Changes In HbO Research Articles

#658 Analysis of cerebral blood volume and flow changes in ESRD patients undergoing hemodialysis using functional near-infrared spectroscopy

Abstract Background and Aims End stage renal disease (ESRD) patients undergoing hemodialysis experience diverse neurological complications. However, studies regarding how hemodialysis is related to these neurological problems are limited. This study investigated cerebral blood volume (CBV) and cerebral blood flow (CBF) during hemodialysis using functional near-infrared spectroscopy (fNIRS) to analyze cerebral hemodynamic changes. Method ESRD patients undergoing maintenance hemodialysis without a history of neurological disorders were enrolled prospectively. The fNIRS data were collected using a NIRSIT Lite device. The fNIRS values were recorded three times for each patient: before the start of hemodialysis (pre-HD), 1 h after the start of hemodialysis (mid-HD), and after the end of hemodialysis (post-HD). The average changes in oxy-hemoglobin (HbO2), deoxy-hemoglobin (HbR), total hemoglobin (HbT, calculated as HbO2 + HbR) concentrations, and in hemoglobin concentration difference (HbD, calculated as HbO2 – HbR) were analyzed. We then compared the differences in changes in HbO2, HbR, HbT, and HbD according to the hemodialysis period. Results Thirty hemodialysis patients were analyzed. Between the Pre-HD and Post-HD periods, there were significant differences in changes in HbO2 (0.005 ± 0.001 µM vs. 0.015 ± 0.004 µM, p=0.046) and HbT (0.006 ± 0.001 µM vs. 0.016 ± 0.008 µM, p=0.029). Additionally, between Pre-HD and Post-HD periods, HbD tended to increase; however, this was not statistically significant (0.005 ± 0.001 µM vs. 0.014 ± 0.004 µM, p=0.094). Conclusion We demonstrated that during one hemodialysis session, the relative change in CBV increased post-HD compared with pre-HD. These results are expected to help understand the mechanisms underlying the effects of hemodialysis on brain function.

65 Neuroscience in the Everyday World: Lateralization of Brain Activity During Dual-Task Walking

Objective:Functional near-infrared spectroscopy (fNIRS) is a non-invasive functional neuroimaging method that takes advantage of the optical properties of hemoglobin to provide an indirect measure of brain activation via task-related relative changes in oxygenated hemoglobin (HbO). Its advantage over fMRI is that fNIRS is portable and can be used while walking and talking. In this study, we used fNIRS to measure brain activity in prefrontal and motor region of interests (ROIs) during single- and dual-task walking, with the goal of identifying neural correlates.Participants and Methods:Nineteen healthy young adults [mean age=25.4 (SD=4.6) years; 14 female] engaged in five tasks: standing single-task cognition (serial-3 subtraction); single-task walking at a self-selected comfortable speed on a 24.5m oval-shaped course (overground walking) and on a treadmill; and dual-task cognition+walking on the same overground course and treadmill (8 trials/condition: 20 seconds standing rest, 30 seconds task). Performance on the cognitive task was quantified as the number of correct subtractions, number of incorrect subtractions, number of self-corrected errors, and percent accuracy over the 8 trials. Walking speed (m/sec) was recorded for all walking conditions. fNIRS data were collected on a system consisting of 16 sources, 15 detectors, and 8 short-separation detectors in the following ROIs: right and left lateral frontal (RLF, LLF), right and left medial frontal (RMF, LMF), right and left medial superior frontal (RMSF, LMSF), and right and left motor (RM, LM). Lateral and medial refer to ROIs’ relative positions on lateral prefrontal cortex. fNIRS data were analyzed in Homer3 using a spline motion correction and the iterative weighted least squares method in the general linear model. Correlations between the cognitive/speed variables and ROI HbO data were applied using a Bonferroni adjustment for multiple comparisons.Results:Subjects with missing cognitive data were excluded from analyses, resulting in sample sizes of 18 for the single-task cognition, dual-task overground walking, and dual-task treadmill walking conditions. During dual-task overground walking, there was a significant positive correlation between walking speed and relative change in HbO in RMSF [r(18)=.51, p<.05] and RM [r(18)=.53, p<.05)]. There was a significant negative correlation between total number of correct subtractions and relative change in HbO in LMSF ([r(18)=-.75, p<.05] and LM [r(18)=-.52, p<.05] during dual-task overground walking. No other significant correlations were identified.Conclusions:These results indicate that there is lateralization of the cognitive and motor components of overground dual-task walking. The right hemisphere appears to be more active the faster people walk during the dual-task. By contrast, the left hemisphere appears to be less active when people are working faster on the cognitive task (i.e., serial-3 subtraction). The latter results suggest that automaticity of the cognitive task (i.e., more total correct subtractions) is related to decreased brain activity in the left hemisphere. Future research will investigate whether there is a change in cognitive automaticity over trials and if there are changes in lateralization patterns in neurodegenerative disorders that are known to differentially affect the hemispheres (e.g., Parkinson’s disease).

