Structural atlas-based spatial registration for functional near-infrared spectroscopy enabling inter-study data integration

Using preregistration as a tool for transparent fNIRS study design

Significance

The expansion of functional near-infrared spectroscopy (fNIRS) methodology and analysis tools gives rise to various design and analytical decisions that researchers have to make. Several recent efforts have developed guidelines for preprocessing, analyzing, and reporting practices. For the planning stage of fNIRS studies, similar guidance is desirable. Study preregistration helps researchers to transparently document study protocols before conducting the study, including materials, methods, and analyses, and thus, others to verify, understand, and reproduce a study. Preregistration can thus serve as a useful tool for transparent, careful, and comprehensive fNIRS study design.

Aim

We aim to create a guide on the design and analysis steps involved in fNIRS studies and to provide a preregistration template specified for fNIRS studies.

Approach

The presented preregistration guide has a strong focus on fNIRS specific requirements, and the associated template provides examples based on continuous-wave (CW) fNIRS studies conducted in humans. These can, however, be extended to other types of fNIRS studies.

Results

On a step-by-step basis, we walk the fNIRS user through key methodological and analysis-related aspects central to a comprehensive fNIRS study design. These include items specific to the design of CW, task-based fNIRS studies, but also sections that are of general importance, including an in-depth elaboration on sample size planning.

Conclusions

Our guide introduces these open science tools to the fNIRS community, providing researchers with an overview of key design aspects and specification recommendations for comprehensive study planning. As such it can be used as a template to preregister fNIRS studies or merely as a tool for transparent fNIRS study design.

Increased Inertia Triggers Linear Responses in Motor Cortices during Large-Extent Movements-A fNIRS Study

Activities of daily living consist of accurate, coordinated movements, which require the upper limbs to constantly interact with environmental loads. The magnitude of the load was shown to affect kinematic outcomes in healthy subjects. Moreover, the increase in load facilitates the recovery of motor function in patients with neurological disorders. Although Brodmann Areas 4 and 6 were found to be active during loaded movements, it remains unclear whether stronger activation can be triggered simply by increasing the load magnitude. If such a linear relationship exists, it may provide a basis for the closed-loop adjustment of treatment plans in neurorehabilitation. Fourteen healthy participants were instructed to lift their hands to their armpits. The movements were grouped in blocks of 25 s. Each block was assigned a magnitude of inertial loads, either 0 pounds (bare hand), 3 pounds, or 15 pounds. Hemodynamic fNIRS signals were recorded throughout the experiment. Both channel-wise and ROI-wise analyses found significant activations against all three magnitudes of inertia. The generalized linear model revealed significant increases in the beta coefficient of 0.001673/pound in BA4 and 0.001338/pound in BA6. The linear trend was stronger in BA6 (conditional r2 = 0.9218) than in BA4 (conditional r2 = 0.8323).

Imagined speech increases the hemodynamic response and functional connectivity of the dorsal motor cortex

Objective. Decoding imagined speech from brain signals could provide a more natural, user-friendly way for developing the next generation of the brain-computer interface (BCI). With the advantages of non-invasive, portable, relatively high spatial resolution and insensitivity to motion artifacts, the functional near-infrared spectroscopy (fNIRS) shows great potential for developing the non-invasive speech BCI. However, there is a lack of fNIRS evidence in uncovering the neural mechanism of imagined speech. Our goal is to investigate the specific brain regions and the corresponding cortico-cortical functional connectivity features during imagined speech with fNIRS.Approach. fNIRS signals were recorded from 13 subjects' bilateral motor and prefrontal cortex during overtly and covertly repeating words. Cortical activation was determined through the mean oxygen-hemoglobin concentration changes, and functional connectivity was calculated by Pearson's correlation coefficient.Main results. (a) The bilateral dorsal motor cortex was significantly activated during the covert speech, whereas the bilateral ventral motor cortex was significantly activated during the overt speech. (b) As a subregion of the motor cortex, sensorimotor cortex (SMC) showed a dominant dorsal response to covert speech condition, whereas a dominant ventral response to overt speech condition. (c) Broca's area was deactivated during the covert speech but activated during the overt speech. (d) Compared to overt speech, dorsal SMC(dSMC)-related functional connections were enhanced during the covert speech.Significance. We provide fNIRS evidence for the involvement of dSMC in speech imagery. dSMC is the speech imagery network's key hub and is probably involved in the sensorimotor information processing during the covert speech. This study could inspire the BCI community to focus on the potential contribution of dSMC during speech imagery.

