Measurement of brain activation during an upright stepping reaction task using functional near‐infrared spectroscopy

Functional near‐infrared spectroscopy (fNIRS) is a non‐invasive brain imaging technology that uses light to measure changes in cortical hemoglobin concentrations. FNIRS measurements are recorded through fiber optic cables, which allow the participant to wear the fNIRS sensors while standing upright. Thus, fNIRS technology is well suited to study cortical brain activity during upright balance, stepping, and gait tasks. In this study, fNIRS was used to measure changes in brain activation from the frontal, motor, and premotor brain regions during an upright step task that required subjects to step laterally in response to visual cues that required executive function control. We hypothesized that cognitive processing during complex stepping cues would elicit brain activation of the frontal cortex in areas involved in cognition. Our results show increased prefrontal activation associated with the processing of the stepping cues. Moreover, these results demonstrate the potential to use fNIRS to investigate cognitive processing during cognitively demanding balance and gait studies. Hum Brain Mapp 34:2817–2828, 2013. © 2012 Wiley Periodicals, Inc.     

Cortical activation patterns to spatially presented pure tone stimuli with different intensities measured by functional near‐infrared spectroscopy

Functional near‐infrared spectroscopy (fNIRS) is an emerging technique for the assessment of functional activity of the cerebral cortex. Recently fNIRS was also envisaged as a novel neuroimaging approach for measuring the auditory cortex activity in the field of in auditory diagnostics. This study aimed to investigate differences in brain activity related to spatially presented sounds with different intensities in 10 subjects by means of functional near‐infrared spectroscopy (fNIRS). We found pronounced cortical activation patterns in the temporal and frontal regions of both hemispheres. In contrast to these activation patterns, we found deactivation patterns in central and parietal regions of both hemispheres. Furthermore our results showed an influence of spatial presentation and intensity of the presented sounds on brain activity in related regions of interest. These findings are in line with previous fMRI studies which also reported systematic changes of activation in temporal and frontal areas with increasing sound intensity. Although clear evidence for contralaterality effects and hemispheric asymmetries were absent in the group data, these effects were partially visible on the single subject level. Concluding, fNIRS is sensitive enough to capture differences in brain responses during the spatial presentation of sounds with different intensities in several cortical regions. Our results may serve as a valuable contribution for further basic research and the future use of fNIRS in the area of central auditory diagnostics.     

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.

     

Noninvasive continuous functional near‐infrared spectroscopy combined with electroencephalography recording of frontal lobe seizures

Purpose: To investigate spatial and metabolic changes associated with frontal lobe seizures. Methods: Functional near‐infrared spectroscopy combined with electroencephalography (EEG‐fNIRS) recordings of patients with confirmed nonlesional refractory frontal lobe epilepsy (FLE). Key Findings: Eighteen seizures from nine patients (seven male, mean age 27 years, range 13–46 years) with drug‐refractory FLE were captured during EEG‐fNIRS recordings. All seizures were coupled with significant hemodynamic variations that were greater with electroclinical than with electrical seizures. fNIRS helped in the identification of seizures in three patients with more subtle ictal EEG abnormalities. Hemodynamic changes consisted of local increases in oxygenated (HbO) and total hemoglobin (HbT) but heterogeneous deoxygenated hemoglobin (HbR) behavior. Furthermore, rapid hemodynamic alterations were observed in the homologous contralateral region, even in the absence of obvious propagated epileptic activity. The extent of HbO activation adequately lateralized the epileptogenic side in the majority of patients. Significance: EEG‐fNIRS reveals complex spatial and metabolic changes during focal frontal lobe seizures. Further characterization of these changes could improve seizure detection, localization, and understanding of the impact of focal seizures.     

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.     

Increase of frontal cerebral blood volume during transcranial magnetic stimulation in depression is related to treatment effectiveness: A pilot study with near‐infrared spectroscopy

Aim

Alterations of cerebral blood flow have been reported in studies of depression treated by transcranial magnetic stimulation (TMS). However, the relation between these changes in activity during stimulation and the effectiveness of TMS is not known. The aim of this study was to determine whether changes in frontal cerebral blood volume measured as frontal hemoglobin concentration (fHbC) during TMS are correlated with clinical outcomes of treatment.