The prefrontal cortex is differentially involved in implicit and explicit facial emotion processing: An fNIRS study

Despite extensive research, the differential roles of the prefrontal cortex (PFC) in implicit and explicit facial emotion processing remain elusive. Functional near-infrared spectroscopy (fNIRS) is a neuroimaging technique that can measure changes in both oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) concentrations. Currently, how HbO and HbR change during facial emotion processing remains unclear. Here, fNIRS was used to examine and compare PFC activation during implicit and explicit facial emotion processing. Forty young adults performed a facial-matching task that required either emotion discrimination (explicit task) or age discrimination (implicit task), and the activation of their PFCs was measured by fNIRS. Participants attempted the task on two occasions to determine whether their activation patterns were maintained over time. The PFC displayed increases in HbO and/or decreases in HbR during the implicit and explicit facial emotion tasks. Importantly, there were significantly greater changes in PFC HbO during the explicit task, whereas no significant difference in HbR changes between conditions was found. Between sessions, HbO changes were reduced across tasks, but the difference in HbO changes between the implicit and explicit tasks remained unchanged. The test-retest reliability of the behavioral measures was excellent, whereas that of fNIRS measures was mostly poor to fair. Thus, the PFC plays a specific role in recognizing facial expressions, and its differential involvement in implicit and explicit facial emotion processing can be consistently captured at the group level by changes in HbO. This study demonstrates the potential of fNIRS for elucidating the neural mechanisms underlying facial emotion recognition.

Changes in functional neuroimaging measures as novices gain proficiency on the fundamentals of laparoscopic surgery suturing task.

As trainees practice fundamental surgical skills, they typically rely on performance measures such as time and errors, which are limited in their sensitivity. The goal of our study was to evaluate the use of portable neuroimaging measures to map the neural processes associated with learning basic surgical skills. Twenty-one subjects completed 15 sessions of training on the fundamentals of laparoscopic surgery (FLS) suture with intracorporeal knot-tying task in a box trainer. Functional near infrared spectroscopy data were recorded using an optode montage that covered the prefrontal and sensorimotor brain areas throughout the task. Average oxy-hemoglobin (HbO) changes were determined for repetitions performed during the first week of training compared with the third week of training. Statistical differences between the time periods were evaluated using a general linear model of the HbO changes. Average performance scores across task repetitions increased significantly from the first day to the last day of training ( ). During the first day of training, there was significant lateral prefrontal cortex (PFC) activation. On the final day, significant activation was observed in the PFC, as well as the sensorimotor areas. When comparing the two periods, significant differences in activation ( ) were found for the right medial PFC and the right inferior parietal gyrus. While gaining proficiency, trainees activated the perception-action cycle to build a perceptual model and then apply the model to improve task execution. Learners engaged the sensorimotor areas more substantially as they developed skill on the FLS suturing task. These findings are consistent with findings for the FLS pattern cutting task and contribute to the development of objective metrics for skill evaluation.

