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We conducted functional magnetic resonance imaging fMRI with a visual search paradigm to test the hypothesis that aging is associated with increased frontoparietal involvement in both target detection and bottom-up attentional guidance featural salience.
Participants were 68 healthy adults, distributed continuously across years of age. The search target was defined by a conjunction of color and orientation. Each display contained one item that was larger than the others i. Analyses of search reaction time RT indicated that bottom-up attentional guidance from the size singleton when coincident with the target was relatively constant as a function of age.
Frontoparietal fMRI activation related to target detection was constant as a function of age, as was the reduction in activation associated with salient targets. However, for individuals 35 years of age and older, engagement of the left frontal eye field FEF in bottom-up guidance was more prominent than for younger individuals.
Further, the age-related differences in left FEF activation were a consequence of decreasing resting-state functional connectivity in visual sensory regions. These findings indicate that age-related compensatory effects may be expressed in the relation between activation and behavior, rather than in the magnitude of activation, and that relevant changes in the activation-RT relation may begin at a relatively early point in adulthood. Current theories of visual attention characterize target identification in terms of the comparison between a template of the target-defining features e.
Target selection is the result of combined influences of activated features, top-down goals, bottom-up visual salience, the selection history of recent trials, and noise Awh, et al. Visual salience has a pronounced influence on performance Theeuwes and Burger, ; Treue, , but under some conditions a salient display item e. Functional magnetic resonance imaging fMRI and related techniques have revealed some of the neural mechanisms of visual attention Kastner, ; Miller and Buschman, ; Noudoost, et al.