Decreased prefrontal activation during letter fluency task in adults with pervasive developmental disorders: A near-infrared spectroscopy study

Assessing Frontal Lobe Function on Verbal Fluency and Emotion Recall in Autism Spectrum Disorder by fNIRS

This study applied the functional near-infrared spectroscopy (fNIRS) to investigate frontal activity in autism when performing verbal fluency test and emotion recall task. We recruited 32 autistic adults without intellectual disability and 30 typically-developing controls (TDC). Prefrontal hemodynamic changes were evaluated by fNIRS when the participants performed the verbal fluency test and emotion recall task. fNIRS signals in the prefrontal cortex were compared between autism and TDC. Compared to TDC, autistic adults showed comparable performance on the verbal fluency test but exhibited lower frontal activity on the vegetable category. In the verbal fluency test, left frontal activity in TDC significantly increased in the vegetable category (vs. fruit category). In the emotion recall task, left frontal activity increased significantly in TDC when recalling emotional (vs. neutral) events. This increase of left frontal activity on the more difficult works was not found in autism. Similarly, brain activities were related to test performance only in TDC but not in autism. In addition, more severe social deficits were associated with lower frontal activity when recalling emotional events, independent of autism diagnosis. Findings suggested reduced frontal activity in autism, as compared to TDC, when performing verbal fluency tests. The reduction of left frontal activation in verbal fluency test and emotion recall tasks might reflect on the social deficits of the individual. The fNIRS may potentially be applied in assessing frontal lobe function in autism and social deficits in general population. Trial registration number: NCT04010409.

Reduced prefrontal hemodynamic responses measured using near-infrared spectroscopy in adults with autism spectrum disorder

Aim

Functional neuroimaging studies have suggested that prefrontal cortex dysfunction occurs in individuals with autism spectrum disorder (ASD). Near-infrared spectroscopy (NIRS) is a noninvasive optical tool used to investigate oxygenation and hemodynamic responses in the cerebral cortex by measuring changes in oxygenated hemoglobin. Previous studies using NIRS have suggested that male children with ASD exhibit reduced hemodynamic responses in the dorsolateral prefrontal cortex; however, only a few studies examined this response in adults with ASD.

Methods

We examined the characteristics of prefrontal hemodynamic responses in 114 adults with ASD and 84 typically developing controls. Relative concentrations of oxygenated hemoglobin were measured with frontal probes every 0.1 s during the Stroop color-word task, using 24-channel NIRS.

Results

Our findings demonstrated that the oxygenated hemoglobin changes in the ASD group were significantly smaller than those in the control group at channels 19, 20, 23, and 24- located over the orbitofrontal cortex and frontal pole (p <0.05 for all three channels). The differences in oxygenated hemoglobin changes at Ch 20 were significantly correlated with the Autism-Spectrum Quotient Japanese version (AQ-J) total score and attention switching score, which is a symptom cluster of AQ-J (p = 0.043 and p = 0.009, respectively).

Conclusion

Adults with ASD have reduced prefrontal hemodynamic responses as measured using near-infrared spectroscopy and the reduced activity of the frontal pole in particular is related to reduced attentional function.

fNIRS Studies of Individuals with Speech and Language Impairment Underreport Sociodemographics: A Systematic Review

Functional near-infrared spectroscopy (fNIRS) is a promising tool for scientific discovery and clinical application. However, its utility depends upon replicable reporting. We evaluate reporting of sociodemographics in fNIRS studies of speech and language impairment and asked the following: (1) Do refereed fNIRS publications report participant sociodemographics? (2) For what reasons are participants excluded from analysis? This systematic review was preregistered with PROSPERO (CRD42022342959) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Searches in August 2022 included the terms: (a) fNIRS or functional near-infrared spectroscopy or NIRS or near-infrared spectroscopy, (b) speech or language, and (c) disorder or impairment or delay. Searches yielded 38 qualifying studies from 1997 to present. Eight studies (5%) reported at least partial information on race or ethnicity. Few studies reported SES (26%) or language background (47%). Most studies reported geographic location (100%) and gender/sex (89%). Underreporting of sociodemographics in fNIRS studies of speech and language impairment hinders the generalizability of findings. Replicable reporting is imperative for advancing the utility of fNIRS.

Effects of an online mindfulness-based intervention on brain haemodynamics: a pilot randomized controlled trial using functional near-infrared spectroscopy

Although many neuroimaging studies have evaluated changes in the prefrontal cortex during mindfulness-based interventions, most of these studies were cross-sectional studies of skilled participants or involved pre-post comparisons before and after a single session. While functional near-infrared spectroscopy is a useful tool to capture changes in the hemodynamic response of the prefrontal cortex during continuous mindfulness-based intervention, its ability to detect the accumulated effects of continuous mindfulness-based intervention is currently unclear. We investigated whether a 12-wk online mindfulness-based intervention changed the hemodynamic response of the prefrontal cortex during a verbal fluency task. Eighty-two healthy university students were randomly allocated to a 12-wk online mindfulness-based intervention group or a wait-list control group. The integral values of oxygenated hemoglobin measured using functional near-infrared spectroscopy before and after the intervention were compared to the values in the wait-list group. The intervention condition showed significantly greater functional near-infrared spectroscopy signal activation than the control condition; however, the effect sizes before and after the intervention were small. Thus, continuous mindfulness-based intervention could alter prefrontal cortex function, and functional near-infrared spectroscopy could be useful for measuring the accumulated effects of continuous mindfulness-based interventions. With a better understanding of the association between mindfulness and functional near-infrared spectroscopy signals, functional near-infrared spectroscopy can be used for biofeedback analyses.

Developmental changes in prefrontal cortex activation in children with or without autism spectrum traits on near-infrared spectroscopy

BACKGROUND

Autism spectrum disorder (ASD) ranges from mild to severe symptoms, with autistic traits possibly distributed throughout the population. However, the precise neurodevelopmental differences in children with autistic traits remain unknown.

