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Abstract
The cerebral microcirculation undergoes dynamic changes in parallel with the development of neurons, glia, and their energy metabolism throughout gestation and postnatally. Cerebral blood flow (CBF), oxygen consumption, and glucose consumption are as low as 20% of adult levels in humans born prematurely but eventually exceed adult levels at ages 3 to 11 years, which coincide with the period of continued brain growth, synapse formation, synapse pruning, and myelination. Neurovascular coupling to sensory activation is present but attenuated at birth. By 2 postnatal months, the increase in CBF often is disproportionately smaller than the increase in oxygen consumption, in contrast to the relative hyperemia seen in adults. Vascular smooth muscle myogenic tone increases in parallel with developmental increases in arterial pressure. CBF autoregulatory response to increased arterial pressure is intact at birth but has a more limited range with arterial hypotension. Hypoxia-induced vasodilation in preterm fetal sheep with low oxygen consumption does not sustain cerebral oxygen transport, but the response becomes better developed for sustaining oxygen transport by term. Nitric oxide tonically inhibits vasomotor tone, and glutamate receptor activation can evoke its release in lambs and piglets. In piglets, astrocyte-derived carbon monoxide plays a central role in vasodilation evoked by glutamate, ADP, and seizures, and prostanoids play a large role in endothelial-dependent and hypercapnic vasodilation. Overall, homeostatic mechanisms of CBF regulation in response to arterial pressure, neuronal activity, carbon dioxide, and oxygenation are present at birth but continue to develop postnatally as neurovascular signaling pathways are dynamically altered and integrated. © 2021 American Physiological Society. Compr Physiol 11:1-62, 2021.
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2
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Zhang F, Cheong D, Khan AF, Chen Y, Ding L, Yuan H. Correcting physiological noise in whole-head functional near-infrared spectroscopy. J Neurosci Methods 2021; 360:109262. [PMID: 34146592 DOI: 10.1016/j.jneumeth.2021.109262] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 05/20/2021] [Accepted: 06/14/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Functional near-infrared spectroscopy (fNIRS) has been increasingly employed to monitor cerebral hemodynamics in normal and diseased conditions. However, fNIRS suffers from its susceptibility to superficial activity and systemic physiological noise. The objective of the study was to establish a noise reduction method for fNIRS in a whole-head montage. NEW METHOD We have developed an automated denoising method for whole-head fNIRS. A high-density montage consisting of 109 long-separation channels and 8 short-separation channels was used for recording. Auxiliary sensors were also used to measure motion, respiration and pulse simultaneously. The method incorporates principal component analysis and general linear model to identify and remove a globally uniform superficial component. Our denoising method was evaluated in experimental data acquired from a group of healthy human subjects during a visually cued motor task and further compared with a minimal preprocessing method and three established denoising methods in the literature. Quantitative metrics including contrast-to-noise ratio, within-subject standard deviation and adjusted coefficient of determination were evaluated. RESULTS After denoising, whole-head topography of fNIRS revealed focal activations concurrently in the primary motor and visual areas. COMPARISON WITH EXISTING METHODS Analysis showed that our method improves upon the four established preprocessing methods in the literature. CONCLUSIONS An automatic, effective and robust preprocessing pipeline was established for removing physiological noise in whole-head fNIRS recordings. Our method can enable fNIRS as a reliable tool in monitoring large-scale, network-level brain activities for clinical uses.
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Affiliation(s)
- Fan Zhang
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, USA
| | - Daniel Cheong
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, USA
| | - Ali F Khan
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, USA
| | - Yuxuan Chen
- School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA
| | - Lei Ding
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, USA; Institute for Biomedical Engineering, Science and Technology, University of Oklahoma, Norman, OK, USA
| | - Han Yuan
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, USA; Institute for Biomedical Engineering, Science and Technology, University of Oklahoma, Norman, OK, USA.
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3
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Carrier M, Guilbert J, Lévesque JP, Tremblay MÈ, Desjardins M. Structural and Functional Features of Developing Brain Capillaries, and Their Alteration in Schizophrenia. Front Cell Neurosci 2021; 14:595002. [PMID: 33519380 PMCID: PMC7843388 DOI: 10.3389/fncel.2020.595002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/04/2020] [Indexed: 12/19/2022] Open
Abstract
Schizophrenia affects more than 1% of the world's population and shows very high heterogeneity in the positive, negative, and cognitive symptoms experienced by patients. The pathogenic mechanisms underlying this neurodevelopmental disorder are largely unknown, although it is proposed to emerge from multiple genetic and environmental risk factors. In this work, we explore the potential alterations in the developing blood vessel network which could contribute to the development of schizophrenia. Specifically, we discuss how the vascular network evolves during early postnatal life and how genetic and environmental risk factors can lead to detrimental changes. Blood vessels, capillaries in particular, constitute a dynamic and complex infrastructure distributing oxygen and nutrients to the brain. During postnatal development, capillaries undergo many structural and anatomical changes in order to form a fully functional, mature vascular network. Advanced technologies like magnetic resonance imaging and near infrared spectroscopy are now enabling to study how the brain vasculature and its supporting features are established in humans from birth until adulthood. Furthermore, the contribution of the different neurovascular unit elements, including pericytes, endothelial cells, astrocytes and microglia, to proper brain function and behavior, can be dissected. This investigation conducted among different brain regions altered in schizophrenia, such as the prefrontal cortex, may provide further evidence that schizophrenia can be considered a neurovascular disorder.
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Affiliation(s)
- Micaël Carrier
- Axe Neurosciences, Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada.,Department of Molecular Medicine, Université Laval, Québec, QC, Canada
| | - Jérémie Guilbert
- Axe Oncologie, Centre de recherche du CHU de Québec, Université Laval, Québec, QC, Canada.,Department of Physics, Physical Engineering and Optics, Université Laval, Québec, QC, Canada
| | - Jean-Philippe Lévesque
- Axe Oncologie, Centre de recherche du CHU de Québec, Université Laval, Québec, QC, Canada.,Department of Physics, Physical Engineering and Optics, Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Axe Neurosciences, Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada.,Department of Molecular Medicine, Université Laval, Québec, QC, Canada.,Division of Medical Sciences, University of Victoria, Victoria, BC, Canada.,Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada.,Neurology and Neurosurgery Department, McGill University, Montréal, QC, Canada
| | - Michèle Desjardins
- Axe Oncologie, Centre de recherche du CHU de Québec, Université Laval, Québec, QC, Canada.,Department of Physics, Physical Engineering and Optics, Université Laval, Québec, QC, Canada
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4
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Lee W, Ostadi Moghaddam A, Shen S, Phillips H, McFarlin BL, Wagoner Johnson AJ, Toussaint KC. An optomechanogram for assessment of the structural and mechanical properties of tissues. Sci Rep 2021; 11:324. [PMID: 33431940 PMCID: PMC7801423 DOI: 10.1038/s41598-020-79602-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 11/24/2020] [Indexed: 11/25/2022] Open
Abstract
The structural and mechanical properties of tissue and the interplay between them play a critical role in tissue function. We introduce the optomechanogram, a combined quantitative and qualitative visualization of spatially co-registered measurements of the microstructural and micromechanical properties of any tissue. Our approach relies on the co-registration of two independent platforms, second-harmonic generation (SHG) microscopy for quantitative assessment of 3D collagen-fiber microstructural organization, and nanoindentation (NI) for local micromechanical properties. We experimentally validate our method by applying to uterine cervix tissue, which exhibits structural and mechanical complexity. We find statistically significant agreement between the micromechanical and microstructural data, and confirm that the distinct tissue regions are distinguishable using either the SHG or NI measurements. Our method could potentially be used for research in pregnancy maintenance, mechanobiological studies of tissues and their constitutive modeling and more generally for the optomechanical metrology of materials.
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Affiliation(s)
- W Lee
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - A Ostadi Moghaddam
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA
| | - S Shen
- Center for Health, Aging, and Disability (CHAD), College of Applied Health Science, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA
| | - H Phillips
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - B L McFarlin
- Department of Women, Children and Family Health Science, University of Illinois College of Nursing, Chicago, IL, 60612, USA
| | - A J Wagoner Johnson
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA. .,Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA. .,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - K C Toussaint
- School of Engineering, Brown University, Providence, RI, 02912, USA.
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5
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Neonatal NIRS monitoring: recommendations for data capture and review of analytics. J Perinatol 2021; 41:675-688. [PMID: 33589724 PMCID: PMC7883881 DOI: 10.1038/s41372-021-00946-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/20/2020] [Accepted: 01/19/2021] [Indexed: 01/29/2023]
Abstract
Brain injury is one of the most consequential problems facing neonates, with many preterm and term infants at risk for cerebral hypoxia and ischemia. To develop effective neuroprotective strategies, the mechanistic basis for brain injury must be understood. The fragile state of neonates presents unique research challenges; invasive measures of cerebral blood flow and oxygenation assessment exceed tolerable risk profiles. Near-infrared spectroscopy (NIRS) can safely and non-invasively estimate cerebral oxygenation, a correlate of cerebral perfusion, offering insight into brain injury-related mechanisms. Unfortunately, lack of standardization in device application, recording methods, and error/artifact correction have left the field fractured. In this article, we provide a framework for neonatal NIRS research. Our goal is to provide a rational basis for NIRS data capture and processing that may result in better comparability between studies. It is also intended to serve as a primer for new NIRS researchers and assist with investigation initiation.