Changes in task performance and frontal cortex activation within and over sessions during the n-back task

The n-back task is a popular paradigm for studying neurocognitive processing at varying working memory loads. Although much is known about the effects of load on behavior and neural activation during n-back performance, the temporal dynamics of such effects remain unclear. Here, we investigated the within- and between-session stability and consistency of task performance and frontal cortical activation during the n-back task using functional near-infrared spectroscopy (fNIRS). Forty healthy young adults performed the 1-back and 3-back conditions three times per condition. They then undertook identical retest sessions 3 weeks later (M = 21.2 days, SD = 0.9). Over the course of the task, activation in the participants’ frontopolar, dorsomedial, dorsolateral, ventrolateral, and posterolateral frontal cortices was measured with fNIRS. We found significantly improved working memory performance (difference between 1-back and 3-back accuracies) over time both within and between sessions. All accuracy and reaction time measures exhibited good to excellent consistency within and across sessions. Additionally, changes in frontal oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) concentration were maintained over time across timescales, except that load-dependent (3-back > 1-back) HbO changes, particularly in the ventrolateral PFC, diminished over separate sessions. The consistency of fNIRS measures varied greatly, with changes in 3-back dorsolateral and ventrolateral HbO demonstrating fair-to-good consistency both within and between sessions. Overall, this study clarified the temporal dynamics of task performance and frontal activation during the n-back task. The findings revealed the neural mechanisms underlying the change in n-back task performance over time and have practical implications for future n-back research.

Sex differences in neural processing of speech in neonates.

The large majority of studies shows that girls develop their language skills faster than boys in the first few years of life. Are girls born with this advantage in language development? The present study used fNIRS in neonates to investigate sex differences in neural processing of speech within the first days of life. We found that speech stimuli elicited significantly more brain activity than non-speech stimuli in both groups of male and female neonates. However, whereas girls showed significant HbO changes to speech stimuli only within the left hemisphere, boys exhibited simultaneous neural activations in both hemispheres, with a larger and more significant fronto-temporal cluster in the right hemisphere. Furthermore, in boys, the variation in time-to-peak latencies was considerably greater than in girls. These findings suggest an earlier maturation of language-related brain areas in girls and highlight the importance of sex-specific investigations of neural language networks in infants.

Non-invasive assessment of cerebral hemoglobin parameters in intracranial dural arteriovenous fistula using functional near-infrared spectroscopy-A feasibility study.

The purpose of this study was to assess the feasibility of non-invasive assessment of cerebral hemodynamics using functional near-infrared spectroscopy (fNIRS) in patients with intracranial dural arteriovenous fistula (DAVF) and to correlate the hemodynamic changes with definitive endovascular treatment. Twenty-seven DAVF patients and 23 healthy controls underwent 20-mins task-based functional near-infrared spectroscopy and neuropsychology evaluation. The mean change in the hemoglobin concentrations obtained from the prefrontal cortex was assessed for oxyhemoglobin, deoxyhemoglobin, and oxygen saturation (HbO, HbR, and SO2, respectively). The fNIRS data were analyzed and correlated with improvement in neuropsychology scores at 1-month follow-up. There was a significant reduction in HbO in the patient group, while it increased in controls (-2.57E-05 vs. 1.09E-04 mM, p < 0.001). The reduced HbO significantly improved after embolization (-2.1E-04 vs. 9.9E-04, p = 0.05, q = 0.05). In patients with aggressive DAVF (Cognard 2B and above), the change was highly significant (p < 0.001; q = 0.001). A moderate correlation was observed between MMSE scores and HbO changes (ρ = 0.4). fNIRS is a useful non-invasive modality for the assessment of DAVF, and could potentially assist in bedside monitoring of treatment response.

Nested and robust modeling techniques for fNIRS data with demographics and experiment related factors in n-back task

Functional near-infrared spectroscopy (fNIRS) signals are used to measure relative changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) concentrations. Brain response studies constitute multilevel or nested datasets formed by different parts of the brain of individuals and multidimensional datasets. The changes in brain activities under specific stimuli are investigated with the help of statistical analysis. However, these studies ignore the dependence structure between the repeated measures of the same subject, which may cause inaccurate or incomplete findings. In this study, we adopt an advanced statistical method into HbO data controlling for variability within repeated measures of each subject while testing and measuring the degrees of the statistical significance between-subject factors and explanatory variables. The changes in HbO are investigated through a linear mixed model, taking experimental and demographic variables into account with open access neuroscience data. The channels nested within subjects are considered random to capture the differences among individuals. Our findings reveal that n-back conditions and mean response times of the subjects have statistically significant associations with mean HbO.

