Prefrontal Functional Connectivity During the Verbal Fluency Task in Patients With Major Depressive Disorder: A Functional Near-Infrared Spectroscopy Study

Cortical activation for adolescent-onset minor depression and major depressive disorder: an fNIRS study

BACKGROUND

While depression is increasing worldwide, some patients are diagnosed as having Major Depressive Disorder (MDD), but others are diagnosed with minor depression, however, the potential neuro mechanism is unknown.

METHODS

Sixty-two patients with minor depression, 44 adolescents with MDD and 54 healthy adolescents participated in this study. Functional near-infrared spectroscopy (fNIRS), both HAMD and HAMA data were collected from all of the participants.

RESULTS

The result indicates the pervasively decreased activation of BA, 11, 21, 45 and 46 were observed in the MDD group and reduced activation of BA 45 was observed in the minor depression group. However, cortical activation was not observed between the minor depression or MDD groups. Cortical activation was also not correlated with the depressive/anxious score in the minor and MDD groups separately.

CONCLUSIONS

Cortical activation was pervasively decreased in the MDD group and slightly reduced in the minor depression group, which may be a potential neural mechanism. As reduced cortical activation in minor depression, interventions in the early stages of minor depression may help slow or even modify the development of the illness.

Correlation Between Prefrontal Functional Connectivity and the Degree of Cognitive Impairment in Alzheimer's Disease: A Functional Near-Infrared Spectroscopy Study

Background

The development of Alzheimer's disease (AD) can be divided into subjective cognitive decline (SCD), mild cognitive impairment (MCI), and dementia. Early recognition of pre-AD stages may slow the progression of dementia.

Objective

This study aimed to explore functional connectivity (FC) changes of the brain prefrontal cortex (PFC) in AD continuum using functional near-infrared spectroscopy (fNIRS), and to analyze its correlation with cognitive function.

Methods

All participants underwent 48-channel fNIRS at resting-state. Based on Brodmann partitioning, the PFC was divided into eight subregions. The NIRSIT Analysis Tool (v3.7.5) was used to analyze mean ΔHbO2 and FC. Spearman correlation analysis was used to examine associations between FC and cognitive function.

Results

Compared with HC group, the mean ΔHbO2 and FC were different between multiple subregions in the AD continuum. Both mean ΔHbO2 in the left dorsolateral PFC and average FC decreased sequentially from SCD to MCI to AD groups. Additionally, seven pairs of subregions differed in FC among the three groups: the differences between the MCI and SCD groups were in heterotopic connectivity; the differences between the AD and SCD groups were in left intrahemispheric and homotopic connectivity; whereas the MCI and AD groups differed only in homotopic connectivity. Spearman correlation results showed that FCs were positively correlated with cognitive function.

Conclusions

These results suggest that the left dorsolateral PFC may be the key cortical impairment in AD. Furthermore, there are different resting-state prefrontal network patterns in AD continuum, and the degree of cognitive impairment is positively correlated with reduced FC strength.

Hemodynamic signal changes and functional connectivity in acute stroke patients with dysphagia during volitional swallowing: a pilot study

BACKGROUND

Dysphagia is one of the major post-stroke complications, understanding post-stroke changes in cortical excitability and promoting early remodeling of swallowing-related cortical areas to enable accurate treatment is essential for recovery of patients.

OBJECTIVES

We aimed to investigate hemodynamic signal changes and functional connectivity in acute stroke patients with dysphagia compared to age-matched healthy participants in response to volitional swallowing using functional near-infrared spectroscopy (fNIRS) in this pilot study.

METHODS

Patients with first-ever post-stroke dysphagia having an onset of 1-4 weeks and age-matched right-handed healthy subjects were recruited in our study. fNIRS with 47 channels was utilized to detect the oxyhemoglobin (HbO2 ) and reduced hemoglobin (HbR) concentration changes when volitional swallowing. Cohort analysis was performed by a one-sample t-test. Two-sample t-test was utilized to compare the difference in cortical activation between patients with post-stroke dysphagia and healthy subjects. Furthermore, the relative changes in the concentration of the HbO2 throughout the experimental procedure were extracted for the functional connectivity analysis. The Pearson correlation coefficients of the HbO2 concentration of each channel were analyzed on a time series, and then a Fisher Z transformation was then performed, and the transformed values were defined as the functional connection strengths between the channels.

