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Leadley G, Austin T, Bale G. Review of measurements and imaging of cytochrome-c-oxidase in humans using near-infrared spectroscopy: an update. BIOMEDICAL OPTICS EXPRESS 2024; 15:162-184. [PMID: 38223181 PMCID: PMC10783912 DOI: 10.1364/boe.501915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/21/2023] [Indexed: 01/16/2024]
Abstract
This review examines advancements in the measurement and imaging of oxidized cytochrome-c-oxidase (oxCCO) using near-infrared spectroscopy (NIRS) in humans since 2016. A total of 34 published papers were identified, with a focus on both adult and neonate populations. The NIRS-derived oxCCO signal has been demonstrated to correlate with physiological parameters and hemodynamics. New instrumentation, such as systems that allow the imaging of changes of oxCCO with diffuse optical tomography or combine the oxCCO measurement with diffuse correlation spectroscopy measures of blood flow, have advanced the field in the past decade. However, variability in its response across different populations and paradigms and lack of standardization limit its potential as a reliable and valuable indicator of brain health. Future studies should address these issues to fulfill the vision of oxCCO as a clinical biomarker.
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Affiliation(s)
- Georgina Leadley
- Department of Paediatrics, University of Cambridge, UK
- Department of Engineering, University of Cambridge, UK
- Department of Medical Physics and Biomedical Engineering, UCL, UK
| | - Topun Austin
- Department of Paediatrics, University of Cambridge, UK
| | - Gemma Bale
- Department of Engineering, University of Cambridge, UK
- Department of Physics, University of Cambridge, UK
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2
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Siddiqui M, Pinti P, Brigadoi S, Lloyd-Fox S, Elwell CE, Johnson MH, Tachtsidis I, Jones EJH. Using multi-modal neuroimaging to characterise social brain specialisation in infants. eLife 2023; 12:e84122. [PMID: 37818944 PMCID: PMC10624424 DOI: 10.7554/elife.84122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 10/10/2023] [Indexed: 10/13/2023] Open
Abstract
The specialised regional functionality of the mature human cortex partly emerges through experience-dependent specialisation during early development. Our existing understanding of functional specialisation in the infant brain is based on evidence from unitary imaging modalities and has thus focused on isolated estimates of spatial or temporal selectivity of neural or haemodynamic activation, giving an incomplete picture. We speculate that functional specialisation will be underpinned by better coordinated haemodynamic and metabolic changes in a broadly orchestrated physiological response. To enable researchers to track this process through development, we develop new tools that allow the simultaneous measurement of coordinated neural activity (EEG), metabolic rate, and oxygenated blood supply (broadband near-infrared spectroscopy) in the awake infant. In 4- to 7-month-old infants, we use these new tools to show that social processing is accompanied by spatially and temporally specific increases in coupled activation in the temporal-parietal junction, a core hub region of the adult social brain. During non-social processing, coupled activation decreased in the same region, indicating specificity to social processing. Coupling was strongest with high-frequency brain activity (beta and gamma), consistent with the greater energetic requirements and more localised action of high-frequency brain activity. The development of simultaneous multimodal neural measures will enable future researchers to open new vistas in understanding functional specialisation of the brain.
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Affiliation(s)
- Maheen Siddiqui
- Centre for Brain and Cognitive Development, Birkbeck, University of LondonLondonUnited Kingdom
| | - Paola Pinti
- Centre for Brain and Cognitive Development, Birkbeck, University of LondonLondonUnited Kingdom
| | - Sabrina Brigadoi
- Department of Development and Social Psychology, University of PadovaPadovaItaly
- Department of Information Engineering, University of PadovaPadovaItaly
| | - Sarah Lloyd-Fox
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
| | - Clare E Elwell
- Department of Medical Physics and Biomedical Engineering, University College LondonLondonUnited Kingdom
| | - Mark H Johnson
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College LondonLondonUnited Kingdom
| | - Emily JH Jones
- Centre for Brain and Cognitive Development, Birkbeck, University of LondonLondonUnited Kingdom
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3
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Suwalski M, Shoemaker LN, Shoemaker JK, Diop M, Murkin JM, Chui J, St. Lawrence K, Milej D. Assessing the Sensitivity of Multi-Distance Hyperspectral NIRS to Changes in the Oxidation State of Cytochrome C Oxidase in the Brain. Metabolites 2022; 12:metabo12090817. [PMID: 36144221 PMCID: PMC9502461 DOI: 10.3390/metabo12090817] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO2) are frequently used during vascular and cardiac surgeries as a non-invasive means of assessing brain health; however, signal contamination from extracerebral tissues remains a concern. As an alternative, hyperspectral (hs)NIRS can be used to measure changes in the oxidation state of cytochrome c oxidase (ΔoxCCO), which provides greater sensitivity to the brain given its higher mitochondrial concentration versus the scalp. The purpose of this study was to evaluate the depth sensitivity of the oxCCO signal to changes occurring in the brain and extracerebral tissue components. The oxCCO assessment was conducted using multi-distance hsNIRS (source-detector separations = 1 and 3 cm), and metabolic changes were compared to changes in StO2. Ten participants were monitored using an in-house system combining hsNIRS and diffuse correlation spectroscopy (DCS). Data were acquired during carotid compression (CC) to reduce blood flow and hypercapnia to increase flow. Reducing blood flow by CC resulted in a significant decrease in oxCCO measured at rSD = 3 cm but not at 1 cm. In contrast, significant changes in StO2 were found at both distances. Hypercapnia caused significant increases in StO2 and oxCCO at rSD = 3 cm, but not at 1 cm. Extracerebral contamination resulted in elevated StO2 but not oxCCO after hypercapnia, which was significantly reduced by applying regression analysis. This study demonstrated that oxCCO was less sensitive to extracerebral signals than StO2.
