Response inhibition : neural correlates and the impact of ageing

The ability to stop a movement based on changing environmental stimuli is a crucial skill for functioning in the world. Two mechanisms are thought to be involved in stopping; top-down or proactive expectation of stopping, and bottom-up or reactive stopping to stimuli. A group of younger (n = 27) and older adults (n = 12) participated in a Stop-Signal Task to measure stopping ability while functional Near Infrared Spectroscopy (fNIRs) recorded haemodynamic changes in regions of interest of the Pre-Frontal Cortex (PFC). It was hypothesised that neural activity in dorsolateral PFC (DLPFC) would correlate with proactive stopping behaviour, and this was supported by the data. It was also hypothesised that the right inferior frontal cortex (IFC) and supplementary motor area (SMA) would correlate with stopping behaviour, but this was not shown in the data. Older people used more proactive slowing to maintain stopping ability comparable to younger adults. Older adults also exhibited bilateral hyperactivity in the DLPFC during stopping compared to younger adults. Together, these findings demonstrate that older adults engage different stopping strategies to younger adults. This work has implications for older adults in understanding falls and injuries, and demonstrates fNIRs can measure neural correlates of response inhibition.