SUBJECTS AND METHODS

Fifty-three healthy volunteers (32 male and 21 female, mean [standard deviation] age: 12.9 [2.5] years) having a normal intelligence quotient and without social impairment were divided into two groups according to scores of the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS). Subjects with or without autistic traits were placed into the high-PARS (n = 14) or low-PARS (n = 39) group, respectively. Activation of the prefrontal cortex was estimated using change in hemoglobin oxygenation concentration (Δ[oxy-Hb]) on near-infrared spectroscopy (NIRS) during a verbal fluency test. Age-related changes in prefrontal cortex activation were first assessed for each group. Then, the effects of age (elementary school age or junior/senior high school age) and PARS score on Δ[oxy-Hb] in the task were analyzed by two-way analysis of variance.

RESULTS

We observed significant positive correlations between mean Δ[oxy-Hb] and age in the prefrontal cortex region in the low-PARS group. Mean Δ[oxy-Hb] in the low-PARS group was significantly higher than in the high-PARS group. Task performance results were comparable between the groups.

CONCLUSION

In PARS-determined typically developed children, prefrontal cortex activation on NIRS correlated positively with age. In healthy volunteers without ASD but harboring autistic traits, prefrontal cortex activation was markedly lower than in normal counterparts. Our results provide biological evidence that ASD may be a pervasively distributed disorder.

Functional near-infrared spectroscopy in pediatric clinical research: Different pathophysiologies and promising clinical applications

Over its 30 years of existence, functional near-infrared spectroscopy (fNIRS) has matured into a highly versatile tool to study brain function in infants and young children. Its advantages, amongst others, include its ease of application and portability, the option to combine it with electrophysiology, and its relatively good tolerance to movement. As shown by the impressive body of fNIRS literature in the field of cognitive developmental neuroscience, the method's strengths become even more relevant for (very) young individuals who suffer from neurological, behavioral, and/or cognitive impairment. Although a number of studies have been conducted with a clinical perspective, fNIRS cannot yet be considered as a truly clinical tool. The first step has been taken in this direction by studies exploring options in populations with well-defined clinical profiles. To foster further progress, here, we review several of these clinical approaches to identify the challenges and perspectives of fNIRS in the field of developmental disorders. We first outline the contributions of fNIRS in selected areas of pediatric clinical research: epilepsy, communicative and language disorders, and attention-deficit/hyperactivity disorder. We provide a scoping review as a framework to allow the highlighting of specific and general challenges of using fNIRS in pediatric research. We also discuss potential solutions and perspectives on the broader use of fNIRS in the clinical setting. This may be of use to future research, targeting clinical applications of fNIRS in children and adolescents.

Near-infrared spectroscopy in child and adolescent neurodevelopmental disorders

Near-infrared spectroscopy (NIRS) is a noninvasive optical technique that uses the near-infrared spectrum for functional neuroimaging by measuring oxygenation and hemodynamic changes in the cerebral cortex. The advantages of NIRS include its portability and ease of application, which allows for testing with the subject in natural positions, such as sitting or standing. Since 1994, NIRS has been increasingly used to conduct functional activation studies on different psychiatric disorders, most prominently schizophrenia, depression, bipolar disorder, and neurodevelopmental disorders. However, limited information on its use among child and adolescent patients is available. We herein review recent findings obtained using NIRS measurements of the brain during cognitive tasks in neurodevelopmental disorders, such as autism spectrum disorder, attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, and Tourette's disorder. This will facilitate evaluations of the causation and treatment of prefrontal cortex dysfunctions.

Cortical Activation of Swallowing Using fNIRS: A Proof of Concept Study with Healthy Adults

The purpose of this study was to determine whether functional near-infrared spectroscopy (fNIRS) could reliably identify cortical activation patterns as healthy adults engaged in single sip and continuous swallowing tasks. Thirty-three right-handed adults completed two functional swallowing tasks, one control jaw movement task, and one rest task while being imaged with fNIRS. Swallowing tasks included a single sip of 5 mL of water via syringe and continuous straw drinking. fNIRS patches for acquisition of neuroimaging data were placed parallel over left and right hemispheres. Stimuli presentation was controlled with set time intervals and audio instructions. Using a series of linear mixed effect models, results demonstrated clear cortical activation patterns during swallowing. The continuous swallowing task demonstrated significant differences in blood oxygenation and deoxygenation concentration values across nearly all regions examined, but most notably M1 in both hemispheres. Of note is that there were areas of greater activation, particularly on the right hemisphere, when comparing the single sip swallow to the jaw movement control and rest tasks. Results from the current study support the use of fNIRS during investigation of swallowing. The utilization of healthy adults as a method for acquiring normative data is vital for comparison purposes when investigating individuals with disorders, but also in the development of rehabilitation techniques. Identifying activation areas that pertain to swallowing will have important implications for individuals requiring dysphagia therapy.

Ventrolateral prefrontal hemodynamic responses in autism spectrum disorder with and without depression

In clinical settings, autism spectrum disorder (ASD) with comorbid depression is often difficult to diagnose, and should be considered in treatment. However, to our knowledge, no functional imaging study has examined the difference between ASD adolescents with and without comorbid depression. We aimed to compare the characteristics and prefrontal brain function of ASD with and without depression in order to identify a biological marker that can be used to detect the difference. Twenty-eight drug-naïve adolescents with ASD (14 ASD with and 14 ASD without depression) and 14 age- and gender-matched adolescents with typical development were evaluated using several variables. These included intelligence quotient, autism quotient, depression severity using the Beck Depression Inventory 2nd edition (BDI-II), and level of social functioning using the Social Adaptation Self-evaluation Scale (SASS). In addition, frontotemporal hemodynamic responses during a verbal fluency task (VFT) were measured using functional near-infrared spectroscopy (fNIRS). The ASD group, including both of the ASD with and ASD without depression groups, showed smaller hemodynamic responses than the typical development group in portions of the left dorsolateral prefrontal cortex (DLPFC), bilateral ventrolateral prefrontal cortex (VLPFC) and anterior part of the temporal cortex (aTC) during the VFT. Moreover, the smaller hemodynamic responses in the right VLPFC during the VFT in the ASD group were associated with the worse BDI-II and SASS scores. Furthermore, the ASD with depression group showed smaller hemodynamic responses in the right VLPFC during the VFT than the ASD without depression group in a direct comparison. Adolescents with ASD showed reduced activation in broad frontotemporal regions during a cognitive task compared with those with typical development. More specifically, the right VLPFC activation reflected the level of self-estimated depression and social functioning in the ASD subjects, and could be used to discriminate between ASD adolescents with and without depression.