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Affiliation(s)
- Marianne Suwalski
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Correspondence: (M.S.); (D.M.)
| | - Leena N. Shoemaker
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Department of Kinesiology, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - J. Kevin Shoemaker
- Department of Kinesiology, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - Mamadou Diop
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
| | - John M. Murkin
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON N6A 5A5, Canada
| | - Jason Chui
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON N6A 5A5, Canada
| | - Keith St. Lawrence
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
| | - Daniel Milej
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Correspondence: (M.S.); (D.M.)
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Broadband-NIRS System Identifies Epileptic Focus in a Child with Focal Cortical Dysplasia—A Case Study. Metabolites 2022; 12:metabo12030260. [PMID: 35323703 PMCID: PMC8951122 DOI: 10.3390/metabo12030260] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Accepted: 03/12/2022] [Indexed: 12/10/2022] Open
Abstract
Epileptic seizures are transiently occurring symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Previous functional near-infrared spectroscopy (fNIRS) studies during seizures have focused in only monitoring the brain oxygenation and haemodynamic changes. However, few tools are available to measure actual cellular metabolism during seizures, especially at the bedside. Here we use an in-house developed multichannel broadband NIRS (or bNIRS) system, that, alongside the changes in oxy-, deoxy- haemoglobin concentration (HbO2, HHb), also quantifies the changes in oxidised cytochrome-c-oxidase Δ(oxCCO), a marker of cellular oxygen metabolism, simultaneously over 16 different brain locations. We used bNIRS to measure metabolic activity alongside brain tissue haemodynamics/oxygenation during 17 epileptic seizures at the bedside of a 3-year-old girl with seizures due to an extensive malformation of cortical development in the left posterior quadrant. Simultaneously Video-EEG data was recorded from 12 channels. Whilst we did observe the expected increase in brain tissue oxygenation (HbD) during seizures, it was almost diminished in the area of the focal cortical dysplasia. Furthermore, in the area of seizure origination (epileptic focus) ΔoxCCO decreased significantly at the time of seizure generalization when compared to the mean change in all other channels. We hypothesize that this indicates an incapacity to sustain and increase brain tissue metabolism during seizures in the region of the epileptic focus.
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Siddiqui MF, Pinti P, Lloyd-Fox S, Jones EJH, Brigadoi S, Collins-Jones L, Tachtsidis I, Johnson MH, Elwell CE. Regional Haemodynamic and Metabolic Coupling in Infants. Front Hum Neurosci 2022; 15:780076. [PMID: 35185494 PMCID: PMC8854371 DOI: 10.3389/fnhum.2021.780076] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Metabolic pathways underlying brain function remain largely unexplored during neurodevelopment, predominantly due to the lack of feasible techniques for use with awake infants. Broadband near-infrared spectroscopy (bNIRS) provides the opportunity to explore the relationship between cerebral energy metabolism and blood oxygenation/haemodynamics through the measurement of changes in the oxidation state of mitochondrial respiratory chain enzyme cytochrome-c-oxidase (ΔoxCCO) alongside haemodynamic changes. We used a bNIRS system to measure ΔoxCCO and haemodynamics during functional activation in a group of 42 typically developing infants aged between 4 and 7 months. bNIRS measurements were made over the right hemisphere over temporal, parietal and central cortical regions, in response to social and non-social visual and auditory stimuli. Both ΔoxCCO and Δ[HbO2] displayed larger activation for the social condition in comparison to the non-social condition. Integration of haemodynamic and metabolic signals revealed networks of stimulus-selective cortical regions that were not apparent from analysis of the individual bNIRS signals. These results provide the first spatially resolved measures of cerebral metabolic activity alongside haemodynamics during functional activation in infants. Measuring synchronised changes in metabolism and haemodynamics have the potential for uncovering the development of cortical specialisation in early infancy.
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Affiliation(s)
- Maheen F. Siddiqui
- Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, United Kingdom
| | - Paola Pinti
- Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, United Kingdom
| | - Sarah Lloyd-Fox
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Emily J. H. Jones
- Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, United Kingdom
| | - Sabrina Brigadoi
- Department of Development and Social Psychology, University of Padua, Padua, Italy
- Department of Information Engineering, University of Padua, Padua, Italy
| | - Liam Collins-Jones
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Mark H. Johnson
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Clare E. Elwell
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
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6
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Siddiqui MF, Brigadoi S, Collins-Jones L, Lloyd-Fox S, Jones EJH, Tachtsidis I, Johnson MH, Elwell CE. Imaging Cerebral Energy Metabolism in Healthy Infants. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1395:9-15. [PMID: 36527606 DOI: 10.1007/978-3-031-14190-4_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Broadband near-infrared spectroscopy (bNIRS) has the potential to provide non-invasive measures of cerebral haemodynamic changes alongside changes in cellular oxygen utilisation through the measurement of mitochondrial enzyme cytochrome-c-oxidase (oxCCO). It therefore provides the opportunity to explore brain function and specialisation, which remains largely unexplored in infancy. We used bNIRS to measure changes in haemodynamics and changes in oxCCO in 4-to-7-month-old infants over the occipital and right temporal and parietal cortices in response to social and non-social visual and auditory stimuli. Changes in concentration of oxygenated-haemoglobin (Δ[HbO2]), deoxygenated haemoglobin (Δ[HHb]) and change in the oxidation state of oxCCO (Δ[oxCCO]) were calculated using changes in attenuation of light at 120 wavelengths between 780 and900 nm, using the UCLn algorithm. For 4 infants, the attenuation changes in a subset of wavelengths were used to perform image reconstruction, in an age-matched infant model, for channels over the right parietal and temporal cortices, using a multispectral approach which allows direct reconstruction of concentration change data. The volumetric reconstructed images were mapped onto the cortical surface to visualise the reconstructed changes in concentration of HbO2 and HHb and changes in metabolism for both social and non-social stimuli. Spatially localised activation was observed for Δ[oxCCO] and Δ[HbO2] over the temporo-parietal region, in response to the social stimulus. This study provides the first reconstructed images of changes in metabolism in healthy, awake infants.
