151
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Yin X, Xu B, Jiang C, Fu Y, Wang Z, Li H, Shi G. NIRS-based classification of clench force and speed motor imagery with the use of empirical mode decomposition for BCI. Med Eng Phys 2015; 37:280-6. [PMID: 25640806 DOI: 10.1016/j.medengphy.2015.01.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 11/11/2014] [Accepted: 01/11/2015] [Indexed: 11/25/2022]
Abstract
Near-infrared spectroscopy (NIRS) is a non-invasive optical technique used for brain-computer interface (BCI). This study aims to investigate the brain hemodynamic responses of clench force and speed motor imagery and extract task-relevant features to obtain better classification performance. Given the non-stationary characteristics of real hemodynamic measurements, empirical mode decomposition (EMD) was applied to reduce the physiological noise overwhelmed in the task-relevant NIRS signals. Compared with continuous wavelet decomposition, EMD does not require a pre-determined basis function. EMD decomposes the original signals into a set of intrinsic mode functions (IMFs). In this study, joint mutual information was applied to select the optimal features, and support vector machine was used as a classifier. Offline and pseudo-online analyses showed that the most feasible classification accuracy can be obtained using IMFs as input features. Accordingly, an alternative feature is provided to develop the NIRS-BCI system.
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Affiliation(s)
- Xuxian Yin
- State Key Laboratory of Robotics, Shenyang Institute of Automation (SIA), Chinese Academy of Sciences (CAS), Shenyang 110016, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
| | - Baolei Xu
- State Key Laboratory of Robotics, Shenyang Institute of Automation (SIA), Chinese Academy of Sciences (CAS), Shenyang 110016, PR China.
| | - Changhao Jiang
- Key Laboratory of Motor and Brain imaging, Capital Institute of Physical Education, Beijing 100088, China.
| | - Yunfa Fu
- School of Automation and Information Engineering, Kunming University of Science and Technology, Kunming 650500, PR China.
| | - Zhidong Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation (SIA), Chinese Academy of Sciences (CAS), Shenyang 110016, PR China; Department of Advanced Robotics, Chiba Institute of Technology, Chiba 2750016, Japan.
| | - Hongyi Li
- State Key Laboratory of Robotics, Shenyang Institute of Automation (SIA), Chinese Academy of Sciences (CAS), Shenyang 110016, PR China; School of Mechanical Engineering & Automation, Northeastern University, Shenyang, China.
| | - Gang Shi
- State Key Laboratory of Robotics, Shenyang Institute of Automation (SIA), Chinese Academy of Sciences (CAS), Shenyang 110016, PR China.
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152
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Funane T, Sato H, Yahata N, Takizawa R, Nishimura Y, Kinoshita A, Katura T, Atsumori H, Fukuda M, Kasai K, Koizumi H, Kiguchi M. Concurrent fNIRS-fMRI measurement to validate a method for separating deep and shallow fNIRS signals by using multidistance optodes. NEUROPHOTONICS 2015; 2:015003. [PMID: 26157983 PMCID: PMC4478864 DOI: 10.1117/1.nph.2.1.015003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Accepted: 01/05/2015] [Indexed: 05/12/2023]
Abstract
It has been reported that a functional near-infrared spectroscopy (fNIRS) signal can be contaminated by extracerebral contributions. Many algorithms using multidistance separations to address this issue have been proposed, but their spatial separation performance has rarely been validated with simultaneous measurements of fNIRS and functional magnetic resonance imaging (fMRI). We previously proposed a method for discriminating between deep and shallow contributions in fNIRS signals, referred to as the multidistance independent component analysis (MD-ICA) method. In this study, to validate the MD-ICA method from the spatial aspect, multidistance fNIRS, fMRI, and laser-Doppler-flowmetry signals were simultaneously obtained for 12 healthy adult males during three tasks. The fNIRS signal was separated into deep and shallow signals by using the MD-ICA method, and the correlation between the waveforms of the separated fNIRS signals and the gray matter blood oxygenation level-dependent signals was analyzed. A three-way analysis of variance ([Formula: see text]) indicated that the main effect of fNIRS signal depth on the correlation is significant [[Formula: see text], [Formula: see text]]. This result indicates that the MD-ICA method successfully separates fNIRS signals into spatially deep and shallow signals, and the accuracy and reliability of the fNIRS signal will be improved with the method.
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Affiliation(s)
- Tsukasa Funane
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan
- Address all correspondence to: Tsukasa Funane, E-mail:
| | - Hiroki Sato
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan
| | - Noriaki Yahata
- The University of Tokyo, Graduate School of Medicine, Department of Youth Mental Health, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Ryu Takizawa
- The University of Tokyo, Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan
- King’s College London, Institute of Psychiatry, MRC Social, Genetic and Developmental Psychiatry Centre, London, SE5 8AF, United Kingdom
| | - Yukika Nishimura
- The University of Tokyo, Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Akihide Kinoshita
- The University of Tokyo, Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Takusige Katura
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan
| | - Hirokazu Atsumori
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan
| | - Masato Fukuda
- Gunma University Graduate School of Medicine, Department of Psychiatry and Neuroscience, Maebashi, Gunma 371-8511, Japan
| | - Kiyoto Kasai
- The University of Tokyo, Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Hideaki Koizumi
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan
| | - Masashi Kiguchi
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan
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153
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Validation of the hypercapnic calibrated fMRI method using DOT-fMRI fusion imaging. Neuroimage 2014; 102 Pt 2:729-35. [PMID: 25196509 DOI: 10.1016/j.neuroimage.2014.08.052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/26/2014] [Accepted: 08/29/2014] [Indexed: 11/22/2022] Open
Abstract
Calibrated functional magnetic resonance imaging (fMRI) is a widely used method to investigate brain function in terms of physiological quantities such as the cerebral metabolic rate of oxygen (CMRO2). The first and one of the most common methods of fMRI calibration is hypercapnic calibration. This is achieved via simultaneous measures of the blood-oxygenation-level dependent (BOLD) and the arterial spin labeling (ASL) signals during a functional task that evokes regional changes in CMRO2. A subsequent acquisition is then required during which the subject inhales carbon dioxide for short periods of time. A calibration constant, typically labeled M, is then estimated from the hypercapnic data and is subsequently used together with the BOLD-ASL recordings to compute evoked changes in CMRO2 during the functional task. The computation of M assumes a constant CMRO2 during the CO2 inhalation, an assumption that has been questioned since the origin of calibrated fMRI. In this study we used diffuse optical tomography (DOT) together with BOLD and ASL--an alternative calibration method that does not require any gas manipulation and therefore no constant CMRO2 assumption--to cross-validate the estimation of M obtained from a traditional hypercapnic calibration. We found a high correlation between the M values (R=0.87, p<0.01) estimated using these two approaches. The findings serve to validate the hypercapnic fMRI calibration technique and suggest that the inter-subject variability routinely obtained for M is reproducible with an alternative method and might therefore reflect inter-subject physiological variability.