Clinical Applications of Functional Near-Infrared Spectroscopy in Children and Adolescents with Psychiatric Disorders

The purpose of this review is to examine the clinical use of functional near-infrared spectroscopy (fNIRS) in children and adolescents with psychiatric disorders. Many studies have been conducted using objective evaluation tools for psychiatric evaluation, such as predicting psychiatric symptoms and treatment responses. Compared to other tools, fNIRS has the advantage of being a noninvasive, inexpensive, and portable method and can be used with patients in the awake state. This study mainly focused on its use in patients with attention-deficit/hyperactivity disorder and autism spectrum disorder. We hope that research involving fNIRS will be actively conducted in various diseases in the future.

Functional Near-Infrared Spectroscopy in the Study of Speech and Language Impairment Across the Life Span: A Systematic Review

Purpose Functional brain imaging is playing an increasingly important role in the diagnosis and treatment of communication disorders, yet many populations and settings are incompatible with functional magnetic resonance imaging and other commonly used techniques. We conducted a systematic review of neuroimaging studies using functional near-infrared spectroscopy (fNIRS) with individuals with speech or language impairment across the life span. We aimed to answer the following question: To what extent has fNIRS been used to investigate the neural correlates of speech-language impairment? Method This systematic review was preregistered with PROSPERO, the international prospective register of systematic reviews (CRD42019136464). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for preferred reporting items for systematic reviews. The database searches were conducted between February and March of 2019 with the following search terms: (a) fNIRS or functional near-infrared spectroscopy or NIRS or near-infrared spectroscopy, (b) speech or language, and (c) disorder or impairment or delay. Results We found 34 fNIRS studies that involved individuals with speech or language impairment across nine categories: (a) autism spectrum disorders; (b) developmental speech and language disorders; (c) cochlear implantation and deafness; (d) dementia, dementia of the Alzheimer's type, and mild cognitive impairment; (e) locked-in syndrome; (f) neurologic speech disorders/dysarthria; (g) stroke/aphasia; (h) stuttering; and (i) traumatic brain injury. Conclusions Though it is not without inherent challenges, fNIRS may have advantages over other neuroimaging techniques in the areas of speech and language impairment. fNIRS has clinical applications that may lead to improved early and differential diagnosis, increase our understanding of response to treatment, improve neuroprosthetic functioning, and advance neurofeedback.

Delayed prefrontal hemodynamic response associated with suicide risk in autism spectrum disorder

Adults diagnosed with Autism spectrum disorder (ASD) are at high risk of experiencing suicidality compared with other clinical groups. Recently, near-infrared spectroscopy (NIRS) studies have investigated the association between frontotemporal functional abnormalities and suicidality in patients with mood disorders. However, whether these prefrontal hemodynamic responses are associated with suicide vulnerability in individuals with ASD remains unclear. Here, we used 24-channel NIRS to examine the characteristics of prefrontal hemodynamic responses during a verbal fluency task in 20 adults with ASD and in age-, sex-, and intelligence quotient-matched healthy controls. In addition, we used Spearman's correlation analysis to identify the relationship between the time-course of prefrontal hemodynamic activation and the current suicide risk in patients with ASD. We found no significant differences between the verbal fluency task-induced prefrontal hemodynamic responses in the ASD vs. control group. However, we found a significant positive correlation between the current suicide risk score and the time-course of prefrontal hemodynamic activation in the ASD group. Thus, the 24-channel NIRS system appears to be useful in assessing suicide risk in individuals with ASD.

Performance Monitoring via Functional Near Infrared Spectroscopy for Virtual Reality Based Basic Life Support Training

The use of serious game tools in training of medical professions is steadily growing. However, there is a lack of reliable performance assessment methods to evaluate learner’s outcome. The aim of this study is to determine whether functional near infrared spectroscopy (fNIRS) can be used as an additional tool for assessing the learning outcome of virtual reality (VR) based learning modules. The hypothesis is that together with an improvement in learning outcome there would be a decrease in the participants’ cerebral oxygenation levels measured from the prefrontal cortex (PFC) region and an increase of participants’ serious gaming results. To test this hypothesis, the subjects were recruited and divided into four groups with different combinations of prior virtual reality experience and prior Basic Life Support (BLS) knowledge levels. A VR based serious gaming module for teaching BLS and 16-Channel fNIRS system were used to collect data from the participants. Results of the participants’ scores acquired from the serious gaming module were compared with fNIRS measures on the initial and final training sessions. Kruskal Wallis test was run to determine any significant statistical difference between the groups and Mann–Whitney U test was utilized to obtain pairwise comparisons. BLS training scores of the participants acquired from VR based serious game’s the learning management system and fNIRS measurements revealed decrease in use of resources from the PFC, but increase in behavioral performance. Importantly, brain-based measures can provide an additional quantitative metric for trainee’s expertise development and can assist the medical simulation instructors.

Reduced prefrontal hemodynamic response in pediatric autism spectrum disorder measured with near-infrared spectroscopy

BACKGROUND

Functional neuroimaging studies suggest that prefrontal cortex dysfunction is present in people with autism spectrum disorder (ASD). Near-infrared spectroscopy is a noninvasive optical tool for examining oxygenation and hemodynamic changes in the cerebral cortex by measuring changes in oxygenated hemoglobin.

METHODS

Twelve drug-naïve male participants, aged 7-15 years and diagnosed with ASD according to DSM-5 criteria, and 12 age- and intelligence quotient (IQ)-matched healthy control males participated in the present study after giving informed consent. Relative concentrations of oxyhemoglobin were measured with frontal probes every 0.1 s during the Stroop color-word task, using 24-channel near-infrared spectroscopy.

RESULTS

Oxyhemoglobin changes during the Stroop color-word task in the ASD group were significantly smaller than those in the control group at channels 12 and 13, located over the dorsolateral prefrontal cortex (FDR-corrected P: 0.0021-0.0063).

CONCLUSION

The results suggest that male children with ASD have reduced prefrontal hemodynamic responses, measured with near-infrared spectroscopy.