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Affiliation(s)
- M F Siddiqui
- Centre for Brain and Cognitive Development, Department of Psychology, Birkbeck College, University of London, London, UK.
| | - S Brigadoi
- Department of Development and Social Psychology, University of Padova, Padua, Italy.,Department of Information Engineering, University of Padova, Padua, Italy
| | - L Collins-Jones
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - S Lloyd-Fox
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - E J H Jones
- Centre for Brain and Cognitive Development, Department of Psychology, Birkbeck College, University of London, London, UK
| | - I Tachtsidis
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - M H Johnson
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - C E Elwell
- Department of Psychology, University of Cambridge, Cambridge, UK
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7
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Ortega P, Faisal AA. Deep learning multimodal fNIRS and EEG signals for bimanual grip force decoding. J Neural Eng 2021; 18. [PMID: 34350839 DOI: 10.1088/1741-2552/ac1ab3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 08/04/2021] [Indexed: 11/12/2022]
Abstract
Objective.Non-invasive brain-machine interfaces (BMIs) offer an alternative, safe and accessible way to interact with the environment. To enable meaningful and stable physical interactions, BMIs need to decode forces. Although previously addressed in the unimanual case, controlling forces from both hands would enable BMI-users to perform a greater range of interactions. We here investigate the decoding of hand-specific forces.Approach.We maximise cortical information by using electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) and developing a deep-learning architecture with attention and residual layers (cnnatt) to improve their fusion. Our task required participants to generate hand-specific force profiles on which we trained and tested our deep-learning and linear decoders.Main results.The use of EEG and fNIRS improved the decoding of bimanual force and the deep-learning models outperformed the linear model. In both cases, the greatest gain in performance was due to the detection of force generation. In particular, the detection of forces was hand-specific and better for the right dominant hand andcnnattwas better at fusing EEG and fNIRS. Consequently, the study ofcnnattrevealed that forces from each hand were differently encoded at the cortical level.Cnnattalso revealed traces of the cortical activity being modulated by the level of force which was not previously found using linear models.Significance.Our results can be applied to avoid hand-cross talk during hand force decoding to improve the robustness of BMI robotic devices. In particular, we improve the fusion of EEG and fNIRS signals and offer hand-specific interpretability of the encoded forces which are valuable during motor rehabilitation assessment.
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Affiliation(s)
- Pablo Ortega
- Brain and Behaviour Lab, Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.,Brain and Behaviour Lab, Department of Computing, Imperial College London, London SW7 2AZ, United Kingdom
| | - A Aldo Faisal
- Brain and Behaviour Lab, Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.,Brain and Behaviour Lab, Department of Computing, Imperial College London, London SW7 2AZ, United Kingdom.,Data Science Institute, Imperial College London, London, United Kingdom.,MRC London Institute of Medical Sciences, SW7 2AZ London, United Kingdom
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8
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Amendola C, Lacerenza M, Pirovano I, Contini D, Spinelli L, Cubeddu R, Torricelli A, Re R. Optical characterization of 3D printed PLA and ABS filaments for diffuse optics applications. PLoS One 2021; 16:e0253181. [PMID: 34133454 PMCID: PMC8208549 DOI: 10.1371/journal.pone.0253181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 05/28/2021] [Indexed: 01/01/2023] Open
Abstract
The interest for Fused Deposition Modelling (FDM) in the field of Diffuse Optics (DO) is rapidly increasing. The most widespread FDM materials are polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS), thanks to their low cost and easiness-to-print. This is why, in this study, 3D printed samples of PLA and ABS materials were optically characterized in the range from the UV up to the IR wavelengths, in order to test their possible employment for probe construction in DO applications. To this purpose, measurements with Near Infrared Spectroscopy and Diffuse Correlation Spectroscopy techniques were considered. The results obtained show how the material employed for probe construction can negatively affect the quality of DO measurements.
