Abstract:
The properties of neural oscillations during the performance of a spatial recognition memory task were investigated in younger and older adults, with the aim of identifying any changes that may occur in people over the age of 65. Particularly, we focused our analyses on alpha and theta frequencies in order to contribute to the sparse literature, which primarily has researched age-related changes in working memory paradigms. Our spatial recognition memory task involved participants selecting between two object-location choices, one correct and the other incorrect, based on retrieval of previously learned object-location relationships. There was a visuospatial control task in order to isolate the mnemonic component during subsequent analysis. When compared with the younger group’s performance, older participants showed similar levels of accuracy but significantly slower reaction times. Mixed ANOVA revealed a significant interaction of age, brain region and hemisphere for theta band activity, primarily driven by age group differences in frontal regions. For alpha desynchronisation, the only significant difference appeared between parietal recording sites, independent of age. There were no significant group differences in alpha synchronisation amplitudes. We only found one age-related difference in oscillatory properties such as frequency and onset time; the average upper peak frequency for alpha desynchronisation. From visual inspection of topographic maps, age group differences in distribution of power over the scalp appeared to be larger than revealed by ANOVA alone. However, sLORETA found no significant differences between source distributions for any frequency band between age groups. To summarise, on a relatively simple spatial recognition task, minimal age-related differences in the properties of alpha and theta band oscillations emerged from our data. Contrary to predictions based on popular theoretical ageing constructs; there was no clear support for decreased inhibition, overactivation, bilaterality or supplementary recruitment of brain regions in our sample of older participants.