Genetic influences on prefrontal activation during a verbal fluency task in children: A twin study using near-infrared spectroscopy

OBJECTIVE

The genetic and environmental influences on prefrontal function in childhood are underinvestigated due to the difficulty of measuring prefrontal function in young subjects, for which near-infrared spectroscopy (NIRS) is a suitable functional neuroimaging technique that facilitates the easy and noninvasive measurement of blood oxygenation in the superficial cerebral cortices.

METHOD

Using a two-channel NIRS arrangement, we measured changes in bilateral prefrontal blood oxygenation during a category version of the verbal fluency task (VFT) in 27 monozygotic twin pairs and 12 same-sex dizygotic twin pairs ages 5-17 years. We also assessed the participant's full-scale intelligence quotient (FIQ) and retrieved parental socioeconomic status (SES). Classical structured equation modeling was used to estimate the heritability.

RESULTS

The heritability of VFT-related brain activation was estimated to be 44% and 37% in the right and left prefrontal regions, respectively. We also identified a significant genetic contribution (74%) to FIQ, but did not to VFT task performance. Parental SES was not correlated with FIQ, task performance, or task-related prefrontal activation.

CONCLUSIONS

This finding provides further evidence that variance in prefrontal function has a genetic component since childhood and highlights brain function, as measured by NIRS, as a promising candidate for endophenotyping neurodevelopmental disorders.

Reduced prefrontal hemodynamic response in adult attention-deficit hyperactivity disorder as measured by near-infrared spectroscopy

AIM

Recent developments in near-infrared spectroscopy (NIRS) have enabled non-invasive clarification of brain functions in psychiatric disorders. In pediatric attention-deficit hyperactivity disorder (ADHD), reduced prefrontal hemodynamic responses have been observed with NIRS repeatedly. However, there are few studies of adult ADHD by multi-channel NIRS. Therefore, in this study, we used multi-channel NIRS to examine the characteristics of prefrontal hemodynamic responses during the Stroop Color-Word Task (SCWT) in adult ADHD patients and in age- and sex-matched control subjects.

METHODS

Twelve treatment-naïve adults with ADHD and 12 age- and sex-matched healthy control subjects participated in the present study after giving consent. We used 24-channel NIRS to measure the oxygenated hemoglobin (oxy-Hb) changes at the frontal lobes of participants during the SCWT. We compared the oxy-Hb changes between adults with ADHD and control subjects by t-tests with Bonferroni correction.

RESULTS

During the SCWT, the oxy-Hb changes observed in the ADHD group were significantly smaller than those in the control group in channels 11, 16, 18, 21, 22, 23, and 24, corresponding to the prefrontal cortex. At channels 16, 21, 23, and 24 of the ADHD group, there were negative correlations between the symptomatic severity and the oxy-Hb changes.

CONCLUSION

The present study suggests that adults with ADHD have reduced prefrontal hemodynamic response as measured by NIRS.

Differences in frontotemporal dysfunction during social and non-social cognition tasks between patients with autism spectrum disorder and schizophrenia

Although literature evidence suggests deficits in social and non-social cognition in patients with autistic spectrum disorder (ASD) and schizophrenia (SCZ), the difference in neural correlates of the impairments between the two disorders has not been elucidated. We examined brain function in response to a non-social cognition and a social cognition task using functional near-infrared spectroscopy (fNIRS) in 13 patients with ASD, 15 patients with SCZ, and 18 healthy subjects. We assessed the brain function of participants using a verbal fluency task and an emotional facial recognition task. The patients with ASD showed significantly reduced brain activation in the left frontotemporal area during both tasks compared to healthy subjects. The patients with ASD with larger score in ‘attention to detail’ in the autism spectrum quotient showed lower activation of the left frontotemporal area during the two tasks. The patients with SCZ showed significantly reduced activation, compared to healthy subjects, and greater activation, compared to patients with ASD, in the area during the verbal fluency task. The patients with SCZ with more severe symptoms had lower brain activation during the task in this area. Our results suggest that two distinct areas are involved in the distinctive brain pathophysiology relevant to cognitive processing in patients with ASD and SCZ.

Application of Functional Near-Infrared Spectroscopy to the Study of Brain Function in Humans and Animal Models

Functional near-infrared spectroscopy (fNIRS) is a noninvasive optical imaging technique that indirectly assesses neuronal activity by measuring changes in oxygenated and deoxygenated hemoglobin in tissues using near-infrared light. fNIRS has been used not only to investigate cortical activity in healthy human subjects and animals but also to reveal abnormalities in brain function in patients suffering from neurological and psychiatric disorders and in animals that exhibit disease conditions. Because of its safety, quietness, resistance to motion artifacts, and portability, fNIRS has become a tool to complement conventional imaging techniques in measuring hemodynamic responses while a subject performs diverse cognitive and behavioral tasks in test settings that are more ecologically relevant and involve social interaction. In this review, we introduce the basic principles of fNIRS and discuss the application of this technique in human and animal studies.

Comparison of Hemodynamic Responses in the Prefrontal Cortex According to Differences in Self-Efficacy

Although self-efficacy has been used extensively in the field of nursing (e.g., as an outcome measure of nursing interventions), its underlying nature is poorly understood. Investigation of the relationship between self-efficacy and brain activation will help explain the fundamental nature of self-efficacy. In this study, we compared prefrontal activation measured with near-infrared spectroscopy (NIRS) across 89 undergraduate students categorized into three groups based on their General Self-Efficacy Scale scores: low self-efficacy ( n = 59), moderate self-efficacy ( n = 17), and high self-efficacy ( n = 13). Changes in the hemoglobin levels of the prefrontal cortex (PFC) during a verbal fluency task were assessed using two-channel NIRS. Significant differences in the oxygenated hemoglobin (oxy-Hb) level of the left PFC (LPFC) were observed via analysis of variance. Post hoc Tukey’s test showed a significant difference only between low self-efficacy and moderate self-efficacy groups. We found a medium between-group effect size in the moderate self-efficacy group versus the low self-efficacy group for the changes in oxy-Hb levels of the LPFC ( d = .78; 95% confidence interval for effect size [0.22, 1.33]). No significant between-group differences were observed with respect to changes in the oxy-Hb in the right PFC. The results indicate less left prefrontal activation in the low self-efficacy group than in the moderate self-efficacy group. These findings provide evidence to support the fundamental nature of self-efficacy.