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Affiliation(s)
- Caterina Amendola
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
- * E-mail:
| | | | | | - Davide Contini
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
| | - Lorenzo Spinelli
- Istituto di Fotonica e Nanotecnologie (IFN), Consiglio Nazionale delle Ricerche, Milan, Italy
| | - Rinaldo Cubeddu
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
- Istituto di Fotonica e Nanotecnologie (IFN), Consiglio Nazionale delle Ricerche, Milan, Italy
| | - Alessandro Torricelli
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
- Istituto di Fotonica e Nanotecnologie (IFN), Consiglio Nazionale delle Ricerche, Milan, Italy
| | - Rebecca Re
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
- Istituto di Fotonica e Nanotecnologie (IFN), Consiglio Nazionale delle Ricerche, Milan, Italy
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9
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Pinti P, Siddiqui MF, Levy AD, Jones EJH, Tachtsidis I. An analysis framework for the integration of broadband NIRS and EEG to assess neurovascular and neurometabolic coupling. Sci Rep 2021; 11:3977. [PMID: 33597576 PMCID: PMC7889942 DOI: 10.1038/s41598-021-83420-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/28/2021] [Indexed: 01/31/2023] Open
Abstract
With the rapid growth of optical-based neuroimaging to explore human brain functioning, our research group has been developing broadband Near Infrared Spectroscopy (bNIRS) instruments, a technological extension to functional Near Infrared Spectroscopy (fNIRS). bNIRS has the unique capacity of monitoring brain haemodynamics/oxygenation (measuring oxygenated and deoxygenated haemoglobin), and metabolism (measuring the changes in the redox state of cytochrome-c-oxidase). When combined with electroencephalography (EEG), bNIRS provides a unique neuromonitoring platform to explore neurovascular coupling mechanisms. In this paper, we present a novel pipeline for the integrated analysis of bNIRS and EEG signals, and demonstrate its use on multi-channel bNIRS data recorded with concurrent EEG on healthy adults during a visual stimulation task. We introduce the use of the Finite Impulse Response functions within the General Linear Model for bNIRS and show its feasibility to statistically localize the haemodynamic and metabolic activity in the occipital cortex. Moreover, our results suggest that the fusion of haemodynamic and metabolic measures unveils additional information on brain functioning over haemodynamic imaging alone. The cross-correlation-based analysis of interrelationships between electrical (EEG) and haemodynamic/metabolic (bNIRS) activity revealed that the bNIRS metabolic signal offers a unique marker of brain activity, being more closely coupled to the neuronal EEG response.
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Affiliation(s)
- P. Pinti
- grid.83440.3b0000000121901201Department of Medical Physics and Biomedical Engineering, University College London, London, UK ,grid.4464.20000 0001 2161 2573Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, UK
| | - M. F. Siddiqui
- grid.4464.20000 0001 2161 2573Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, UK
| | - A. D. Levy
- grid.83440.3b0000000121901201Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, London, UK ,grid.83440.3b0000000121901201Headache and Facial Pain, Brain Repair and Rehabilitation, Institute of Neurology, University College London, London, UK
| | - E. J. H. Jones
- grid.4464.20000 0001 2161 2573Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, UK
| | - Ilias Tachtsidis
- grid.83440.3b0000000121901201Department of Medical Physics and Biomedical Engineering, University College London, London, UK
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Kovacsova Z, Bale G, Mitra S, Lange F, Tachtsidis I. Absolute quantification of cerebral tissue oxygen saturation with multidistance broadband NIRS in newborn brain. BIOMEDICAL OPTICS EXPRESS 2021; 12:907-925. [PMID: 33680549 PMCID: PMC7901317 DOI: 10.1364/boe.412088] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 05/23/2023]
Abstract
Tissue oximetry with near-infrared spectroscopy (NIRS) is a technique for the measurement of absolute tissue oxygen saturation (StO2). Offering a real-time and non-invasive assessment of brain oxygenation and haemodynamics, StO2 has potential to be used for the assessment of newborn brain injury. Multiple algorithms have been developed to measure StO2, however, issues with low measurement accuracy or extracranial tissue signal contamination remain. In this work, we present a novel algorithm to recover StO2 in the neonate, broadband multidistance oximetry (BRUNO), based on a measurement of the gradient of attenuation against distance measured with broadband NIRS. The performance of the algorithm was compared to two other published algorithms, broadband fitting (BF) and spatially resolved spectroscopy (SRS). The median error when recovering StO2 in light transport simulations on a neonatal head mesh was 0.4% with BRUNO, 4.2% with BF and 9.5% with SRS. BRUNO was more sensitive to brain tissue oxygenation changes, shown in layered head model simulations. Comparison of algorithm performance during full oxygenation-deoxygenation cycles in a homogeneous dynamic blood phantom showed significant differences in the dynamic range of the algorithms; BRUNO recovered StO2 over 0-100%, BF over 0-90% and SRS over 39-80%. Recovering StO2 from data collected in a neonate treated at the neonatal intensive care showed different baseline values; mean StO2 was 64.9% with BRUNO, 67.2% with BF and 73.2% with SRS. These findings highlight the effect of StO2 algorithm selection on oxygenation recovery; applying BRUNO in the clinical care setting could reveal further insight into complex haemodynamic processes occurring during neonatal brain injury.
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Affiliation(s)
- Zuzana Kovacsova
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Gemma Bale
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
- Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK
- Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Subhabrata Mitra
- Institute for Women’s Health, University College London and Neonatal Unit, University College London Hospitals Trust, London, NW1 2BU, UK
| | - Frédéric Lange
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Ilias Tachtsidis
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
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11
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Nitzan M, Nitzan I, Arieli Y. The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation. SENSORS 2020; 20:s20174844. [PMID: 32867184 PMCID: PMC7506757 DOI: 10.3390/s20174844] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 12/12/2022]
Abstract
Adequate oxygen delivery to a tissue depends on sufficient oxygen content in arterial blood and blood flow to the tissue. Oximetry is a technique for the assessment of blood oxygenation by measurements of light transmission through the blood, which is based on the different absorption spectra of oxygenated and deoxygenated hemoglobin. Oxygen saturation in arterial blood provides information on the adequacy of respiration and is routinely measured in clinical settings, utilizing pulse oximetry. Oxygen saturation, in venous blood (SvO2) and in the entire blood in a tissue (StO2), is related to the blood supply to the tissue, and several oximetric techniques have been developed for their assessment. SvO2 can be measured non-invasively in the fingers, making use of modified pulse oximetry, and in the retina, using the modified Beer–Lambert Law. StO2 is measured in peripheral muscle and cerebral tissue by means of various modes of near infrared spectroscopy (NIRS), utilizing the relative transparency of infrared light in muscle and cerebral tissue. The primary problem of oximetry is the discrimination between absorption by hemoglobin and scattering by tissue elements in the attenuation measurement, and the various techniques developed for isolating the absorption effect are presented in the current review, with their limitations.