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154
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The promise of Near-Infrared Spectroscopy (NIRS) for psychological research: A brief review. ANNEE PSYCHOLOGIQUE 2014. [DOI: 10.4074/s0003503314003054] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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155
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Bauernfeind G, Wriessnegger SC, Daly I, Müller-Putz GR. Separating heart and brain: on the reduction of physiological noise from multichannel functional near-infrared spectroscopy (fNIRS) signals. J Neural Eng 2014; 11:056010. [PMID: 25111822 DOI: 10.1088/1741-2560/11/5/056010] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Functional near-infrared spectroscopy (fNIRS) is an emerging technique for the in vivo assessment of functional activity of the cerebral cortex as well as in the field of brain-computer interface (BCI) research. A common challenge for the utilization of fNIRS in these areas is a stable and reliable investigation of the spatio-temporal hemodynamic patterns. However, the recorded patterns may be influenced and superimposed by signals generated from physiological processes, resulting in an inaccurate estimation of the cortical activity. Up to now only a few studies have investigated these influences, and still less has been attempted to remove/reduce these influences. The present study aims to gain insights into the reduction of physiological rhythms in hemodynamic signals (oxygenated hemoglobin (oxy-Hb), deoxygenated hemoglobin (deoxy-Hb)). APPROACH We introduce the use of three different signal processing approaches (spatial filtering, a common average reference (CAR) method; independent component analysis (ICA); and transfer function (TF) models) to reduce the influence of respiratory and blood pressure (BP) rhythms on the hemodynamic responses. MAIN RESULTS All approaches produce large reductions in BP and respiration influences on the oxy-Hb signals and, therefore, improve the contrast-to-noise ratio (CNR). In contrast, for deoxy-Hb signals CAR and ICA did not improve the CNR. However, for the TF approach, a CNR-improvement in deoxy-Hb can also be found. SIGNIFICANCE The present study investigates the application of different signal processing approaches to reduce the influences of physiological rhythms on the hemodynamic responses. In addition to the identification of the best signal processing method, we also show the importance of noise reduction in fNIRS data.
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Affiliation(s)
- G Bauernfeind
- Institute for Knowledge Discovery, Graz University of Technology, A-8010 Graz, Austria
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156
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Goodwin JR, Gaudet CR, Berger AJ. Short-channel functional near-infrared spectroscopy regressions improve when source-detector separation is reduced. NEUROPHOTONICS 2014; 1:015002. [PMID: 26157972 PMCID: PMC4478749 DOI: 10.1117/1.nph.1.1.015002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 05/15/2014] [Accepted: 06/10/2014] [Indexed: 05/07/2023]
Abstract
In functional near-infrared spectroscopy (fNIRS) of human cerebral hemodynamics, dedicated surface-sensitive recording channels are useful for regressing out background hemodynamics and isolating activation-specific responses. A wide variety of source-detector separations have been utilized for this purpose. Here, we report a direct comparison of regression performance between two extremes of the reported range, 13 and 6 mm. Measurements of visual stimulation response (flickering radial checkerboard) were obtained from nine adults using a standard commercial source-detector grid with 13-mm diagonals, into which three extra detector fibers were placed to provide 6-mm channels at certain locations. When the NIRS recordings (17 total trials) were processed, the contrast-to-noise ratio was significantly higher with 6-mm regression channels than with 13 mm. The advantage could be due in part to the undesired sensing of brain activity by the 13-mm channels. We suggest that shorter distances be considered for optimal removal of superficial hemodynamics in NIRS signals from the adult brain.
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Affiliation(s)
- James R. Goodwin
- University of Rochester, The Institute of Optics, Rochester, New York 14627, United States
- Queensland University of Technology, School of Chemistry, Physics and Mechanical Engineering, Brisbane, Queensland 4000, Australia
- Address all correspondence to: J. R. Goodwin, E-mail:
| | - Chantel R. Gaudet
- University of Rochester, The Institute of Optics, Rochester, New York 14627, United States
| | - Andrew J. Berger
- University of Rochester, The Institute of Optics, Rochester, New York 14627, United States
- University of Rochester, Department of Biomedical Engineering, Rochester, New York 14627, United States
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157
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Ishikuro K, Urakawa S, Takamoto K, Ishikawa A, Ono T, Nishijo H. Cerebral functional imaging using near-infrared spectroscopy during repeated performances of motor rehabilitation tasks tested on healthy subjects. Front Hum Neurosci 2014; 8:292. [PMID: 24860474 PMCID: PMC4026732 DOI: 10.3389/fnhum.2014.00292] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/21/2014] [Indexed: 11/29/2022] Open
Abstract
To investigate the relationship between the frontal and sensorimotor cortices and motor learning, hemodynamic responses were recorded from the frontal and sensorimotor cortices using functional near infrared spectroscopy (NIRS) while healthy subjects performed motor learning tasks used in rehabilitation medicine. Whole-head NIRS recordings indicated that response latencies in the anterior dorsomedial prefrontal cortex (aDMPFC) were shorter than in other frontal and parietal areas. Furthermore, the increment rate of the hemodynamic responses in the aDMPFC across the eight repeated trials significantly correlated with those in the other areas, as well as with the improvement rate of task performance across the 8 repeated trials. In the second experiment, to dissociate scalp- and brain-derived hemodynamic responses, hemodynamic responses were recorded from the head over the aDMPFC using a multi-distance probe arrangement. Six probes (a single source probe and 5 detectors) were linearly placed 6 mm apart from each of the neighboring probes. Using independent component analyses of hemodynamic signals from the 5 source-detector pairs, we dissociated scalp- and brain-derived components of the hemodynamic responses. Hemodynamic responses corrected for scalp-derived responses over the aDMPFC significantly increased across the 8 trials and correlated with task performance. In the third experiment, subjects were required to perform the same task with and without transcranial direct current stimulation (tDCS) of the aDMPFC before the task. The tDCS significantly improved task performance. These results indicate that the aDMPFC is crucial for improved performance in repetitive motor learning.
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Affiliation(s)
- Koji Ishikuro
- System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama Toyama, Japan
| | - Susumu Urakawa
- Department of Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama Toyama, Japan
| | - Kouich Takamoto
- Department of Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama Toyama, Japan
| | - Akihiro Ishikawa
- Medical Systems Division, R & D Department, Shimadzu, Co. Ltd. Kyoto, Japan
| | - Taketoshi Ono
- Department of Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama Toyama, Japan
| | - Hisao Nishijo
- System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama Toyama, Japan
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158
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Ferreri L, Bigand E, Perrey S, Muthalib M, Bard P, Bugaiska A. Less Effort, Better Results: How Does Music Act on Prefrontal Cortex in Older Adults during Verbal Encoding? An fNIRS Study. Front Hum Neurosci 2014; 8:301. [PMID: 24860481 PMCID: PMC4026694 DOI: 10.3389/fnhum.2014.00301] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/24/2014] [Indexed: 11/13/2022] Open
Abstract
Several neuroimaging studies of cognitive aging revealed deficits in episodic memory abilities as a result of prefrontal cortex (PFC) limitations. Improving episodic memory performance despite PFC deficits is thus a critical issue in aging research. Listening to music stimulates cognitive performance in several non-purely musical activities (e.g., language and memory). Thus, music could represent a rich and helpful source during verbal encoding and therefore help subsequent retrieval. Furthermore, such benefit could be reflected in less demand of PFC, which is known to be crucial for encoding processes. This study aimed to investigate whether music may improve episodic memory in older adults while decreasing the PFC activity. Sixteen healthy older adults (μ = 64.5 years) encoded lists of words presented with or without a musical background while their dorsolateral prefrontal cortex (DLPFC) activity was monitored using a eight-channel continuous-wave near-infrared spectroscopy (NIRS) system (Oxymon Mk III, Artinis, The Netherlands). Behavioral results indicated a better source-memory performance for words encoded with music compared to words encoded with silence (p < 0.05). Functional NIRS data revealed bilateral decrease of oxyhemoglobin values in the music encoding condition compared to the silence condition (p < 0.05), suggesting that music modulates the activity of the DLPFC during encoding in a less-demanding direction. Taken together, our results indicate that music can help older adults in memory performances by decreasing their PFC activity. These findings open new perspectives about music as tool for episodic memory rehabilitation on special populations with memory deficits due to frontal lobe damage such as Alzheimer’s patients.