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Altun D, Doğan A, Arnaz A, Yüksek A, Yalçinbaş YK, Türköz R, Sarioğlu T. Noninvasive monitoring of central venous oxygen saturation by jugular transcutaneous near-infrared spectroscopy in pediatric patients undergoing congenital cardiac surgery. Turk J Med Sci 2020; 50:1280-1287. [PMID: 32490634 PMCID: PMC7491293 DOI: 10.3906/sag-1911-135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 05/19/2020] [Indexed: 12/26/2022] Open
Abstract
Background and aim In patients undergoing congenital cardiac surgery, it is crucial to maintain oxygen demand-consumption balance. Central venous oxygen saturation (ScvO2) is a useful indicator of oxygen demand and consumption balance which is an invasive method. Near-infrared spectroscopy (NIRS) is a noninvasive, continuous monitoring technique that measures regional tissue oxygenation. NIRS that is placed over the internal jugular vein cutaneous area (NIRSijv) has the potential to show ScvO2 indirectly. In this study, we aimed to determine the correlation between ScvO2 with NIRSijv in pediatric patients undergoing congenital cardiac surgery. Materials and methods Fifty children participated in the study. Four patients were excluded for the inability of internal jugular vein (IJV) catheterization due to technical difficulties. After anesthesia induction, NIRS probes were placed on the IJV site with ultrasound guidance for the measurement of continuous transcutaneous oxygen saturation. The catheter insertion was also done through the IJV from the other side using ultrasound guidance. Cerebral oxygenation monitoring was done using NIRS with a single pediatric probe placed on the right forehead. Values of NIRSijv, cerebral NIRS (NIRSc) and ScvO2, were recorded at certain times until postoperative 24th hour. Results Data were collected at 8 different time points. There was a significant correlation between ScvO2 and NIRSijv in all measurement time points (r = 0.91), (P = 0.001). The mean bias between ScvO2 and NIRSijv was 2.92% and the limits of agreement were from 11% to –5.2%. There was a moderate correlation between ScvO2 and NIRSc (r = 0.45), (P = 0.001). The mean bias between ScvO2 and NIRSc was 2.7% and the limits of agreement were from +26% to –20%. Conclusion In this study, we found a strong correlation between ScvO2 and NIRS measurements taken from the internal jugular vein site. Accordingly, continuous noninvasive monitoring with transcutaneous NIRSijv can be an alternative method as a trend monitor for the central venous oxygen saturation in pediatric cardiac patients undergoing congenital cardiac surgery.
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Affiliation(s)
- Dilek Altun
- Department of Anesthesiology and Reanimation, Vocational School of Health Sciences, Acıbadem Mehmet Ali Aydınlar University, İstanbul, Turkey
| | - Abdullah Doğan
- Department of Cardiovascular Surgery, Acıbadem Bakırköy Hospital, İstanbul, Turkey
| | - Ahmet Arnaz
- Department of Cardiovascular Surgery, Faculty of Medicine, Acıbadem Mehmet Ali Aydınlar University, İstanbul, Turkey
| | - Adnan Yüksek
- Department of Anesthesiology and Reanimation, Acıbadem Bakırköy Hospital, İstanbul, Turkey
| | | | - Riza Türköz
- Department of Cardiovascular Surgery, Acıbadem Bakırköy Hospital, İstanbul, Turkey
| | - Tayyar Sarioğlu
- Department of Pediatric Cardiovascular Surgery, Faculty of Medicine, Acıbadem Mehmet Ali Aydınlar University, İstanbul, Turkey
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7
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Novi SL, Roberts E, Spagnuolo D, Spilsbury BM, Price DC, Imbalzano CA, Forero E, Yodh AG, Tellis GM, Tellis CM, Mesquita RC. Functional near-infrared spectroscopy for speech protocols: characterization of motion artifacts and guidelines for improving data analysis. NEUROPHOTONICS 2020; 7:015001. [PMID: 31956662 PMCID: PMC6953699 DOI: 10.1117/1.nph.7.1.015001] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 12/19/2019] [Indexed: 05/02/2023]
Abstract
Monitoring speech tasks with functional near-infrared spectroscopy (fNIRS) enables investigation of speech production mechanisms and informs treatment strategies for speech-related disorders such as stuttering. Unfortunately, due to movement of the temporalis muscle, speech production can induce relative movement between probe optodes and skin. These movements generate motion artifacts during speech tasks. In practice, spurious hemodynamic responses in functional activation signals arise from lack of information about the consequences of speech-related motion artifacts, as well as from lack of standardized processing procedures for fNIRS signals during speech tasks. To this end, we characterize the effects of speech production on fNIRS signals, and we introduce a systematic analysis to ameliorate motion artifacts. The study measured 50 healthy subjects performing jaw movement (JM) tasks and found that JM produces two different patterns of motion artifacts in fNIRS. To remove these unwanted contributions, we validate a hybrid motion-correction algorithm based sequentially on spline interpolation and then wavelet filtering. We compared performance of the hybrid algorithm with standard algorithms based on spline interpolation only and wavelet decomposition only. The hybrid algorithm corrected 94% of the artifacts produced by JM, and it did not lead to spurious responses in the data. We also validated the hybrid algorithm during a reading task performed under two different conditions: reading aloud and reading silently. For both conditions, we observed significant cortical activation in brain regions related to reading. Moreover, when comparing the two conditions, good agreement of spatial and temporal activation patterns was found only when data were analyzed using the hybrid approach. Overall, the study demonstrates a standardized processing scheme for fNIRS data during speech protocols. The scheme decreases spurious responses and intersubject variability due to motion artifacts.
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Affiliation(s)
- Sergio L. Novi
- University of Campinas, Institute of Physics, Campinas, São Paulo, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology, Campinas, São Paulo, Brazil
| | - Erin Roberts
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - Danielle Spagnuolo
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - Brianna M. Spilsbury
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - D’manda C. Price
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - Cara A. Imbalzano
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - Edwin Forero
- University of Campinas, Institute of Physics, Campinas, São Paulo, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology, Campinas, São Paulo, Brazil
| | - Arjun G. Yodh
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Glen M. Tellis
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - Cari M. Tellis
- Misericordia University, Department of Speech-Language Pathology, Dallas, Pennsylvania, United States
| | - Rickson C. Mesquita
- University of Campinas, Institute of Physics, Campinas, São Paulo, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology, Campinas, São Paulo, Brazil
- Address all correspondence to: Rickson C. Mesquita, E-mail:
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8
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Uchida-Ota M, Arimitsu T, Tsuzuki D, Dan I, Ikeda K, Takahashi T, Minagawa Y. Maternal speech shapes the cerebral frontotemporal network in neonates: A hemodynamic functional connectivity study. Dev Cogn Neurosci 2019; 39:100701. [PMID: 31513977 PMCID: PMC6969365 DOI: 10.1016/j.dcn.2019.100701] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 06/09/2019] [Accepted: 08/05/2019] [Indexed: 12/13/2022] Open
Abstract
Language development and the capacity for communication in infants are predominantly supported by their mothers, beginning when infants are still in utero. Although a mother's speech should thus have a significant impact on her neonate's brain, neurocognitive evidence for this hypothesis remains elusive. The present study examined 37 neonates using near-infrared spectroscopy and observed the interactions between multiple cortical regions while neonates heard speech spoken by their mothers or by strangers. We analyzed the functional connectivity between regions whose response-activation patterns differed between the two types of speakers. We found that when hearing their mothers' speech, functional connectivity was enhanced in both the neonatal left and right frontotemporal networks. On the left it was enhanced between the inferior/middle frontal gyrus and the temporal cortex, while on the right it was enhanced between the frontal pole and temporal cortex. In particular, the frontal pole was more strongly connected to the left supramarginal area when hearing speech from mothers. These enhanced frontotemporal networks connect areas that are associated with language (left) and voice processing (right) at later stages of development. We suggest that these roles are initially fostered by maternal speech.
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Affiliation(s)
- Mariko Uchida-Ota
- Center for Advanced Research on Logic and Sensibility, Keio University, Tokyo, Japan; Center for Research in International Education, Tokyo Gakugei University, Tokyo, Japan
| | - Takeshi Arimitsu
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Daisuke Tsuzuki
- Department of Language Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Ippeita Dan
- Faculty of Science and Engineering, Chuo University, Tokyo, Japan
| | - Kazushige Ikeda
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Takao Takahashi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Yasuyo Minagawa
- Center for Advanced Research on Logic and Sensibility, Keio University, Tokyo, Japan; Department of Psychology, Faculty of Letters, Keio University, Kanagawa, Japan.
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9
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Thomas E, Buss C, Rasmussen JM, Entringer S, Ramirez JSB, Marr M, Rudolph MD, Gilmore JH, Styner M, Wadhwa PD, Fair DA, Graham AM. Newborn amygdala connectivity and early emerging fear. Dev Cogn Neurosci 2019; 37:100604. [PMID: 30581123 PMCID: PMC6538430 DOI: 10.1016/j.dcn.2018.12.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 12/05/2018] [Accepted: 12/05/2018] [Indexed: 12/21/2022] Open
Abstract
Connectivity between the amygdala, insula (Amygdala-aI) and ventral medial prefrontal cortex (Amygdala-vmPFC) have been implicated in individual variability in fear and vulnerability to psychiatric disorders. However, it is currently unknown to what extent connectivity between these regions in the newborn period is relevant for the development of fear and other aspects of negative emotionality (NE), such as sadness. Here, we investigate newborn Am-Ins and Am-vmPFC resting state functional connectivity in relation to developmental trajectories of fear and sadness over the first two years of life using data from the Infant Behavior Questionnaire Revised (IBQ-R) and Early Childhood Behavior Questionnaire (ECBQ) (N=62). Stronger newborn amygdala connectivity predicts higher fear and sadness at 6-months-of-age and less change from 6 to 24-months-of-age. Interestingly, Am-Ins connectivity was specifically relevant for fear and not sadness, while Am-vmPFC was associated only with sadness. Associations remained consistent after considering variation in maternal sensitivity and maternal postnatal depressive symptomology. Already by the time of birth, individual differences in amygdala connectivity are relevant for the expression of fear over the first two-years-of-life. Additionally, specificity is observed, such that connections relevant for fear development are distinct from those predicting sadness trajectories.