fNIRS Studies on Hemispheric Asymmetry in Atypical Neural Function in Developmental Disorders

Functional lateralization is highly replicable trait of human neural system. Many previous studies have indicated the possibility that people with attention-deficits/hyperactivity-disorder (ADHD) and autism spectrum disorder (ASD) show hemispheric asymmetry in atypical neural function. However, despite the abundance of relevant studies, there is still ongoing controversy over this issue. In the present mini-review, we provide an overview of the hemispheric asymmetry in atypical neural function observed in fNIRS studies on people with these conditions. Atypical neural function is defined as group-difference in the task-related concentration change of oxygenated hemoglobin. The existing fNIRS studies give support to the right-lateralized atypicalty in children with ADHD. At the same time, we did not find clear leftward-lateralization in atypical activation in people with ASD. On the basis of these, we discuss the current states and limitation of the existing studies.

Event-related potentials (ERPs) and hemodynamic (functional near-infrared spectroscopy, fNIRS) as measures of schizophrenia deficits in emotional behavior

Recent research evidences supported the significant role of multimethodological neuroscientific approach for the diagnosis and the rehabilitative intervention in schizophrenia. Indeed both electrophysiological and neuroimaging measures in integration each other appear able to furnish a deep overview of the cognitive and affective behavior in schizophrenia patients (SPs). The aim of the present review is focused on the emotional dysfunctional response taking into account the multimeasures for emotional behavior, i.e., the event-related potentials (ERPs) and the hemodynamic profile functional near-infrared spectroscopy (fNIRS). These measures may be considered as predictive measures of the SPs' deficits in emotional behavior. The integration between ERP and fNIRS may support both the prefrontal cortical localization anomaly and the attentional bias toward some specific emotional conditions (mainly negative).

Increased prefrontal hemodynamic change after atomoxetine administration in pediatric attention-deficit/hyperactivity disorder as measured by near-infrared spectroscopy

AIM

Atomoxetine, approved in Japan for the treatment of pediatric attention-deficit/hyperactivity disorder (ADHD) in April 2009, is a nonstimulant that is thought to act presynaptically via the inhibition of norepinephrine reuptake. Near-infrared spectroscopy is a non-invasive optical tool that can be used to study oxygenation and hemodynamic changes in the cerebral cortex. The present study examined the effects of a clinical dose of atomoxetine on changes in prefrontal hemodynamic activity in children with ADHD, as measured by near-infrared spectroscopy using the Stroop Color-Word Task.

METHODS

Ten children with ADHD participated in the present study. We used 24-channel near-infrared spectroscopy to measure the relative concentrations of oxyhemoglobin in the frontal lobes of participants in the drug-naïve condition and those who had received atomoxetine for 8 weeks. Measurements were conducted every 0.1 s during the Stroop Color-Word Task. We used the ADHD Rating Scale-IV-Japanese version (Home Version) to evaluate ADHD symptoms.

RESULTS

We found a significant decrease in ADHD Rating Scale-IV-Japanese version scores, from 30.7 to 22.6 (P=0.003). During the Stroop Color-Word Task, we found significantly higher levels of oxyhemoglobin changes in the prefrontal cortex of participants in the atomoxetine condition compared with those in the drug-naïve condition.

CONCLUSIONS

This increase in oxyhemoglobin changes might indicate an intensified prefrontal hemodynamic response induced by atomoxetine. Near-infrared spectroscopy is a sensitive tool for measuring the pharmacological effects of atomoxetine in children with ADHD.

Frontal lobe function and social adjustment in patients with schizophrenia: near-infrared spectroscopy

OBJECTIVE

The study evaluated relationships between frontal lobe function in patients with schizophrenia and both their social adjustment and medication, using 22-channel near-infrared spectroscopy (NIRS).

METHODS

One hundred ninety-nine stable patients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision schizophrenia, whose medication had not been changed within the preceding 3 months and who were able to visit our clinics for NIRS, were the study subjects. As a comparator, 144 healthy volunteers who underwent a physical examination and the Mini-International Neuropsychiatric Interview also received NIRS.

RESULTS

The main outcomes evaluated were frontal lobe oxyhemoglobin concentration (OxHb) measured by NIRS, current medication, social adjustment, and scores on the Brief Psychiatric Rating Scale. The OxHb in schizophrenic patients (0.878 ± 1.1801 mM mm; n = 199) was significantly lower than that in the healthy volunteers (2.085 ± 1.7480 mM mm: n = 100) (p < 0.001). NIRS-measured OxHb values reflected disease severity and degree of social adjustment in schizophrenic patients.

CONCLUSIONS

Patients with higher OxHb values were socially better adjusted than those with lower OxHb values. Patients treated with atypical antipsychotic monotherapy showed lower treatment resistance and better social adjustment than those treated with combination therapy.

Near infrared spectroscopy study of the frontopolar hemodynamic response and depressive mood in children with major depressive disorder: a pilot study

AIM

The aim of this study was to evaluate the frontopolar hemodynamic response and depressive mood in children with mild or moderate major depressive disorder during six weeks treatment without medication.

METHODS

The subjects were 10 patients with mild or moderate depression. They were depressive drug-naive children and adolescents. The scores of Depression Self Rating Scale (DSRS), the results of the Verbal Fluency Test (VFT), and the concentrations of oxy-hemoglobin (Oxy-Hb) of frontal pole brain assessed by two-channel near infrared spectroscopy (NIRS) after six weeks of treatment was compared with those of initial treatment.

RESULTS

The score of DSRS was significantly reduced after six weeks of initial treatment (p<0.001, t-test). The word number of VFT was not significantly changed after six weeks of treatment. The oxy-Hb concentration significantly increased after six weeks of treatment (p<0.001, t-test).

CONCLUSIONS

This study demonstrated that the concentration of oxy-Hb of frontopolar cortex in children with mild and moderate depression improved along with their depressive mood. These results suggested that concentration of oxy-Hb using NIRS may be used as the state maker for change in depressive mood of children having depression, similar to that in adults.