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Affiliation(s)
- Laura Ferreri
- Laboratoire d'Etude de l'Apprentissage et du Développement (LEAD), CNRS UMR 5022, University of Burgundy , Dijon , France
| | - Emmanuel Bigand
- Laboratoire d'Etude de l'Apprentissage et du Développement (LEAD), CNRS UMR 5022, University of Burgundy , Dijon , France
| | - Stephane Perrey
- Movement to Health (M2H), EuroMov, Montpellier-1 University , Montpellier , France
| | - Makii Muthalib
- Movement to Health (M2H), EuroMov, Montpellier-1 University , Montpellier , France
| | - Patrick Bard
- Laboratoire d'Etude de l'Apprentissage et du Développement (LEAD), CNRS UMR 5022, University of Burgundy , Dijon , France
| | - Aurélia Bugaiska
- Laboratoire d'Etude de l'Apprentissage et du Développement (LEAD), CNRS UMR 5022, University of Burgundy , Dijon , France
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159
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Pouliot P, Tran TPY, Birca V, Vannasing P, Tremblay J, Lassonde M, Nguyen DK. Hemodynamic changes during posterior epilepsies: an EEG-fNIRS study. Epilepsy Res 2014; 108:883-90. [PMID: 24755234 DOI: 10.1016/j.eplepsyres.2014.03.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 02/19/2014] [Accepted: 03/16/2014] [Indexed: 11/30/2022]
Abstract
Posterior epilepsies are mainly characterized clinically by visual symptoms. Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive imaging technique that has the potential to monitor hemodynamic changes during epileptic activity. Combined with electroencephalography (EEG), 9 patients with posterior epilepsies were recorded using EEG-fNIRS with large sampling (19 EEG electrodes and over 100 fNIRS channels). Spikes and seizures were carefully marked on EEG traces, and convolved with a standard hemodynamic response function for general linear model (GLM) analysis. GLM results for seizures (in 3 patients) and spikes (7 patients) were broadly sensitive to the epileptic focus in 7/9 patients, and specific in 5/9 patients with fNIRS deoxyhemoglobin responses lateralized to the correct lobe, and to plausible locations within the occipital or parietal lobes. This work provides evidence that EEG-fNIRS is a sensitive technique for monitoring posterior epileptic activity.
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Affiliation(s)
- Philippe Pouliot
- Département de génie électrique, École Polytechnique de Montréal, C.P. 6079, Succ. Centre-ville, Montréal, QC, Canada H3C3A7; Institut de cardiologie de Montréal, Centre de recherche, 5000 Rue Bélanger Est, Montréal, QC, Canada H1T1C8.
| | - Thi Phuoc Yen Tran
- Service de neurologie, Hôpital Notre-Dame du CHUM, 1560 Rue Sherbrooke Est, Montréal, QC, Canada H3L4M1
| | - Véronica Birca
- Service de neurologie, Hôpital Notre-Dame du CHUM, 1560 Rue Sherbrooke Est, Montréal, QC, Canada H3L4M1
| | - Phetsamone Vannasing
- Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC, Canada H3T1C5
| | - Julie Tremblay
- Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC, Canada H3T1C5
| | - Maryse Lassonde
- Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC, Canada H3T1C5; Centre de recherche en neuropsychologie et cognition, Département de psychologie, Université de Montréal, Montréal, QC, Canada H3C3J7
| | - Dang Khoa Nguyen
- Service de neurologie, Hôpital Notre-Dame du CHUM, 1560 Rue Sherbrooke Est, Montréal, QC, Canada H3L4M1
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160
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Li J, Qiu L. Temporal correlation of spontaneous hemodynamic activity in language areas measured with functional near-infrared spectroscopy. BIOMEDICAL OPTICS EXPRESS 2014; 5:587-95. [PMID: 24575351 PMCID: PMC3920887 DOI: 10.1364/boe.5.000587] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/19/2014] [Accepted: 01/20/2014] [Indexed: 05/21/2023]
Abstract
Functional near-infrared spectroscopy (fNIRS) was used to investigate resting state connectivity of language areas including bilateral inferior frontal gyrus (IFG) and superior temporal gyrus (STG). Thirty-two subjects participated in the experiment, including twenty adults and twelve children. Spontaneous hemodynamic fluctuations were recorded, and then intra- and inter-hemispheric temporal correlations of these signals were computed. The correlations of all hemoglobin components were observed significantly higher for adults than children. Moreover, the differences for the STG were more significant than for the IFG. In the adult group, differences in the correlations between males and females were not significant. Our results suggest by measuring resting state intra- and inter-hemispheric correlations, fNIRS is able to provide qualitative and quantitative evaluation on the functioning of the cortical network.
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161
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Gagnon L, Yücel MA, Boas DA, Cooper RJ. Further improvement in reducing superficial contamination in NIRS using double short separation measurements. Neuroimage 2014. [PMID: 23403181 DOI: 10.1016/j.neuroimage.2013.01.073.further] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023] Open
Abstract
Near-Infrared Spectroscopy (NIRS) allows the recovery of the evoked hemodynamic response to brain activation. In adult human populations, the NIRS signal is strongly contaminated by systemic interference occurring in the superficial layers of the head. An approach to overcome this difficulty is to use additional NIRS measurements with short optode separations to measure the systemic hemodynamic fluctuations occurring in the superficial layers. These measurements can then be used as regressors in the post-experiment analysis to remove the systemic contamination and isolate the brain signal. In our previous work, we showed that the systemic interference measured in NIRS is heterogeneous across the surface of the scalp. As a consequence, the short separation measurement used in the regression procedure must be located close to the standard NIRS channel from which the evoked hemodynamic response of the brain is to be recovered. Here, we demonstrate that using two short separation measurements, one at the source optode and one at the detector optode, further increases the performance of the short separation regression method compared to using a single short separation measurement. While a single short separation channel produces an average reduction in noise of 33% for HbO, using a short separation channel at both source and detector reduces noise by 59% compared to the standard method using a general linear model (GLM) without short separation. For HbR, noise reduction of 3% is achieved using a single short separation and this number goes to 47% when two short separations are used. Our work emphasizes the importance of integrating short separation measurements both at the source and at the detector optode of the standard channels from which the hemodynamic response is to be recovered. While the implementation of short separation sources presents some difficulties experimentally, the improvement in noise reduction is significant enough to justify the practical challenges.
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Affiliation(s)
- Louis Gagnon
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA.
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162
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Statistical analysis of fNIRS data: A comprehensive review. Neuroimage 2014; 85 Pt 1:72-91. [DOI: 10.1016/j.neuroimage.2013.06.016] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/20/2013] [Accepted: 06/07/2013] [Indexed: 11/16/2022] Open
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163
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Scholkmann F, Kleiser S, Metz AJ, Zimmermann R, Mata Pavia J, Wolf U, Wolf M. A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology. Neuroimage 2014; 85 Pt 1:6-27. [PMID: 23684868 DOI: 10.1016/j.neuroimage.2013.05.004] [Citation(s) in RCA: 1009] [Impact Index Per Article: 100.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/12/2013] [Accepted: 05/03/2013] [Indexed: 01/09/2023] Open
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164
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Basso Moro S, Cutini S, Ursini ML, Ferrari M, Quaresima V. Prefrontal cortex activation during story encoding/retrieval: a multi-channel functional near-infrared spectroscopy study. Front Hum Neurosci 2013; 7:925. [PMID: 24427131 PMCID: PMC3876278 DOI: 10.3389/fnhum.2013.00925] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/17/2013] [Indexed: 12/14/2022] Open
Abstract
Encoding, storage and retrieval constitute three fundamental stages in information processing and memory. They allow for the creation of new memory traces, the maintenance and the consolidation of these traces over time, and the access and recover of the stored information from short or long-term memory. Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures concentration changes of oxygenated-hemoglobin (O2Hb) and deoxygenated-hemoglobin (HHb) in cortical microcirculation blood vessels by means of the characteristic absorption spectra of hemoglobin in the near-infrared range. In the present study, we monitored, using a 16-channel fNIRS system, the hemodynamic response during the encoding and retrieval processes (EP and RP, respectively) over the prefrontal cortex (PFC) of 13 healthy subjects (27.2 ± 2.6 years) while were performing the “Logical Memory Test” (LMT) of the Wechsler Memory Scale. A LMT-related PFC activation was expected; specifically, it was hypothesized a neural dissociation between EP and RP. The results showed a heterogeneous O2Hb/HHb response over the mapped area during the EP and the RP, with a O2Hb progressive and prominent increment in ventrolateral PFC (VLPFC) since the beginning of the EP. During the RP a broader activation, including the VLPFC, the dorsolateral PFC and the frontopolar cortex, was observed. This could be explained by the different contributions of the PFC regions in the EP and the RP. Considering the fNIRS applicability for the hemodynamic monitoring during the LMT performance, this study has demonstrated that fNIRS could be utilized as a valuable clinical diagnostic tool, and that it has the potential to be adopted in patients with cognitive disorders or slight working memory deficits.
