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Gemma Learmonth, Monika Harvey; Age-related changes in the hemispheric lateralisation of pre-stimulus alpha.. Journal of Vision 2016;16(12):1270. doi: 10.1167/16.12.1270.
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© ARVO (1962-2015); The Authors (2016-present)
The covert direction of attention towards one side of space is typically accompanied by a reduction of inhibitory alpha band (8-13Hz) activity within the contralateral visual cortex (Rihs et al., 2007; 2009; Thut et al., 2006). Indeed, larger alpha modulations are correlated with improved accuracy and reaction times during cued detection/discrimination tasks (Thut et al., 2006). Although older adults show a preserved ability to direct their endogenous attention, the dynamic neural modulation of contralateral alpha observed in young adults is diminished in this group (Hong et al., 2015). Here we aimed to investigate whether pre-stimulus alpha asymmetry between the left vs right visual cortex is present in an uncued spatial attention paradigm, and secondly whether this pattern of hemispheric lateralisation changes as a consequence of healthy aging. We presented 20 young (age 18-25) and 20 older (age 60-80) adults with a lateralised visual detection task during EEG recording. Temporal spectral evolution (TSE) was used to quantify alpha amplitude in the left (P3/P7/O1) vs right (P4/P8/O2) posterior regions of interest (ROI) within a 1000ms pre-stimulus window. Overall, young adults exhibited a larger pre-stimulus alpha amplitude compared to older adults. There was an interaction between age and ROI, with young adults displaying a larger alpha asymmetry towards the right vs left ROI and, conversely, older adults in the left vs right ROI. We are currently working towards analysing this data on a single trial basis to investigate whether these age-related differences are predictive of our behavioural measures. We conclude that there are specific changes in the hemispheric lateralisation of alpha band activity during the healthy aging process, and that these changes are observable in tasks which do not require an endogenous allocation of attention.
Meeting abstract presented at VSS 2016
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