Real time detection of cognitive load using fNIRS: A deep learning approach

Functional near infrared spectroscopy (fNIRS) is a non-invasive tool for monitoring functional brain activation that records changes in oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR) concentrations. fNIRS is well accepted in the cognitive study where the signals are intended to measure cognitive load in the human brain. Concentration changes in HbO and HbR help in classifying the cognitive states of human brain. There are several machine learning classification techniques to distinguish different cognitive states. Some conventional machine learning methods, which are easier to implement, undergo a complex processing phase before training the network and also suffer from low accuracy due to inappropriate data preprocessing. Deep learning based convolutional neural network (CNN) having automatic feature engineering capability plays a very important role in efficiently classifying different cognitive states. The present work uses two open-access datasets on fNIRS signal. The datasets are taken for two cognitive states: mental task (MT) and resting state or baseline task (BL). The concentration changes of HbO and HbR are computed using the modified Beer–Lambert law. The band-pass filter is used to remove additional noise from the signals. Here, topographical brain images are generated from the data of 2 s window with 1 s overlapping for both HbO and HbR. Global normalization is applied to the filtered data for better visualization of the images. The brain images are fed to the proposed CNN model in order to classify them into MT or BL. The accuracy of the classification and the comparative study shows the superiority of the proposed model over two existing models.

Bilinguals have more effective executive function: Evidence from an fNIRS study of the neural correlates of cognitive shifting

Aims and objectives/purpose/research questions: The bilingual advantage in executive function (EF) has recently been explored with functional near-infrared spectroscopy (fNIRS) technology, but the results are still controversial because of the limited statistical analysis. This study aims to fill the gap by replicating the existing studies and advancing the statistical analysis. Design/methodology/approach: Altogether, 35 preschoolers (aged between 4.1 and 6.3 years, Mage = 5.0 years, SD = 0.59) completed the Peabody Picture Vocabulary Test—Fourth Edition (PPVT-4) and the Dimensional Change Card Sort (DCCS) task. Their behavioral performance and the associated brain activities during the three sessions of the DCCS task were measured using fNIRS. In addition, they were classified into either Bilingual or Monolingual groups based on the PPVT scores. Data and analysis: t-tests and quadratic regression analyses were conducted to examine whether children’s performance in the DCCS was related to their bilingualism and whether the changes in oxygenated hemoglobin (HbO) in the prefrontal regions were related to their bilingualism and performance in the DCCS. Findings/conclusions: The behavioral data analysis indicated no significant differences between the monolinguals and bilinguals. However, the fNIRS evidence indicated that (1) the monolinguals had to recruit 15 channels to complete the cognitive shifting of DCCS tasks, whereas the bilinguals only employed 11; (2) the bilinguals had significantly more brain activation with fewer channels in BA 44 than the monolinguals, demonstrating more effective executive function. Originality: This study has advanced the statistical analysis of the HbO changes for the cognitive shifting in the DCCS by confirming the nonlinear U-shape by quadratic regression a better fit than the linear V-shape by GLM. Significance/implications: This finding implies that early bilingual experience has equipped young children with more effective executive function.

Functional near-infrared spectroscopy to assess pain in neonatal circumcisions.

Pain assessment is challenging in neonates. Behavioral and physiological pain scales do not assess neocortical nociception, essential to pain encoding and central pain pathway development. Functional near-infrared spectroscopy (fNIRS) can assess neocortical activation to noxious stimuli from changes in oxy-(HbO) and total-hemoglobin concentrations (HbT). This study aims to assess fNIRS nociceptive functional activation in the prefrontal cortex of neonates undergoing circumcision through changes in HbO and HbT, and the correlation between changes in fNIRS and Neonatal Infant Pain Scale (NIPS), a behavioral pain assessment scale. In healthy term neonates, HbO, HbT, and NIPS were recorded during sequential circumcision events 1-Prep before local anesthetic injection; 2-Local anesthetic injection; 3-Prep before incision; 4-Oral sucrose; 5-Incision; 6-Gomco (hemostatic device) attached; 7-Gomco twisted on; and 8-Gomco removed. fNIRS and NIPS changes after each event were assessed with Wilcoxon signed-rank test and summarized as median and interquartile range (IQR). Changes in fNIRS vs. NIPS were correlated with Spearman coefficient. In 31 neonates fNIRS increased (median [IQR] µmol/L) with noxious events: Local injection (HbO: 1.1 [0.5, 3.1],p<.001; HbT: 2.3 [0.2, 7.6],p<.001), Gomco attached (HbO: 0.7 [0.1, 1.7],p=.002; HbT: 0.7 [-0.2, 2.9],p=.02), and Gomco twisted on (HbO: 0.5 [-0.2, 1.7],p=.03; HbT: 0.8 [-0.1, 3.3],p=.02). fNIRS decreased with non-noxious event: Prep before incision (HbO: -0.6 [-1.2, -0.2]p<.001; HbT: -1 [-1.8, -0.4],p<.001). Local anesthetic attenuated fNIRS increases to subsequent sharp stimuli. NIPS increased with subsequent sharp stimuli despite local anesthetic. Although fNIRS and NIPS changed in the same direction, there was not a strong correlation between them. During neonatal circumcision, changes in fNIRS differed between different types of painful stimuli, which was not the case for NIPS, suggesting that fNIRS may complement NIPS to assess the quality of pain.