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Affiliation(s)
- Meir Nitzan
- Department of Physics/Electro-Optics Engineering, Jerusalem College of Technology, 21 Havaad Haleumi St., Jerusalem 91160, Israel;
- Correspondence:
| | - Itamar Nitzan
- Monash Newborn, Monash Children’s Hospital, Melbourne 3168, Australia;
- Department of Neonatology, Shaare Zedek Medical Center, Shmuel Bait St 12, Jerusalem 9103102, Israel
| | - Yoel Arieli
- Department of Physics/Electro-Optics Engineering, Jerusalem College of Technology, 21 Havaad Haleumi St., Jerusalem 91160, Israel;
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12
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Attention and Capacity Limits in Perception: A Cellular Metabolism Account. J Neurosci 2020; 40:6801-6811. [PMID: 32747442 PMCID: PMC7455219 DOI: 10.1523/jneurosci.2368-19.2020] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 06/10/2020] [Accepted: 06/18/2020] [Indexed: 01/19/2023] Open
Abstract
Limits on perceptual capacity result in various phenomena of inattentional blindness. Here we propose a neurophysiological account attributing these perceptual capacity limits directly to limits on cerebral cellular metabolism. We hypothesized that overall cerebral energy supply remains constant, regardless of overall mental processing demands; therefore, an attention mechanism is required to regulate limited cellular metabolism levels in line with attended task demands. Increased perceptual load in a task (imposing a greater demand on neural computations) should thus result in increased metabolism underlying attended processing, and reduced metabolism mediating unattended processing. We tested this prediction measuring oxidation states of cytochrome c oxidase (oxCCO), an intracellular marker of cellular metabolism. Broadband near-infrared spectroscopy was used to record oxCCO levels from human visual cortex while participants (both sexes) performed a rapid sequential visual search task under either high perceptual load (complex feature-conjunction search) or low load (feature pop-out search). A task-irrelevant, peripheral checkerboard was presented on a random half of trials. Our findings showed that oxCCO levels in visual cortex regions responsive to the attended-task stimuli were increased in high versus low perceptual load, whereas oxCCO levels related to unattended processing were significantly reduced. A negative temporal correlation of these load effects further supported our metabolism trade-off account. These results demonstrate an attentional compensation mechanism that regulates cellular metabolism levels according to processing demands. Moreover, they provide novel evidence for the widely held stipulation that overall cerebral metabolism levels remain constant regardless of mental task demand and establish a neurophysiological account for capacity limits in perception. SIGNIFICANCE STATEMENT We investigated whether capacity limits in perception can be explained by the effects of attention on the allocation of limited cellular metabolic energy for perceptual processing. We measured the oxidation state of cytochrome c oxidase, an intracellular measure of metabolism, in human visual cortex during task performance. The results showed increased levels of cellular metabolism associated with attended processing and reduced levels of metabolism underlying unattended processing when the task was more demanding. A temporal correlation between these effects supported an attention-directed metabolism trade-off. These findings support an account for inattentional blindness grounded in cellular biochemistry. They also provide novel evidence for the claim that cerebral processing is limited by a constant energy supply, which thus requires attentional regulation.
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Broadband NIRS Cerebral Evaluation of the Hemodynamic and Oxidative State of Cytochrome-c-Oxidase Responses to +Gz Acceleration in Healthy Volunteers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1232:339-345. [PMID: 31893429 PMCID: PMC7612835 DOI: 10.1007/978-3-030-34461-0_43] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We used a miniature broadband NIRS system to monitor concentration changes in brain oxygenation (oxy- and deoxy- haemoglobin [HbO2], [HHb]) and oxidised cytochrome-c-oxidase ([oxCCO]) during a high +Gz acceleration, induced by a human centrifuge, on two healthy experienced volunteers (2 male, 34 and 37 years). We performed a sequence of several +Gz exposures that were terminated at the onset of visual symptoms (loss of peripheral vision). Systemic parameters were recorded (i.e. heart rate, blood pressure and arterial saturation), and brain tissue blood volume changes ([HbT] = [HbO2] + [HHb]) and oxygen delivery ([HbDiff] = [HbO2] - [HHb]) were calculated. Volunteer 1 demonstrated a decrease in [HbT] of −3.49 ± 0.02 μMol and [HbDiff] of −3.23 ± 0.44 μMol, and an increase of [oxCCO] of 0.42 ± 0.01μMol. Volunteer 2 demonstrated a decrease in [HbDiff] of −4.37 ± 0.23 μMol, and no significant change in [HbT] (0.53 ± 0.06 μMol) and [oxCCO] (0.09 ± 0.06 μMol). The variability of the brain metabolic response was related to the level of ischaemia, suggesting that suppression of metabolism was due to lack of glucose substrate delivery rather than oxygen availability.