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Affiliation(s)
- Elina Thomas
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
| | - Claudia Buss
- Charité -Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany; Development, Health and Disease Research Program, University of California, Irvine, Irvine, CA, USA
| | - Jerod M Rasmussen
- Charité -Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Sonja Entringer
- Charité -Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany; Development, Health and Disease Research Program, University of California, Irvine, Irvine, CA, USA
| | - Julian S B Ramirez
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
| | - Mollie Marr
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
| | - Marc D Rudolph
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
| | - John H Gilmore
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Martin Styner
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Pathik D Wadhwa
- Charité -Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Damien A Fair
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA; Department of Psychiatry, Oregon Health & Science University, Portland, OR, USA; Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, USA
| | - Alice M Graham
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA.
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Wheelock MD, Culver JP, Eggebrecht AT. High-density diffuse optical tomography for imaging human brain function. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:051101. [PMID: 31153254 PMCID: PMC6533110 DOI: 10.1063/1.5086809] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 04/14/2019] [Indexed: 05/08/2023]
Abstract
This review describes the unique opportunities and challenges for noninvasive optical mapping of human brain function. Diffuse optical methods offer safe, portable, and radiation free alternatives to traditional technologies like positron emission tomography or functional magnetic resonance imaging (fMRI). Recent developments in high-density diffuse optical tomography (HD-DOT) have demonstrated capabilities for mapping human cortical brain function over an extended field of view with image quality approaching that of fMRI. In this review, we cover fundamental principles of the diffusion of near infrared light in biological tissue. We discuss the challenges involved in the HD-DOT system design and implementation that must be overcome to acquire the signal-to-noise necessary to measure and locate brain function at the depth of the cortex. We discuss strategies for validation of the sensitivity, specificity, and reliability of HD-DOT acquired maps of cortical brain function. We then provide a brief overview of some clinical applications of HD-DOT. Though diffuse optical measurements of neurophysiology have existed for several decades, tremendous opportunity remains to advance optical imaging of brain function to address a crucial niche in basic and clinical neuroscience: that of bedside and minimally constrained high fidelity imaging of brain function.
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Affiliation(s)
- Muriah D. Wheelock
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | - Adam T. Eggebrecht
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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11
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Hendrikx D, Smits A, Lavanga M, De Wel O, Thewissen L, Jansen K, Caicedo A, Van Huffel S, Naulaers G. Measurement of Neurovascular Coupling in Neonates. Front Physiol 2019; 10:65. [PMID: 30833901 PMCID: PMC6387909 DOI: 10.3389/fphys.2019.00065] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 01/21/2019] [Indexed: 01/01/2023] Open
Abstract
Neurovascular coupling refers to the mechanism that links the transient neural activity to the subsequent change in cerebral blood flow, which is regulated by both chemical signals and mechanical effects. Recent studies suggest that neurovascular coupling in neonates and preterm born infants is different compared to adults. The hemodynamic response after a stimulus is later and less pronounced and the stimulus might even result in a negative (hypoxic) signal. In addition, studies both in animals and neonates confirm the presence of a short hypoxic period after a stimulus in preterm infants. In clinical practice, different methodologies exist to study neurovascular coupling. The combination of functional magnetic resonance imaging or functional near-infrared spectroscopy (brain hemodynamics) with EEG (brain function) is most commonly used in neonates. Especially near-infrared spectroscopy is of interest, since it is a non-invasive method that can be integrated easily in clinical care and is able to provide results concerning longer periods of time. Therefore, near-infrared spectroscopy can be used to develop a continuous non-invasive measurement system, that could be used to study neonates in different clinical settings, or neonates with different pathologies. The main challenge for the development of a continuous marker for neurovascular coupling is how the coupling between the signals can be described. In practice, a wide range of signal interaction measures exist. Moreover, biomedical signals often operate on different time scales. In a more general setting, other variables also have to be taken into account, such as oxygen saturation, carbon dioxide and blood pressure in order to describe neurovascular coupling in a concise manner. Recently, new mathematical techniques were developed to give an answer to these questions. This review discusses these recent developments.
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Affiliation(s)
- Dries Hendrikx
- Department of Electrical Engineering, KU Leuven, Leuven, Belgium
- imec, Leuven, Belgium
| | - Anne Smits
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Neonatal Intensive Care Unit, University Hospitals Leuven, Leuven, Belgium
| | - Mario Lavanga
- Department of Electrical Engineering, KU Leuven, Leuven, Belgium
- imec, Leuven, Belgium
| | - Ofelie De Wel
- Department of Electrical Engineering, KU Leuven, Leuven, Belgium
- imec, Leuven, Belgium
| | - Liesbeth Thewissen
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Neonatal Intensive Care Unit, University Hospitals Leuven, Leuven, Belgium
| | - Katrien Jansen
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Neonatal Intensive Care Unit, University Hospitals Leuven, Leuven, Belgium
- Child Neurology, University Hospitals Leuven, Leuven, Belgium
| | - Alexander Caicedo
- Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Bogotá, Colombia
| | - Sabine Van Huffel
- Department of Electrical Engineering, KU Leuven, Leuven, Belgium
- imec, Leuven, Belgium
| | - Gunnar Naulaers
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Neonatal Intensive Care Unit, University Hospitals Leuven, Leuven, Belgium
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12
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Vesoulis ZA, Liao SM, Mathur AM. Late failure of cerebral autoregulation in hypoxic-ischemic encephalopathy is associated with brain injury: a pilot study. Physiol Meas 2018; 39:125004. [PMID: 30270845 PMCID: PMC6289666 DOI: 10.1088/1361-6579/aae54d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Post-resuscitation reperfusion following hypoxic-ischemia (HIE) is associated with secondary brain injury in neonates. OBJECTIVE To quantify the association between perfusion exceeding autoregulatory limits and brain injury. APPROACH Continuous mean arterial blood pressure (MABP) and cerebral near-infrared spectroscopy (NIRS) data were prospectively collected from infants with HIE. Cerebral oximetry index (COx) was calculated as a moving correlation coefficient between MABP and NIRS. Upper and lower limits of autoregulation were identified by transition from negative to positive correlation. The proportion of time MABP above (hyperperfusion) and below (hypoperfusion) autoregulatory limits was calculated during therapeutic hypothermia (days 1-3). MAIN RESULTS Sixteen infants were included; injury was noted in 7/16. There was no significance in hyperperfusion burden between injured and uninjured infants during day one (7% versus 10%, p = 0.88) or two (4% versus 2%, p = 0.88), but there was a marked increase for injured infants on day three (54% versus 14%, p = 0.02). There was a corollary decrease in hypoperfusion for injured versus uninjured infants on day 3 (6% versus 24%, p = 0.05). SIGNIFICANCE HIE infants with brain injury have a late failure of cerebral autoregulation, manifested as a hyperperfusion burden, suggesting pathologic events are active on day 3 of hypothermia. This finding may help to identify infants which might need additional neuroprotection.
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Affiliation(s)
- Zachary A. Vesoulis
- Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Steve M. Liao
- Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Amit M. Mathur
- Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
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13
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de Roever I, Bale G, Mitra S, Meek J, Robertson NJ, Tachtsidis I. Investigation of the Pattern of the Hemodynamic Response as Measured by Functional Near-Infrared Spectroscopy (fNIRS) Studies in Newborns, Less Than a Month Old: A Systematic Review. Front Hum Neurosci 2018; 12:371. [PMID: 30333736 PMCID: PMC6176492 DOI: 10.3389/fnhum.2018.00371] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 08/29/2018] [Indexed: 01/03/2023] Open
Abstract
It has been 20 years since functional near-infrared spectroscopy (fNIRS) was first used to investigate the evoked hemodynamic response to a stimulus in newborns. The hemodynamic response to functional activation is well-established in adults, with an observed increase in concentration change of oxygenated hemoglobin (Δ[HbO2]) and decrease in deoxygenated hemoglobin (Δ[HHb]). However, functional studies in newborns have revealed a mixed response, particularly with Δ[HHb] where an inconsistent change in direction is observed. The reason for this heterogeneity is unknown, with potential explanations arising from differing physiology in the developing brain, or differences in instrumentation or methodology. The aim of this review is to collate the findings from studies that have employed fNIRS to monitor cerebral hemodynamics in term newborn infants aged 1 day-1 month. A total of 46 eligible studies were identified; some studies investigated more than one stimulus type, resulting in a total of 51 reported results. The NIRS parameters reported varied across studies with 50/51 cases reporting Δ[HbO2], 39/51 reporting Δ[HHb], and 13/51 reporting total hemoglobin concentration Δ[HbT] (Δ[HbO2] + Δ[HHb]). However, of the 39 cases reporting Δ[HHb] in graphs or tables, only 24 studies explicitly discussed the response (i.e., direction of change) of this variable. In the studies where the fNIRS responses were discussed, 46/51 cases observed an increase in Δ[HbO2], 7/51 observed an increase or varied Δ[HHb], and 2/51 reported a varied or negative Δ[HbT]. An increase in Δ[HbO2] and decrease or no change in Δ[HHb] was observed in 15 studies. By reviewing this body of literature, we have identified that the majority of research articles reported an increase in Δ[HbO2] across various functional tasks and did not report the response of Δ[HHb]. Confirming the normal, healthy hemodynamic response in newborns will allow identification of unhealthy patterns and their association to normal neurodevelopment.
