title: Distinguishing attentional gain and tuning in young and older adults.
abstract: Here we examined with functional magnetic resonance imaging (fMRI) whether advanced age affects 2 mechanisms of attention that are widely thought to enhance signal processing in the sensory neocortex: gain and tuning. Healthy young and older adults discriminated faces under varying levels of object competition while fMRI was acquired. In young adults, cortical response magnitude to attended faces was maintained despite increasing competition, consistent with gain. Cortical response selectivity, indexed from repetition suppression, also increased only for attended faces despite increasing competition, consistent with tuning. Older adults exhibited intact gain, but altered tuning, with extrastriate cortical tuning determined by object salience rather than attention. Moreover, the magnitude of this susceptibility to stimulus-driven processing was associated with a redistribution of attention-driven competitive processes to the frontal cortices. These data indicate that although both gain and tuning are modulated by increased perceptual competition, they are functionally dissociable in the extrastriate cortices, exhibit differential susceptibility to advanced aging, and spare the frontal cortices a considerable processing burden through early selection.
authors.affiliation: Department of Psychology, University of Toronto, Toronto, Ontario, Canada; Collaborative Program in Neuroscience, University of Toronto, Toronto, Ontario, Canada. Electronic address: taylor.schmitz@mrc-cbu.cam.ac.uk.
authors.forename: Taylor W
authors.initials: TW
authors.lastname: Schmitz
authors.affiliation: Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Dixon
authors.affiliation: Department of Psychology, University of Toronto, Toronto, Ontario, Canada; Collaborative Program in Neuroscience, University of Toronto, Toronto, Ontario, Canada; Rotman Research Institute of Baycrest Centre, Toronto, Ontario, Canada.
authors.forename: Adam K
authors.initials: AK
authors.lastname: Anderson
authors.affiliation: Department of Psychology, University of Toronto, Toronto, Ontario, Canada; Collaborative Program in Neuroscience, University of Toronto, Toronto, Ontario, Canada; Rotman Research Institute of Baycrest Centre, Toronto, Ontario, Canada. Electronic address: eve.derosa@cornell.edu.
authors.forename: Eve
authors.initials: E
authors.lastname: De Rosa
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology / Q000502:physiology* / Q000523:psychology*; D001288:Attention / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008606:Mental Processes / Q000502:physiology; D019579:Neocortex / Q000473:pathology* / Q000502:physiology*; D010465:Perception / Q000502:physiology; D055815:Young Adult
keywords: Aging; Attentional gain; Attentional tuning; Functional magnetic resonance imaging; Object-selective attention; Perception