RESULTS

In this present study, a total of nine patients with acute post-stroke dysphagia were enrolled in the patient group and nine age-matched healthy participants in the healthy control group. Our study observed that the extensive regions of the cerebral cortex were activated in the healthy control group, while the activation area of patient group's cortical regions was quite limited. The mean functional connectivity strength of participants was 0.485 ± 0.105 in the healthy control group, and 0.252 ± 0.146 in the patient group, with a significant difference between the two groups (p = 0.001).

CONCLUSION

Compared to the healthy individuals, cerebral cortex regions of acute stroke patients were only marginally activated during volitional swallowing task, and the average functional connectivity strength of cortical network in patients was relatively weaker.

A pilot study to explore the effect of udenafil on cerebral hemodynamics in older adults

OBJECTIVE

Phosphodiesterase-5 inhibitors (PDE5Is) enhance vasodilation. We investigated the effects of PDE5I on cerebral hemodynamics during cognitive tasks using functional near-infrared spectroscopy (fNIRS).

METHODS

This study used a crossover design. Twelve cognitively healthy men participants (mean age, 59 ± 3 years; range, 55-65 years) were recruited and randomly assigned to the experimental or control arm, then the experimental and control arm were exchanged after 1 week. Udenafil 100 mg was administered to participants in the experimental arm once daily for 3 days. We measured the fNIRS signal during the resting state and four cognitive tasks three times for each participant: at baseline, in the experimental arm, and in the control arm.

RESULTS

Behavioral data did not show a significant difference between the experimental and control arms. The fNIRS signal showed significant decreases in the experimental arm compared to the control arm during several cognitive tests: verbal fluency test (left dorsolateral prefrontal cortex, T = -3.02, p = 0.014; left frontopolar cortex, T = -4.37, p = 0.002; right dorsolateral prefrontal cortex, T = -2.59, p = 0.027), Korean-color word Stroop test (left orbitofrontal cortex, T = -3.61, p = 0.009), and social event memory test (left dorsolateral prefrontal cortex, T = -2.35, p = 0.043; left frontopolar cortex, T = -3.35, p = 0.01).

INTERPRETATION

Our results showed a paradoxical effect of udenafil on cerebral hemodynamics in older adults. This contradicts our hypothesis, but it suggests that fNIRS is sensitive to changes in cerebral hemodynamics in response to PDE5Is.

A Hybrid GCN and Filter-Based Framework for Channel and Feature Selection: An fNIRS-BCI Study

In this study, a channel and feature selection methodology is devised for brain-computer interface (BCI) applications using functional near-infrared spectroscopy (fNIRS). A graph convolutional network (GCN) is employed to select the appropriate and correlated fNIRS channels. Furthermore, in the feature extraction phase, the performance of two filter-based feature selection algorithms, (i) the minimum redundancy maximum relevance (mRMR) and (ii) ReliefF, is investigated. The five most commonly used temporal statistical features (i.e., mean, slope, maximum, skewness, and kurtosis) are used, whereas the conventional support vector machine (SVM) is utilized as a classifier for training and testing. The proposed methodology is validated using an available online dataset of motor imagery (left- and right-hand), mental arithmetic, and baseline tasks. First, the efficacy of the proposed methodology is shown for two-class BCI applications (i.e., left- vs. right-hand motor imagery and mental arithmetic vs. baseline). Second, the proposed framework is applied to four-class BCI applications (i.e., left- vs. right-hand motor imagery vs. mental arithmetic vs. baseline). The results show that the number of appropriate channels and features was significantly reduced, resulting in a significant increase in classification accuracy for both two-class and four-class BCI applications, respectively. Furthermore, both mRMR (i.e., 87.8% for motor imagery, 87.1% for mental arithmetic, and 78.7% for four-class) and ReliefF (i.e., 90.7% for motor imagery, 93.7% for mental arithmetic, and 81.6% for four-class) yielded high average classification accuracy $\left(p<0.05\right)$ . However, the results of the ReliefF algorithm are more stable and significant.

Differentiating people with schizophrenia from healthy controls in a developing Country: An evaluation of portable functional near infrared spectroscopy (fNIRS) as an adjunct diagnostic tool

INTRODUCTION

This study aimed to evaluate portable functional near-infrared spectroscopy (fNIRS) device as an adjunct diagnostic tool in Vietnam to assess hemodynamics when people with schizophrenia and healthy controls performed cognitive tasks.