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Affiliation(s)
- Isabel de Roever
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Gemma Bale
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Subhabrata Mitra
- Department of Neonatology, Institute for Women's Health, University College London, London, United Kingdom
| | - Judith Meek
- Department of Neonatology, Institute for Women's Health, University College London, London, United Kingdom
| | - Nicola J. Robertson
- Department of Neonatology, Institute for Women's Health, University College London, London, United Kingdom
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
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14
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Cusack R, McCuaig O, Linke AC. Methodological challenges in the comparison of infant fMRI across age groups. Dev Cogn Neurosci 2018; 33:194-205. [PMID: 29158073 PMCID: PMC6969274 DOI: 10.1016/j.dcn.2017.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 09/29/2017] [Accepted: 11/07/2017] [Indexed: 01/31/2023] Open
Abstract
Functional MRI (fMRI) in infants is rapidly growing and providing fundamental insights into the origins of brain functions. Comparing brain development at different ages is particularly powerful, but there are a number of methodological challenges that must be addressed if confounds are to be avoided. With development, brains change in composition in a way that alters their tissue contrast, and in size, shape, and gyrification, requiring careful image processing strategies and age-specific standard templates. The hemodynamic response and other aspects of physiology change with age, requiring careful paradigm design and analysis methods. Infants move more, particularly around the second year of age, and move in a different way to adults. This movement can lead to distortion in fMRI images, and requires tailored techniques during acquisition and post-processing. Infants have different sleep patterns, and their sensory periphery is changing macroscopically and in its neural pathways. Finally, once data have been acquired and analyzed, there are important considerations during mapping of brain processes and cognitive functions across age groups. In summary, new methods are critical to the comparison across age groups, and key to maximizing the rate at which infant fMRI can provide insight into the fascinating questions about the origin of cognition.
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Affiliation(s)
- Rhodri Cusack
- Brain and Mind Institute, Western University, Canada; Trinity College, Dublin, Ireland.
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15
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Mohammadi-Nejad AR, Mahmoudzadeh M, Hassanpour MS, Wallois F, Muzik O, Papadelis C, Hansen A, Soltanian-Zadeh H, Gelovani J, Nasiriavanaki M. Neonatal brain resting-state functional connectivity imaging modalities. PHOTOACOUSTICS 2018; 10:1-19. [PMID: 29511627 PMCID: PMC5832677 DOI: 10.1016/j.pacs.2018.01.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 01/12/2018] [Accepted: 01/27/2018] [Indexed: 05/12/2023]
Abstract
Infancy is the most critical period in human brain development. Studies demonstrate that subtle brain abnormalities during this state of life may greatly affect the developmental processes of the newborn infants. One of the rapidly developing methods for early characterization of abnormal brain development is functional connectivity of the brain at rest. While the majority of resting-state studies have been conducted using magnetic resonance imaging (MRI), there is clear evidence that resting-state functional connectivity (rs-FC) can also be evaluated using other imaging modalities. The aim of this review is to compare the advantages and limitations of different modalities used for the mapping of infants' brain functional connectivity at rest. In addition, we introduce photoacoustic tomography, a novel functional neuroimaging modality, as a complementary modality for functional mapping of infants' brain.
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Affiliation(s)
- Ali-Reza Mohammadi-Nejad
- CIPCE, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
- Departments of Radiology and Research Administration, Henry Ford Health System, Detroit, MI, USA
| | - Mahdi Mahmoudzadeh
- INSERM, U1105, Université de Picardie, CURS, F80036, Amiens, France
- INSERM U1105, Exploration Fonctionnelles du Système Nerveux Pédiatrique, South University Hospital, F80054, Amiens Cedex, France
| | | | - Fabrice Wallois
- INSERM, U1105, Université de Picardie, CURS, F80036, Amiens, France
- INSERM U1105, Exploration Fonctionnelles du Système Nerveux Pédiatrique, South University Hospital, F80054, Amiens Cedex, France
| | - Otto Muzik
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA
- Department of Radiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Christos Papadelis
- Boston Children’s Hospital, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Anne Hansen
- Boston Children’s Hospital, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Hamid Soltanian-Zadeh
- CIPCE, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
- Departments of Radiology and Research Administration, Henry Ford Health System, Detroit, MI, USA
- Department of Radiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Juri Gelovani
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA
- Molecular Imaging Program, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA
| | - Mohammadreza Nasiriavanaki
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
- Molecular Imaging Program, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA
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16
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Issard C, Gervain J. Variability of the hemodynamic response in infants: Influence of experimental design and stimulus complexity. Dev Cogn Neurosci 2018; 33:182-193. [PMID: 29397345 PMCID: PMC6969282 DOI: 10.1016/j.dcn.2018.01.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 01/26/2018] [Accepted: 01/26/2018] [Indexed: 12/27/2022] Open
Abstract
Measuring brain activity in developmental populations remains a major challenge despite great technological advances. Among the numerous available methods, functional near-infrared spectroscopy (fNIRS), an imaging modality that probes the hemodynamic response, is a powerful tool for recording brain activity in a great variety of situations and populations. Neurocognitive studies with infants have often reported inverted hemodynamic responses, i.e. a decrease instead of an increase in regional blood oxygenation, but the exact physiological explanation and cognitive interpretation of this response remain unclear. Here, we first provide an overview of the basic principles of NIRS and its use in cognitive developmental neuroscience. We then review the infant fNIRS literature to show that the hemodynamic response is modulated by experimental design and stimulus complexity, sometimes leading to hemodynamic responses with non-canonical shapes. We also argue that this effect is further modulated by the age of participants, the cortical regions involved, and the developmental stage of the tested cognitive process. We argue that this variability needs to be taken into account when designing and interpreting developmental studies measuring the hemodynamic response.
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Affiliation(s)
- Cécile Issard
- Laboratoire Psychologie de la Perception, Université Paris Descartes, Centre Universitaire des Saints-Pères, 45 rue des Saints Pères, 75006 Paris, France.
| | - Judit Gervain
- Laboratoire Psychologie de la Perception, Université Paris Descartes, Centre Universitaire des Saints-Pères, 45 rue des Saints Pères, 75006 Paris, France; Laboratoire Psychologie de la Perception, CNRS UMR 8242, Centre Universitaire des Saints-Pères, 45 rue des Saints Pères, 75006 Paris, France.
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17
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Lee CW, Cooper RJ, Austin T. Diffuse optical tomography to investigate the newborn brain. Pediatr Res 2017; 82:376-386. [PMID: 28419082 DOI: 10.1038/pr.2017.107] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 02/06/2017] [Indexed: 11/09/2022]
Abstract
Over the past 15 years, functional near-infrared spectroscopy (fNIRS) has emerged as a powerful technology for studying the developing brain. Diffuse optical tomography (DOT) is an extension of fNIRS that combines hemodynamic information from dense optical sensor arrays over a wide field of view. Using image reconstruction techniques, DOT can provide images of the hemodynamic correlates to neural function that are comparable to those produced by functional magnetic resonance imaging. This review article explains the principles of DOT, and highlights the growing literature on the use of DOT in the study of healthy development of the infant brain, and the study of novel pathophysiology in infants with brain injury. Current challenges, particularly around instrumentation and image reconstruction, will be discussed, as will the future of this growing field, with particular focus on whole-brain, time-resolved DOT.
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Affiliation(s)
- Chuen Wai Lee
- neoLAB, The Evelyn Perinatal Imaging Centre, The Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.,Department of Neonatology, The Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Robert J Cooper
- neoLAB, The Evelyn Perinatal Imaging Centre, The Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.,Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Topun Austin
- neoLAB, The Evelyn Perinatal Imaging Centre, The Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.,Department of Neonatology, The Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
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18
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Abdalmalak A, Milej D, Diop M, Shokouhi M, Naci L, Owen AM, St. Lawrence K. Can time-resolved NIRS provide the sensitivity to detect brain activity during motor imagery consistently? BIOMEDICAL OPTICS EXPRESS 2017; 8:2162-2172. [PMID: 28736662 PMCID: PMC5516814 DOI: 10.1364/boe.8.002162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/15/2017] [Accepted: 02/27/2017] [Indexed: 05/20/2023]
Abstract
Previous functional magnetic resonance imaging (fMRI) studies have shown that a subgroup of patients diagnosed as being in a vegetative state are aware and able to communicate by performing a motor imagery task in response to commands. Due to the fMRI's cost and accessibility, there is a need for exploring different imaging modalities that can be used at the bedside. A promising technique is functional near infrared spectroscopy (fNIRS) that has been successfully applied to measure brain oxygenation in humans. Due to the limited depth sensitivity of continuous-wave NIRS, time-resolved (TR) detection has been proposed as a way of enhancing the sensitivity to the brain, since late arriving photons have a higher probability of reaching the brain. The goal of this study was to assess the feasibility and sensitivity of TR fNIRS in detecting brain activity during motor imagery. Fifteen healthy subjects were recruited in this study, and the fNIRS results were validated using fMRI. The change in the statistical moments of the distribution of times of flight (number of photons, mean time of flight and variance) were calculated for each channel to determine the presence of brain activity. The results indicate up to an 86% agreement between fMRI and TR-fNIRS and the sensitivity ranging from 64 to 93% with the highest value determined for the mean time of flight. These promising results highlight the potential of TR-fNIRS as a portable brain computer interface for patients with disorder of consciousness.
