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Philip Ko, Bryant Duda, Erin Hussey, Emily Mason, Geoffrey Woodman, Brandon Ally; The neural correlates of visual working memory decline in normal aging.. Journal of Vision 2012;12(9):175. doi: https://doi.org/10.1167/12.9.175.
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Visual working memory (VWM) allows for the temporary retention of information and is critical for normal daily functioning. Older adults show lower VWM capacity compared to younger adults (Brockmole et al., 2008), which could significantly impact their performance in common but potentially dangerous contexts such as driving (Rizzo et al., 2009). To better understand the neural underpinnings of the age-related decline in VWM, we examined the electrophysiological index of VWM maintenance in healthy older and younger adults. Specifically, the contralateral delay activity (or CDA) of an observer’s event-related potentials (ERPs) provides a measure of what is actively maintained in VWM and predicts that individual’s VWM capacity (Vogel & Machizawa, 2004). In the current study, younger (mean age = 22.9 years) and older adults (mean age = 68.2 years) viewed a bilateral visual display and were cued to remember a variable number of colored objects in one hemifield. Both younger and older adults showed a significant CDA in posterior regions, but the CDA of older adults was significantly reduced in amplitude. Despite this electrophysiological effect, there were no statistical differences across groups in the behavioral estimates of VWM capacity. Our electrooculogram recordings showed that this dissociation was due to the older adults using overt selection to aid maintenance of the information in VWM. That is, older adults made more deviant eye movements towards the target hemifield during encoding and well into the maintenance period. The failure of older adults to inhibit eye movements (Wilson et al., VSS 2011) suggests that they utilize overt spatial attention to compensate for loss in the ability to covertly maintain representations in VWM compared to younger adults.
Meeting abstract presented at VSS 2012
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