METHODS

One hundred fifty-seven participants were divided into schizophrenia (n = 110) and healthy controls group (n = 47), which were recruited by match of age, and gender. Hemodynamic responses in the frontal cortex were monitored with a 48-channel portable device during the Stroop Color-Word Test (SCWT) and Verbal Fluency Test (VFT). General linear model compared the differences in oxyhemoglobin (HbO₂) levels between the two groups. The Receiver Operating Characteristic (ROC) graph was generated for each neuroanatomical area.

RESULTS

People with schizophrenia did not show significant activation in the frontal lobe during the SCWT and VFT as compared to pre-task. During the VFT, the area under the ROC curve of the bilateral dorsolateral prefrontal cortex, bilateral orbitofrontal cortex, bilateral frontopolar prefrontal cortex, and bilateral ventrolateral prefrontal cortex were greater than 0.7 (p < 0.001). The area under the ROC curve (AUC) for the right orbitofrontal cortex was maximal during the VFT (AUC = 0.802, 95%CI = 0.731-0.872). The Youden's index reached a peak (0.57) at the optimal cut-point value (HbO₂ cutoff <0.209 μmol/ml for schizophrenia) in which the sensitivity was 85%; specificity was 72%; positive predictive value (PPV) was 0.88; negative predictive value (NPV) was 0.68 and correct classification rate was 76%.

DISCUSSION

Assessing hemodynamics during VFT by portable fNIRS offers the potential as an adjunct diagnostic tool for schizophrenia in developing countries.

The fNIRS evaluation of frontal and temporal lobe cortical activation in Chinese first-episode medication-naïve and recurrent depression during a verbal fluency task

Background

Functional near-infrared spectroscopy (fNIRS) identifies neurophysiological differences between psychiatric disorders by assessing cortical hemodynamic function. Few trials have studied differences in brain functional activity between first-episode medication-naïve depression patients (FMD) and recurrent major depression (RMD). We aimed to determine the differences between FMD and RMD in oxygenated hemoglobin concentration ([oxy-Hb]), and to investigate the correlation between frontotemporal cortex activation and clinical symptoms.

Methods

We recruited 40 patients with FMD, 53 with RMD, and 38 healthy controls (HCs) from May 2021 to April 2022. Symptom severity was assessed with the 24-item Hamilton Depression Rating Scale (HAM-D) and the Hamilton Anxiety Rating Scale (HAM-A). A 52-channel fNIRS measured changes in [oxy-Hb] during VFT performance.

Results

Both patient groups performed poorly during the VFT task compared with HC (FDR p < 0.05), but there was no significant difference between the two patient groups. Analysis of variance showed that mean [oxy-Hb] activation was lower in both the frontal and temporal lobes in the MDD group compared with HCs (FDR p < 0.05). Additionally, patients with RMD had a significantly lower hemodynamic response in the right dorsolateral prefrontal cortex (DLPFC) and dorsal frontal pole cortex (DFPC) than patients with FMD (FDR p < 0.05). No significant correlation was found between changes in mean [oxy-Hb] and either medical history or clinical symptoms (FDR p < 0.05).

Conclusion

The presence of different neurofunctional activity in some of the same brain regions in FMD and RMD patients implied a link between the level of complexity activation in frontal regions and the stage of MDD. Cognitive impairment may already be present at the beginning of an MDD episode.

Clinical trial registration

www.chictr.org.cn, identifier ChiCTR2100043432.

Brain-computer interface to predict impulse buying behavior using functional near-infrared spectroscopy

As the rate of vaccination against COVID-19 is increasing, demand for overseas travel is also increasing. Despite people's preference for duty-free shopping, previous studies reported that duty-free shopping increases impulse buying behavior. There are also self-reported tools to measure their impulse buying behavior, but it has the disadvantage of relying on the human memory and perception. Therefore, we propose a Brain-Computer Interface (BCI)-based brain signal processing methodology to supplement these limitations and to reduce ambiguity and conjecture of data. To achieve this goal, we focused on the brain's prefrontal cortex (PFC) activity, which supervises human decision-making and is closely related to impulse buying behavior. The PFC activation is observed by recording signals using a functional near-infrared spectroscopy (fNIRS) while inducing impulse buying behavior in virtual computing environments. We found that impulse buying behaviors were not only higher in online duty-free shops than in online regular stores, but the fNIRS signals were also different on the two sites. We also achieved an average accuracy of 93.78% in detecting impulse buying patterns using a support vector machine. These results were identical to the people's self-reported responses. This study provides evidence as a potential biomarker for detecting impulse buying behavior with fNIRS.