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Affiliation(s)
- Androu Abdalmalak
- Department of Medical Biophysics, Western University, London, ON, Canada
- Imaging Division, Lawson Health Research Institute, London, ON, Canada
| | - Daniel Milej
- Department of Medical Biophysics, Western University, London, ON, Canada
- Imaging Division, Lawson Health Research Institute, London, ON, Canada
| | - Mamadou Diop
- Department of Medical Biophysics, Western University, London, ON, Canada
- Imaging Division, Lawson Health Research Institute, London, ON, Canada
| | - Mahsa Shokouhi
- Department of Medical Biophysics, Western University, London, ON, Canada
- Imaging Division, Lawson Health Research Institute, London, ON, Canada
| | - Lorina Naci
- Brain and Mind Institute, Western University, London, ON, Canada
| | - Adrian M. Owen
- Brain and Mind Institute, Western University, London, ON, Canada
| | - Keith St. Lawrence
- Department of Medical Biophysics, Western University, London, ON, Canada
- Imaging Division, Lawson Health Research Institute, London, ON, Canada
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19
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Kashou NH, Dar IA, Hasenstab KA, Nahhas RW, Jadcherla SR. Somatic stimulation causes frontoparietal cortical changes in neonates: a functional near-infrared spectroscopy study. NEUROPHOTONICS 2017; 4:011004. [PMID: 27570791 PMCID: PMC4981749 DOI: 10.1117/1.nph.4.1.011004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/02/2016] [Indexed: 06/06/2023]
Abstract
Palmar and plantar grasp are the foremost primitive neonatal reflexes and functions. Persistence of these reflexes in infancy is a sign of evolving cerebral palsy. Our aims were to establish measurement feasibility in a clinical setting and to characterize changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbD) concentration in the bilateral frontoparietal cortex in unsedated neonates at the crib-side using functional near-infrared spectroscopy (fNIRS). We hypothesized that bilateral concentration changes will occur upon somatic central and peripheral somatic stimulation. Thirteen preterm neonates (five males) underwent time 1, and six (two males) returned for time 2 (mean [Formula: see text] and 47.0 weeks, respectively). Signals from a total of 162 somatic stimuli responses were measured. Response amplitude, duration, and latency were log-transformed and compared between palmar, plantar, and oromotor stimuli using linear mixed models, adjusted for cap, electroencephalogram abnormality, time (1 versus 2), and Sarnat score, if necessary. The oromotor stimulus resulted in a 50% greater response than the palmar or plantar stimuli for HbO left and right hemisphere duration ([Formula: see text]). There were no other statistically significant differences between stimuli for any other outcome ([Formula: see text]). Utilizing fNIRS in conjunction with occupational and physical therapy maneuvers is efficacious to study modifiable and restorative neurophysiological mechanisms.
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Affiliation(s)
- Nasser H. Kashou
- Wright State University, Biomedical, Industrial and Human Factors Engineering, 3640 Colonel Glenn Highway, Dayton, Ohio 45435, United States
| | - Irfaan A. Dar
- Wright State University, Biomedical, Industrial and Human Factors Engineering, 3640 Colonel Glenn Highway, Dayton, Ohio 45435, United States
- The Research Institute at Nationwide Children's Hospital, Innovative Research Program in Neonatal and Infant Feeding Disorders, 700 Children's Drive, Columbus, Ohio 43205, United States
| | - Kathryn A. Hasenstab
- The Research Institute at Nationwide Children's Hospital, Innovative Research Program in Neonatal and Infant Feeding Disorders, 700 Children's Drive, Columbus, Ohio 43205, United States
| | - Ramzi W. Nahhas
- Wright State University, Department of Community Health, 3123 Research Boulevard, Kettering, Ohio 45420, United States
- Wright State University, Department of Psychiatry, 3123 Research Boulevard, Kettering, Ohio 45420, United States
| | - Sudarshan R. Jadcherla
- The Research Institute at Nationwide Children's Hospital, Innovative Research Program in Neonatal and Infant Feeding Disorders, 700 Children's Drive, Columbus, Ohio 43205, United States
- The Ohio State University, College of Medicine, Division of Neonatology, Department of Pediatrics, 370 West 9th Avenue, Columbus, Ohio 43210, United States
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20
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Kozberg MG, Hillman EMC. Neurovascular coupling develops alongside neural circuits in the postnatal brain. NEUROGENESIS 2016; 3:e1244439. [PMID: 27900344 DOI: 10.1080/23262133.2016.1244439] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 10/20/2022]
Abstract
In the adult brain, increases in local neural activity are accompanied by increases in regional blood flow. This relationship between neural activity and hemodynamics is termed neurovascular coupling and provides the blood flow-dependent contrast detected in functional magnetic resonance imaging (fMRI). Neurovascular coupling is commonly assumed to be consistent and reliable from birth; however, numerous studies have demonstrated markedly different hemodynamics in the early postnatal brain. Our recent study in J. Neuroscience examined whether different hemodynamics in the immature brain are driven by differences in the underlying spatiotemporal properties of neural activity during this period of robust neural circuit expansion. Using a novel wide-field optical imaging technique to visualize both neural activity and hemodynamics in the mouse brain, we observed longer duration and increasingly complex patterns of neural responses to stimulus as cortical connectivity developed over time. However, imaging of brain blood flow, oxygenation, and metabolism in the same mice demonstrated an absence of coupled blood flow responses in the newborn brain. This lack of blood flow coupling was shown to lead to oxygen depletions following neural activations - depletions that may affect the duration of sustained neural responses and could be important to the vascular patterning of the rapidly developing brain. These results are a step toward understanding the unique neurovascular and neurometabolic environment of the newborn brain, and provide new insights for interpretation of fMRI BOLD studies of early brain development.
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Affiliation(s)
- Mariel G Kozberg
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Mortimer B. Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Science, Columbia University, New York, NY, USA; Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Elizabeth M C Hillman
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Mortimer B. Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Science, Columbia University , New York, NY, USA
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21
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Abstract
Near-infrared spectroscopy (NIRS) was originally designed for clinical monitoring of tissue oxygenation, and it has also been developed into a useful tool in neuroimaging studies, with the so-called functional NIRS (fNIRS). With NIRS, cerebral activation is detected by measuring the cerebral hemoglobin (Hb), where however, the precise correlation between NIRS signal and neural activity remains to be fully understood. This can in part be attributed to the situation that NIRS signals are inherently subject to contamination by signals arising from extracerebral tissue. In recent years, several approaches have been investigated to distinguish between NIRS signals originating in cerebral tissue and signals originating in extracerebral tissue. Selective measurements of cerebral Hb will enable a further evolution of fNIRS. This chapter is divided into six sections: first a summary of the basic theory of NIRS, NIRS signals arising in the activated areas, correlations between NIRS signals and fMRI signals, correlations between NIRS signals and neural activities, and the influence of a variety of extracerebral tissue on NIRS signals and approaches to this issue are reviewed. Finally, future prospects of fNIRS are described.
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Affiliation(s)
- Y Hoshi
- Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan.
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22
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Kozberg M, Hillman E. Neurovascular coupling and energy metabolism in the developing brain. PROGRESS IN BRAIN RESEARCH 2016; 225:213-42. [PMID: 27130418 DOI: 10.1016/bs.pbr.2016.02.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In the adult brain, increases in local neural activity are almost always accompanied by increases in local blood flow. However, many functional imaging studies of the newborn and developing human brain have observed patterns of hemodynamic responses that differ from adult responses. Among the proposed mechanisms for the observed variations is that neurovascular coupling itself is still developing in the perinatal brain. Many of the components thought to be involved in actuating and propagating this hemodynamic response are known to still be developing postnatally, including perivascular cells such as astrocytes and pericytes. Both neural and vascular networks expand and are then selectively pruned over the first year of human life. Additionally, the metabolic demands of the newborn brain are still evolving. These changes are highly likely to affect early postnatal neurovascular coupling, and thus may affect functional imaging signals in this age group. This chapter will discuss the literature relating to neurovascular development. Potential effects of normal and aberrant development of neurovascular coupling on the newborn brain will also be explored, as well as ways to effectively utilize imaging techniques that rely on hemodynamic modulation such as fMRI and NIRS in younger populations.
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Affiliation(s)
- M Kozberg
- Columbia University, New York, NY, United States.
| | - E Hillman
- Columbia University, New York, NY, United States; Kavli Institute for Brain Science, Columbia University, New York, NY, United States; Mortimer B. Zuckerman Institute for Mind Brain and Behavior, Columbia University, New York, NY, United States.
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23
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Singh H, Cooper R, Lee CW, Dempsey L, Brigadoi S, Edwards A, Airantzis D, Everdell N, Michell A, Holder D, Austin T, Hebden J. Neurovascular Interactions in the Neurologically Compromised Neonatal Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 876:485-492. [PMID: 26782249 DOI: 10.1007/978-1-4939-3023-4_61] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Neurological brain injuries such as hypoxic ischaemic encephalopathy (HIE) and associated conditions such as seizures have been associated with poor developmental outcome in neonates. Our limited knowledge of the neurological and cerebrovascular processes underlying seizures limits their diagnosis and timely treatment. Diffuse optical tomography (DOT) provides haemodynamic information in the form of changes in concentration of de/oxygenated haemoglobin, which can improve our understanding of seizures and the relationship between neural and vascular processes. Using simultaneous EEG-DOT, we observed distinct haemodynamic changes which are temporally correlated with electrographic seizures. Here, we present DOT-EEG data from two neonates clinically diagnosed as HIE. Our results highlight the wealth of mutually-informative data that can be obtained using DOT-EEG techniques to understand neurovascular coupling in HIE neonates.