Lower prefrontal activity in adults with obsessive-compulsive disorder as measured by near-infrared spectroscopy

Recent developments in near-infrared spectroscopy (NIRS) have enabled the non-invasive elucidation of the neurobiological underpinnings of psychiatric disorders. Functional neuroimaging studies in human patients have suggested that the frontal cortex and subcortical structures may play a role in the pathophysiology of obsessive-compulsive disorder (OCD). Here we used NIRS to investigate neurobiological function in 12 patients with OCD and 12 age- and sex-matched, healthy control subjects. The relative concentrations of oxyhemoglobin (oxy-Hb) were measured with prefrontal probes every 0.1 s, during performance of a Stroop color-word task, using 24-channel NIRS. Oxy-Hb changes in the prefrontal cortex of the OCD group were significantly smaller than those in the control group, especially in the left lateral prefrontal cortex. These results suggest that patients with OCD have reduced prefrontal hemodynamic responses as measured by NIRS.

Usefulness of near-infrared spectroscopy to detect brain dysfunction in children with autism spectrum disorder when inferring the mental state of others

AIMS

The purpose of this study was to examine the usefulness of near-infrared spectroscopy (NIRS) for identifying abnormalities in prefrontal brain activity in children with autism spectrum disorders (ASD) as they inferred the mental states of others.

METHODS

The subjects were 16 children with ASD aged between 8 and 14 years and 16 age-matched healthy control children. Oxygenated hemoglobin concentration was measured in the subject's prefrontal brain region on NIRS during tasks expressing a person's mental state (MS task) and expressing an object's characteristics (OC task).

RESULTS

There was a significant main effect of group (ASD vs control), with the control group having more activity than the ASD group. But there was no significant main effect of task (MS task vs OC task) or hemisphere (right vs left). Significant interactions of task and group were found, with the control group showing more activity than the ASD group during the MS task relative to the OC task.

CONCLUSIONS

NIRS showed that there was lower activity in the prefrontal brain area when children with ASD performed MS tasks. Therefore, clinicians might be able to use NIRS and these tasks for conveniently detecting brain dysfunction in children with ASD related to inferring mental states, in the clinical setting.

Reduced prefrontal hemodynamic response in pediatric obsessive-compulsive disorder as measured by near-infrared spectroscopy

Recent developments in near-infrared spectroscopy (NIRS) have enabled non-invasive clarification of brain functions in psychiatric disorders. Functional neuroimaging studies of patients with obsessive-compulsive disorder (OCD) have suggested that the frontal cortex and subcortical structures may play a role in the pathophysiology of the disorder. Twelve treatment-naïve children with OCD and 12 age- and sex-matched healthy control subjects participated in the present study after giving consent. The relative concentrations of oxyhemoglobin (oxy-Hb) were measured with prefrontal probes every 0.1 s during the Stroop color-word task, using 24-channel NIRS machines. During the Stroop color-word task, the oxy-Hb changes in the OCD group were significantly smaller than those in the control group in the prefrontal cortex, especially in the frontopolar cortex. The present study suggests that children with OCD have reduced prefrontal hemodynamic response as measured by NIRS.

Multichannel fNIRS assessment of overt and covert confrontation naming

Confrontation naming tasks assess cognitive processes involved in the main stage of word production. However, in fMRI, the occurrence of movement artifacts necessitates the use of covert paradigms, which has limited clinical applications. Thus, we explored the feasibility of adopting multichannel functional near-infrared spectroscopy (fNIRS) to assess language function during covert and overt naming tasks. Thirty right-handed, healthy adult volunteers underwent both naming tasks and cortical hemodynamics measurement using fNIRS. The overt naming task recruited the classical left-hemisphere language areas (left inferior frontal, superior and middle temporal, precentral, and postcentral gyri) exemplified by an increase in the oxy-Hb signal. Activations were bilateral in the middle and superior temporal gyri. However, the covert naming task recruited activation only in the left-middle temporal gyrus. The activation patterns reflected a major part of the functional network for overt word production, suggesting the clinical importance of fNIRS in the diagnosis of aphasic patients.

Functional near-infrared spectroscopy for the assessment of speech related tasks

Over the past years functional near-infrared spectroscopy (fNIRS) has substantially contributed to the understanding of language and its neural correlates. In contrast to other imaging techniques, fNIRS is well suited to study language function in healthy and psychiatric populations due to its cheap and easy application in a quiet and natural measurement setting. Its relative insensitivity for motion artifacts allows the use of overt speech tasks and the investigation of verbal conversation. The present review focuses on the numerous contributions of fNIRS to the field of language, its development, and related psychiatric disorders but also on its limitations and chances for the future.

Sleep problems and early developmental delay: implications for early intervention programs

Sleep disorders negatively impact behavior, cognition, and growth--the same areas targeted by early intervention. Conversely, developmental delays and disabilities may themselves precipitate sleep disorders. Young children with developmental delays experience sleep disorders at a higher rate than do typically developing children; the most common types are difficulties initiating or maintaining sleep and sleep disordered breathing. To date, attention has been focused on sleep problems in children with specific conditions (e.g., autism, genetic syndromes, prematurity, and seizure disorder). The authors review evidence of sleep problems' broader impact across the range of children screened for early intervention. Eligibility evaluations for early intervention address the five developmental domains: adaptive, motor, cognitive, communication, and socioemotional. Disordered sleep may be symptomatic of socioemotional and adaptive problems. Assessing sleep problems within the evaluation may help establish eligibility for early intervention services and would maximize developmental potential by ensuring timely identification, referral, and treatment.

Multi-channel near-infrared spectroscopy shows reduced activation in the prefrontal cortex during facial expression processing in pervasive developmental disorder

AIM

The purpose of the present study was to investigate whether individuals with pervasive developmental disorders (PDD) show differential activation during an emotional activation task compared with age- and sex-matched controls, by measuring changes in the concentration of oxygenated (oxyHb) and deoxygenated (deoxyHb) hemoglobin, using near-infrared spectroscopy (NIRS).

METHODS

Fourteen patients with PDD and 14 age- and sex-matched healthy controls participated in the study. The relative changes of concentrations of oxyHb and deoxyHb were measured on NIRS during an implicit processing task of fearful expression using Japanese standard faces.