Acupuncture With deqi Modulates the Hemodynamic Response and Functional Connectivity of the Prefrontal-Motor Cortical Network

As a world intangible cultural heritage, acupuncture is considered an essential modality of complementary and alternative therapy to Western medicine. Despite acupuncture’s long history and public acceptance, how the cortical network is modulated by acupuncture remains largely unclear. Moreover, as the basic acupuncture unit for regulating the central nervous system, how the cortical network is modulated during acupuncture at the Hegu acupoint is mostly unclear. Here, multi-channel functional near-infrared spectroscopy (fNIRS) data were recorded from twenty healthy subjects for acupuncture manipulation, pre- and post-manipulation tactile controls, and pre- and post-acupuncture rest controls. Results showed that: (1) acupuncture manipulation caused significantly increased acupuncture behavioral deqi performance compared with tactile controls. (2) The bilateral prefrontal cortex (PFC) and motor cortex were significantly inhibited during acupuncture manipulation than controls, which was evidenced by the decreased power of oxygenated hemoglobin (HbO) concentration. (3) The bilateral PFC’s hemodynamic responses showed a positive correlation trend with acupuncture behavioral performance. (4) The network connections with bilateral PFC as nodes showed significantly increased functional connectivity during acupuncture manipulation compared with controls. (5) Meanwhile, the network’s efficiency was improved by acupuncture manipulation, evidenced by the increased global efficiency and decreased shortest path length. Taken together, these results reveal that a cooperative PFC-Motor functional network could be modulated by acupuncture manipulation at the Hegu acupoint. This study provides neuroimaging evidence that explains acupuncture’s neuromodulation effects on the cortical network.

Dancing Improves Emotional Regulation in Women With Methamphetamine Use Disorder But Use of a Cycle Ergometer Does Not

Background

Emotional regulation is crucial to people who receive a diagnosis of methamphetamine (MA) use disorder. Although evidence that exercise improves emotional regulation is robust, little is known about whether exercise will improve emotional processing in women with MA use disorder.

Methods

In the present study, 36 women with MA use disorder aged 20 to 34 years and residing in the Drug Rehabilitation Bureau of Mogan Mountain in Zhejiang province were assigned to 1 of 2 exercise intervention groups-dancing or stationary cycling. Both types of exercise were performed at 65-75% of the maximum heart rate for 30 min. Immediately before and after the exercise bout, the participants were asked to score their feelings using a nine-point Likert scale as they viewed emotionally negative, positive, or neutral images in blocks of 20 images each, for a total of 60 images. Concurrent with viewing the images and self-rating their emotions, the women also underwent functional near-infrared spectroscopy to assess changes in brain activity.

Results

There were no significant differences in the demographic or MA use characteristics assessed for the women between the two exercise groups. We found main effect of image valence (F _2,33 = 69.61, p < 0.01), significant interaction effect of time and image valence was found (F _2,33 = 4.27, p < 0.05) and trend increase in the self-rated emotional scale score for viewing negative images in both groups after 30-min exercise intervention, and the dancing group presented more significant trends than cycling group. In addition, activation in the dorsolateral prefrontal cortex of dancers, but not of cyclists, while viewing negative images was significantly lower after vs. before dancing (F _2,33 = 5.43, p < 0.05). This result suggested that 30 min of dancing decreased neural activity in women with MA use disorder while they viewed negative images specifically in a brain region known to guide the selection of appropriate behaviors, and to shift attention.Taken together, the findings of this study suggest that for women with MA abuse disorder, 30 min of dancing, rather than of stationary cycling, may ameliorate negative emotional reactions by decreasing attention to negative stimuli.

Watching video of discrete maneuvers yields better action memory and greater activation in the middle temporal gyrus in half-pipe snowboarding athletes

Although motor performance training often involves action observation, it has been controversial whether individual aesthetic sport athletes benefit more from watching videos of discrete maneuvers (DMs) or continuous runs (CRs). In the present study, half-pipe snowboarding athletes completed a visual 2-back task with DM and CR conditions. To explore the neural mechanisms of action memory processing, brain hemodynamic activity during the task was monitored with functional near-infrared spectroscopy (fNIRS). Compared to watching CR videos, watching DM videos tended to yield better action memory performance and greater activation in the middle temporal gyrus to these athletes, suggesting that watching DM videos may have a tendency to improve action memory more effectively. Evidence of two pathways underlying half-pipe snowboarding action processing was obtained. Watching of CR videos and watching of DM videos might be associated with activation of more sensorimotor regions and more semantic regions, respectively, during memory consolidation.

