Event-related near-infrared spectroscopy detects conflict in the motor cortex in a Stroop task

Assessing prefrontal cortex activity in Graves' disease: a functional near-infrared spectroscopy study

Introduction

Graves' disease (GD) is associated with cognitive, emotional, and fatigue difficulties. Objective measures of cognitive dysfunction have yielded mixed results. The aim of this study was to investigated whether premenopausal female patients with first-time hyperthyroid GD (mean age 34 years) exhibit cognitive fatigability and altered functional activity in the prefrontal cortex (PFC) using functional near-infrared spectroscopy (fNIRS) during an exhausting cognitive task.

Methods

Using the Animal Stroop test, we compared patients with GD (N = 28) and healthy controls (N = 28) before and after a 30-min cognitively exhausting reading comprehension task.

Results

Both groups showed improvements in Stroop task performance after the reading task (p < 0.001, η p 2 = 0.389), and no group differences were observed in cognitive performance. Increased activation in the left dorsolateral prefrontal cortex post-test was found for controls but not for patients with GD. Exploratory analyses showed higher increases in oxy-hemoglobin levels post-test in the PFC of controls compared to patients with GD, indicating reduced PFC involvement in patients with GD.

Discussion

In conclusion, we were not able to show any change in the functional activity of the PFC after prolonged mental activity in this set-up using fNIRS of hyperthyroid GD patients. Further studies are needed to understand the mechanism behind self-reported fatigue in GD.

Reduced oxygen supply to the prefrontal cortex during the Stroop task in migraine patients with aura: A preliminary functional near-infrared spectroscopy study

The role of the cerebrovascular system in migraine pathogenesis is critical. Several studies have demonstrated alterations in the regional cerebral blood flow that persist during headache-free intervals. In the present study, we aimed to measure the prefrontal hemodynamic responses to the cognitive task in interictal episodic migraineurs. We enrolled eight migraine patients with aura (mean age 25.75 ± 4.39 years), twelve migraine patients without aura (mean age 28.25 ± 6.59 years), and eleven age- and education-matched healthy subjects. We employed the Victoria Stroop task to assess executive functions, specifically selective attention and inhibitory control. The mean changes in the oxy-Hb, deoxy-Hb and total Hb concentrations during the Stroop interference (incongruent minus neutral) were recorded by functional near-infrared spectroscopy (fNIRS). Our preliminary results indicated that migraine patients with aura had higher reaction time (p = 0.033) and lower prefrontal oxy-Hb activity (p = 0.036) during the Stroop interference compared to healthy subjects. For the left lateral prefrontal cortex, migraine with aura group showed lower oxy-Hb activity than the healthy subjects during the Stroop interference (p = 0.009). However, there were no such differences in the right lateral prefrontal cortex. Additionally, we found a relationship between prefrontal oxygenation and the severity of headaches, the frequency of attacks, and the number of monthly migraine days. We noticed a decrease in prefrontal blood flow in migraine patients with aura, even during the interictal periods. This may indicate that migraine with aura could be a persistent neurovascular uncoupling disorder. Moreover, the reduced oxygen supply to the prefrontal cortex may be associated with impaired frontal lobe functions.

Open access dataset integrating EEG and fNIRS during Stroop tasks

Conflict monitoring and processing are crucial components of the human cognitive system, with significant implications for daily life and the diagnosis of cognitive disorders. The Stroop task, combined with brain function detection technology, has been widely employed as a classical paradigm for investigating conflict processing. However, there remains a lack of public datasets that integrate Electroencephalogram (EEG) and functional Near-infrared Spectroscopy (fNIRS) to simultaneously record brain activity during a Stroop task. We introduce a dual-modality Stroop task dataset incorporating 34-channel EEG (sampling frequency is 1000 Hz) and 20-channel high temporal resolution fNIRS (sampling frequency is 100 Hz) measurements covering the whole frontal cerebral cortex from 21 participants (9 females/12 males, aged 23.0 ± 2.3 years). Event-related potential analysis of EEG recordings and activation analysis of fNIRS recordings were performed to show the significant Stroop effect. We expected that the data provided would be utilized to investigate multimodal data processing algorithms during cognitive processing.