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Affiliation(s)
- Sara Basso Moro
- Department of Life, Health and Environmental Sciences, University of L'Aquila L'Aquila, Italy
| | - Simone Cutini
- Department of General Psychology, University of Padua Padova, Italy
| | - Maria Laura Ursini
- Department of Life, Health and Environmental Sciences, University of L'Aquila L'Aquila, Italy
| | - Marco Ferrari
- Department of Life, Health and Environmental Sciences, University of L'Aquila L'Aquila, Italy
| | - Valentina Quaresima
- Department of Life, Health and Environmental Sciences, University of L'Aquila L'Aquila, Italy
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Peng K, Nguyen DK, Tayah T, Vannasing P, Tremblay J, Sawan M, Lassonde M, Lesage F, Pouliot P. fNIRS-EEG study of focal interictal epileptiform discharges. Epilepsy Res 2013; 108:491-505. [PMID: 24439212 DOI: 10.1016/j.eplepsyres.2013.12.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 10/22/2013] [Accepted: 12/05/2013] [Indexed: 10/25/2022]
Abstract
Functional near-infrared spectroscopy (fNIRS) acquired with electroencephalography (EEG) is a relatively new non-invasive neuroimaging technique with potential for long term monitoring of the epileptic brain. Simultaneous EEG-fNIRS recording allows the spatio-temporal reconstruction of the hemodynamic response in terms of the concentration changes in oxy-hemoglobin (HbO) and deoxy-hemoglobin (HbR) associated with recorded epileptic events such as interictal epileptic discharges (IEDs) or seizures. While most previous studies investigating fNIRS in epilepsy had limitations due to restricted spatial coverage and small sample sizes, this work includes a sufficiently large number of channels to provide an extensive bilateral coverage of the surface of the brain for a sample size of 40 patients with focal epilepsies. Topographic maps of significant activations due to each IED type were generated in four different views (dorsal, frontal, left and right) and were compared with the epileptic focus previously identified by an epileptologist. After excluding 5 patients due to the absence of IEDs and 6 more with mesial temporal foci too deep for fNIRS, we report that significant HbR (respectively HbO) concentration changes corresponding to IEDs were observed in 62% (resp. 38%) of patients with neocortical epilepsies. This HbR/HbO response was most significant in the epileptic focus region among all the activations in 28%/21% of patients.
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Affiliation(s)
- Ke Peng
- Département de génie électrique, École Polytechnique de Montréal, C.P. 6079, Succ. Centre-ville, Montréal, QC, Canada H3C3A7
| | - Dang Khoa Nguyen
- Service de neurologie, Hôpital Notre-Dame du CHUM, 1560 Rue Sherbrooke Est, Montréal, QC, Canada H3L4M1
| | - Tania Tayah
- Service de neurologie, Hôpital Notre-Dame du CHUM, 1560 Rue Sherbrooke Est, Montréal, QC, Canada H3L4M1
| | - Phetsamone Vannasing
- Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC, Canada H3T1C5
| | - Julie Tremblay
- Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC, Canada H3T1C5
| | - Mohamad Sawan
- Département de génie électrique, École Polytechnique de Montréal, C.P. 6079, Succ. Centre-ville, Montréal, QC, Canada H3C3A7
| | - Maryse Lassonde
- Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC, Canada H3T1C5; Centre de recherche en neuropsychologie et cognition, Département de psychologie, Université de Montréal, Montréal, QC, Canada H3C3J7
| | - Frédéric Lesage
- Département de génie électrique, École Polytechnique de Montréal, C.P. 6079, Succ. Centre-ville, Montréal, QC, Canada H3C3A7; Institut de cardiologie de Montréal, Centre de recherche, 5000 Rue Bélanger Est, Montréal, QC, Canada H1T1C8
| | - Philippe Pouliot
- Département de génie électrique, École Polytechnique de Montréal, C.P. 6079, Succ. Centre-ville, Montréal, QC, Canada H3C3A7; Institut de cardiologie de Montréal, Centre de recherche, 5000 Rue Bélanger Est, Montréal, QC, Canada H1T1C8.
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166
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Hemmati Berivanlou N, Setarehdan SK, Ahmadi Noubari H. Evoked hemodynamic response estimation using ensemble empirical mode decomposition based adaptive algorithm applied to dual channel functional near infrared spectroscopy (fNIRS). J Neurosci Methods 2013; 224:13-25. [PMID: 24365048 DOI: 10.1016/j.jneumeth.2013.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 12/09/2013] [Accepted: 12/12/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND The quality of the functional near infrared spectroscopy (fNIRS) recordings is highly degraded by the presence of physiological interferences. It is crucial to efficiently separate the evoked hemodynamic responses (EHRs) from other background hemodynamic activities prior to any further processing. NEW METHOD This paper presents a novel algorithm for physiological interferences reduction from the dual channel fNIRS measurements using ensemble empirical mode decomposition (EEMD) technique. The proposed algorithm is comprised of two main steps: (1) decomposing reference signal into its constituents called intrinsic mode functions (IMFs) and (2) adaptively defining appropriate weights of the corresponding IMFs to estimate the proportion of physiological interference in standard channel measurement. RESULTS Performance of the proposed algorithm was evaluated using both synthetic and semi-real brain hemodynamic data based on four parameters of relative mean squared error (rMSE), Pearson's correlation coefficient (R(2)), percentage estimation error of peak amplitude (EPA) and peak latency (EL). COMPARISON WITH EXISTING METHODS Results obtained from synthetic data revealed that both the EEMD based normalized least mean squares (EEMD-NLMS) and EEMD based recursive least squares (EEMD-RLS) methods could reduce the average rMSE by at least 34% and 49%, respectively, when compared with widely used methods: block averaging, band-pass filtering and principal and/or independent component analysis. Furthermore, the two proposed methods outperform the regression method in reducing rMSE by at least 21% and 35% respectively when applied to semi-real data. CONCLUSIONS An effective algorithm for estimating the EHRs from raw fNIRS data was proposed in which no assumption about the amplitude, shape and duration of the responses is considered.