Cognition and Brain Activation in Response to Various Doses of Caffeine: A Near-Infrared Spectroscopy Study

Caffeine, which is widely used for enhancing athletic performance, has been suggested to have a positive impact on cognition via stimulating the brain. However, no study published to date has explored the effects of different doses of caffeine ingestion on brain activation via cortical hemodynamics. The purpose of the present crossover, double-blind study was to investigate the effects of low, moderate, and high doses of caffeine ingestion on cognitive performance and brain activation. Ten healthy male subjects ingested placebo or caffeine (3, 6, or 9 mg/kg body mass). The effects of each treatment condition were evaluated by Stroop tasks before and 60 min after the ingestion of caffeine. Reaction time (RT) and accuracy of responses to congruent and incongruent stimuli were assessed. As an index of brain activation with cognition, levels of oxygenated hemoglobin (HbO) were measured via near-infrared spectroscopy. A 4 × 2 mixed ANOVA revealed that there were significant interaction effects for RT in both incongruent and congruent conditions (P < 0.01, Pη² = 0.384; P < 0.05, Pη² = 0.259; and P < 0.05, Pη² = 0.309). Both 3 and 6 mg/kg of caffeine ingestion significantly decreased RT to incongruent stimuli. The only dose of caffeine to decrease RT in response to congruent stimuli was 3 mg/kg. None of the doses of caffeine administered affected accuracy of responses to incongruent or congruent stimuli. Under the congruent stimulus condition, ingestion of 3 mg/kg of caffeine significantly increased mean HbO in the dorsolateral prefrontal cortex, frontal pole area, ventrolateral prefrontal cortex (P < 0.01, Pη² = 0.319; P < 0.05, Pη² = 0.263; and P < 0.05, Pη² = 0.259, respectively). None of the doses of caffeine investigated affected HbO under the incongruent stimulus condition. Ingestion of low-dose caffeine has greater effects on cognition and brain activation than moderate and high doses of caffeine, suggesting that low-dose caffeine may be a selective supplement in enhancing executive function and prefrontal activities.

Denoising of neuronal signal from mixed systemic low-frequency oscillation using peripheral measurement as noise regressor in near-infrared imaging

Functional near-infrared spectroscopy (fNIRS) is a noninvasive functional imaging technique measuring hemodynamic changes including oxygenated ( O 2 Hb ) and deoxygenated (HHb) hemoglobin. Low frequency (LF; 0.01 to 0.15 Hz) band is commonly analyzed in fNIRS to represent neuronal activation. However, systemic physiological artifacts (i.e., nonneuronal) likely occur also in overlapping frequency bands. We measured peripheral photoplethysmogram (PPG) signal concurrently with fNIRS (at prefrontal region) to extract the low-frequency oscillations (LFOs) as systemic noise regressors. We investigated three main points in this study: (1) the relationship between prefrontal fNIRS and peripheral PPG signals; (2) the denoising potential using these peripheral LFOs, and (3) the innovative ways to avoid the false-positive result in fNIRS studies. We employed spatial working memory (WM) and control tasks (e.g., resting state) to illustrate these points. Our results showed: (1) correlation between signals from prefrontal fNIRS and peripheral PPG is region-dependent. The high correlation with peripheral ear signal (i.e., O 2 Hb ) occurred mainly in frontopolar regions in both spatial WM and control tasks. This may indicate the finding of task-dependent effect even in peripheral signals. We also found that the PPG recording at the ear has a high correlation with prefrontal fNIRS signal than the finger signals. (2) The systemic noise was reduced by 25% to 34% on average across regions, with a maximum of 39% to 58% in the highly correlated frontopolar region, by using these peripheral LFOs as noise regressors. (3) By performing the control tasks, we confirmed that the statistically significant activation was observed in the spatial WM task, not in the controls. This suggested that systemic (and any other) noises unlikely violated the major statistical inference. (4) Lastly, by denoising using the task-related signals, the significant activation of region-of-interest was still observed suggesting the manifest task-evoked response in the spatial WM task.

Adaptive algorithm utilizing acceptance rate for eliminating noisy epochs in block-design functional near-infrared spectroscopy data: application to study in attention deficit/hyperactivity disorder children

Functional near-infrared spectroscopy (fNIRS) signals are prone to problems caused by motion artifacts and physiological noises. These noises unfortunately reduce the fNIRS sensitivity in detecting the evoked brain activation while increasing the risk of statistical error. In fNIRS measurements, the repetitive resting-stimulus cycle (so-called block-design analysis) is commonly adapted to increase the sample number. However, these blocks are often affected by noises. Therefore, we developed an adaptive algorithm to identify, reject, and select the noise-free and/or least noisy blocks in accordance with the preset acceptance rate. The main features of this algorithm are personalized evaluation for individual data and controlled rejection to maintain the sample number. Three typical noise criteria (sudden amplitude change, shifted baseline, and minimum intertrial correlation) were adopted. Depending on the quality of the dataset used, the algorithm may require some or all noise criteria with distinct parameters. Aiming for real applications in a pediatric study, we applied this algorithm to fNIRS datasets obtained from attention deficit/hyperactivity disorder (ADHD) children as had been studied previously. These datasets were divided for training and validation purposes. A validation process was done to examine the feasibility of the algorithm regardless of the types of datasets, including those obtained under sample population (ADHD or typical developing children), intervention (nonmedication and drug/placebo administration), and measurement (task paradigm) conditions. The algorithm was optimized so as to enhance reproducibility of previous inferences. The optimum algorithm design involved all criteria ordered sequentially (0.047 mM mm of amplitude change, 0.029    mM    mm / s of baseline slope, and 0.6 × interquartile range of outlier threshold for each criterion, respectively) and presented complete reproducibility in both training and validation datasets. Compared to the visual-based rejection as done in the previous studies, the algorithm achieved 71.8% rejection accuracy. This suggests that the algorithm has robustness and potential to substitute for visual artifact-detection.