RESULTS

PDD patients had significantly reduced oxyHb changes in the prefrontal cortex (PFC) compared to healthy controls.

CONCLUSION

PFC dysfunction may exist in PDD.

Developmental changes of prefrontal activation in humans: a near-infrared spectroscopy study of preschool children and adults

Previous morphological studies indicated that development of the human prefrontal cortex (PFC) appears to continue into late adolescence. Although functional brain imaging studies have sought to determine the time course of functional development of the PFC, it is unclear whether the developmental change occurs after adolescence to adulthood and when it achieves a peak because of the narrow or discontinuous range in the participant's age. Moreover, previous functional studies have not focused on the anterior frontal region, that is, the frontopolar regions (BA9/10). Thus, the present study investigated the developmental change in frontopolar PFC activation associated with letter fluency task by using near-infrared spectroscopy (NIRS), in subjects from preschool children to adults. We analyzed the relative concentration of hemoglobin (ΔHb) in the prefrontal cortex measured during the activation task in 48 typically-developing children and adolescents and 22 healthy adults. Consistent with prior morphological studies, we found developmental change with age in the children/adolescents. Moreover, the average Δoxy-Hb in adult males was significantly larger than that in child/adolescent males, but was not true for females. These data suggested that functional development of the PFC continues into late adolescence. Although the developmental change of the frontopolar PFC was independent of gender from childhood to adolescence, in adulthood a gender difference was shown.

Frontal activation and connectivity using near-infrared spectroscopy: verbal fluency language study

Near infrared spectroscopy (NIRS) is an optical technique with high temporal resolution and reasonably good spatial resolution, which allows non invasive measurement of the blood oxygenation of tissue. The current work is focused in assessing and correlating brain activation, connectivity and cortical lateralization of the frontal cortex in response to language-based stimuli, using NIRS. Experimental studies were performed on 15 normal right-handed adults, wherein the participants were presented with a verbal fluency task. The hemodynamic responses in the pre- and anterior frontal cortex were assessed in response to a Word generation task in comparison to the baseline random Jaw movement and Rest conditions. The functional connectivity analysis was performed using zero-order correlations and the cortical lateralization was evaluated as well. An increase in oxy- and a decrease in deoxy-hemoglobin were observed during verbal fluency task in the frontal cortex. Unlike in the pre-frontal cortex, the hemodynamic response in the anterior frontal during verbal fluency task was not significantly different from that during random Jaw movement. Bilateral activation and symmetrical connectivity were observed in the pre-frontal cortex, independent of the stimuli presented. A left cortical dominance and asymmetry connectivity was observed in the anterior frontal during the verbal fluency task. The work is focused to target the pediatric epileptic populations in the future, where understanding the brain functionality (activation, connectivity, and dominance) in response to language is essential as a part of the pre-surgical evaluation in a clinical environment.

Dieting tendency and eating behavior problems in eating disorder correlate with right frontotemporal and left orbitofrontal cortex: a near-infrared spectroscopy study

Frontal lobe dysfunctions have been implicated as one of the pathophysiological bases in eating disorder (ED). Neural substrates of ED have been examined in neuroimaging studies employing symptom-related stimuli, such as food and body-image distortion, but with inconsistent results because of differences in study design, task, and stimulus used. In order to elucidate frontal lobe dysfunction correlates of clinical symptoms in ED, we examined the frontal lobe function during a cognitive task, not a symptom-related task, using near-infrared spectroscopy (NIRS), which is suitable for the functional neuroimaging study of ED because of its complete noninvasiveness and natural measurement setting. Regional hemodynamic changes were monitored during a verbal fluency task (letter version) using a 52-channel NIRS apparatus in 27 female ED patients and 27 matched healthy controls, and their correlations with clinical symptoms assessed using the Eating Attitude Scale (EAT-26) were examined. Regional hemodynamic changes were significantly smaller in the ED group than in the control group in the bilateral orbitofrontal and right frontotemporal regions, and negatively correlated with dieting tendency scores in EAT-26 in the right frontotemporal regions and with the eating restriction and binge eating scores in the left orbitofrontal regions. The clinical symptoms of ED are considered to consist of two components: dieting tendency that correlates with the right frontotemporal cortex and eating behavior problems that correlate with left the orbitofrontal cortex.

Effects of sedative and nonsedative antihistamines on prefrontal activity during verbal fluency task in young children: a near-infrared spectroscopy (NIRS) study

INTRODUCTION

Antagonists of histamine H(1) receptors (antihistamines) are widely used for the treatment of allergic disorders in children. These drugs' sedative effect on brain function, however, has been mostly examined in adults.

OBJECTIVE

The objective of this study was to examine the effects of anitihistamines on prefrontal cortex activity in young children using near-infrared spectroscopy (NIRS), a novel brain-imaging method.

MATERIALS AND METHODS

In 15 healthy children (mean age, 7.7 years), we examined changes of oxygenated hemoglobin concentration in the prefrontal cortex while they performed a verbal fluency task 3 h after taking a sedating antihistamine (ketotifen), nonsedating antihistamine (epinastine), or placebo.

RESULTS

Ketotifen significantly impaired behavioral performance and cortical activation at the lateral prefrontal cortex compared with placebo. There were no sedative effects on neural response or behavioral performance after epinastine administration.

CONCLUSIONS

NIRS revealed that sedating and nonsedating antihistamines exert differential effects on brain hemodynamic response in young children.

Impaired prefrontal hemodynamic maturation in autism and unaffected siblings

Background

Dysfunctions of the prefrontal cortex have been previously reported in individuals with autism spectrum disorders (ASD). Previous studies reported that first-degree relatives of individuals with ASD show atypical brain activity during tasks associated with social function. However, developmental changes in prefrontal dysfunction in ASD and genetic influences on the phenomena remain unclear. In the present study, we investigated the change in hemoglobin concentration in the prefrontal cortex as measured with near-infrared spectroscopy, in children and adults with ASD during the letter fluency test. Moreover, to clarify the genetic influences on developmental changes in the prefrontal dysfunction in ASD, unaffected siblings of the ASD participants were also assessed.