The Effects of Inter-Set Recovery Time on Explosive Power, Electromyography Activity, and Tissue Oxygenation during Plyometric Training.

Performing continuous sets to failure is fatiguing during the plyometric training. Cluster sets have been used to redistribute total rest time to create short frequent sets so that muscle fatigue can be avoided. The purpose of the study was to investigate the effects of inter-set recovery time on lower extremity explosive power, neuromuscular activity, and tissue oxygenation during plyometric exercise and recovery. An integrated assessment of explosive power, muscle electrical activity, and tissue oxygenation was adopted in the present study to help understand local muscle metabolism and fatigue during plyometric exercise and recovery. Ten university male basketball players participated in this study. Subjects performed 4 groups of exercise, each group comprised of 3 sets of jumps: 1, 2, 3, or 5 min. Surface electromyography (sEMG) signals were collected from 9 lower extremity muscles; near-infrared spectroscopy (NIRS) was recorded on vastus lateralis; mechanical data during plyometric exercise were collected from a force plate. No significant differences among sets and among groups were found regarding explosive power, jump height, EMG intensity, mean power frequency, the rate of tissue saturation index, and HbO2 changes between baseline and recovery. The current study has shown no muscular fatigue induced during the 4 groups of exercise. The results of this study may help inform recommendations concerning the recovery time during plyometric exercises at low loads (30% 1 RM).

Spatiotemporal monitoring of changes in oxy/deoxy-hemoglobin concentration and blood pulsation on human skin using smartphone-enabled remote multispectral photoplethysmography.

We propose a smartphone-enabled remote multispectral photoplethysmography (SP-rmPPG) system and method to realize spatiotemporal monitoring of perfusion changes and pulsations of the oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) information of the effective blood volume within light interrogated skin tissue beds. The system is implemented on an unmodified smartphone utilizing its built-in camera and flashlight to acquire videos of the skin reflectance. The SP-rmPPG method converts the RGB video into multispectral cubes, upon which to decouple the dynamic changes in HbO2 and Hb information using a modified Beer-Lambert law and the selective wavelength bands of 500 nm and 650 nm. Blood pulsation amplitudes are then obtained by applying a window-based lock-in amplification on the derived spatiotemporal changes in HbO2 or Hb signals. To demonstrate the feasibility of proposed method, we conduct two experiments on the skin tissue beds that are conditioned by occlusive maneuver of supplying arteries: one using the popular blood cuff pressure maneuver on the upper arm, and another artificially inducing a transient ischemic condition on the facial skin tissue beds by finger pressing on the supplying external carotid artery. The cuff experiment shows that the measured dynamic information of HbO2 and Hb in the downstream agrees well with the parallel measurements of oxygenation saturation given by the standard pulse oximeter. We also observe the expected imbalance of spatiotemporal changes in the HbO2 and Hb between the right and left cheeks when the transient ischemic condition is induced in the one side of facial skin tissue beds. The results from the two experiments sufficiently demonstrate the feasibility of the proposed method to monitor the spatiotemporal changes in the skin hemodynamics, including blood oxygenation and pulsation amplitudes. Considering the ever-growing accessibility and affordability of the smartphone to the general public, the proposed strategy promises the early screening of vascular diseases and improving general public health particularly in rural areas with low resource settings.