Selective Effects of Postural Control on Spatial vs. Nonspatial Working Memory: A Functional Near-Infrared Spectral Imaging Study

Background: Previous evidence suggests that postural control processing may be more related to spatial working memory (SWM) than to nonspatial working memory (NWM). Methodological discrepancies between spatial and nonspatial cognitive tasks have made direct comparisons between the two systems difficult.

Methods: To explore the neural mechanisms of SWM and NWM relative to that of postural control, participants were subjected a cognitive-posture dual-task paradigm, consisting of a 3-back letter working memory (WM) task, using physically identical stimuli with spatial and nonspatial components memorized in different sessions, and a standing balance task with a tandem stance. Additionally, there were two control sessions: a single-postural control session wherein participants pressed mouse buttons at random while standing; and a single-cognitive task control session wherein subjects completed a WM task while seated. The subjects underwent functional near-infrared spectral imaging (fNIRS) during task performance, wherein oxygenated hemoglobin concentration ([HbO]) was measured in frontal and parietal regions.

Results: Postural control reduced discernment in the SWM task significantly, but did not affect NWM task performance. fNIRS showed that postural control had a significant tendency to decrease the [HbO] in the frontal-parietal network of the left hemisphere when participants completed the SWM task. No posture-associated differences in [HbO] were observed in NWM-related areas during NWM task performance. Behavioral and fNIRS data demonstrated that postural control had a selective interaction with SWM. Specifically, postural control reduced SWM discrimination and SWM-related brain activity (frontal-parietal network), but not NWM discrimination or NWM-related brain activity. Furthermore, the multiple linear regression analysis showed that SWM, but not NWM, was an important predictor of postural control. These results suggest that postural control may share more cognitive resources with SWM than with NWM.

Feasibility of Functional Near-Infrared Spectroscopy (fNIRS) to Investigate the Mirror Neuron System: An Experimental Study in a Real-Life Situation

The mirror neuron system (MNS), mainly including the premotor cortex (PMC), inferior frontal gyrus (IFG), superior parietal lobule (SPL), and rostral inferior parietal lobule (IPL), has attracted extensive attention as a possible neural mechanism of social interaction. Owing to high ecological validity, functional near-infrared spectroscopy (fNIRS) has become an ideal approach for exploring the MNS. Unfortunately, for the feasibility of fNIRS to detect the MNS, none of the four dominant regions were found in previous studies, implying a very limited capacity of fNIRS to investigate the MNS. Here, we adopted an experimental paradigm in a real-life situation to evaluate whether the MNS activity, including four dominant regions, can be detected by using fNIRS. Specifically, 30 right-handed subjects were asked to complete a table-setting task that included action execution and action observation. A double density probe configuration covered the four regions of the MNS in the left hemisphere. We used a traditional channel-based group analysis and also a ROI-based group analysis to find which regions are activated during both action execution and action observation. The results showed that the IFG, adjacent PMC, SPL, and IPL were involved in both conditions, indicating the feasibility of fNIRS to detect the MNS. Our findings provide a foundation for future research to explore the functional role of the MNS in social interaction and various disorders using fNIRS.

Effects of levocetirizine and diphenhydramine on regional glucose metabolic changes and hemodynamic responses in the human prefrontal cortex during cognitive tasks

OBJECTIVE

Antihistamines often have sedative side effects. This was the first study to measure regional cerebral glucose (energy) consumption and hemodynamic responses in young adults during cognitive tests after antihistamine administration.

METHODS

In this double-blind, placebo-controlled, three-way crossover study, 18 healthy young Japanese men received single doses of levocetirizine 5 mg and diphenhydramine 50 mg at intervals of at least six days. Subjective feeling, task performances, and brain activity were evaluated during three cognitive tests (word fluency, two-back, and Stroop). Regional cerebral glucose consumption changes were measured using positron emission tomography with [¹⁸ F]fluorodeoxyglucose. Regional hemodynamic responses were measured using near-infrared spectroscopy.

RESULTS

Energy consumption in prefrontal regions was significantly increased after antihistamine administration, especially diphenhydramine, whereas prefrontal hemodynamic responses, evaluated with oxygenated hemoglobin levels, were significantly lower with diphenhydramine treatment. Stroop test accuracy was significantly impaired by diphenhydramine, but not by levocetirizine. There was no significant difference in subjective sleepiness.

