Zhunussova, A. | bioRxiv Science

bioRxiv2025

Pupil dilation as a marker of attention/effort in aging and mild cognitive impairment

Pupil dilation (PD) can be easily measured and reflects responses to subjectively salient or cognitively demanding events. It therefore holds promise as a cognitive marker especially for individuals with mild cognitive impairment (MCI) or other neurodegenerative conditions with restricted abilities to respond in cognitive assessments. We assessed PD during two tasks, an oddball task for investigating attentional allocation and a Simon task which additionally allows for investigating cognitive effort in younger adults (YAs), older adults (OAs), and patients with MCI. PD is a useful marker for investigating attention and cognitive effort in MCI, as suggested by elevated PD to salient stimuli in particular of individuals with better attentional control in MCI patients, as well as YAs and OAs. Measurement of PD may serve as an easy-to-administer measure to assess changes in cognitive function in healthy aging and MCI.

neuroscience↗

bioRxiv2024

Electrophysiological correlates of cognitive reserve in healthy older adults at different cognitive states

High cognitive reserve (CR) is associated with a set of lifestyle factors such as high education level and occupational attainment. Studies suggest that CR is linked to enhanced executive control functions. Nevertheless, it is unclear what are the functional neural activity patterns linked to high CR and to what extent they are steady across different cognitive states. The aim of the present study was to investigate electrophysiological differences between low CR (LCR) and high CR (HCR) at rest and during the performance of two cognitive control tasks with different difficulty level. Thus, 67 older adults performed an experimental session consisting of two spatial stimulus-response compatibility (SRC) tasks (i.e., the Simon task, and the more demanding spatial Stroop task), and a resting state during an electroencephalogram (EEG) recording. Cognitive control was better in HCR than LCR group, as revealed by higher accuracy in HCR compared to LCR group in incongruent conditions of the tasks. Moreover, event-related brain potentials (ERP) showed earlier latencies (P300) in HCR than LCR and time/frequency analysis showed higher alpha activity in HCR than LCR during the performance of the tasks, while no differences were observed at rest within any of the analyzed frequency bands. Higher P300 frontalization was observed in LCR than HCR in the more difficult task but it was not related to frontalization within a specific frequency band. Overall, results showed that electrophysiological differences between high and low CR depend on the cognitive state, with greater CR-related differences emerging at increased task demands.

neuroscience↗