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Carmel Mevorach, Brandon Ashinoff, Stephen Mayhew; Age-mediated parietal contribution to salience suppresion. Journal of Vision 2018;18(10):980. doi: 10.1167/18.10.980.
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© ARVO (1962-2015); The Authors (2016-present)
Cognitive aging has been associated with a decline in inhibitory processes. Older participants seem to be less capable at inhibiting distractors, especially when they are more salient than targets. While various neuronal changes have also been documented as a function of age the underlying brain mechanisms that mediate this behavioural change are still poorly understood. Interestingly, there is a striking similarity between old participants' performance in a salience-suppression task (Tsvetanov et al., 2013) and the effect of inhibitory brain stimulation over the left IPS in young participants performing the same task (Mevorach et al., 2009). Furthermore, the left IPS contribution in young participants appears to be proactive - in anticipation of the impending stimuli. Proactive control is thought to be specifically impaired in old age, where a shift toward reactive control (a late-correction mechanism) has been observed (Braver, 2012). To assess whether brain activation patterns in old age fit with this idea of shift from proactive to reactive control, we recorded brain activation using fMRI in two groups of old and young adult participants while they performed a salience-based suppression task. Specifically we ask whether activations in left IPS or left TPJ (previously linked to reactive control in young adults) are mediated by age. Our results show a qualitative difference in brain activation in the two groups when salient distractors had to be ignored (which is apparent even when global differences in cerebral blood flow between the groups are controlled for). While both groups show left IPS activation, the older participants seem to rely on additional activation in the left TPJ (as well as left IFG). We argue that this left lateralized parietal activation is associated with a reactive inhibition network that is most likely engaged in old age to overcome an initial capture by the salient distractors.
Meeting abstract presented at VSS 2018
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