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Affiliation(s)
- Nima Hemmati Berivanlou
- Control and Intelligent Processing Center of Excellence, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Seyed Kamaledin Setarehdan
- Control and Intelligent Processing Center of Excellence, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Hossein Ahmadi Noubari
- Control and Intelligent Processing Center of Excellence, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran; Electrical and Computer Engineering Department, University of British Columbia, Vancouver, Canada
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167
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Harrivel AR, Weissman DH, Noll DC, Peltier SJ. Monitoring attentional state with fNIRS. Front Hum Neurosci 2013; 7:861. [PMID: 24379771 PMCID: PMC3861695 DOI: 10.3389/fnhum.2013.00861] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 11/26/2013] [Indexed: 11/13/2022] Open
Abstract
The ability to distinguish between high and low levels of task engagement in the real world is important for detecting and preventing performance decrements during safety-critical operational tasks. We therefore investigated whether functional Near Infrared Spectroscopy (fNIRS), a portable brain neuroimaging technique, can be used to distinguish between high and low levels of task engagement during the performance of a selective attention task. A group of participants performed the multi-source interference task (MSIT) while we recorded brain activity with fNIRS from two brain regions. One was a key region of the “task-positive” network, which is associated with relatively high levels of task engagement. The second was a key region of the “task-negative” network, which is associated with relatively low levels of task engagement (e.g., resting and not performing a task). Using activity in these regions as inputs to a multivariate pattern classifier, we were able to predict above chance levels whether participants were engaged in performing the MSIT or resting. We were also able to replicate prior findings from functional magnetic resonance imaging (fMRI) indicating that activity in task-positive and task-negative regions is negatively correlated during task performance. Finally, data from a companion fMRI study verified our assumptions about the sources of brain activity in the fNIRS experiment and established an upper bound on classification accuracy in our task. Together, our findings suggest that fNIRS could prove quite useful for monitoring cognitive state in real-world settings.
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Affiliation(s)
- Angela R Harrivel
- Bioscience and Technology Branch, NASA Glenn Research Center Cleveland, OH, USA ; fMRI Laboratory, Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA
| | | | - Douglas C Noll
- fMRI Laboratory, Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA
| | - Scott J Peltier
- fMRI Laboratory, Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA
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168
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Ferreri L, Aucouturier JJ, Muthalib M, Bigand E, Bugaiska A. Music improves verbal memory encoding while decreasing prefrontal cortex activity: an fNIRS study. Front Hum Neurosci 2013; 7:779. [PMID: 24339807 PMCID: PMC3857524 DOI: 10.3389/fnhum.2013.00779] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 10/29/2013] [Indexed: 11/13/2022] Open
Abstract
Listening to music engages the whole brain, thus stimulating cognitive performance in a range of non-purely musical activities such as language and memory tasks. This article addresses an ongoing debate on the link between music and memory for words. While evidence on healthy and clinical populations suggests that music listening can improve verbal memory in a variety of situations, it is still unclear what specific memory process is affected and how. This study was designed to explore the hypothesis that music specifically benefits the encoding part of verbal memory tasks, by providing a richer context for encoding and therefore less demand on the dorsolateral prefrontal cortex (DLPFC). Twenty-two healthy young adults were subjected to functional near-infrared spectroscopy (fNIRS) imaging of their bilateral DLPFC while encoding words in the presence of either a music or a silent background. Behavioral data confirmed the facilitating effect of music background during encoding on subsequent item recognition. fNIRS results revealed significantly greater activation of the left hemisphere during encoding (in line with the HERA model of memory lateralization) and a sustained, bilateral decrease of activity in the DLPFC in the music condition compared to silence. These findings suggest that music modulates the role played by the DLPFC during verbal encoding, and open perspectives for applications to clinical populations with prefrontal impairments, such as elderly adults or Alzheimer's patients.
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Affiliation(s)
- Laura Ferreri
- Laboratory for the Study of Learning and Development, CNRS UMR 5022, Department of Psychology, University of BurgundyDijon, France
| | | | - Makii Muthalib
- Movement to Health, EUROMOV, Montpellier-1 UniversityMontpellier, France
| | - Emmanuel Bigand
- Laboratory for the Study of Learning and Development, CNRS UMR 5022, Department of Psychology, University of BurgundyDijon, France
| | - Aurelia Bugaiska
- Laboratory for the Study of Learning and Development, CNRS UMR 5022, Department of Psychology, University of BurgundyDijon, France
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169
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Prefrontal Cortex Activated Bilaterally by a Tilt Board Balance Task: A Functional Near-Infrared Spectroscopy Study in a Semi-Immersive Virtual Reality Environment. Brain Topogr 2013; 27:353-65. [DOI: 10.1007/s10548-013-0320-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 09/25/2013] [Indexed: 12/14/2022]
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170
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Niu H, Li Z, Liao X, Wang J, Zhao T, Shu N, Zhao X, He Y. Test-retest reliability of graph metrics in functional brain networks: a resting-state fNIRS study. PLoS One 2013; 8:e72425. [PMID: 24039763 PMCID: PMC3767699 DOI: 10.1371/journal.pone.0072425] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/08/2013] [Indexed: 01/24/2023] Open
Abstract
Recent research has demonstrated the feasibility of combining functional near-infrared spectroscopy (fNIRS) and graph theory approaches to explore the topological attributes of human brain networks. However, the test-retest (TRT) reliability of the application of graph metrics to these networks remains to be elucidated. Here, we used resting-state fNIRS and a graph-theoretical approach to systematically address TRT reliability as it applies to various features of human brain networks, including functional connectivity, global network metrics and regional nodal centrality metrics. Eighteen subjects participated in two resting-state fNIRS scan sessions held ∼20 min apart. Functional brain networks were constructed for each subject by computing temporal correlations on three types of hemoglobin concentration information (HbO, HbR, and HbT). This was followed by a graph-theoretical analysis, and then an intraclass correlation coefficient (ICC) was further applied to quantify the TRT reliability of each network metric. We observed that a large proportion of resting-state functional connections (∼90%) exhibited good reliability (0.6< ICC <0.74). For global and nodal measures, reliability was generally threshold-sensitive and varied among both network metrics and hemoglobin concentration signals. Specifically, the majority of global metrics exhibited fair to excellent reliability, with notably higher ICC values for the clustering coefficient (HbO: 0.76; HbR: 0.78; HbT: 0.53) and global efficiency (HbO: 0.76; HbR: 0.70; HbT: 0.78). Similarly, both nodal degree and efficiency measures also showed fair to excellent reliability across nodes (degree: 0.52∼0.84; efficiency: 0.50∼0.84); reliability was concordant across HbO, HbR and HbT and was significantly higher than that of nodal betweenness (0.28∼0.68). Together, our results suggest that most graph-theoretical network metrics derived from fNIRS are TRT reliable and can be used effectively for brain network research. This study also provides important guidance on the choice of network metrics of interest for future applied research in developmental and clinical neuroscience.
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Affiliation(s)
- Haijing Niu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Zhen Li
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Xuhong Liao
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
- Zhejiang Key Laboratory for Research in Assessment of Cognitive Impairments, Hangzhou, China
| | - Jinhui Wang
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
| | - Tengda Zhao
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Ni Shu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Xiaohu Zhao
- Imaging Department, Shanghai TongJi Hospital, TongJi University, Shanghai, China
- * E-mail: (YH); (XHZ)
| | - Yong He
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
- * E-mail: (YH); (XHZ)
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171
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Yücel MA, Selb J, Boas DA, Cash SS, Cooper RJ. Reducing motion artifacts for long-term clinical NIRS monitoring using collodion-fixed prism-based optical fibers. Neuroimage 2013; 85 Pt 1:192-201. [PMID: 23796546 DOI: 10.1016/j.neuroimage.2013.06.054] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/23/2013] [Accepted: 06/14/2013] [Indexed: 11/30/2022] Open
Abstract
As the applications of near-infrared spectroscopy (NIRS) continue to broaden and long-term clinical monitoring becomes more common, minimizing signal artifacts due to patient movement becomes more pressing. This is particularly true in applications where clinically and physiologically interesting events are intrinsically linked to patient movement, as is the case in the study of epileptic seizures. In this study, we apply an approach common in the application of EEG electrodes to the application of specialized NIRS optical fibers. The method provides improved optode-scalp coupling through the use of miniaturized optical fiber tips fixed to the scalp using collodion, a clinical adhesive. We investigate and quantify the performance of this new method in minimizing motion artifacts in healthy subjects, and apply the technique to allow continuous NIRS monitoring throughout epileptic seizures in two epileptic in-patients. Using collodion-fixed fibers reduces the percent signal change of motion artifacts by 90% and increases the SNR by 6 and 3 fold at 690 and 830 nm wavelengths respectively when compared to a standard Velcro-based array of optical fibers. The SNR has also increased by 2 fold during rest conditions without motion with the new probe design because of better light coupling between the fiber and scalp. The change in both HbO and HbR during motion artifacts is found to be statistically lower for the collodion-fixed fiber probe. The collodion-fixed optical fiber approach has also allowed us to obtain good quality NIRS recording of three epileptic seizures in two patients despite excessive motion in each case.