Lateralization difference in functional activity during Stroop tasks: a functional near-infrared spectroscopy and EEG simultaneous study

Introduction

Conflict monitoring and processing is an important part of the human cognitive system, it plays a key role in many studies of cognitive disorders.

Methods

Based on a Chinese word-color match Stroop task, which included incongruent and neutral stimuli, the Electroencephalogram (EEG) and functional Near-infrared Spectroscopy (fNIRS) signals were recorded simultaneously. The Pearson correlation coefficient matrix was calculated to analyze brain connectivity based on EEG signals. Granger Causality (GC) method was employed to analyze the effective connectivity of bilateral frontal lobes. Wavelet Transform Coherence (WTC) was used to analyze the functional connectivity of the bilateral hemisphere and ipsilateral hemisphere.

Results

Results indicated that brain connectivity analysis on EEG signals did not show any significant lateralization, while fNIRS analysis results showed the frontal lobes especially the left frontal lobe play the leading role in dealing with conflict tasks. The human brain shows leftward lateralization while processing the more complicated incongruent stimuli. This is demonstrated by the higher functional connectivity in the left frontal lobe and the information flow from the left frontal lobe to the right frontal lobe.

Discussion

Our findings in brain connectivity during cognitive conflict processing demonstrated that the dual modality method combining EEG and fNIRS is a valuable tool to excavate more information through cognitive and physiological studies.

Short-Term High-Intensity Interval Exercise Promotes Motor Cortex Plasticity and Executive Function in Sedentary Females

Previous research has demonstrated that regular exercise modulates motor cortical plasticity and cognitive function, but the influence of short-term high-intensity interval training (HIIT) remains unclear. In the present study, the effect of short-term HIIT on neuroplasticity and executive function was assessed in 32 sedentary females. Half of the participants undertook 2 weeks of HIIT. Paired-pulse transcranial magnetic stimulation (ppTMS) was used to measure motor cortical plasticity via short intracortical inhibition (SICI) and intracortical facilitation (ICF). We further adapted the Stroop task using functional near-infrared spectroscopy (fNIRS) to evaluate executive function in the participants. The results indicated that, compared with the control group, the HIIT group exhibited decreased ICF. In the Stroop task, the HIIT group displayed greater activation in the left dorsolateral prefrontal cortex (DLPFC) and left orbitofrontal cortex (OFC) even though no significant difference in task performance was observed. These findings indicate that short-term HIIT may modulate motor cortical plasticity and executive function at the neural level.

Identification of the Cognitive Interference Effect Related to Stroop Stimulation: Using Dynamic Causal Modeling of Effective Connectivity in Functional Near-Infrared Spectroscopy (fNIRS)

Background:

The Stroop test is a well-known model to denote the decline in performance under the incongruent condition, which requires selective attention and control of competitive responses. Functional near-infrared spectroscopy can identify activated brain regions associated with the Stroop interference effect.

Objective:

This research aims to identify the neural correlates associated with the Stroop tasks within the brain activated regions.

Materials and Methods:

In this cross sectional study, twelve right-handed healthy controls were investigated by means of a multi-channels fNIRS unit during the execution of the Stroop test. Effective connectivity changes in the prefrontal cortex between Stroop attentional conflict and rest states were calculated using DCM approach to investigate (1) areas known for selective attention and (2) analyze inter-network functional connectivity strength (FCS) by selecting several brain functional networks.

Results:

The results indicated that an increased activity was recorded in the LDLPFC during incongruent condition, while under neutral condition, the increase in activity was even more pronounced in those areas. Effect of Stroop interference associated with significant consistent causes an increase in the RDLPFC to DMPFC, LDLPFC to DMPFC and LDLPFC to RPFC effective connectivity strengths.

Conclusion:

This study showed the use of DCM algorithm for fNIRS data with respect to fMRI has provided additional information about the directional connectivity and causal interactions in LPFC networks during a conflict processing. Eventually, high temporal resolution fNIRS can be a promising tool for monitoring functional brain activation under the cognitive paradigms in neurological research and psychotherapy applications.