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Affiliation(s)
- H Singh
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK. .,BORL, Department of Medical Physics and Bioengineering, UCL, London, UK.
| | - R Cooper
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,BORL, Department of Medical Physics and Bioengineering, UCL, London, UK
| | - C W Lee
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,Neonatal Unit, Rosie Hospital, Cambridge University Hospitals, Cambridge, UK
| | - L Dempsey
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,BORL, Department of Medical Physics and Bioengineering, UCL, London, UK
| | - S Brigadoi
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,BORL, Department of Medical Physics and Bioengineering, UCL, London, UK
| | - A Edwards
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,Neonatal Unit, Rosie Hospital, Cambridge University Hospitals, Cambridge, UK
| | - D Airantzis
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,Neonatal Unit, Rosie Hospital, Cambridge University Hospitals, Cambridge, UK
| | - N Everdell
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,BORL, Department of Medical Physics and Bioengineering, UCL, London, UK
| | - A Michell
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,Neonatal Unit, Rosie Hospital, Cambridge University Hospitals, Cambridge, UK
| | - D Holder
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,Neonatal Unit, Rosie Hospital, Cambridge University Hospitals, Cambridge, UK
| | - T Austin
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,Neonatal Unit, Rosie Hospital, Cambridge University Hospitals, Cambridge, UK
| | - J Hebden
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge, UK.,BORL, Department of Medical Physics and Bioengineering, UCL, London, UK
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Cusack R, Wild C, Linke AC, Arichi T, Lee DSC, Han VK. Optimizing stimulation and analysis protocols for neonatal fMRI. PLoS One 2015; 10:e0120202. [PMID: 26266954 PMCID: PMC4534447 DOI: 10.1371/journal.pone.0120202] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 11/06/2014] [Indexed: 12/22/2022] Open
Abstract
The development of brain function in young infants is poorly understood. The core challenge is that infants have a limited behavioral repertoire through which brain function can be expressed. Neuroimaging with fMRI has great potential as a way of characterizing typical development, and detecting abnormal development early. But, a number of methodological challenges must first be tackled to improve the robustness and sensitivity of neonatal fMRI. A critical one of these, addressed here, is that the hemodynamic response function (HRF) in pre-term and term neonates differs from that in adults, which has a number of implications for fMRI. We created a realistic model of noise in fMRI data, using resting-state fMRI data from infants and adults, and then conducted simulations to assess the effect of HRF of the power of different stimulation protocols and analysis assumptions (HRF modeling). We found that neonatal fMRI is most powerful if block-durations are kept at the lower range of those typically used in adults (full on/off cycle duration 25-30s). Furthermore, we show that it is important to use the age-appropriate HRF during analysis, as mismatches can lead to reduced power or even inverted signal. Where the appropriate HRF is not known (for example due to potential developmental delay), a flexible basis set performs well, and allows accurate post-hoc estimation of the HRF.
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Affiliation(s)
- Rhodri Cusack
- Brain and Mind Institute, Western University, London, Canada
- Children’s Health Research Institute, London, Canada
- * E-mail:
| | - Conor Wild
- Brain and Mind Institute, Western University, London, Canada
| | - Annika C. Linke
- Brain and Mind Institute, Western University, London, Canada
| | - Tomoki Arichi
- Department of Perinatal Imaging and Health, King’s College London, London, United Kingdom
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | | | - Victor K. Han
- Children’s Health Research Institute, London, Canada
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Perera T, Lewis PM, Davidson AJ, Junor P, Bottrell S. A pilot study to determine whether visually evoked hemodynamic responses are preserved in children during inhalational anesthesia. Paediatr Anaesth 2015; 25:317-26. [PMID: 25557014 DOI: 10.1111/pan.12590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/04/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND Anesthetic depth is an important parameter to monitor during surgery, yet remains difficult to quantify, particularly in young children where developmental changes influence the electroencephalogram. A more fundamental physiological response to stimulation is the increase in cerebral blood flow secondary to increased metabolic demand, referred to as flow-metabolism coupling (FMC) and measurable using near-infrared spectroscopy (NIRS). Little is known about the effect of anesthesia on FMC; therefore, we studied visually evoked hemodynamic responses (VEHRs) using NIRS in children undergoing general anesthesia for minor surgical procedures. METHOD We recruited 23 children (aged 2-5 years), undergoing surgery requiring general anesthesia. VEHRs were measured for 30 min using NIRS, including 5 min of baseline recording after anesthetic induction. Parameters recorded using NIRS included the concentrations of oxygenated (oxy), deoxygenated (deoxy), and total hemoglobin (Hb), which were separated into epochs for evoked response analysis after filtration of motion artifact and baseline drift. Goodness-of-fit statistics and classification rules were used to determine the existence of evoked responses, and a modified Gaussian equation was used to model each evoked response. RESULTS Near-infrared spectroscopy data were recorded in 20/23 children, of whom nine showed a VEHR. No responses were seen in the baseline control data. When examining the relationship between VEHR and anesthetic agents, we noted that for 8/10 patients in whom preoperative or intraoperative fentanyl were administered and VEHRs were absent. CONCLUSION We have shown that VEHRs can be detected using NIRS in some anesthetized children. Administration of fentanyl was associated with an absence of VEHRs. The mechanism underlying this association is unclear.
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Affiliation(s)
- Thushara Perera
- Department of Electronic Engineering, La Trobe University, Bundoora, Vic., Australia; Department of Anaesthesia and Pain Management, Murdoch Children's Research Institute, Parkville, Vic., Australia
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Graham AM, Pfeifer JH, Fisher PA, Lin W, Gao W, Fair DA. The potential of infant fMRI research and the study of early life stress as a promising exemplar. Dev Cogn Neurosci 2014; 12:12-39. [PMID: 25459874 PMCID: PMC4385461 DOI: 10.1016/j.dcn.2014.09.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 09/24/2014] [Accepted: 09/29/2014] [Indexed: 01/09/2023] Open
Abstract
fMRI research with infants and toddlers has increased rapidly over the past decade. Infant fMRI has provided unique insight into early functional brain development. Complex methodological challenges associated with infant fMRI warrant careful consideration and ongoing research. Infant fMRI has potential to contribute to multiple fields of study. The study of early life stress is a prime example of a field that is ripe to benefit from this technique.
Functional magnetic resonance imaging (fMRI) research with infants and toddlers has increased rapidly over the past decade, and provided a unique window into early brain development. In the current report, we review the state of the literature, which has established the feasibility and utility of task-based fMRI and resting state functional connectivity MRI (rs-fcMRI) during early periods of brain maturation. These methodologies have been successfully applied beginning in the neonatal period to increase understanding of how the brain both responds to environmental stimuli, and becomes organized into large-scale functional systems that support complex behaviors. We discuss the methodological challenges posed by this promising area of research. We also highlight that despite these challenges, early work indicates a strong potential for these methods to influence multiple research domains. As an example, we focus on the study of early life stress and its influence on brain development and mental health outcomes. We illustrate the promise of these methodologies for building on, and making important contributions to, the existing literature in this field.
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Affiliation(s)
- Alice M Graham
- Department of Behavioral Neuroscience, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, United States.
| | - Jennifer H Pfeifer
- Department of Psychology, University of Oregon, 1715 Franklin Boulevard, Eugene, OR 97403, United States
| | - Philip A Fisher
- Department of Psychology, University of Oregon, 1715 Franklin Boulevard, Eugene, OR 97403, United States
| | - Weili Lin
- Departments of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Wei Gao
- Departments of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Damien A Fair
- Department of Psychology, University of Oregon, 1715 Franklin Boulevard, Eugene, OR 97403, United States; Department of Psychiatry, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, United States; Advanced Imaging Research Center, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, United States
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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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Singh H, Cooper RJ, Wai Lee C, Dempsey L, Edwards A, Brigadoi S, Airantzis D, Everdell N, Michell A, Holder D, Hebden JC, Austin T. Mapping cortical haemodynamics during neonatal seizures using diffuse optical tomography: a case study. Neuroimage Clin 2014; 5:256-65. [PMID: 25161892 PMCID: PMC4141980 DOI: 10.1016/j.nicl.2014.06.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/25/2014] [Accepted: 06/26/2014] [Indexed: 01/08/2023]
Abstract
Seizures in the newborn brain represent a major challenge to neonatal medicine. Neonatal seizures are poorly classified, under-diagnosed, difficult to treat and are associated with poor neurodevelopmental outcome. Video-EEG is the current gold-standard approach for seizure detection and monitoring. Interpreting neonatal EEG requires expertise and the impact of seizures on the developing brain remains poorly understood. In this case study we present the first ever images of the haemodynamic impact of seizures on the human infant brain, obtained using simultaneous diffuse optical tomography (DOT) and video-EEG with whole-scalp coverage. Seven discrete periods of ictal electrographic activity were observed during a 60 minute recording of an infant with hypoxic-ischaemic encephalopathy. The resulting DOT images show a remarkably consistent, high-amplitude, biphasic pattern of changes in cortical blood volume and oxygenation in response to each electrographic event. While there is spatial variation across the cortex, the dominant haemodynamic response to seizure activity consists of an initial increase in cortical blood volume prior to a large and extended decrease typically lasting several minutes. This case study demonstrates the wealth of physiologically and clinically relevant information that DOT-EEG techniques can yield. The consistency and scale of the haemodynamic responses observed here also suggest that DOT-EEG has the potential to provide improved detection of neonatal seizures.