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Affiliation(s)
- Meryem A Yücel
- HMS/MIT/MGH Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA; Harvard Medical School, Charlestown, MA, USA.
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172
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A semi-immersive virtual reality incremental swing balance task activates prefrontal cortex: a functional near-infrared spectroscopy study. Neuroimage 2013; 85 Pt 1:451-60. [PMID: 23684867 DOI: 10.1016/j.neuroimage.2013.05.031] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 04/17/2013] [Accepted: 05/03/2013] [Indexed: 12/14/2022] Open
Abstract
Previous functional near-infrared spectroscopy (fNIRS) studies indicated that the prefrontal cortex (PFC) is involved in the maintenance of the postural balance after external perturbations. So far, no studies have been conducted to investigate the PFC hemodynamic response to virtual reality (VR) tasks that could be adopted in the field of functional neurorehabilitation. The aim of this fNIRS study was to assess PFC oxygenation response during an incremental and a control swing balance task (ISBT and CSBT, respectively) in a semi-immersive VR environment driven by a depth-sensing camera. It was hypothesized that: i) the PFC would be bilaterally activated in response to the increase of the ISBT difficulty, as this cortical region is involved in the allocation of attentional resources to maintain postural control; and ii) the PFC activation would be greater in the right than in the left hemisphere considering its dominance for visual control of body balance. To verify these hypotheses, 16 healthy male subjects were requested to stand barefoot while watching a 3 dimensional virtual representation of themselves projected onto a screen. They were asked to maintain their equilibrium on a virtual blue swing board susceptible to external destabilizing perturbations (i.e., randomizing the forward-backward direction of the impressed pulse force) during a 3-min ISBT (performed at four levels of difficulty) or during a 3-min CSBT (performed constantly at the lowest level of difficulty of the ISBT). The center of mass (COM), at each frame, was calculated and projected on the floor. When the subjects were unable to maintain the COM over the board, this became red (error). After each error, the time required to bring back the COM on the board was calculated (returning time). An eight-channel continuous wave fNIRS system was employed for measuring oxygenation changes (oxygenated-hemoglobin, O2Hb; deoxygenated-hemoglobin, HHb) related to the PFC activation (Brodmann Areas 10, 11 and 46). The results have indicated that the errors increased between the first and the second level of difficulty of the ISBT, then decreased and remained constant; the returning time progressively increased during the first three levels of difficulty and then remained constant. During the CSBT, the errors and the returning time did not change. In the ISBT, the increase of the first three levels of difficulty was accompanied by a progressive increase in PFC O2Hb and a less consistent decrease in HHb. A tendency to plateau was observable for PFC O2Hb and HHb changes in the fourth level of difficulty of the ISBT, which could be partly explained by a learning effect. A right hemispheric lateralization was not found. A lower amplitude of increase in O2Hb and decrease in HHb was found in the PFC in response to the CSBT with respect to the ISBT. This study has demonstrated that the oxygenation increased over the PFC while performing an ISBT in a semi-immersive VR environment. These data reinforce the involvement of the PFC in attention-demanding balance tasks. Considering the adaptability of this virtual balance task to specific neurological disorders, the absence of motion sensing devices, and the motivating/safe semi-immersive VR environment, the ISBT adopted in this study could be considered valuable for diagnostic testing and for assessing the effectiveness of functional neurorehabilitation.
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173
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Strangman GE, Zhang Q, Li Z. Scalp and skull influence on near infrared photon propagation in the Colin27 brain template. Neuroimage 2013; 85 Pt 1:136-49. [PMID: 23660029 DOI: 10.1016/j.neuroimage.2013.04.090] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 04/09/2013] [Accepted: 04/18/2013] [Indexed: 11/24/2022] Open
Abstract
Near-infrared neuromonitoring (NIN) is based on near-infrared spectroscopy (NIRS) measurements performed through the intact scalp and skull. Despite the important effects of overlying tissue layers on the measurement of brain hemodynamics, the influence of scalp and skull on NIN sensitivity are not well characterized. Using 3555 Monte Carlo simulations, we estimated the sensitivity of individual continuous-wave NIRS measurements to brain activity over the entire adult human head by introducing a small absorption perturbation to brain gray matter and quantifying the influence of scalp and skull thickness on this sensitivity. After segmenting the Colin27 template into five tissue types (scalp, skull, cerebrospinal fluid, gray matter and white matter), the average scalp thickness was 6.9 ± 3.6 mm (range: 3.6-11.2mm), while the average skull thickness was 6.0 ± 1.9 mm (range: 2.5-10.5mm). Mean NIN sensitivity - defined as the partial path length through gray matter divided by the total photon path length - ranged from 0.06 (i.e., 6% of total path length) at a 20mm source-detector separation, to over 0.19 at 50mm separations. NIN sensitivity varied substantially around the head, with occipital pole exhibiting the highest NIRS sensitivity to gray matter, whereas inferior frontal regions had the lowest sensitivity. Increased scalp and skull thickness were strongly associated with decreased sensitivity to brain tissue. Scalp thickness always exhibited a slightly larger effect on sensitivity than skull thickness, but the effect of both varied with SD separation. We quantitatively characterize sensitivity around the head as well as the effects of scalp and skull, which can be used to interpret NIN brain activation studies as well as guide the design, development and optimization of NIRS devices and sensors.
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Affiliation(s)
- Gary E Strangman
- Neural Systems Group, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA.