Methods

Fifteen drug‐resistant patients with depression underwent a standard treatment regimen of TMS to the left dorsolateral prefrontal cortex. We recorded fHbC during stimulation at the start and end of the TMS treatment series using near‐infrared spectroscopy. Symptom severity was determined using the Montgomery–Åsberg Depression Rating Scale.

Results

At the start of the TMS series, fHbC increased during stimulation in a majority of patients with no relation to symptom severity. However, at the end of the series, fHbC increase during stimulation was negatively correlated with the Montgomery–Åsberg Depression Rating Scale score and positively with the score reduction. Patients showing a decreasing response of fHbC during TMS at the end of the series experienced less clinical improvement.

Conclusion

These results suggest that the maintenance of frontal activation during stimulation in the course of TMS series is related to the effectiveness in the treatment of depression. Measurement of fHbC during stimulation is informative in the clinical use of TMS.

     

Reduced frontopolar activation during verbal fluency task associated with poor social functioning in late‐onset major depression: Multi‐channel near‐infrared spectroscopy study

Aim: Functional neuroimaging studies to date have indicated prefrontal dysfunction in late‐onset major depression (LOD). The relationships between prefrontal dysfunction and clinical characteristics including social functioning, however, have been unclear. The objective of the present study was to evaluate prefrontal hemodynamic response related to an executive task in LOD and to assess the relationship between activation in the prefrontal regions and clinical characteristics including social functioning. Methods: Twenty‐four subjects with LOD and 30 age‐ and gender‐matched healthy subjects were recruited for the present study. Hemoglobin concentration changes in the prefrontal and superior temporal cortical surface area were measured during verbal fluency task (VFT) using 52‐channel near‐infrared spectroscopy (NIRS), which enables real‐time monitoring of cerebral blood volume (CBV) in the cortical surface area. Results: The two groups had a distinct spatiotemporal pattern of oxy‐hemoglobin concentration change; LOD patients had less activation in a broad area covering both prefrontal and superior temporal cortices than healthy controls. In addition, reduced activation of the frontopolar region had a significant positive correlation with lower self‐assessment of social functioning scores in the patient group. Conclusion: Reduced frontopolar cortical activation was associated with social functioning impairment in patients with LOD, and NIRS may be an efficient clinical tool for monitoring these characteristics.     

Monitoring and control of amygdala neurofeedback involves distributed information processing in the human brain

Brain–computer interfaces provide conscious access to neural activity by means of brain‐derived feedback (“neurofeedback”). An individual's abilities to monitor and control feedback are two necessary processes for effective neurofeedback therapy, yet their underlying functional neuroanatomy is still being debated. In this study, healthy subjects received visual feedback from their amygdala response to negative pictures. Activation and functional connectivity were analyzed to disentangle the role of brain regions in different processes. Feedback monitoring was mapped to the thalamus, ventromedial prefrontal cortex (vmPFC), ventral striatum (VS), and rostral PFC. The VS responded to feedback corresponding to instructions while rPFC activity differentiated between conditions and predicted amygdala regulation. Control involved the lateral PFC, anterior cingulate, and insula. Monitoring and control activity overlapped in the VS and thalamus. Extending current neural models of neurofeedback, this study introduces monitoring and control of feedback as anatomically dissociated processes, and suggests their important role in voluntary neuromodulation.     

Cerebral hemodynamics in newborn infants exposed to speech sounds: a whole-head optical topography study

Considerable knowledge on neural development related to speech perception has been obtained by functional imaging studies using near-infrared spectroscopy (optical topography). In particular, a pioneering study showed stronger left-dominant activation in the temporal lobe for (normal) forward speech (FW) than for (reversed) backward speech (BW) in neonates. However, it is unclear whether this stronger left-dominant activation for FW is equally observed for any language or is clearer for the mother tongue. We hypothesized that the maternal language elicits clearer activation than a foreign language in newborns because of their prenatal and/or few-day postnatal exposure to the maternal language. To test this hypothesis, we developed a whole-head optode cap for 72-channel optical topography and visualized the spatiotemporal hemodynamics in the brains of 17 Japanese newborns when they were exposed to FW and BW in their maternal language (Japanese) and in a foreign language (English). Statistical analysis showed that all sound stimuli together induced significant activation in the bilateral temporal regions and the frontal region. They also showed that the left temporal-parietal region was significantly more active for Japanese FW than Japanese BW or English FW, while no significant difference between FW and BW was shown for English. This supports our hypothesis and suggests that the few-day-old brain begins to become attuned to the maternal language. Together with a finding of equivalent activation for all sound stimuli in the adjacent measurement positions in the temporal region, these findings further clarify the functional organization of the neonatal brain.     