Prefrontal cortex-mediated executive function as assessed by Stroop task performance associates with weight loss among overweight and obese adolescents and young adults

People with cognitive deficits or executive dysfunction are often overweight or obese. Several human neuroimaging studies have found that executive function (EF) predicts food intake and weight gain; however, fewer studies have investigated the relationship between EF and weight loss. The Stroop task is a classic measure of EF that is used in many neuroimaging studies. In the present work, functional near infrared spectroscopy (fNIRS) data were collected during performance of the Stroop task from a sample of overweight or obese adolescents and young adults (n=31) who participated in a summer fitness and weight loss camp. We assessed the Stroop effect by interference in the reaction time (RT) to visual challenges, and by alterations in levels of oxygenated hemoglobin, as detected by fNIRS. In line with previous studies, we found that the Stroop effect was successfully induced by different visual task conditions among obese/overweight individuals. Moreover, our results reveal that better Stroop task performance is correlated with greater weight loss over a4-weekfitness intervention. Indeed, behavioral data demonstrated that reduced RT interference predicted a greater percentage of weight loss. Moreover, overweight/obese individuals with a greater hemodynamic response in the left ventrolateral and bilateral dorsolateral prefrontal cortex due to the Stroop effect lost more weight during the short-term fitness intervention than participants with lower levels of activation of these neural regions. Overall, our results support a role for prefrontal cortex-mediated EF in influencing food intake and weight loss outcomes in a population of a previously unstudied age.

Hemodynamic responses on prefrontal cortex related to meditation and attentional task

Recent neuroimaging studies state that meditation increases regional cerebral blood flow (rCBF) in the prefrontal cortex (PFC). The present study employed functional near infrared spectroscopy (fNIRS) to evaluate the relative hemodynamic changes in PFC during a cognitive task. Twenty-two healthy male volunteers with ages between 18 and 30 years (group mean age ± SD; 22.9 ± 4.6 years) performed a color-word stroop task before and after 20 min of meditation and random thinking. Repeated measures ANOVA was performed followed by a post hoc analysis with Bonferroni adjustment for multiple comparisons between the mean values of “During” and “Post” with “Pre” state. During meditation there was an increased in oxy-hemoglobin (ΔHbO) and total hemoglobin (ΔTHC) concentration with reduced deoxy-hemoglobin (ΔHbR) concentration over the right prefrontal cortex (rPFC), whereas in random thinking there was increased ΔHbR with reduced total hemoglobin concentration on the rPFC. The mean reaction time (RT) was shorter during stroop color word task with concomitant reduction in ΔTHC after meditation, suggestive of improved performance and efficiency in task related to attention. Our findings demonstrated that meditation increased cerebral oxygenation and enhanced performance, which was associated with activation of the PFC.

Prefrontal cortex activation during story encoding/retrieval: a multi-channel functional near-infrared spectroscopy study

Encoding, storage and retrieval constitute three fundamental stages in information processing and memory. They allow for the creation of new memory traces, the maintenance and the consolidation of these traces over time, and the access and recover of the stored information from short or long-term memory. Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures concentration changes of oxygenated-hemoglobin (O₂Hb) and deoxygenated-hemoglobin (HHb) in cortical microcirculation blood vessels by means of the characteristic absorption spectra of hemoglobin in the near-infrared range. In the present study, we monitored, using a 16-channel fNIRS system, the hemodynamic response during the encoding and retrieval processes (EP and RP, respectively) over the prefrontal cortex (PFC) of 13 healthy subjects (27.2 ± 2.6 years) while were performing the “Logical Memory Test” (LMT) of the Wechsler Memory Scale. A LMT-related PFC activation was expected; specifically, it was hypothesized a neural dissociation between EP and RP. The results showed a heterogeneous O₂Hb/HHb response over the mapped area during the EP and the RP, with a O₂Hb progressive and prominent increment in ventrolateral PFC (VLPFC) since the beginning of the EP. During the RP a broader activation, including the VLPFC, the dorsolateral PFC and the frontopolar cortex, was observed. This could be explained by the different contributions of the PFC regions in the EP and the RP. Considering the fNIRS applicability for the hemodynamic monitoring during the LMT performance, this study has demonstrated that fNIRS could be utilized as a valuable clinical diagnostic tool, and that it has the potential to be adopted in patients with cognitive disorders or slight working memory deficits.