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174
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Scarpa F, Brigadoi S, Cutini S, Scatturin P, Zorzi M, Dell'Acqua R, Sparacino G. A reference-channel based methodology to improve estimation of event-related hemodynamic response from fNIRS measurements. Neuroimage 2013; 72:106-19. [DOI: 10.1016/j.neuroimage.2013.01.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 12/17/2012] [Accepted: 01/13/2013] [Indexed: 10/27/2022] Open
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175
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Funane T, Atsumori H, Katura T, Obata AN, Sato H, Tanikawa Y, Okada E, Kiguchi M. Quantitative evaluation of deep and shallow tissue layers' contribution to fNIRS signal using multi-distance optodes and independent component analysis. Neuroimage 2013; 85 Pt 1:150-65. [PMID: 23439443 DOI: 10.1016/j.neuroimage.2013.02.026] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 02/04/2013] [Indexed: 11/24/2022] Open
Abstract
To quantify the effect of absorption changes in the deep tissue (cerebral) and shallow tissue (scalp, skin) layers on functional near-infrared spectroscopy (fNIRS) signals, a method using multi-distance (MD) optodes and independent component analysis (ICA), referred to as the MD-ICA method, is proposed. In previous studies, when the signal from the shallow tissue layer (shallow signal) needs to be eliminated, it was often assumed that the shallow signal had no correlation with the signal from the deep tissue layer (deep signal). In this study, no relationship between the waveforms of deep and shallow signals is assumed, and instead, it is assumed that both signals are linear combinations of multiple signal sources, which allows the inclusion of a "shared component" (such as systemic signals) that is contained in both layers. The method also assumes that the partial optical path length of the shallow layer does not change, whereas that of the deep layer linearly increases along with the increase of the source-detector (S-D) distance. Deep- and shallow-layer contribution ratios of each independent component (IC) are calculated using the dependence of the weight of each IC on the S-D distance. Reconstruction of deep- and shallow-layer signals are performed by the sum of ICs weighted by the deep and shallow contribution ratio. Experimental validation of the principle of this technique was conducted using a dynamic phantom with two absorbing layers. Results showed that our method is effective for evaluating deep-layer contributions even if there are high correlations between deep and shallow signals. Next, we applied the method to fNIRS signals obtained on a human head with 5-, 15-, and 30-mm S-D distances during a verbal fluency task, a verbal working memory task (prefrontal area), a finger tapping task (motor area), and a tetrametric visual checker-board task (occipital area) and then estimated the deep-layer contribution ratio. To evaluate the signal separation performance of our method, we used the correlation coefficients of a laser-Doppler flowmetry (LDF) signal and a nearest 5-mm S-D distance channel signal with the shallow signal. We demonstrated that the shallow signals have a higher temporal correlation with the LDF signals and with the 5-mm S-D distance channel than the deep signals. These results show the MD-ICA method can discriminate between deep and shallow signals.
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Affiliation(s)
- Tsukasa Funane
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
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176
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Further improvement in reducing superficial contamination in NIRS using double short separation measurements. Neuroimage 2013; 85 Pt 1:127-35. [PMID: 23403181 DOI: 10.1016/j.neuroimage.2013.01.073] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/23/2013] [Accepted: 01/29/2013] [Indexed: 11/24/2022] Open
Abstract
Near-Infrared Spectroscopy (NIRS) allows the recovery of the evoked hemodynamic response to brain activation. In adult human populations, the NIRS signal is strongly contaminated by systemic interference occurring in the superficial layers of the head. An approach to overcome this difficulty is to use additional NIRS measurements with short optode separations to measure the systemic hemodynamic fluctuations occurring in the superficial layers. These measurements can then be used as regressors in the post-experiment analysis to remove the systemic contamination and isolate the brain signal. In our previous work, we showed that the systemic interference measured in NIRS is heterogeneous across the surface of the scalp. As a consequence, the short separation measurement used in the regression procedure must be located close to the standard NIRS channel from which the evoked hemodynamic response of the brain is to be recovered. Here, we demonstrate that using two short separation measurements, one at the source optode and one at the detector optode, further increases the performance of the short separation regression method compared to using a single short separation measurement. While a single short separation channel produces an average reduction in noise of 33% for HbO, using a short separation channel at both source and detector reduces noise by 59% compared to the standard method using a general linear model (GLM) without short separation. For HbR, noise reduction of 3% is achieved using a single short separation and this number goes to 47% when two short separations are used. Our work emphasizes the importance of integrating short separation measurements both at the source and at the detector optode of the standard channels from which the hemodynamic response is to be recovered. While the implementation of short separation sources presents some difficulties experimentally, the improvement in noise reduction is significant enough to justify the practical challenges.
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177
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Abdelmalak B, Cata J, Bonilla A, You J, Kopyeva T, Vogel J, Campbell S, Sessler D. Intraoperative tissue oxygenation and postoperative outcomes after major non-cardiac surgery: an observational study. Br J Anaesth 2013; 110:241-249. [DOI: 10.1093/bja/aes378] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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178
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Cooper RJ, Selb J, Gagnon L, Phillip D, Schytz HW, Iversen HK, Ashina M, Boas DA. A systematic comparison of motion artifact correction techniques for functional near-infrared spectroscopy. Front Neurosci 2012; 6:147. [PMID: 23087603 PMCID: PMC3468891 DOI: 10.3389/fnins.2012.00147] [Citation(s) in RCA: 255] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 09/17/2012] [Indexed: 11/29/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) is susceptible to signal artifacts caused by relative motion between NIRS optical fibers and the scalp. These artifacts can be very damaging to the utility of functional NIRS, particularly in challenging subject groups where motion can be unavoidable. A number of approaches to the removal of motion artifacts from NIRS data have been suggested. In this paper we systematically compare the utility of a variety of published NIRS motion correction techniques using a simulated functional activation signal added to 20 real NIRS datasets which contain motion artifacts. Principle component analysis, spline interpolation, wavelet analysis, and Kalman filtering approaches are compared to one another and to standard approaches using the accuracy of the recovered, simulated hemodynamic response function (HRF). Each of the four motion correction techniques we tested yields a significant reduction in the mean-squared error (MSE) and significant increase in the contrast-to-noise ratio (CNR) of the recovered HRF when compared to no correction and compared to a process of rejecting motion-contaminated trials. Spline interpolation produces the largest average reduction in MSE (55%) while wavelet analysis produces the highest average increase in CNR (39%). On the basis of this analysis, we recommend the routine application of motion correction techniques (particularly spline interpolation or wavelet analysis) to minimize the impact of motion artifacts on functional NIRS data.
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Affiliation(s)
- Robert J Cooper
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School Charlestown, MA, USA
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Cooper RJ, Caffini M, Dubb J, Fang Q, Custo A, Tsuzuki D, Fischl B, Wells W, Dan I, Boas DA. Validating atlas-guided DOT: a comparison of diffuse optical tomography informed by atlas and subject-specific anatomies. Neuroimage 2012; 62:1999-2006. [PMID: 22634215 DOI: 10.1016/j.neuroimage.2012.05.031] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 04/24/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022] Open
Abstract
We describe the validation of an anatomical brain atlas approach to the analysis of diffuse optical tomography (DOT). Using MRI data from 32 subjects, we compare the diffuse optical images of simulated cortical activation reconstructed using a registered atlas with those obtained using a subject's true anatomy. The error in localization of the simulated cortical activations when using a registered atlas is due to a combination of imperfect registration, anatomical differences between atlas and subject anatomies and the localization error associated with diffuse optical image reconstruction. When using a subject-specific MRI, any localization error is due to diffuse optical image reconstruction only. In this study we determine that using a registered anatomical brain atlas results in an average localization error of approximately 18 mm in Euclidean space. The corresponding error when the subject's own MRI is employed is 9.1 mm. In general, the cost of using atlas-guided DOT in place of subject-specific MRI-guided DOT is a doubling of the localization error. Our results show that despite this increase in error, reasonable anatomical localization is achievable even in cases where the subject-specific anatomy is unavailable.
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Affiliation(s)
- Robert J Cooper
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
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180
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Funane T, Atsumori H, Kiguchi M, Tanikawa Y, Okada E. Dynamic phantom with two stage-driven absorbers for mimicking hemoglobin changes in superficial and deep tissues. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:047001. [PMID: 22559692 DOI: 10.1117/1.jbo.17.4.047001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In near-infrared spectroscopy (NIRS) for monitoring brain activity and cerebral functional connectivity, the effect of superficial tissue on NIRS signals needs to be considered. Although some methods for determining the effect of scalp and brain have been proposed, direct validation of the methods has been difficult because the actual absorption changes cannot be known. In response to this problem, we developed a dynamic phantom that mimics hemoglobin changes in superficial and deep tissues, thus allowing us to experimentally validate the methods. Two absorber layers are independently driven with two one-axis automatic stages. We can use the phantom to design any type of waveform (e.g., brain activity or systemic fluctuation) of absorption change, which can then be reproducibly measured. To determine the effectiveness of the phantom, we used it for a multiple source-detector distance measurement. We also investigated the performance of a subtraction method with a short-distance regressor. The most accurate lower-layer change was obtained when a shortest-distance channel was used. Furthermore, when an independent component analysis was applied to the same data, the extracted components were in good agreement with the actual signals. These results demonstrate that the proposed phantom can be used for evaluating methods of discriminating the effects of superficial tissue.
