: A
authors.lastname: Luxen
authors.forename: Christophe
authors.initials: C
authors.lastname: Phillips
authors.forename: Howard M
authors.initials: HM
authors.lastname: Cooper
authors.forename: Gilles
authors.initials: G
authors.lastname: Vandewalle
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology* / Q000528:radiation effects; D056344:Executive Function / Q000502:physiology* / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008568:Memory / Q000502:physiology* / Q000528:radiation effects*; D055815:Young Adult
keywords: fMRI; non–image-forming