Functional brain connectivity related to surgical skill dexterity in physical and virtual simulation environments.

.Significance: Surgical simulators, both virtual and physical, are increasingly used as training tools for teaching and assessing surgical technical skills. However, the metrics used for assessment in these simulation environments are often subjective and inconsistent.Aim: We propose functional activation metrics, derived from brain imaging measurements, to objectively assess the correspondence between brain activation with surgical motor skills for subjects with varying degrees of surgical skill.Approach: Cortical activation based on changes in the oxygenated hemoglobin (HbO) of 36 subjects was measured using functional near-infrared spectroscopy at the prefrontal cortex (PFC), primary motor cortex, and supplementary motor area (SMA) due to their association with motor skill learning. Inter-regional functional connectivity metrics, namely, wavelet coherence (WCO) and wavelet phase coherence were derived from HbO changes to correlate brain activity to surgical motor skill levels objectively.Results: One-way multivariate analysis of variance found a statistically significant difference in the inter-regional WCO metrics for physical simulator based on Wilk’s Λ for expert versus novice, , . Partial eta squared effect size for the inter-regional WCO metrics was found to be highest between the central prefrontal cortex (CPFC) and SMA, CPFC-SMA (). Two-tailed Mann–Whitney U tests with a 95% confidence interval showed baseline equivalence and a statistically significant () difference in the CPFC-SMA WPCO metrics for the physical simulator training group () versus the untrained control group () following training for 10 consecutive days in addition to the pretest and posttest days.Conclusion: We show that brain functional connectivity WCO metric corresponds to surgical motor skills in the laparoscopic physical simulators. Functional connectivity between the CPFC and the SMA is lower for subjects that exhibit expert surgical motor skills than untrained subjects in laparoscopic physical simulators.

Dynamics of the Prefrontal Cortex during Chess-Based Problem-Solving Tasks in Competition-Experienced Chess Players: An fNIR Study.

This study aimed to compare the dynamics of the prefrontal cortex (PFC), between adult and adolescent chess players, during chess-based problem-solving tasks of increasing level of difficulty, relying on the identification of changes in oxygenated hemoglobin (HbO2) and hemoglobin (HHb) through the functional near-infrared spectroscopy (fNIRS) method. Thirty male federated chess players (mean age: 24.15 ± 12.84 years), divided into adults and adolescents, participated in this cross-sectional study. Participants were asked to solve three chess problems with different difficulties (low, medium, and high) while changes in HbO2 and HHb were measured over the PFC in real-time with an fNIRS system. Results indicated that the left prefrontal cortex (L-PFC) increased its activation with the difficulty of the task in both adolescents and adults. Interestingly, differences in the PFC dynamics but not in the overall performance were found between adults and adolescents. Our findings contributed to a better understanding of the PFC resources mobilized during complex tasks in both adults and adolescents.

Pre-frontal Cortex Oxygenation Changes During Aerobic Exercise in Elite Athletes Experiencing Sport-Related Concussion.

Aims: Recent research suggests that aerobic exercise can be performed safely within the first week following a concussion injury and that early initiation of exercise may speed recovery. To better understand the physiological changes during a concussion, we tested the hypothesis that mild-to-intense exercise testing can be performed within days immediately following injury, and can be used to discern differences between the concussed and normal healthy state. Thus, the purpose was to observe the cerebral hemodynamic responses to incremental exercise testing performed acutely post-concussion in high-performance athletes.Methods: This study was a within- and between-experimental design, with seven male university ice hockey teams participating. A subgroup of five players acted as control subjects (CON) and was tested at the same time as the 14 concussed (mTBI) players on Day 2, 4, and 7 post-concussion. A 5-min resting baseline and 5-min exercise bouts of mild (EX1), moderate (EX2), and high (EX3) intensity exercise were performed on a cycle ergometer. Near-infrared spectroscopy was used to monitor pre-frontal cortex oxy-haemoglobin (HbO2), deoxy-haemoglobin (HHb), and total blood volume (tHb) changes.Results: ANOVA compared differences between testing days and groups, and although large percentage changes in HbO2 (20–30%), HHb (30–40%), and tHb (30–40%) were recorded, no significant (p ≤ 0.05) differences in cerebral hemodynamics occurred between mTBI vs. CON during aerobic exercise testing on any day post-injury. Furthermore, there was a linear relationship between exercise intensity vs. cerebral hemodynamics during testing for each day (r2 = 0.83–0.99).Conclusion: These results demonstrate two novel findings: (1) mild-to-intense aerobic exercise testing can be performed safely as early as Day 2 post-concussion injury in a controlled laboratory environment; and (2) evidence-based objective measures such as cerebral hemodynamics can easily be collected using near-infrared spectroscopy (NIRS) to monitor physiological changes during the first-week post-injury. This research has important implications for monitoring physiological recovery post-injury and establishing new rehabilitation guidelines.

