Aging effects on prefrontal cortex oxygenation in a posture-cognition dual-task: an fNIRS pilot study

Abstract Objective Greater intraindividual variability (IIV) in behavioral and cognitive performance is a risk factor for adverse outcomes but research concerning IIV in neural signal is scarce. Using functional near-infrared spectroscopy (fNIRS), we showed that IIV in oxygenated hemoglobin (HbO2) levels in the prefrontal cortex increased from single task (Single-Task-Walk–STW; Single-Task-Alpha–STA) to Dual-Task-Walk (DTW) conditions in older adults. Herein, we predicted that, consistent with the neural inefficiency hypothesis, reduced cortical thickness would be associated with greater increases in IIV in fNIRS-derived HbO2 from single tasks to DTW when adjusting for behavioral performance. Method Participants were right-handed older adults without dementia recruited from the community (N = 55; M(SD) age = 74.84(4.97); %female = 49.1). Neuroimaging included fNIRS for HbO2 levels in the prefrontal cortex during tasks and MRI for cortical thickness. IIV was operationalized using the SD of fNIRS-derived HbO2 observations assessed during a 30-s interval in each experimental condition. Results Moderation analyses, assessed through linear mixed effects models, revealed that in several frontal (p < 0.02), parietal (p < 0.02), temporal (p < 0.01), and occipital (p < 0.01) regions, thinner cortex was associated with greater increases in HbO2 IIV from the single tasks to DTW. Conclusion Reduced cortical thickness was associated with inefficient increases in IIV in fNIRS-derived HbO2 from single tasks to dual-task walking. Worse IIV in gait performance under DTW predicts adverse mobility outcomes. Reduced cortical thickness and worse IIV of fNIRS-derived HbO2 during DTW are possible brain mechanisms that explain the risk of developing mobility impairments in aging and disease populations.

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Modifications in Prefrontal Cortex Oxygenation in Linear and Curvilinear Dual Task Walking: A Combined fNIRS and IMUs Study

Sensors ◽

10.3390/s21186159 ◽

2021 ◽

Vol 21 (18) ◽

pp. 6159

Author(s):

Valeria Belluscio ◽

Gabriele Casti ◽

Marco Ferrari ◽

Valentina Quaresima ◽

Maria Sofia Sappia ◽

...

Keyword(s):

Prefrontal Cortex ◽

Dual Task ◽

Near Infrared ◽

Cognitive Task ◽

Real Life ◽

Motor Task ◽

Hemoglobin Concentration ◽

Cortical Activation ◽

Functional Near Infrared Spectroscopy ◽

Gait Quality

Increased oxygenated hemoglobin concentration of the prefrontal cortex (PFC) has been observed during linear walking, particularly when there is a high attention demand on the task, like in dual-task (DT) paradigms. Despite the knowledge that cognitive and motor demands depend on the complexity of the motor task, most studies have only focused on usual walking, while little is known for more challenging tasks, such as curved paths. To explore the relationship between cortical activation and gait biomechanics, 20 healthy young adults were asked to perform linear and curvilinear walking trajectories in single-task and DT conditions. PFC activation was assessed using functional near-infrared spectroscopy, while gait quality with four inertial measurement units. The Figure-of-8-Walk-Test was adopted as the curvilinear trajectory, with the “Serial 7s” test as concurrent cognitive task. Results show that walking along curvilinear trajectories in DT led to increased PFC activation and decreased motor performance. Under DT walking, the neural correlates of executive function and gait control tend to be modified in response to the cognitive resources imposed by the motor task. Being more representative of real-life situations, this approach to curved walking has the potential to reveal crucial information and to improve people’ s balance, safety, and life’s quality.

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What Does Sleeping Brain Tell About Stress? A Pilot Functional Near-Infrared Spectroscopy Study Into Stress-Related Cortical Hemodynamic Features During Sleep

Frontiers in Computer Science ◽

10.3389/fcomp.2021.774949 ◽

2021 ◽

Vol 3 ◽

Author(s):

Zilu Liang

Keyword(s):

Prefrontal Cortex ◽

Infrared Spectroscopy ◽

Pilot Study ◽

Near Infrared Spectroscopy ◽

Dorsolateral Prefrontal Cortex ◽

Near Infrared ◽

Functional Near Infrared Spectroscopy ◽

Stress Indicators ◽

Measured Stress ◽

Dorsolateral Prefrontal

People with mental stress often experience disturbed sleep, suggesting stress-related abnormalities in brain activity during sleep. However, no study has looked at the physiological oscillations in brain hemodynamics during sleep in relation to stress. In this pilot study, we aimed to explore the relationships between bedtime stress and the hemodynamics in the prefrontal cortex during the first sleep cycle. We tracked the stress biomarkers, salivary cortisol, and secretory immunoglobulin A (sIgA) on a daily basis and utilized the days of lower levels of measured stress as natural controls to the days of higher levels of measured stress. Cortical hemodynamics was measured using a cutting-edge wearable functional near-infrared spectroscopy (fNIRS) system. Time-domain, frequency-domain features as well as nonlinear features were derived from the cleaned hemodynamic signals. We proposed an original ensemble algorithm to generate an average importance score for each feature based on the assessment of six statistical and machine learning techniques. With all channels counted in, the top five most referred feature types are Hurst exponent, mean, the ratio of the major/minor axis standard deviation of the Poincaré plot of the signal, statistical complexity, and crest factor. The left rostral prefrontal cortex (RLPFC) was the most relevant sub-region. Significantly strong correlations were found between the hemodynamic features derived at this sub-region and all three stress indicators. The dorsolateral prefrontal cortex (DLPFC) is also a relevant cortical area. The areas of mid-DLPFC and caudal-DLPFC both demonstrated significant and moderate association to all three stress indicators. No relevance was found in the ventrolateral prefrontal cortex. The preliminary results shed light on the possible role of the RLPCF, especially the left RLPCF, in processing stress during sleep. In addition, our findings echoed the previous stress studies conducted during wake time and provides supplementary evidence on the relevance of the dorsolateral prefrontal cortex in stress responses during sleep. This pilot study serves as a proof-of-concept for a new research paradigm to stress research and identified exciting opportunities for future studies.

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