How are the motor system activity and functional connectivity between the cognitive and sensorimotor systems modulated by athletic expertise?

Expertise offers a unique insight into how our brain functions. The purpose of this experiment was to determine if motor system activity and functional connectivity between the cognitive system and sensorimotor system is differentially modulated by an individual's level of expertise. This goal was achieved through the acquisition of functional neuroimaging data in 10 expert volleyball players and 10 novice individuals who were presented with a series of sentences describing possible technical volleyball-specific motor acts and acts that cannot be performed as positive ("Do …!") or negative ("Don't …") commands, while they were silently reading them and deciding whether the actions were technically feasible or not. Compared with novices, experts' activity in the left primary motor cortex hand area (M1) and in the left premotor cortex (Pm) was decreased by impossible actions presented as positive commands. Sensorimotor activation in response to action-related stimuli is not that automatic as held since we found that these areas were deactivated during the task, and their functional connectivity to the primary visual cortex was strengthened for possible actions presented as positive commands, reflecting the neural processes underlying the interaction between motor and visual imagery. These results suggest that the neural activity within the key areas implicitly triggered by motor simulation is a function of the expertise, action feasibility, and context.

Are the neural correlates of subitizing and estimation dissociable? An fNIRS investigation

Human performance in visual enumeration tasks typically shows two distinct patterns as a function of set size. For small sets, usually up to 4 items, numerosity judgments are extremely rapid, precise and confident, a phenomenon known as subitizing. When this limit is exceeded and serial counting is precluded, exact enumeration gives way to estimation: performance becomes error-prone and more variable. Surprisingly, despite the importance of subitizing and estimation in numerical cognition, only few neuroimaging studies have examined whether the neural activity related to these two phenomena can be dissociated. In the present work, we used multi-channel near-infrared spectroscopy (fNIRS) to measure hemodynamic activity of the bilateral parieto-occipital cortex during a visual enumeration task. Participants had to judge the numerosity of dot arrays and indicate it by means of verbal response. We observed a different hemodynamic pattern in the parietal cortex, both in terms of amplitude modulation and temporal profile, for numerosities below and beyond the subitizing range. Crucially, the neural dissociation between subitizing and estimation was strongest at the level of right IPS. The present findings confirm that fNIRS can be successfully used to detect subtle temporal differences in hemodynamic activity and to produce inferences on the neural mechanisms underlying cognitive functions.

Number-space interactions in the human parietal cortex: Enlightening the SNARC effect with functional near-infrared spectroscopy

Interactions between numbers and space have become a major issue in cognitive neuroscience, because they suggest that numerical representations might be deeply rooted in cortical networks that also subserve spatial cognition. The spatial-numerical association of response codes (SNARC) is the most robust and widely replicated demonstration of the link between numbers and space: in magnitude comparison or parity judgments, participants' reaction times to small numbers are faster with left than right effectors, whereas the converse is found for large numbers. However, despite the massive body of research on number-space interactions, the nature of the SNARC effect remains controversial and no study to date has identified its hemodynamic correlates. Using functional near-infrared spectroscopy, we found a hemodynamic signature of the SNARC effect in the bilateral intraparietal sulcus, a core region for numerical magnitude representation, and left angular gyrus (ANG), a region implicated in verbal number processing. Activation of intraparietal sulcus was also modulated by numerical distance. Our findings point to number semantics as cognitive locus of number-space interactions, thereby revealing the intrinsic spatial nature of numerical magnitude representation. Moreover, the involvement of left ANG is consistent with the mediating role of verbal/cultural factors in shaping interactions between numbers and space.