Multi-modal neuroimaging of dual-task walking: Structural MRI and fNIRS analysis reveals prefrontal grey matter volume moderation of brain activation in older adults

It has been well established over the last two decades that walking is not merely an automatic, motoric activity; it also utilizes executive function circuits, which play an increasingly important role in walking for older people and those with mobility and cognitive deficits. Dual-task walking, such as walking while performing a cognitive task, is a necessary skill for everyday functioning, and has been shown to activate prefrontal lobe areas in healthy older people. Another well-established point in healthy aging is the loss of grey matter, and in particular loss of frontal lobe grey matter volume. However, the relationship between increased frontal lobe activity during dual-task walking and loss of frontal grey matter in healthy aging remains unknown.In the current study, we combined oxygenated hemoglobin (HbO2) data from functional near-infrared spectroscopy (fNIRS), taken during dual-task walking, with structural MRI volumetrics in a cohort of healthy older subjects to identify this relationship. We studied fifty-five relatively healthy, older participants (≥65 years) during two separate sessions: fNIRS to measure HbO2 changes between single-task (i.e., normal walking) and dual-task walking-while-talking, and high-resolution, structural MRI to measure frontal lobe grey matter volumes. Linear mixed effects modeling was utilized to determine the moderation effect of grey matter volume on the change in prefrontal oxygenated hemoglobin between the two walking tasks, while controlling for covariates including task performance. We found a highly significant interaction effect between frontal grey matter volume and task on HbO2 levels (p < 0.0001). Specifically, increased HbO2 levels during dual-task compared to single-task walking were associated with reduced frontal grey matter volume. Regional analysis identified bilateral superior and rostral middle gyri as the primary areas driving these results. The findings provide support for the concept of neural inefficiency: in the absence of behavioral gains, grey matter loss in relatively healthy, older individuals leads to over-activation of frontal lobe during a cognitively demanding walking task with established clinical and predictive utility.

Assessing Usability of Wealth Management Portals using Neurophysiological Tools: Eye-tracking and fNIRS Study

Assessing Usability of Wealth Management Portals using Neurophysiological Tools: Eye-tracking and fNIRS Study

Towards Neuroadaptive Personal Learning Environments: Using fNIRS to Detect Changes in Attentional State

Towards Neuroadaptive Personal Learning Environments: Using fNIRS to Detect Changes in Attentional State

Functional connectivity of the PFC via partial correlation

Functional near-infrared spectroscopy (fNIRS) has been applied to study of brain oxygenation and metabolism. In this study, we aimed to investigate the partial correlation (PC) in fNIRS signals on functional connectivity in the prefrontal cortex (PFC) during a modified version of the color-word matching Stroop task. A continuous wave 16 channels near-infrared spectroscopy device (ARGES Cerebro, Hemosoft Inc., Turkey) was used to measure the changes in HbO2 and Hb concentrations from 12 healthy volunteers. Partial correlation (PC) values were computed for each stimulus condition. The results of ANOVA test (p<0.05) in HbO2 and Hb signals indicate the bilateral connections between two brain hemispheres. The partial correlation analysis, by removing the common effect of channel interference, offers a suitable measure to evaluate the performance of the prefrontal cortex. Also, the results of partial correlation showed that compared to Hb signal, HbO2 signal is more sensitive to brain activities. This study suggests that fNIRS is a valuable tool for demonstrating the relationship between cortical function in complex cognitive activities.