Methodology/Principal Findings

Study participants included 27 individuals with high-functioning ASD, age- and IQ-matched 24 healthy non-affected siblings, and 27 unrelated healthy controls aged 5 to 39 years. The relative concentration of hemoglobin ([Hb]) in the prefrontal cortex was measured during the letter fluency task. For children, neither the [oxy-Hb] change during the task nor task performances differed significantly among three groups. For adults, the [oxy-Hb] increases during the task were significantly smaller in the bilateral prefrontal cortex in ASD than those in control subjects, although task performances were similar. In the adult siblings the [oxy-Hb] change was intermediate between those in controls and ASDs.

Conclusion/Significance

Although indirectly due to a cross-sectional design, the results of this study indicate altered age-related change of prefrontal activity during executive processing in ASD. This is a first near-infrared spectroscopy study that implies alteration in the age-related changes of prefrontal activity in ASD and genetic influences on the phenomena.

Association between catechol-O-methyltrasferase Val108/158Met genotype and prefrontal hemodynamic response in schizophrenia

Background

“Imaging genetics” studies have shown that brain function by neuroimaging is a sensitive intermediate phenotype that bridges the gap between genes and psychiatric conditions. Although the evidence of association between functional val108/158met polymorphism of the catechol-O-methyltransferase gene (COMT) and increasing risk for developing schizophrenia from genetic association studies remains to be elucidated, one of the most topical findings from imaging genetics studies is the association between COMT genotype and prefrontal function in schizophrenia. The next important step in the translational approach is to establish a useful neuroimaging tool in clinical settings that is sensitive to COMT variation, so that the clinician could use the index to predict clinical response such as improvement in cognitive dysfunction by medication. Here, we investigated spatiotemporal characteristics of the association between prefrontal hemodynamic activation and the COMT genotype using a noninvasive neuroimaging technique, near-infrared spectroscopy (NIRS).

Methodology/Principal Findings

Study participants included 45 patients with schizophrenia and 60 healthy controls matched for age and gender. Signals that are assumed to reflect regional cerebral blood volume were monitored over prefrontal regions from 52-channel NIRS and compared between two COMT genotype subgroups (Met carriers and Val/Val individuals) matched for age, gender, premorbid IQ, and task performance. The [oxy-Hb] increase in the Met carriers during the verbal fluency task was significantly greater than that in the Val/Val individuals in the frontopolar prefrontal cortex of patients with schizophrenia, although neither medication nor clinical symptoms differed significantly between the two subgroups. These differences were not found to be significant in healthy controls.

Conclusions/Significance

These data suggest that the prefrontal NIRS signals can noninvasively detect the impact of COMT variation in patients with schizophrenia. NIRS may be a promising candidate translational approach in psychiatric neuroimaging.

Functional near-infrared spectroscopy reveals altered hemispheric laterality in relation to schizotypy during verbal fluency task

Previous functional neuroimaging studies have demonstrated that patients with schizophrenia and those with schizotypal personality disorder (SPD) show reduced laterality, or relative right hemispheric dominance, during the performance of cognitive activation tasks; however, neuroimaging studies looking at non-clinical schizotypy have been few. We have recently reported that schizotypal traits at a non-clinical level are associated with right prefrontal dominance during a letter version of the verbal fluency task (VFT), but it is unknown whether such relationship between schizotypy and functional laterality would be observed across various cognitive tasks. Here we examined the relationships of schizotypal traits as measured by the Schizotypal Personality Questionnaire (SPQ) in healthy adults with hemispheric lateralization of prefrontal activation during letter and category VFTs, using near-infrared spectroscopy. Thirty-two participants were divided into high- (n=16) and low- (n=16) SPQ groups by the median split of the total SPQ score. The high-SPQ group, but not low-SPQ group, showed significantly right-greater-than-left asymmetry of prefrontal activation during letter VFT, whereas such pronounced hemispheric asymmetry in relation to schizotypy was not found during category VFT. These results indicate that non-clinical schizotypy is related to right prefrontal preference during the letter version of VFT in particular, suggesting that the association between schizotypal traits and functional laterality may vary depending on cognitive activation tasks.

Reduced frontopolar activation during verbal fluency task in schizophrenia: a multi-channel near-infrared spectroscopy study

Functional neuroimaging studies to date have shown prefrontal dysfunction during executive tasks in schizophrenia. However, relationships between hemodynamic response in prefrontal sub-regions and clinical characteristics have been unclear. The objective of this study is to evaluate prefrontal hemodynamic response related to an executive task in schizophrenia and to assess the relationship between activation in the prefrontal sub-regions and clinical status. Fifty-five subjects with schizophrenia and age- and gender-matched 70 healthy subjects were recruited for this case-control study in a medical school affiliated hospital in the Tokyo metropolitan area, Japan. We measured hemoglobin concentration changes in the prefrontal (dorsolateral, ventrolateral, and frontopolar regions) and superior temporal cortical surface area during verbal fluency test using 52-channel near-infrared spectroscopy, which enables real-time monitoring of cerebral blood volumes in the cortical surface area under a more restraint-free environment than positron emission tomography or functional magnetic resonance imaging. The two groups showed distinct spatiotemporal pattern of oxy-hemoglobin concentration change during verbal fluency test. Schizophrenia patients were associated with slower and reduced increase in prefrontal activation than healthy controls. In particular, reduced activations of the frontopolar region, rather than lateral prefrontal or superior temporal regions, showed significant positive correlations with lower global assessment of functioning scores in the patient group, although task performance was not significantly associated with the scores. These results suggest that reduced frontopolar cortical activation is associated with functional impairment in patients with schizophrenia and that near-infrared spectroscopy may be an efficient clinical tool for monitoring these characteristics.

Functional near-infrared spectroscopy: current status and future prospects

Near-infrared spectroscopy (NIRS), which was originally designed for clinical monitoring of tissue oxygenation, has been developing into a useful tool for neuroimaging studies (functional near-infrared spectroscopy). This technique, which is completely noninvasive, does not require strict motion restriction and can be used in a daily life environment. It is expected that NIRS will provide a new direction for cognitive neuroscience research, more so than other neuroimaging techniques, although several problems with NIRS remain to be explored. This review demonstrates the strengths and the advantages of NIRS, clarifies the problems, and identifies the limitations of NIRS measurements. Finally, its future prospects are described.