CONCLUSIONS

Physiological "coupling" between metabolism and perfusion in the healthy human brain may not be maintained under pharmacological influence due to antihistamines. This uncoupling may be caused by a combination of increased energy demands in the prefrontal regions and suppression of vascular permeability in brain capillaries after antihistamine treatment. Further research is needed to validate this hypothesis.

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.

NIRS-Based Hyperscanning Reveals Inter-brain Neural Synchronization during Cooperative Jenga Game with Face-to-Face Communication

Functional near-infrared spectroscopy (fNIRS) is an increasingly popular technology for studying social cognition. In particular, fNIRS permits simultaneous measurement of hemodynamic activity in two or more individuals interacting in a naturalistic setting. Here, we used fNIRS hyperscanning to study social cognition and communication in human dyads engaged in cooperative and obstructive interaction while they played the game of Jenga™. Novel methods were developed to identify synchronized channels for each dyad and a structural node-based spatial registration approach was utilized for inter-dyad analyses. Strong inter-brain neural synchrony (INS) was observed in the posterior region of the right middle and superior frontal gyrus, in particular Brodmann area 8 (BA8), during cooperative and obstructive interaction. This synchrony was not observed during the parallel game play condition and the dialog section, suggesting that BA8 was involved in goal-oriented social interaction such as complex interactive movements and social decision-making. INS was also observed in the dorsomedial prefrontal cortex (dmPFC), in particular Brodmann 9, during cooperative interaction only. These additional findings suggest that BA9 may be particularly engaged when theory-of-mind (ToM) is required for cooperative social interaction. The new methods described here have the potential to significantly extend fNIRS applications to social cognitive research.

Tutorial on platform for optical topography analysis tools

Optical topography/functional near-infrared spectroscopy (OT/fNIRS) is a functional imaging technique that noninvasively measures cerebral hemoglobin concentration changes caused by neural activities. The fNIRS method has been extensively implemented to understand the brain activity in many applications, such as neurodisorder diagnosis and treatment, cognitive psychology, and psychiatric status evaluation. To assist users in analyzing fNIRS data with various application purposes, we developed a software called platform for optical topography analysis tools (POTATo). We explain how to handle and analyze fNIRS data in the POTATo package and systematically describe domain preparation, temporal preprocessing, functional signal extraction, statistical analysis, and data/result visualization for a practical example of working memory tasks. This example is expected to give clear insight in analyzing data using POTATo. The results specifically show the activated dorsolateral prefrontal cortex is consistent with previous studies. This emphasizes analysis robustness, which is required for validating decent preprocessing and functional signal interpretation. POTATo also provides a self-developed plug-in feature allowing users to create their own functions and incorporate them with established POTATo functions. With this feature, we continuously encourage users to improve fNIRS analysis methods. We also address the complications and resolving opportunities in signal analysis.

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

The incidence of traumatic brain injury (TBI) in the United States was 3.5 million cases in 2009, according to the Centers for Disease Control and Prevention. It is a contributing factor in 30.5% of injury-related deaths among civilians. Additionally, since 2000, more than 260,000 service members were diagnosed with TBI, with the vast majority classified as mild or concussive (76%). The objective assessment of TBI via imaging is a critical research gap, both in the military and civilian communities. In 2011, the Department of Defense (DoD) prepared a congressional report summarizing the effectiveness of seven neuroimaging modalities (computed tomography [CT], magnetic resonance imaging [MRI], transcranial Doppler [TCD], positron emission tomography, single photon emission computed tomography, electrophysiologic techniques [magnetoencephalography and electroencephalography], and functional near-infrared spectroscopy) to assess the spectrum of TBI from concussion to coma. For this report, neuroimaging experts identified the most relevant peer-reviewed publications and assessed the quality of the literature for each of these imaging technique in the clinical and research settings. Although CT, MRI, and TCD were determined to be the most useful modalities in the clinical setting, no single imaging modality proved sufficient for all patients due to the heterogeneity of TBI. All imaging modalities reviewed demonstrated the potential to emerge as part of future clinical care. This paper describes and updates the results of the DoD report and also expands on the use of angiography in patients with TBI.

Dysfunction of ventrolateral prefrontal cortex underlying social anxiety disorder: A multi-channel NIRS study

Social anxiety disorder (SAD) is characterized by strong fear and anxiety during social interactions. Although ventrolateral prefrontal cortex (VLPFC) activity in response to emotional stimuli is related to pathological anxiety, little is known about the relationship between VLPFC activity and social anxiety. This study aimed to investigate whether VLPFC activity was involved in SAD and whether VLPFC activity was related to the level of social anxiety. Twenty-four drug-naïve patients with SAD and 35 healthy controls underwent near-infrared spectroscopy (NIRS) scanning while performing a verbal fluency task (VFT). Results indicated that, compared to the healthy controls, the SAD patients exhibited smaller changes of oxygenated hemoglobin (oxy-Hb) concentrations in the VLPFC during the VFT. Furthermore, the right VLPFC activation was negatively correlated with social avoidance. In contrast to the latter, the healthy controls exhibited a positive correlation between changes of oxy-Hb concentrations in the bilateral VLPFC and social fear. Our findings provide evidence for VLPFC dysfunction in SAD, and indicate that the VLPFC dysfunction may contribute to the difference between normal and abnormal social anxiety.

