Abstract
Task-switching (TS) paradigm is a well-known validated tool useful for exploring the neural substrates of cognitive control, in particular the activity of the lateral and medial prefrontal cortex. This work is aimed at investigating how physiological aging influences hemodynamic response during the execution of a color-shape TS paradigm. A multi-channel near infrared spectroscopy (fNIRS) was used to measure hemodynamic activity in 27 young (30.00 ± 7.90 years) and 11 elderly participants (57.18 ± 9.29 years) healthy volunteers (55% male, age range: (19–69) years) during the execution of a TS paradigm. Two holders were placed symmetrically over the left/right hemispheres to record cortical activity [oxy-(HbO) and deoxy-hemoglobin (HbR) concentration] of the dorso-lateral prefrontal cortex (DLPFC), the dorsal premotor cortex (PMC), and the dorso-medial part of the superior frontal gyrus (sFG). TS paradigm requires participants to repeat the same task over a variable number of trials, and then to switch to a different task during the trial sequence. A two-sample t-test was carried out to detect differences in cortical responses between groups. Multiple linear regression analysis was used to evaluate the impact of age on the prefrontal neural activity. Elderly participants were significantly slower than young participants in both color- (p < 0.01, t = −3.67) and shape-single tasks (p = 0.026, t = −2.54) as well as switching (p = 0.026, t = −2.41) and repetition trials (p = 0.012, t = −2.80). Differences in cortical activation between groups were revealed for HbO mean concentration of switching task in the PMC (p = 0.048, t = 2.94). In the whole group, significant increases of behavioral performance were detected in switching trials, which positively correlated with aging. Multivariate regression analysis revealed that the HbO mean concentration of switching task in the PMC (p = 0.01, β = −0.321) and of shape single-task in the sFG (p = 0.003, β = 0.342) were the best predictors of age effects. Our findings demonstrated that TS might be a reliable instrument to gather a measure of cognitive resources in older people. Moreover, the fNIRS-related brain activity extracted from frontoparietal cortex might become a useful indicator of aging effects.
Highlights
Task-switching paradigm is a well-known and validated tool for exploring executive control processes and neural correlates of cognitive cost and it is often used to assess age-related executive deficits (Wilckens et al, 2017)
We investigated the hemodynamic response in the frontoparietal areas during the execution of a task-switching paradigm by means of functional near-infrared spectroscopy (fNIRS) on a population of healthy participants, and we characterized the selective influence of physiological aging on brain hemodynamic response by using multiple linear regression
An independent two sample t-test revealed significantly longer reaction time (RT) for elderly compared to young participants in both color- (p < 0.01, t = −3.67; Cohen’s d = −1.21, effect size = 0.52) and shape-single tasks (p = 0.026, t = −2.54; Cohen’s d = −0.84, effect size = 0.39) as well as switching (p = 0.026, t = −2.41; Cohen’s d = −0.79, effect size = 0.37) and repetition trials (p = 0.012, t = −2.80; Cohen’s d = −0.92, effect size = 0.42)
Summary
Task-switching paradigm is a well-known and validated tool for exploring executive control processes and neural correlates of cognitive cost and it is often used to assess age-related executive deficits (Wilckens et al, 2017). This paradigm requires the repetition of the same task over a variable number of trials (i.e., repetition trials) and the rapid alternation between two different tasks at some point of the trials sequence (i.e., switch trials). Taskswitching performance may be improved using task cues, which provide valid information about the upcoming target and allow for time to prepare for a given trial (Schapkin et al, 2014). Task cues “effect” is associated to maintaining and reconfiguration processes of a task set in working memory (Wilckens et al, 2017)
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