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Affiliation(s)
- Harsimrat Singh
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Robert J. Cooper
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Chuen Wai Lee
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - Laura Dempsey
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Andrea Edwards
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - Sabrina Brigadoi
- Department of Developmental Psychology, University of Padova, Padova, Italy
| | - Dimitrios Airantzis
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Nick Everdell
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Andrew Michell
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Neurophysiology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - David Holder
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Jeremy C. Hebden
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Topun Austin
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
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Jadcherla SR, Pakiraih JF, Hasenstab KA, Dar I, Gao X, Bates DG, Kashou NH. Esophageal reflexes modulate frontoparietal response in neonates: Novel application of concurrent NIRS and provocative esophageal manometry. Am J Physiol Gastrointest Liver Physiol 2014; 307:G41-9. [PMID: 24789204 PMCID: PMC4080167 DOI: 10.1152/ajpgi.00350.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Central and peripheral neural regulation of swallowing and aerodigestive reflexes is unclear in human neonates. Functional near infrared spectroscopy (NIRS) is a noninvasive method to measure changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbD). Pharyngoesophageal manometry permits evaluation of aerodigestive reflexes. Modalities were combined to investigate feasibility and to test neonatal frontoparietal cortical changes during pharyngoesophageal (visceral) stimulation and/or swallowing. Ten neonates (45.6 ± 3.0 wk postmenstrual age, 4.1 ± 0.5 kg) underwent novel pharyngoesophageal manometry concurrent with NIRS. To examine esophagus-brain interactions, we analyzed cortical hemodynamic response (HDR) latency and durations during aerodigestive provocation and esophageal reflexes. Data are presented as means ± SE or percent. HDR rates were 8.84 times more likely with basal spontaneous deglutition compared with sham stimuli (P = 0.004). Of 182 visceral stimuli, 95% were analyzable for esophageal responses, 38% for HDR, and 36% for both. Of analyzable HDR (n = 70): 1) HbO concentration (μmol/l) baseline 1.5 ± 0.7 vs. 3.7 ± 0.7 poststimulus was significant (P = 0.02), 2) HbD concentration (μmol/l) between baseline 0.1 ± 0.4 vs. poststimulus -0.5 ± 0.4 was not significant (P = 0.73), and 3) hemispheric lateralization was 21% left only, 29% right only, and 50% bilateral. During concurrent esophageal and NIRS responses (n = 66): 1) peristaltic reflexes were present in 74% and HDR in 61% and 2) HDR was 4.75 times more likely with deglutition reflex vs. secondary peristaltic reflex (P = 0.016). Concurrent NIRS with visceral stimulation is feasible in neonates, and frontoparietal cortical activation is recognized. Deglutition contrasting with secondary peristalsis is related to cortical activation, thus implicating higher hierarchical aerodigestive protective functional neural networks.
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Affiliation(s)
- Sudarshan R. Jadcherla
- 1Divisions of Neonatology and Pediatric Gastroenterology and Nutrition, Nationwide Children's Hospital, Columbus, Ohio; ,2Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio; ,3Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio;
| | - Joanna F. Pakiraih
- 2Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio; ,5Department of Radiology, Nationwide Children's Hospital, Columbus, Ohio
| | - Kathryn A. Hasenstab
- 2Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio;
| | - Irfaan Dar
- 2Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio; ,4Biomedical, Industrial & Human Factors Engineering, Wright State University, Ohio; and
| | - Xiaoyu Gao
- 2Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio;
| | - D. Gregory Bates
- 3Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio; ,5Department of Radiology, Nationwide Children's Hospital, Columbus, Ohio
| | - Nasser H. Kashou
- 4Biomedical, Industrial & Human Factors Engineering, Wright State University, Ohio; and
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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: 993] [Impact Index Per Article: 99.3] [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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Resolving the transition from negative to positive blood oxygen level-dependent responses in the developing brain. Proc Natl Acad Sci U S A 2013; 110:4380-5. [PMID: 23426630 DOI: 10.1073/pnas.1212785110] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The adult brain exhibits a local increase in cortical blood flow in response to external stimulus. However, broadly varying hemodynamic responses in the brains of newborn and young infants have been reported. Particular controversy exists over whether the "true" neonatal response to stimulation consists of a decrease or an increase in local deoxyhemoglobin, corresponding to a positive (adult-like) or negative blood oxygen level-dependent (BOLD) signal in functional magnetic resonance imaging (fMRI), respectively. A major difficulty with previous studies has been the variability in human subjects and measurement paradigms. Here, we present a systematic study in neonatal rats that charts the evolution of the cortical blood flow response during postnatal development using exposed-cortex multispectral optical imaging. We demonstrate that postnatal-day-12-13 rats (equivalent to human newborns) exhibit an "inverted" hemodynamic response (increasing deoxyhemoglobin, negative BOLD) with early signs of oxygen consumption followed by delayed, active constriction of pial arteries. We observed that the hemodynamic response then matures via development of an initial hyperemic (positive BOLD) phase that eventually masks oxygen consumption and balances vasoconstriction toward adulthood. We also observed that neonatal responses are particularly susceptible to stimulus-evoked systemic blood pressure increases, leading to cortical hyperemia that resembles adult positive BOLD responses. We propose that this confound may account for much of the variability in prior studies of neonatal cortical hemodynamics. Our results suggest that functional magnetic resonance imaging studies of infant and child development may be profoundly influenced by the maturing neurovascular and autoregulatory systems of the neonatal brain.
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Liao SM, Ferradal SL, White BR, Gregg N, Inder TE, Culver JP. High-density diffuse optical tomography of term infant visual cortex in the nursery. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:081414. [PMID: 23224175 PMCID: PMC3391961 DOI: 10.1117/1.jbo.17.8.081414] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 06/05/2012] [Accepted: 06/08/2012] [Indexed: 05/19/2023]
Abstract
Advancements in antenatal and neonatal medicine over the last few decades have led to significant improvement in the survival rates of sick newborn infants. However, this improvement in survival has not been matched by a reduction in neurodevelopmental morbidities with increasing recognition of the diverse cognitive and behavioral challenges that preterm infants face in childhood. Conventional neuroimaging modalities, such as cranial ultrasound and magnetic resonance imaging, provide an important definition of neuroanatomy with recognition of brain injury. However, they fail to define the functional integrity of the immature brain, particularly during this critical developmental period. Diffuse optical tomography methods have established success in imaging adult brain function; however, few studies exist to demonstrate their feasibility in the neonatal population. We demonstrate the feasibility of using recently developed high-density diffuse optical tomography (HD-DOT) to map functional activation of the visual cortex in healthy term-born infants. The functional images show high contrast-to-noise ratio obtained in seven neonates. These results illustrate the potential for HD-DOT and provide a foundation for investigations of brain function in more vulnerable newborns, such as preterm infants.
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Affiliation(s)
- Steve M. Liao
- Washington University School of Medicine, Department of Pediatrics, 660 S. Euclid Ave, St. Louis, Missouri 63110
| | - Silvina L. Ferradal
- Washington University, Department of Biomedical Engineering, Whitaker Hall, Campus Box 1097, One Brookings Drive, St. Louis, Missouri 63130
- Washington University School of Medicine, Department of Radiology, 660 S. Euclid Ave, St. Louis, Missouri 63110
| | - Brian R. White
- Washington University School of Medicine, Department of Radiology, 660 S. Euclid Ave, St. Louis, Missouri 63110
- Washington University, Department of Physics, Campus Box 1105, One Brookings Drive, St. Louis, Missouri 63130
| | - Nicholas Gregg
- University of Pittsburgh School of Medicine, M240 Scaife Hall, 3550 Terrace Street, Pittsburgh, Pennsylvania 15261
| | - Terrie E. Inder
- Washington University School of Medicine, Department of Pediatrics, 660 S. Euclid Ave, St. Louis, Missouri 63110
| | - Joseph P. Culver
- Washington University, Department of Biomedical Engineering, Whitaker Hall, Campus Box 1097, One Brookings Drive, St. Louis, Missouri 63130
- Washington University School of Medicine, Department of Radiology, 660 S. Euclid Ave, St. Louis, Missouri 63110
- Washington University, Department of Physics, Campus Box 1105, One Brookings Drive, St. Louis, Missouri 63130
- Address all correspondence to: Joseph P. Culver, Washington University School of Medicine, Department of Radiology, 4525 Scott Avenue, Room 1137, St. Louis, Missouri 63110. Tel: 314-747-1341; E-mail:
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Lee W, Donner EJ, Nossin-Manor R, Whyte HEA, Sled JG, Taylor MJ. Visual functional magnetic resonance imaging of preterm infants. Dev Med Child Neurol 2012; 54:724-9. [PMID: 22715952 DOI: 10.1111/j.1469-8749.2012.04342.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The aim of this study was to determine the feasibility of undertaking visual functional magnetic resonance imaging (fMRI) in very preterm children. METHOD Forty-seven infants born at less than 32 weeks gestational age (25 males, 22 females; mean (SD) age at birth 28.8 wks [1.9]) were scanned using 1.5 T MRI as part of a longitudinal neuroimaging study. These infants were scanned at preterm age (within 2 wks of birth) and at term-equivalent age. Quantitative T2* data and fMRI in response to visual stimuli (flashing strobe) were acquired in this population. T2* values were compared at preterm age and at term-equivalent age using a two-tailed t-test. A general linear model was used to evaluate occipital lobe response to visual stimuli. RESULTS T2* values were significantly higher at preterm age than at term-equivalent age in both the medial and lateral occipital lobes (preterm infants: 187.2 ms and 198.4 ms respectively; term infants: 110.9 ms and 133.2 ms respectively; p<0.002). Significant positive occipital lobe activation (q<0.01) was found in 3 out of 65 (5%) fMRIs carried out at preterm age and in 19 out of 26 (73%) scans carried out at term-equivalent age. INTERPRETATION Visual stimuli do not elicit a reliable blood oxygen level-dependent (BOLD) response in very preterm infants during the preterm period. This suggests that BOLD fMRI may not be the appropriate modality for investigating occipital lobe function in very preterm infants.
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Affiliation(s)
- Wayne Lee
- Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, ON, Canada.