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We investigated ventrolateral prefrontal cortex (VLPFC) activity induced by the performance of the verbal fluency task.

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Smaller changes of oxygenated hemoglobin (oxy-Hb) concentrations in bilateral VLPFC in SAD patients

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Negative correlation between changes of oxy-Hb concentrations in right VLPFC and social avoidance in SAD patients

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Positive correlation between changes of oxy-Hb concentrations in bilateral VLPFC and social fear in healthy subjects

Right temporal activation differs between melancholia and nonmelancholic depression: a multichannel near-infrared spectroscopy study

The aim of this study was to determine whether melancholia differs from nonmelancholic depression in frontotemporal functioning by means of multichannel near-infrared spectroscopy. We recruited 32 major depressive disorder (MDD) patients with melancholic features (MDD-MF), 28 MDD patients with nonmelancholic features (MDD-NMF), and 24 healthy controls. Regional hemodynamic changes induced by a verbal fluency task (VFT) were monitored, and their correlations with depressive symptoms were examined. In comparison with the controls, significant differences were observed in mean oxygenated hemoglobin (oxy-Hb) changes induced by VFT in patients with MDD-MF in 25 channels (p = 0.000-0.047) and in those with MDD-NMF in 12 channels (p = 0.000-0.023). Moreover, patients with MDD-MF had significantly smaller mean oxy-Hb changes than those with MDD-NMF in 8 channels of the right temporal region (p = 0.001-0.048). No significant correlations were observed between mean oxy-Hb changes and the Hamilton rating scale for depression (HAMD) 17 total score in both groups of patients with MDD. On examining each item of HAMD17, psychomotor retardation in patients with MDD-MF showed a significant positive correlation with mean oxy-Hb changes in the right temporal region (ch43; ρ = 0.55; p = 0.001), whereas that in patients with MDD-NMF showed a significant negative correlation with mean oxy-Hb changes in the frontal and left temporal regions in 3 channels (ρ = -0.60 to -0.53; p = 0.000-0.004). In conclusion, our results indicate that melancholia is qualitatively distinct from nonmelancholic depression both clinically and biologically.

Prefrontal correlates of approach preferences for alcohol stimuli in alcohol dependence

An approach bias for alcohol stimuli (i.e. faster approach than avoidance reactions) might facilitate relapses in alcohol dependence. Neurobiological models suggest hypersensitivity in the reward system [inter alia nucleus accumbens and orbitofrontal cortex (OFC)] to cause pathologically enhanced approach impulses towards alcohol stimuli. At the same time, in alcohol dependence, these structures are only insufficiently controlled by a hypoactive dorsolateral prefrontal cortex (DLPFC). The present study investigated the cortical aspects of this model with functional near-infrared spectroscopy in 21 alcohol-dependent in-patients and 21 healthy controls (HC; comparable in age, gender and education) during performance of the Approach-Avoidance Task (AAT) for the first time. Complementing previous findings, in reaction times (RTs), patients showed stronger approach preferences for alcohol than non-alcohol stimuli. For non-alcohol stimuli, patients even displayed avoidance preferences. The reversed pattern was found in HC. Group differences in activity of the OFC were identical to those in RTs, revealing patients to assign higher subjective value to approaching alcohol stimuli. In both groups, regulatory activity in the right DLPFC was stronger during avoiding than approaching alcohol pictures. Probable awareness of the behavioural hypotheses due to explicit task instructions and patients' deficient prefrontal function might account for this equally aligned pattern. Results are discussed with regard to recent findings revealing a reduced behavioural approach bias and risk for relapse by applying a retraining version of the AAT. Functional measurements might serve as a method for monitoring the corresponding neurobiological changes and-possibly-predicting the success of such a training.

Genetic variation in MAOA modulates prefrontal cortical regulation of approach-avoidance reactions

BACKGROUND

Regulation of automatic approach and avoidance behavior requires affective and cognitive control, which are both influenced by a genetic variation in the gene encoding Monoamine Oxidase A (termed MAOA-uVNTR).

METHODS

The current study investigated MAOA genotype as a moderator of prefrontal cortical activation measured with functional near-infrared spectroscopy (fNIRS) in 37 healthy young adults during performance of the approach-avoidance task with positive and negative pictures.

