title: Shedding light on the effect of priority instructions during dual-task performance in younger and older adults: A fNIRS study.
abstract: Age-related differences in the ability to perform two tasks simultaneously (or dual-task) have become a major concern in aging neurosciences and have often been assessed with two distinct paradigms; the Psychological Refractory Period (PRP) and the Dual-Task (DT) paradigms. PRP studies assess participants when they give Priority to one task over the other (complete A then B), whereas in DT studies participants give Equal priority to both tasks (complete A and B). The Equal condition could be viewed as adding an executive control component to the task since the participants must spontaneously monitor attention between tasks. In the current study, we assessed the effect of priority instructions (Priority vs. Equal) on the dual-task performance and brain activity of younger (n = 16) and older adults (n = 19) with functional near infra-red spectroscopy (fNIRS). In younger adults, the Priority condition showed right-sided activation in the prefrontal cortex during DT execution. Older adults showed bilateral frontal activation, yet restrained to specific areas. They showed increased activation in DT vs. single task condition in the left dorsolateral prefrontal cortex (DLPFC) and the bilateral ventrolateral prefrontal cortex (VLPFC). In the Equal condition, the DT condition showed isolated left DLPFC and VLPFC activation in younger adults and widespread bilateral DLPFC activation in older adults. These results suggest that for both older and younger adults, priority effects are associated with distinct patterns of prefrontal activation. Age-related differences also exist in these patterns such that prefrontal activation seems to be more spread out at different sites in older adults when they are instructed to give Equal priority to both tasks.
authors.affiliation: Traumatic Brain Injury Program, McGill University Health Center - Montreal General Hospital, 1650 Cedar Ave, D19-115, Montréal, Québec, H3G 1A4, Canada; Département de Psychologie, Université du Québec à Montréal, C.P. 8888, succursale Centre-ville, Montréal, Québec, H3C 3P8, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Chemin Queen Mary, Montréal, Québec, H3W 1W4, Canada. Electronic address: maude.lague-beauvais@muhc.mcgill.ca.
authors.forename: Maude
authors.initials: M
authors.lastname: Laguë-Beauvais
authors.affiliation: Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Chemin Queen Mary, Montréal, Québec, H3W 1W4, Canada; McGill University & Institut Raymond Dewar, 3600 rue Berri, Montréal, Québec, H2L 4G9, Canada.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Fraser
authors.affiliation: Département de Psychologie, Université du Québec à Montréal, C.P. 8888, succursale Centre-ville, Montréal, Québec, H3C 3P8, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Chemin Queen Mary, Montréal, Québec, H3W 1W4, Canada.
authors.forename: Laurence
authors.initials: L
authors.lastname: Desjardins-Crépeau
authors.affiliation: Département de Psychologie, Université du Québec à Montréal, C.P. 8888, succursale Centre-ville, Montréal, Québec, H3C 3P8, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Chemin Queen Mary, Montréal, Québec, H3W 1W4, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Castonguay
authors.affiliation: Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Chemin Queen Mary, Montréal, Québec, H3W 1W4, Canada; École polytechnique de Montréal, 2900, Boulevard Édouard-Montpetit, Montréal, Québec, H3T 1J4, Canada.
authors.forename: Michèle
authors.initials: M
authors.lastname: Desjardins
authors.affiliation: École polytechnique de Montréal, 2900, Boulevard Édouard-Montpetit, Montréal, Québec, H3T 1J4, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lesage
authors.affiliation: Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Chemin Queen Mary, Montréal, Québec, H3W 1W4, Canada; Department of Psychology and PERFORM Centre, Concordia University, 7141 Sherbrooke St. W., PC 2.411, Montréal, Québec, H4B 1R6, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Bherer
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D055815:Young Adult
keywords: Aging; Dual-task; Executive functions; Neuroimaging; Prefrontal cortex; fNIRS