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Kaynezhad P, Mitra S, Bale G, Bauer C, Lingam I, Meehan C, Avdic-Belltheus A, Martinello KA, Bainbridge A, Robertson NJ, Tachtsidis I. Quantification of the severity of hypoxic-ischemic brain injury in a neonatal preclinical model using measurements of cytochrome-c-oxidase from a miniature broadband-near-infrared spectroscopy system. NEUROPHOTONICS 2019; 6:045009. [PMID: 31737744 PMCID: PMC6855218 DOI: 10.1117/1.nph.6.4.045009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/14/2019] [Indexed: 05/05/2023]
Abstract
We describe the development of a miniaturized broadband near-infrared spectroscopy system (bNIRS), which measures changes in cerebral tissue oxyhemoglobin ( [ HbO 2 ] ) and deoxyhemoglobin ([HHb]) plus tissue metabolism via changes in the oxidation state of cytochrome-c-oxidase ([oxCCO]). The system is based on a small light source and a customized mini-spectrometer. We assessed the instrument in a preclinical study in 27 newborn piglets undergoing transient cerebral hypoxia-ischemia (HI). We aimed to quantify the recovery of the HI insult and estimate the severity of the injury. The recovery in brain oxygenation ( Δ [ HbDiff ] = Δ [ HbO 2 ] - Δ [ HHb ] ), blood volume ( Δ [ HbT ] = Δ [ HbO 2 ] + Δ [ HHb ] ), and metabolism ( Δ [ oxCCO ] ) for up to 30 min after the end of HI were quantified in percentages using the recovery fraction (RF) algorithm, which quantifies the recovery of a signal with respect to baseline. The receiver operating characteristic analysis was performed on bNIRS-RF measurements compared to proton ( H 1 ) magnetic resonance spectroscopic (MRS)-derived thalamic lactate/N-acetylaspartate (Lac/NAA) measured at 24-h post HI insult; Lac/NAA peak area ratio is an accurate surrogate marker of neurodevelopmental outcome in babies with neonatal HI encephalopathy. The Δ [ oxCCO ] -RF cut-off threshold of 79% within 30 min of HI predicted injury severity based on Lac/NAA with high sensitivity (100%) and specificity (93%). A significant difference in thalamic Lac/NAA was noticed ( p < 0.0001 ) between the two groups based on this cut-off threshold of 79% Δ [ oxCCO ] -RF. The severe injury group ( n = 13 ) had ∼ 30 % smaller recovery in Δ [ HbDiff ] -RF ( p = 0.0001 ) and no significant difference was observed in Δ [ HbT ] -RF between groups. At 48 h post HI, significantly higher P 31 -MRS-measured inorganic phosphate/exchangeable phosphate pool (epp) ( p = 0.01 ) and reduced phosphocreatine/epp ( p = 0.003 ) were observed in the severe injury group indicating persistent cerebral energy depletion. Based on these results, the bNIRS measurement of the oxCCO recovery fraction offers a noninvasive real-time biomarker of brain injury severity within 30 min following HI insult.
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Affiliation(s)
- Pardis Kaynezhad
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
- Address all correspondence to Ilias Tachtsidis, E-mail:
| | - Subhabrata Mitra
- University College London, Institute for Women’s Health, London, United Kingdom
| | - Gemma Bale
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Cornelius Bauer
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Ingran Lingam
- University College London, Institute for Women’s Health, London, United Kingdom
| | - Christopher Meehan
- University College London, Institute for Women’s Health, London, United Kingdom
| | | | | | - Alan Bainbridge
- University College London Hospital, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Nicola J. Robertson
- University College London, Institute for Women’s Health, London, United Kingdom
| | - Ilias Tachtsidis
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
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15
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Sassaroli A, Blaney G, Fantini S. Dual-slope method for enhanced depth sensitivity in diffuse optical spectroscopy. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2019; 36:1743-1761. [PMID: 31674440 PMCID: PMC7160974 DOI: 10.1364/josaa.36.001743] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Using diffusion theory, we show that a dual-slope method is more effective than single-slope methods or single-distance methods at enhancing sensitivity to deeper tissue. The dual-slope method requires a minimum of two sources and two detectors arranged in specially configured arrays. In particular, we present diffusion theory results for a symmetrical linear array of two sources (separated by 55 mm) that sandwich two detectors (separated by 15 mm), for which dual slopes achieve maximal sensitivity at a depth of about 5 mm for direct current (DC) intensity (as measured in continuous-wave spectroscopy) and 11 mm for phase (as measured in frequency-domain spectroscopy) under typical values of the tissue optical properties (absorption coefficient: ∼0.01mm-1, reduced scattering coefficient: ∼1mm-1). This result is a major advance over single-distance or single-slope data, which feature maximal sensitivity to shallow tissue (<2mm for the intensity, <5mm for the phase).
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A Mini-Review on Functional Near-Infrared Spectroscopy (fNIRS): Where Do We Stand, and Where Should We Go? PHOTONICS 2019. [DOI: 10.3390/photonics6030087] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This mini-review is aimed at briefly summarizing the present status of functional near-infrared spectroscopy (fNIRS) and predicting where the technique should go in the next decade. This mini-review quotes 33 articles on the different fNIRS basics and technical developments and 44 reviews on the fNIRS applications published in the last eight years. The huge number of review articles about a wide spectrum of topics in the field of cognitive and social sciences, functional neuroimaging research, and medicine testifies to the maturity achieved by this non-invasive optical vascular-based functional neuroimaging technique. Today, fNIRS has started to be utilized on healthy subjects while moving freely in different naturalistic settings. Further instrumental developments are expected to be done in the near future to fully satisfy this latter important aspect. In addition, fNIRS procedures, including correction methods for the strong extracranial interferences, need to be standardized before using fNIRS as a clinical tool in individual patients. New research avenues such as interactive neurosciences, cortical activation modulated by different type of sport performance, and cortical activation during neurofeedback training are highlighted.