RESULTS

Carriers of the low- compared to the high-expressing genetic variant (MAOA-L vs. MAOA-H) showed increasing regulatory activity in the right dorsolateral prefrontal cortex (DLPFC) during incompatible conditions (approach negative, avoid positive). This might have been a compensatory mechanism for stronger emotional reactions as shown in previous studies and might have prevented any influence of incompatibility on behavior. In contrast, fewer errors but also lower activity in the right DLPFC during processing of negative compared to positive stimuli indicated MAOA-H carriers to have used other regulatory areas. This resulted in slower reaction times in incompatible conditions, but--in line with the known better cognitive regulation efficiency--allowed them to perform incompatible reactions without activating the DLPFC as the highest control instance. Carriers of one low- and one high-expressing allele lay as an intermediate group between the reactions of the low- and high-expressing groups.

CONCLUSIONS

The relatively small sample size and restriction to fNIRS for assessment of cortical activity limit our findings. Nevertheless, these first results suggest monoam-inergic mechanisms to contribute to interindividual differences in the two basic behavioral principles of approach and avoidance and their neuronal correlates.

Spatial registration for functional near-infrared spectroscopy: from channel position on the scalp to cortical location in individual and group analyses

Functional near-infrared spectroscopy (fNIRS) has now become widely accepted as a common functional imaging modality. In order for fNIRS to achieve genuine neuroimaging citizenship, it would ideally be equipped with functional and structural image analyses. However, fNIRS measures cortical activities from the head surface without anatomical information of the object being measured. In this review article, we will present a methodological overview of spatial registration of fNIRS data to overcome this technical drawback of fNIRS. We first introduce and explore the use of standard stereotaxic space and anatomical labeling. Second, we explain different ways of describing scalp landmarks using 10-20 based systems. Third, we describe the simplest case of fNIRS data co-registration to a subject's own MRI. Fourth, we extend the concept to fNIRS data registration of group data. Fifth, we describe probabilistic registration methods, which use a reference-MRI database instead of a subject's own MRIs, and thus enable MRI-free registration for standalone fNIRS data. Sixth, we further extend the concept of probabilistic registration to three-dimensional image reconstruction in diffuse optical tomography. Seventh, we describe a 3D-digitizer-free method for the virtual registration of fNIRS data. Eighth, we provide practical guidance on how these techniques are implemented in software. Finally, we provide information on current resources and limitations for spatial registration of child and infant data. Through these technical descriptions, we stress the importance of presenting fNIRS data on a common platform to facilitate both intra- and inter-modal data sharing among the neuroimaging community.

Prefrontal activation in response to emotional words in patients with bipolar disorder and major depressive disorder

Abnormal emotional processing is involved in the pathophysiology of bipolar disorder (BD) and major depressive disorder (MDD). However, whether the neural mechanism underlying this deficit is a trait characteristic of BD and MDD is unclear. The aim of this study was to elucidate the similarities and differences in processing of emotional stimuli between patients with BD and MDD in remission, using functional near-infrared spectroscopy (fNIRS). Thirty-two patients (16 with BD and 16 with MDD) and 20 healthy control subjects matched for age, sex, handedness, and years of education were included. An emotional Stroop task, including happy, sad, and threat words, was used. The relative oxygenated and deoxygenated hemoglobin concentration ([oxy-Hb] and [deoxy-Hb]) changes in the frontal region were measured using 52-channels of NIRS. During the threat task, compared to healthy control subjects, patients with BD showed significantly increased [oxy-Hb] in the left inferior frontal region whereas patients with MDD showed significantly increased [oxy-Hb] in the left middle frontal region. During the happy task, compared to healthy control subjects, patients with BD showed significantly decreased [oxy-Hb] in the middle frontal region in both hemispheres. Moreover, patients with BD exhibited decreased [oxy-Hb] and increased [deoxy-Hb] in the superior frontal and middle frontal regions compared to MDD in response to the happy stimulus. No significant differences in [oxy-Hb] or [deoxy-Hb] were seen between the groups during the sad task. These results suggest that abnormal neural responses to emotional stimuli in patients with mood disorders in remission may be a trait characteristic, that negative emotional stimuli are associated with similar prefrontal responses, and that positive emotional stimuli are associated with different prefrontal responses in patients with BD and MDD. These findings indicate that different neural circuits play a role in emotional processing in BD and MDD; this may aid the elucidation of the pathophysiology of these two disorders.