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Affiliation(s)
- Tsukasa Funane
- Hitachi Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
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181
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Gagnon L, Cooper RJ, Yücel MA, Perdue KL, Greve DN, Boas DA. Short separation channel location impacts the performance of short channel regression in NIRS. Neuroimage 2012; 59:2518-28. [PMID: 21945793 PMCID: PMC3254723 DOI: 10.1016/j.neuroimage.2011.08.095] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/19/2011] [Accepted: 08/30/2011] [Indexed: 11/16/2022] Open
Abstract
Near-Infrared Spectroscopy (NIRS) allows the recovery of cortical oxy- and deoxyhemoglobin changes associated with evoked brain activity. NIRS is a back-reflection measurement making it very sensitive to the superficial layers of the head, i.e. the skin and the skull, where systemic interference occurs. As a result, the NIRS signal is strongly contaminated with systemic interference of superficial origin. A recent approach to overcome this problem has been the use of additional short source-detector separation optodes as regressors. Since these additional measurements are mainly sensitive to superficial layers in adult humans, they can be used to remove the systemic interference present in longer separation measurements, improving the recovery of the cortical hemodynamic response function (HRF). One question that remains to answer is whether or not a short separation measurement is required in close proximity to each long separation NIRS channel. Here, we show that the systemic interference occurring in the superficial layers of the human head is inhomogeneous across the surface of the scalp. As a result, the improvement obtained by using a short separation optode decreases as the relative distance between the short and the long measurement is increased. NIRS data was acquired on 6 human subjects both at rest and during a motor task consisting of finger tapping. The effect of distance between the short and the long channel was first quantified by recovering a synthetic hemodynamic response added over the resting-state data. The effect was also observed in the functional data collected during the finger tapping task. Together, these results suggest that the short separation measurement must be located as close as 1.5 cm from the standard NIRS channel in order to provide an improvement which is of practical use. In this case, the improvement in Contrast-to-Noise Ratio (CNR) compared to a standard General Linear Model (GLM) procedure without using any small separation optode reached 50% for HbO and 100% for HbR. Using small separations located farther than 2 cm away resulted in mild or negligible improvements only.
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Affiliation(s)
- Louis Gagnon
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
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183
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Li H, Tak S, Ye JC. Lipschitz-Killing curvature based expected Euler characteristics for p-value correction in fNIRS. J Neurosci Methods 2011; 204:61-67. [PMID: 22074819 DOI: 10.1016/j.jneumeth.2011.10.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 09/09/2011] [Accepted: 10/18/2011] [Indexed: 11/30/2022]
Abstract
Functional near-infrared spectroscopy (fNIRS) is a non-invasive imaging approach for measuring brain activities based on changes in the cerebral concentrations of hemoglobin. Recently, statistical analysis based on a general linear model (GLM) has become popular. Here, to impose statistical significance on the activation detected by fNIRS, family-wise error (FWE) rate control is important. However, unlike fMRI, in which measurements are densely sampled on a regular lattice and Gaussian smoothing makes the resulting random field homogeneous, the random fields from fNIRS are inhomogeneous due to the interpolation from sparsely and irregularly distributed optode locations. Thus, tube formula based correction has been proposed to address this issue. However, Sun's tube formula cannot be used for general random fields such as F-statistics. To overcome these difficulties, we employ the expected Euler characteristic approach based on Lipschitz-Killing curvature (LKC) to control the family-wise error rate. We compared this correction method with Sun's tube formula for t-statistics to confirm the existing method. Based on this comparison, we show that covariance estimation should be modified to consider channel-wise least-square residual correlation. These new results supplement the existing tool of statistical parameter mapping for fNIRS.
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Affiliation(s)
- Hua Li
- Bio Imaging and Signal Processing Lab., Dept. of Bio and Brain Engineering, KAIST, 373-1 Guseong-dong Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Sungho Tak
- Bio Imaging and Signal Processing Lab., Dept. of Bio and Brain Engineering, KAIST, 373-1 Guseong-dong Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Jong Chul Ye
- Bio Imaging and Signal Processing Lab., Dept. of Bio and Brain Engineering, KAIST, 373-1 Guseong-dong Yuseong-gu, Daejeon 305-701, Republic of Korea.
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Tong Y, Hocke LM, Frederick BD. Isolating the sources of widespread physiological fluctuations in functional near-infrared spectroscopy signals. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:106005. [PMID: 22029352 PMCID: PMC3210192 DOI: 10.1117/1.3638128] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Physiological fluctuations at low frequency (<0.1 Hz) are prominent in functional near-infrared spectroscopy (fNIRS) measurements in both resting state and functional task studies. In this study, we used the high spatial resolution and full brain coverage of functional magnetic resonance imaging (fMRI) to understand the origins and commonalities of these fluctuations. Specifically, we applied a newly developed method, regressor interpolation at progressive time delays, to analyze concurrently recorded fNIRS and fMRI data acquired both in a resting state study and in a finger tapping study. The method calculates the voxelwise correlations between blood oxygen level dependent (BOLD) fMRI and fNIRS signals with different time shifts and localizes the areas in the brain that highly correlate with the fNIRS signal recorded at the surface of the head. The results show the wide spatial distribution of this physiological fluctuation in BOLD data, both in task and resting states. The brain areas that are highly correlated with global physiological fluctuations observed by fNIRS have a pattern that resembles the venous system of the brain, indicating the blood fluctuation from veins on the brain surface might strongly contribute to the overall fNIRS signal.
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Affiliation(s)
- Yunjie Tong
- McLean Hospital, Brain Imaging Center, 115 Mill Street, Belmont, Massachusetts 02478, USA.
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185
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Virtanen J, Noponen T, Kotilahti K, Virtanen J, Ilmoniemi RJ. Accelerometer-based method for correcting signal baseline changes caused by motion artifacts in medical near-infrared spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:087005. [PMID: 21895332 DOI: 10.1117/1.3606576] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In medical near-infrared spectroscopy (NIRS), movements of the subject often cause large step changes in the baselines of the measured light attenuation signals. This prevents comparison of hemoglobin concentration levels before and after movement. We present an accelerometer-based motion artifact removal (ABAMAR) algorithm for correcting such baseline motion artifacts (BMAs). ABAMAR can be easily adapted to various long-term monitoring applications of NIRS. We applied ABAMAR to NIRS data collected in 23 all-night sleep measurements and containing BMAs from involuntary movements during sleep. For reference, three NIRS researchers independently identified BMAs from the data. To determine whether the use of an accelerometer improves BMA detection accuracy, we compared ABAMAR to motion detection based on peaks in the moving standard deviation (SD) of NIRS data. The number of BMAs identified by ABAMAR was similar to the number detected by the humans, and 79% of the artifacts identified by ABAMAR were confirmed by at least two humans. While the moving SD of NIRS data could also be used for motion detection, on average 2 out of the 10 largest SD peaks in NIRS data each night occurred without the presence of movement. Thus, using an accelerometer improves BMA detection accuracy in NIRS.
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Affiliation(s)
- Jaakko Virtanen
- Aalto University School of Science, Department of Biomedical Engineering and Computational Science, P.O. Box 12200, FI-00076 Aalto, Finland.
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