Investigating The Effects of Ageing on Interhemispheric Communication Using Visual Short-Term Memory Binding

Psychological study into the functional significance of age-related neural structural changes has become increasingly important due to global population ageing. As the largest interhemispheric commissure, the fundamental role of the corpus callosum is to integrate hemispheric information. However, the effect of age-associated callosal degeneration on interhemispheric functioning remains unknown. The current study aimed to investigate the effect of age on interhemispheric communication using a novel visual short-term memory colour-colour binding task. Thirty younger (aged 18-30 years) and thirty older (aged 65-80 years) adults were tachistoscopically presented with two bi-coloured objects in different hemifield conditions; within-hemifield and across-hemifield. Subjects were then required to discern whether the test object corresponded with either of the two previously presented objects. Across 128 randomised trials, the percentage of correct binding responses was recorded across new association, new colour, and match conditions. The results revealed no statistically significant interaction between age and hemifield conditions was observed; however, older, and younger adults produced marginally superior across-hemifield performance. Moreover, regardless of hemifield display, younger adults performed significantly more accurately overall. Those findings suggest that the age-resistant occipital splenium tract may have provided a protective effect for the interhemispheric transfer of visual information, reducing age effects for binding accuracy. Older adults' cognition may be therefore improved by performing cognitive skills using visual modalities. Future research should investigate the factors underlying this protective effect to identify whether it could be transferred to other white matter tracts to moderate the effects of age-related cognitive decline.