Hemodynamic analysis of the frontal cortex using multi-task fNIRS in major depressive disorder

BACKGROUND

Appropriate task selection is the key to fNIRS-based major depressive disorder (MDD) diagnosis and treatment; however, there exists no unified rule for task selection, which limits its clinical application.

METHODS

Four tasks were employed to investigate the hemodynamic characteristics of MDD during motor, emotional, cognitive, and combinational tasks. A total of 69 subjects were studied: 50 with MDD and 19 healthy controls. The integral value of oxy-hemoglobin and the asymmetric characteristics of the bilateral frontal lobe were used to demonstrate the hemodynamic changes in MDD during different tasks. A detailed analysis and comparison among different tasks were conducted.

RESULTS

Compared with deoxy-hemoglobin (deoxy-Hb), oxy-Hb was more significant to differentiate between MDD subjects and healthy controls. In subjects with MDD, lower activation of the frontal lobe and smaller integral values of oxy-Hb were observed. In most task paradigms, MDD subjects and healthy controls exhibited diametrically opposite left-right frontal asymmetry. For the integral value of oxy-Hb and the asymmetric characteristics of the bilateral frontal lobe, the differences between MDD subjects and healthy controls under the combinational task were more significant than that under the single tasks.

LIMITATIONS

Brain fatigue patterns over time and their effect on the hemodynamic analysis of MDD should be studied further.

CONCLUSIONS

The difference in hemodynamic characteristics between MDD subjects and healthy controls is closely related to the choice of task, and the combinational task showed better discrimination than the single tasks. It provides guidance for the appropriate task design for MDD in clinics.

Effects of Acupuncture on Cortical Activation in Patients with Disorders of Consciousness: A Functional Near-Infrared Spectroscopy Study

Background. Disorder of consciousness (DoC) is a clinical condition caused by severe brain damage. Some studies have reported that acupuncture, a traditional Chinese treatment, could facilitate the recovery of the patient’s consciousness. The therapeutic effects of acupuncture may be due to its modulation of facilitating cortex (PFC) activity, but it has not been greatly demonstrated. Objectives. We intended to observe the effects of acupuncture on prefrontal cortical activity, explore the potential correlation between cortical activation and the severity of DoC, and analyze the functional brain network connectivity to provide a theoretical basis for its application in clinical practice. Methods. Participants diagnosed with DoC were included in the study. Before the intervention, we assessed the patient’s state of consciousness using relevant scales, such as the Glasgow coma scale (GCS) and the coma recovery scale-revised (CRS-R). All patients received acupuncture manipulation with the functional near-infrared spectroscopy (fNIRS) system monitored. Result. A total of 16 subjects participated in our study. We observed that the concentration of oxygenated hemoglobin (HbO) in the PFC was increased during the acupuncture manipulation and declined during the resting state. Then, the connection strength of the left cerebral cortex was generally higher than that of the right. Finally, we observed only a weak difference in hemodynamic responses of PFC between the vegetative state (VS) and minimally conscious state (MCS) groups. However, the difference was not statistically significant. Conclusion. Our results indicated that acupuncture can increase the concentration of HbO in the PFC and strengthen the connection strength of the left cerebral cortex. However, our present study did not find a significant correlation between the cortical hemodynamic response and the severity of DoC.

Characteristics of brain connectivity during verbal fluency test: Convolutional neural network for functional near-infrared spectroscopy analysis

Human connectome describes the complicated connection matrix of nervous system among human brain. It also possesses high potential of assisting doctors to monitor the brain injuries and recoveries in patients. In order to unravel the enigma of neuron connections and functions, previous research has strived to dig out the relations between neurons and brain regions. Verbal fluency test (VFT) is a general neuropsychological test, which has been used in functional connectivity investigations. In this study, we employed convolutional neural network (CNN) on a brain hemoglobin concentration changes (ΔHB) map obtained during VFT to investigate the connections of activated brain areas and different mental status. Our results show that feature of functional connectivity can be identified accurately with the employment of CNN on ΔHB mapping, which is beneficial to improve the understanding of brain functional connections.