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Khan B, Wildey C, Francis R, Tian F, Delgado MR, Liu H, MacFarlane D, Alexandrakis G. Improving optical contact for functional near‑infrared brain spectroscopy and imaging with brush optodes. BIOMEDICAL OPTICS EXPRESS 2012; 3:878-98. [PMID: 22567582 PMCID: PMC3342194 DOI: 10.1364/boe.3.000878] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 04/01/2012] [Accepted: 04/02/2012] [Indexed: 05/18/2023]
Abstract
A novel brush optode was designed and demonstrated to overcome poor optical contact with the scalp that can occur during functional near infrared spectroscopy (fNIRS) and imaging due to light obstruction by hair. The brush optodes were implemented as an attachment to existing commercial flat-faced (conventional) fiber bundle optodes. The goal was that the brush optodes would thread through hair and improve optical contact on subjects with dense hair. Simulations and experiments were performed to assess the magnitude of these improvements. FNIRS measurements on 17 subjects with varying hair colors (blonde, brown, and black) and hair densities (0-2.96 hairs/mm(2)) were performed during a finger tapping protocol for both flat and brush optodes. In addition to reaching a study success rate of almost 100% when using the brush optode extensions, the measurement setup times were reduced by a factor of three. Furthermore, the brush optodes enabled improvements in the activation signal-to-noise ratio (SNR) by up to a factor of ten as well as significant (p < 0.05) increases in the detected area of activation (dAoA). The measured improvements in SNR were matched by Monte Carlo (MC) simulations of photon propagation through scalp and hair. In addition, an analytical model was derived to mathematically estimate the observed light power losses due to different hair colors and hair densities. Interestingly, the derived analytical formula produced excellent estimates of the experimental data and MC simulation results despite several simplifying assumptions. The analytical model enables researchers to readily estimate the light power losses due to obstruction by hair for both flat-faced fiber bundles and individual fibers for a given subject.
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Affiliation(s)
- Bilal Khan
- Department of Bioengineering, University of Texas at Arlington, 500 UTA Boulevard, Arlington, Texas 76010, USA
| | - Chester Wildey
- MRRA Inc., 3621 Smoke Tree Trail, Euless, Texas 76040, USA
| | - Robert Francis
- Department of Electrical Engineering, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | - Fenghua Tian
- Department of Bioengineering, University of Texas at Arlington, 500 UTA Boulevard, Arlington, Texas 76010, USA
| | - Mauricio R. Delgado
- Department of Neurology, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, Texas 75219, USA
- Department of Neurology, University of Texas Southwestern Medical Center at Dallas, 5901 Forest Park Road, Dallas, Texas 75390, USA
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, 500 UTA Boulevard, Arlington, Texas 76010, USA
| | - Duncan MacFarlane
- Department of Electrical Engineering, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | - George Alexandrakis
- Department of Bioengineering, University of Texas at Arlington, 500 UTA Boulevard, Arlington, Texas 76010, USA
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Aslin RN. Questioning the questions that have been asked about the infant brain using near-infrared spectroscopy. Cogn Neuropsychol 2012; 29:7-33. [PMID: 22329690 DOI: 10.1080/02643294.2012.654773] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Near-infrared spectroscopy (NIRS) is a noninvasive diffuse optical-imaging technique that can measure local metabolic demand in the surface of the cortex due to differential absorption of light by oxygenated and deoxygenated blood. Over the past decade, NIRS has become increasingly used as a complement to other neuroimaging techniques, such as electroencephalography (EEG), magnetoencephalography (MEG), and functional magnetic resonance imaging (fMRI), particularly in paediatric populations who cannot easily be tested using fMRI and MEG. In this review of empirical findings from human infants, ranging in age from birth to 12 months of age, a number of interpretive concerns are raised about what can be concluded from NIRS data. In addition, inconsistencies across studies are highlighted, and strategies are proposed for enhancing the reliability of NIRS data gathered from infants. Finally, a variety of new and promising advances in NIRS techniques are highlighted.
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Affiliation(s)
- Richard N Aslin
- Department of Brain and Cognitive Sciences, University of Rochester, NY, USA.
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Habermehl C, Holtze S, Steinbrink J, Koch SP, Obrig H, Mehnert J, Schmitz CH. Somatosensory activation of two fingers can be discriminated with ultrahigh-density diffuse optical tomography. Neuroimage 2011; 59:3201-11. [PMID: 22155031 DOI: 10.1016/j.neuroimage.2011.11.062] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/01/2011] [Accepted: 11/21/2011] [Indexed: 11/30/2022] Open
Abstract
Topographic non-invasive near infrared spectroscopy (NIRS) has become a well-established tool for functional brain imaging. Applying up to 100 optodes over the head of a subject, allows achieving a spatial resolution in the centimeter range. This resolution is poor compared to other functional imaging tools. However, recently it was shown that diffuse optical tomography (DOT) as an extension of NIRS based on high-density (HD) probe arrays and supplemented by an advanced image reconstruction procedure allows describing activation patterns with a spatial resolution in the millimeter range. Building on these findings, we hypothesize that HD-DOT may render very focal activations accessible which would be missed by the traditionally used sparse arrays. We examined activation patterns in the primary somatosensory cortex, since its somatotopic organization is very fine-grained. We performed a vibrotactile stimulation study of the first and fifth finger in eight human subjects, using a 900-channel continuous-wave DOT imaging system for achieving a higher resolution than conventional topographic NIRS. To compare the results to a well-established high-resolution imaging technique, the same paradigm was investigated in the same subjects by means of functional magnetic resonance imaging (fMRI). In this work, we tested the advantage of ultrahigh-density probe arrays and show that highly focal activations would be missed by classical next-nearest neighbor NIRS approach, but also by DOT, when using a sparse probe array. Distinct activation patterns for both fingers correlated well with the expected neuroanatomy in five of eight subjects. Additionally we show that activation for different fingers is projected to different tissue depths in the DOT image. Comparison to the fMRI data yielded similar activation foci in seven out of ten finger representations in these five subjects when comparing the lateral localization of DOT and fMRI results.
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Affiliation(s)
- Christina Habermehl
- Berlin NeuroImaging Center, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany.
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Hillman EMC, Amoozegar CB, Wang T, McCaslin AFH, Bouchard MB, Mansfield J, Levenson RM. In vivo optical imaging and dynamic contrast methods for biomedical research. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4620-43. [PMID: 22006910 PMCID: PMC3263788 DOI: 10.1098/rsta.2011.0264] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
This paper provides an overview of optical imaging methods commonly applied to basic research applications. Optical imaging is well suited for non-clinical use, since it can exploit an enormous range of endogenous and exogenous forms of contrast that provide information about the structure and function of tissues ranging from single cells to entire organisms. An additional benefit of optical imaging that is often under-exploited is its ability to acquire data at high speeds; a feature that enables it to not only observe static distributions of contrast, but to probe and characterize dynamic events related to physiology, disease progression and acute interventions in real time. The benefits and limitations of in vivo optical imaging for biomedical research applications are described, followed by a perspective on future applications of optical imaging for basic research centred on a recently introduced real-time imaging technique called dynamic contrast-enhanced small animal molecular imaging (DyCE).
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Affiliation(s)
- Elizabeth M C Hillman
- Laboratory for Functional Optical Imaging, Department of Biomedical Engineering, and Columbia University in the City of New York, New York, NY 10027, USA.
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Bedside optical imaging of occipital resting-state functional connectivity in neonates. Neuroimage 2011; 59:2529-38. [PMID: 21925609 DOI: 10.1016/j.neuroimage.2011.08.094] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 08/07/2011] [Accepted: 08/30/2011] [Indexed: 11/20/2022] Open
Abstract
Resting-state networks derived from temporal correlations of spontaneous hemodynamic fluctuations have been extensively used to elucidate the functional organization of the brain in adults and infants. We have previously developed functional connectivity diffuse optical tomography methods in adults, and we now apply these techniques to study functional connectivity in newborn infants at the bedside. We present functional connectivity maps in the occipital cortices obtained from healthy term-born infants and premature infants, including one infant with an occipital stroke. Our results suggest that functional connectivity diffuse optical tomography has potential as a valuable clinical tool for the early detection of functional deficits and for providing prognostic information on future development.
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Bauer AQ, Nothdurft RE, Erpelding TN, Wang LV, Culver JP. Quantitative photoacoustic imaging: correcting for heterogeneous light fluence distributions using diffuse optical tomography. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:096016. [PMID: 21950930 PMCID: PMC3188642 DOI: 10.1117/1.3626212] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 05/18/2023]
Abstract
The specificity of molecular and functional photoacoustic (PA) images depends on the accuracy of the photoacoustic absorption spectroscopy. The PA signal is proportional to the product of the optical absorption coefficient and local light fluence; quantitative PA measurements of the optical absorption coefficient therefore require an accurate estimation of optical fluence. Light-modeling aided by diffuse optical tomography (DOT) can be used to map the required fluence and to reduce errors in traditional PA spectroscopic analysis. As a proof-of-concept, we designed a tissue-mimicking phantom to demonstrate how fluence-related artifacts in PA images can lead to misrepresentations of tissue properties. To correct for these inaccuracies, the internal fluence in the tissue phantom was estimated by using DOT to reconstruct spatial distributions of the absorption and reduced scattering coefficients of multiple targets within the phantom. The derived fluence map, which only consisted of low spatial frequency components, was used to correct PA images of the phantom. Once calibrated to a known absorber, this method reduced errors in estimated absorption coefficients from 33% to 6%. These results experimentally demonstrate that combining DOT with PA imaging can significantly reduce fluence-related errors in PA images, while producing quantitatively accurate, high-resolution images of the optical absorption coefficient.
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Affiliation(s)
- Adam Q Bauer
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110, USA.
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Two-detector Corrected Near Infrared Spectroscopy (C-NIRS) detects hemodynamic activation responses more robustly than single-detector NIRS. Neuroimage 2011; 55:1679-85. [DOI: 10.1016/j.neuroimage.2011.01.043] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 01/07/2011] [Accepted: 01/13/2011] [Indexed: 11/23/2022] Open
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