Correlation between prefrontal cortex activity during working memory tasks and natural mood independent of personality effects: an optical topography study

Interactions between mood and cognition have drawn much attention in the fields of psychology and neuroscience. Recent neuroimaging studies have examined a neural basis of the mood-cognition interaction that which emphasize the role of the prefrontal cortex (PFC). Although these studies have shown that natural mood variations among participants are correlated with PFC activity during cognitive tasks, they did not control for personality differences. Our aim in this study was to clarify the relationship between natural mood and PFC activity by partialling out the effects of personality. Forty healthy adults completed self-report questionnaires assessing natural mood (the Profile of Mood States) and personality (the NEO Five-Factor Inventory and the Behavioral Inhibition/Activation Systems scales). They performed verbal and spatial working memory (WM) tasks while their PFC activity was measured using optical topography, a non-invasive, low-constraint neuroimaging tool. Correlation analysis showed that the level of negative mood was inversely associated with PFC activity during the verbal WM task, which replicated our previous findings. Furthermore, the negative correlation between negative mood and PFC activity remained significant after controlling for participants' personality traits, suggesting that natural mood is an independent contributing factor of PFC activity during verbal WM tasks.

Normative database of judgment of complexity task with functional near infrared spectroscopy--application for TBI

The ability to assess frontal lobe function in a rapid, objective, and standardized way, without the need for expertise in cognitive test administration might be particularly helpful in mild traumatic brain injury (TBI), where objective measures are needed. Functional near infrared spectroscopy (fNIRS) is a reliable technique to noninvasively measure local hemodynamic changes in brain areas near the head surface. In this paper, we are combining fNIRS and frameless stereotaxy which allowed us to co-register the functional images with previously acquired anatomical MRI volumes. In our experiment, the subjects were asked to perform a task, evaluating the complexity of daily life activities, previously shown with fMRI to activate areas of the anterior frontal cortex. We reconstructed averaged oxyhemoglobin and deoxyhemoglobin data from 20 healthy subjects in a spherical coordinate. The spherical coordinate is a natural representation of surface brain activation projection. Our results show surface activation projected from the medial frontopolar cortex which is consistent with previous fMRI results. With this original technique, we will construct a normative database for a simple cognitive test which can be useful in evaluating cognitive disability such as mild traumatic brain injury.

Prefrontal activation patterns of automatic and regulated approach-avoidance reactions - a functional near-infrared spectroscopy (fNIRS) study

INTRODUCTION

The present pilot study investigated cortical processes during automatic and regulated approach-avoidance reactions for the first time. METHODS 1: In 15 healthy volunteers, prefrontal activity was measured with functional near-infrared spectroscopy (fNIRS) during performance of a joystick version of the Approach-Avoidance Task (AAT). In experiment 1, participants approached (pulled towards their body) and avoided (pushed away from their body) positive and negative pictures. RESULTS 1: Incompatible, regulated reactions (avoid positive, approach negative) compared to compatible, automatic reactions (approach positive, avoid negative) caused stronger activation in terms of a decrease of deoxygenated haemoglobin (HHb) in right dorsolateral prefrontal cortex (DLPFC) (i.e., in one of the main instances for behavioural control in humans). METHODS 2: In the context of pathologically enhanced approach tendencies in addiction disorders and of planned future studies, we presented alcohol and non-alcohol pictures in experiment 2. RESULTS 2: Here, left anterior lateral orbitofrontal cortex as part of the general reward system processing secondary rewards showed stronger activation in terms of increased oxygenated haemoglobin (O(2)Hb) during approaching compared to avoiding alcohol pictures. This difference was positively correlated with participants' expectation about beneficial effects of alcohol in terms of emotional regulation.

DISCUSSION

Despite some limitations due to the pilot character of the study, our results suggest that further combinations of the AAT and functional imaging methods will reveal detailed insight into neuronal mechanisms constituting approach-avoidance as basic behavioural principles and into specifically altered sub-processes in alcohol dependence.

Sound to language: different cortical processing for first and second languages in elementary school children as revealed by a large-scale study using fNIRS

A large-scale study of 484 elementary school children (6-10 years) performing word repetition tasks in their native language (L1-Japanese) and a second language (L2-English) was conducted using functional near-infrared spectroscopy. Three factors presumably associated with cortical activation, language (L1/L2), word frequency (high/low), and hemisphere (left/right), were investigated. L1 words elicited significantly greater brain activation than L2 words, regardless of semantic knowledge, particularly in the superior/middle temporal and inferior parietal regions (angular/supramarginal gyri). The greater L1-elicited activation in these regions suggests that they are phonological loci, reflecting processes tuned to the phonology of the native language, while phonologically unfamiliar L2 words were processed like nonword auditory stimuli. The activation was bilateral in the auditory and superior/middle temporal regions. Hemispheric asymmetry was observed in the inferior frontal region (right dominant), and in the inferior parietal region with interactions: low-frequency words elicited more right-hemispheric activation (particularly in the supramarginal gyrus), while high-frequency words elicited more left-hemispheric activation (particularly in the angular gyrus). The present results reveal the strong involvement of a bilateral language network in children's brains depending more on right-hemispheric processing while acquiring unfamiliar/low-frequency words. A right-to-left shift in laterality should occur in the inferior parietal region, as lexical knowledge increases irrespective of language.