Proceedings of The Physiological Society

Ageing and Degeneration (Edinburgh, UK) (2015) Proc Physiol Soc 33, PC26

Poster Communications

The effects of age and physical fitness on an fMRI study of selective attention in older adults

J. F. Betts1, A. Dennis1, C. Sexton1, N. Rawlings1, H. Dawes2, K. Nobre3, H. Johansen-Berg1

1. Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom. 2. Oxford Brookes University, Oxford, United Kingdom. 3. Department of Psychiatry, University of Oxford, Oxford, United Kingdom.

  • Figure 1. Positive association of VO2 max with BOLD response in the irrelevant>relevant face condition. MNI coordinates of cluster max: x=24, y=60, z=30; right frontal pole. P<0.05.

IntroductionSelective attention plays an important role in working memory (WM) performance. Top-down modulation is required to both enhance neural activity associated with relevant information and suppress that associated with irrelevant information, allowing an individual to restrict attention to relevant inputs and focus memory capacity appropriately. The prefrontal cortex (PFC) may play a key role, adjusting the strength of functional coupling between brain regions in accordance with stimulus relevance1. Age-related impairments in WM are thought to be associated with increased sensitivity to interference from distracting information and reduced ability to selectively attend to relevant information2.Physical fitness may be associated with the maintenance of cognitive function in older adults. Aerobic fitness training has been shown to improve performance in measures of selective attention3 and greater physical fitness has been hypothesised to increase top-down modulation during task execution4.Here, we use fMRI to investigate the effects of age and cardiovascular (CV) fitness on the BOLD response to relevant and irrelevant face stimuli during a selective attention task. We hypothesise that individuals with lower age or greater CV fitness may show evidence of greater top-down modulation than those of higher age or lower fitness.Methods45 adults aged 60+ (66.80±5.76 yrs, 31 female) underwent BOLD fMRI while performing a selective attention task. Blocks of face and house stimuli were presented in a random order, with repeats of some stimuli. In each block, either faces or houses were designated as ‘relevant' and the other ‘irrelevant'. Participants were asked to judge whether the relevant stimuli were novel or repeated and to ignore irrelevant stimuli. CV fitness (VO2 max) was measured on a cycle ergometer. FEAT analysis5 was used to analyse the fMRI response in each stimulus condition.ResultsParticipants showed different activations when presented with face stimuli in irrelevant versus relevant conditions. We observed no effect of age. Preliminary analyses testing for a positive relationship between CV fitness and BOLD signal identified a positive association in the right frontal pole in the irrelevant>relevant condition (Fig1).ConclusionsWe have observed an effect of CV fitness on the BOLD response in a selective attention task in older adults. Higher fit individuals show signs of greater PFC demand in irrelevant conditions, possibly reflecting greater suppression of distracting information. Our results support the hypothesis that physical fitness may have an effect on top-down modulation in this population, though further work is required to explore this possibility.

Where applicable, experiments conform with Society ethical requirements