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Lange F, Dunne L, Hale L, Tachtsidis I. MAESTROS: A Multiwavelength Time-Domain NIRS System to Monitor Changes in Oxygenation and Oxidation State of Cytochrome-C-Oxidase. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2019; 25:7100312. [PMID: 30450021 PMCID: PMC6054019 DOI: 10.1109/jstqe.2018.2833205] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/30/2018] [Accepted: 04/30/2018] [Indexed: 05/17/2023]
Abstract
We present a multiwavelength, multichannel, time-domain near-infrared spectroscopy system named MAESTROS. This instrument can measure absorption and scattering coefficients and can quantify the concentrations of oxy- and deoxy-haemoglobin ([HbO2], [HHb]), and oxidation state of cytochrome-c-oxidase ([oxCCO]). This system is composed of a supercontinuum laser source coupled with two acousto-optic tuneable filters. The light is collected by four photomultipliers tubes, connected to a router to redirect the signal to a single time-correlated single-photon counting card. The interface between the system and the tissue is based on optical fibres. This arrangement allows us to resolve up to 16 wavelengths, within the range of 650-900 nm, at a sampling rate compatible with the physiology (from 0.5 to 2 Hz). In this paper, we describe the system and assess its performance based on two specifically designed protocols for photon migration instruments, the basic instrument protocol and nEUROPt protocols, and on a well characterized liquid phantom based on Intralipid and water. Then, the ability to resolve [HbO2 ], [HHb], and [oxCCO] is demonstrated on a homogeneous liquid phantom, based on blood for [HbO2], [HHb], and yeast for [oxCCO]. In the future, the system could be used to monitor brain tissue physiology.
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Affiliation(s)
- Frederic Lange
- 1Biomedical Optics Research Laboratory Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BTU.K
| | - Luke Dunne
- 1Biomedical Optics Research Laboratory Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BTU.K
| | - Lucy Hale
- 2Biomedical Optics Research Laboratory Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BTU.K
- 3Electronic and Electrical Engineering University College London LondonWC1E 7JEU.K
| | - Ilias Tachtsidis
- 1Biomedical Optics Research Laboratory Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BTU.K
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Tsang WWN, Chan KK, Cheng CN, Hu FSF, Mak CTK, Wong JWC. Tai Chi practice on prefrontal oxygenation levels in older adults: A pilot study. Complement Ther Med 2018; 42:132-136. [PMID: 30670231 DOI: 10.1016/j.ctim.2018.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/04/2018] [Accepted: 11/05/2018] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE The role of exercise in preventing or delaying age-related cognitive decline is an important focus of rehabilitation. Tai Chi (TC) is a traditional Chinese exercise that has been found to improve cognitive function. However, the mechanism underlying this improvement is still unknown. We compared the effects of TC practice (mind-body exercise) and arm ergometry (AE; body focused exercise) on prefrontal cortex activity between TC practitioners and non-practitioners. DESIGN This cross-sectional study included 16 older female subjects (8 TC practitioners and 8 non-practitioners). The practitioners had each practiced TC for at least 7 years. Prefrontal cortex activity was measured using the prefrontal oxygenation level obtained with near-infrared spectroscopy. During the spectroscopy measurement, the participants performed TC, after watching a video of 12-form seated Yang Style TC, and AE in a subsequent session. RESULTS We found significantly greater changes in the levels of oxyhemoglobin (HbO2; p = 0.022) and total hemoglobin (cHb; p = 0.002) in the TC condition compared with the AE condition in all participants. In the TC practitioner group, a similar trend was shown in the change of HbO2 (p = 0.117) and cHb (p = 0.051) when practicing TC versus AE. However, in the non-practitioner group, we found a statistically greater change in cHb (p = 0.005) but not in HbO2 (p = 0.056). CONCLUSION The older adults had higher brain activity when practicing TC compared with AE, and a significant effect was observed in the non-practitioner group. These pilot results may provide insight into the underlying mechanism of the effectiveness of TC practice in preventing cognitive decline in older adults.
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Affiliation(s)
- William W N Tsang
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China.
| | - K K Chan
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Cecelia N Cheng
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Fanny S F Hu
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Clarence T K Mak
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Joey W C Wong
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
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Lange F, Peyrin F, Montcel B. Broadband time-resolved multi-channel functional near-infrared spectroscopy system to monitor in vivo physiological changes of human brain activity. APPLIED OPTICS 2018; 57:6417-6429. [PMID: 30117872 DOI: 10.1364/ao.57.006417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/21/2018] [Indexed: 05/18/2023]
Abstract
We have developed a broadband time-resolved multi-channel near-infrared spectroscopy system that can monitor the physiological responses of the adult human brain. This system is composed of a supercontinuum laser for the source part and of an intensified charge-coupled device camera coupled with an imaging spectrometer for the detection part. It allows the detection of the spectral, from 600 to 900 nm, and spatial dimensions as well as the arrival time of photon information simultaneously. We describe the setup and its characterization in terms of temporal instrument response function, wavelength sensitivity, and stability. The ability of the system to detect the hemodynamic response is then demonstrated. First, an in vivo experiment on an adult volunteer was performed to monitor the response in the arm during a cuff occlusion. Second, the response in the brain during a cognitive task was monitored on a group of five healthy volunteers. Moreover, looking at the response at different time windows, we could monitor the hemodynamic response in depth, enhancing the detection of the cortical activation. Those first results demonstrate the ability of our system to discriminate between the responses of superficial and deep tissues, addressing an important issue in functional near-infrared spectroscopy.