Frontal and temporal cortical functional recovery after electroconvulsive therapy for depression: A longitudinal functional near-infrared spectroscopy study

While the efficacy and tolerability of electroconvulsive therapy (ECT) for depression has been well established, the acute effects of ECT on brain function remain unclear. Particularly, although cognitive dysfunction has been consistently observed after ECT, little is known about the extent and time course of ECT-induced brain functional changes, as observed during cognitive tasks. Considering the acute antidepressant effects of ECT on depression, aberrant brain functional responses during cognitive tasks in patients with depression may improve immediately after this treatment. To clarify changes in cortical functional responses to cognitive tasks following ECT, we used task-related functional near-infrared spectroscopy (NIRS) to assess 30 patients with major depressive disorder or bipolar depression before and after an ECT series, as well as 108 healthy controls. Prior to ECT, patients exhibited significantly smaller [oxy-Hb] values in the bilateral frontal cortex during a letter verbal fluency task (VFT) compared with healthy controls. We found a significant increase in [oxy-Hb] values in the bilateral frontal cortex during the VFT after ECT in the patient group. A decrease in depression severity was significantly correlated with an increase in [oxy-Hb] values in the right ventrolateral prefrontal cortex following ECT. This is the first NIRS study to evaluate brain functional changes before vs. after ECT. Impaired functional responses, observed during the cognitive task in depressed patients, were normalized after ECT. Thus, recovery from abnormal functional responses to cognitive tasks in the frontal brain regions may be associated with the acute therapeutic effects of ECT for depression.     

It is more than Interference: Examining the neurohemodynamic correlates of the flanker task with functional near‐infrared spectroscopy

Previous functional near‐infrared spectroscopy studies using the Eriksen flanker task, in contrast to functional magnetic resonance imaging studies, revealed the quite puzzling finding of an inverted conflict effect, that is, greater middle and superior frontal activation in response compatible than in response incompatible trials. However, since neither prior functional near‐infrared spectroscopy studies nor most previous functional magnetic resonance imaging studies separated between an identical and a compatible condition, it is hard to pinpoint whether this discrepancy occurs on the level of stimulus processing or response generation. By assigning two letters to both left (D, F) and right (J, K) hand reactions, we were able to separate identical (e.g., JJJ) and compatible (e.g., JKJ) conditions that solely differ in their stimulus congruency. Replicating prior functional magnetic resonance imaging findings, we found the standard conflict effect at the transition of superior and middle frontal gyrus, when comparing the activation in compatible trials to that in incompatible trials. Both changes in oxygenated and deoxygenated hemoglobin thus pointed to more effortful processing in incompatible trials. Interestingly, however, identical trials showed the highest activation in this region, according to both changes in oxygenated and deoxygenated blood. A finding that mirrors and extends prior functional near‐infrared spectroscopy findings, which only regarded oxygenated blood. We argue that this pattern of results does not reflect the standard conflict effect. We rather assume that other processes like perceptual familiarity or strategic readjustment might be at play.     

Near‐infrared spectroscopy during exercise and recovery in children with juvenile dermatomyositis

Introduction: We hypothesized that microvascular disturbances in muscle tissue play a role in the reduced exercise capacity in juvenile dermatomyositis (JDM). Methods: Children with JDM, children with juvenile idiopathic arthritis (clinical controls), and healthy children performed a maximal incremental cycloergometric test from which normalized concentration changes in oxygenated hemoglobin (Δ[O₂Hb]) and total hemoglobin (Δ[tHb]) as well as the half‐recovery times of both signals were determined from the vastus medialis and vastus lateralis muscles using near‐infrared spectroscopy. Results: Children with JDM had lower Δ[tHb] values in the vastus medialis at work rates of 25%, 50%, 75%, and 100% of maximal compared with healthy children; the increase in Δ[tHb] with increasing intensity seen in healthy children was absent in children with JDM. Other outcome measures did not differ by group. Conclusions: The results suggest that children with JDM may experience difficulties in increasing muscle blood volume with more strenuous exercise. Muscle Nerve, 2013