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20
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Luo Y, Li G, Fu Z, Guan Y, Zhang S, Lin L. A method to eliminate the influence of incident light variations in spectral analysis. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:063103. [PMID: 29960534 DOI: 10.1063/1.5025768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The intensity of the light source and consistency of the spectrum are the most important factors influencing the accuracy in quantitative spectrometric analysis. An efficient "measuring in layer" method was proposed in this paper to limit the influence of inconsistencies in the intensity and spectrum of the light source. In order to verify the effectiveness of this method, a light source with a variable intensity and spectrum was designed according to Planck's law and Wien's displacement law. Intra-lipid samples with 12 different concentrations were prepared and divided into modeling sets and prediction sets according to different incident lights and solution concentrations. The spectra of each sample were measured with five different light intensities. The experimental results showed that the proposed method was effective in eliminating the influence caused by incident light changes and was more effective than normalized processing.
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Affiliation(s)
- Yongshun Luo
- State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Gang Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Zhigang Fu
- Medical Examination Centre, No. 254 Hospital of PLA, Tianjin 300142, China
| | - Yang Guan
- Medical Examination Centre, No. 254 Hospital of PLA, Tianjin 300142, China
| | - Shengzhao Zhang
- State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Ling Lin
- State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China
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Investigation of Confounding Factors in Measuring Tissue Saturation with NIRS Spatially Resolved Spectroscopy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1072:307-312. [PMID: 30178363 PMCID: PMC6142855 DOI: 10.1007/978-3-319-91287-5_49] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Performing absolute measurements of tissue saturation of the brain with near-infrared spectroscopy (NIRS) is a clinically desirable brain monitoring tool. Tissue oxygenation index (TOI) is an indicator of absolute tissue mixed arterial and venous oxygen saturation, and can be calculated using a NIRS technique called spatially resolved spectroscopy (SRS). SRS instruments measure the change of light attenuation with distance by using multiple light source-detector distances at two or more wavelengths. The aim of the study is to use broadband NIRS SRS data to investigate the effects on the calculation of TOI of different parameters: wavelength selection, scattering dependence, source-detector distance, and resolving for water. In total, 55 neonates with hypoxic-ischemic encephalopathy were monitored using a broadband multi-distance continuous wave NIRS system; 172 datasets were recorded. Using a "Standard" approach, TOI values between 0 and 100% ("good") were calculated in 157/172 datasets with a mean TOI of 50%. By changing the wavelength selection, the number of "good" data sets increases to 165/172 with a mean of 60%. Alteration of the dependence of scattering on wavelength acts as a constant which shifts the absolute value of TOI significantly (p < 0.05), demonstrating the importance of having a subject-appropriate estimation of scattering dependence. In general, changing the combination of source-detector distances does not significantly alter the TOI (the mean TOI ranges from 41% to 53%) which suggests that the algorithm is robust to different source-detector combinations. The study shows the broadband NIRS SRS algorithm gives the opportunity to explore the calculation of TOI and could further improve the measurement of tissue saturation in a clinical setting.
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Highton D, Chitnis D, Brigadoi S, Phan P, Tachtsidis I, Cooper R, Everdell N, Hebden J, Smith M, Elwell CE. A Fibreless Multiwavelength NIRS System for Imaging Localised Changes in Cerebral Oxidised Cytochrome C Oxidase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1072:339-343. [PMID: 30178368 DOI: 10.1007/978-3-319-91287-5_54] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Measurement of the oxidation state of cytochrome c oxidase (oxCCO) can inform directly on neuronal metabolism. Conventionally this has been measured in vivo using benchtop broadband near infrared spectroscopy (NIRS) systems. Spatially resolved measures of oxCCO have recently been made possible using a multichannel fibre-based broadband NIRS system. We describe the use of a fibreless multiwavelength NIRS system using light emitting diodes (LED) designed specifically to image localised changes in oxCCO and hence neuronal metabolism. A fibreless system consisting of four modules, each containing two LED sources and four photodiode detectors, was developed. Each LED source contained eight LED dies (780, 811, 818, 842, 850, 882, 891 and 901 nm) assembled in an area of 1.5 × 1.5 mm. A well-established hyperoxia protocol was used to evaluate the oxCCO spatially resolved measurement capabilities of the system and, subsequently, its imaging capabilities were tested using a functional activation paradigm. A multi-spectral image reconstruction approach was used to provide images of Δ[HbO2], Δ[HHb] and Δ[oxCCO] from the multi-distance, multi-channel optical datasets. This novel fibreless multiwavelength NIRS system allows imaging of localised changes in oxCCO in the human brain, and has potential for development as an inexpensive, wearable, continuous monitor of cerebral energetics in a range of experimental and clinical scenarios.
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Affiliation(s)
- D Highton
- Neurocritical Care Unit, National Hospital for Neurology and Neurosurgery, London, UK.,University of Queensland, Brisbane, Australia
| | - D Chitnis
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK
| | - S Brigadoi
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK.,Department of Developmental and Social Psychology, University of Padova, Padua, Italy
| | - P Phan
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK
| | - I Tachtsidis
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK
| | - R Cooper
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK
| | - N Everdell
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK
| | - J Hebden
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK
| | - M Smith
- Neurocritical Care Unit, National Hospital for Neurology and Neurosurgery, London, UK.,Department of Medical Physics and Biomedical Engineering, UCL, London, UK.,NIHR University College London Hospitals Biomedical Research Centre, London, UK
| | - C E Elwell
- Department of Medical Physics and Biomedical Engineering, UCL, London, UK.
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