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Lee YS, Shim M, Choi GY, Kim SH, Lim W, Jeong JW, Jung YJ, Hwang HJ. Neuromodulatory feasibility of a current limiter-based tDCS device: a resting-state electroencephalography study. Biomed Eng Lett 2023; 13:407-415. [PMID: 37519870 PMCID: PMC10382376 DOI: 10.1007/s13534-023-00269-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 01/02/2023] [Accepted: 02/01/2023] [Indexed: 02/10/2023] Open
Abstract
Recently, we introduced a current limiter-based novel transcranial direct-current stimulation (tDCS) device that does not generate significant tDCS-induced electrical artifacts, thereby facilitating simultaneous electroencephalography (EEG) measurement during tDCS application. In this study, we investigated the neuromodulatory effect of the tDCS device using resting-state EEG data measured during tDCS application in terms of EEG power spectral densities (PSD) and brain network indices (clustering coefficient and path length). Resting-state EEG data were recorded from 10 healthy subjects during both eyes-open (EO) and eyes-closed (EC) states for each of five different conditions (baseline, sham, post-sham, tDCS, and post-tDCS). In the tDCS condition, tDCS was applied for 12 min with a current intensity of 1.5 mA, whereas tDCS was applied only for the first 30 s in the sham condition. EEG PSD and brain network indices were computed for the alpha frequency band most closely associated with resting-state EEG. Both alpha PSD and network indices were found to significantly increase during and after tDCS application compared to those of the baseline condition in the EO state, but not in the EC state owing to the ceiling effect. Our results demonstrate the neuromodulatory effect of the tDCS device that does not generate significant tDCS-induced electrical artifacts, thereby allowing simultaneous measurement of electrical brain activity. We expect our novel tDCS device to be practically useful in exploring the impact of tDCS on neuromodulation more precisely using ongoing EEG data simultaneously measured during tDCS application.
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Affiliation(s)
- Yun-Sung Lee
- Department of Electronics and Information, Korea University, 30019 Sejong, Republic of Korea
- Interdisciplinary Graduate Program for Artificial Intelligence Smart Convergence Technology, Korea University, Sejong, Republic of Korea
| | - Miseon Shim
- Department of Electronics and Information, Korea University, 30019 Sejong, Republic of Korea
| | - Ga-Young Choi
- Department of Electronics and Information, Korea University, 30019 Sejong, Republic of Korea
| | - Sang Ho Kim
- Department of Industrial Engineering, Kumoh National Institute of Technology, 39177 Gumi, Republic of Korea
| | - Wansu Lim
- Department of Aeronautics, Mechanical, and Electronic Convergence Engineering, Kumoh National Institute of Technology, 39177 Gumi, Republic of Korea
| | - Jin-Woo Jeong
- Department of Data Science, Seoul National University of Science and Technology, 01811 Seoul, Republic of Korea
| | - Young-Jin Jung
- School of Healthcare and Biomedical Engineering, Chonnam National University, 59626 Yeosu, Republic of Korea
- 50, Daehak-ro, 59626 Yeosu-si, Jeollanam-do Republic of Korea
| | - Han-Jeong Hwang
- Department of Electronics and Information, Korea University, 30019 Sejong, Republic of Korea
- Interdisciplinary Graduate Program for Artificial Intelligence Smart Convergence Technology, Korea University, Sejong, Republic of Korea
- Sejong-ro, Jochiwon-eup, 2511, 30019 Sejong-si, Republic of Korea
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Degan S, Feng Y, Hoffmann U, Turner DA. Placement of Extracranial Stimulating Electrodes and Measurement of Cerebral Blood Flow and Intracranial Electrical Fields in Anesthetized Mice. J Vis Exp 2023:10.3791/65195. [PMID: 37335103 PMCID: PMC10476879 DOI: 10.3791/65195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023] Open
Abstract
The detection of cerebral blood flow (CBF) responses to various forms of neuronal activation is critical for understanding dynamic brain function and variations in the substrate supply to the brain. This paper describes a protocol for measuring CBF responses to transcranial alternating current stimulation (tACS). Dose-response curves are estimated both from the CBF change occurring with tACS (mA) and from the intracranial electric field (mV/mm). We estimate the intracranial electrical field based on the different amplitudes measured by glass microelectrodes within each side of the brain. In this paper, we describe the experimental setup, which involves using either bilateral laser Doppler (LD) probes or laser speckle imaging (LSI) to measure the CBF; as a result, this setup requires anesthesia for the electrode placement and stability. We present a correlation between the CBF response and the current as a function of age, showing a significantly larger response at higher currents (1.5 mA and 2.0 mA) in young control animals (12-14 weeks) compared to older animals (28-32 weeks) (p < 0.005 difference). We also demonstrate a significant CBF response at electrical field strengths <5 mV/mm, which is an important consideration for eventual human studies. These CBF responses are also strongly influenced by the use of anesthesia compared to awake animals, the respiration control (i.e., intubated vs. spontaneous breathing), systemic factors (i.e., CO2), and local conduction within the blood vessels, which is mediated by pericytes and endothelial cells. Likewise, more detailed imaging/recording techniques may limit the field size from the entire brain to only a small region. We describe the use of extracranial electrodes for applying tACS stimulation, including both homemade and commercial electrode designs for rodents, the concurrent measurement of the CBF and intracranial electrical field using bilateral glass DC recording electrodes, and the imaging approaches. We are currently applying these techniques to implement a closed-loop format for augmenting the CBF in animal models of Alzheimer's disease and stroke.
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Affiliation(s)
- Simone Degan
- Department of Neurosurgery, Duke University Medical Center
| | - Yu Feng
- Department of Neurosurgery, Duke University Medical Center
| | - Ulrike Hoffmann
- Department of Anesthesiology and Pain Management, University Texas Southwestern Medical School
| | - Dennis A Turner
- Department of Neurosurgery, Duke University Medical Center; Department of Neurobiology, Duke University Medical Center; Department of Biomedical Engineering, Duke University; Research and Surgery Services, Durham VA Medical Center;
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Arora Y, Dutta A. Perspective: Disentangling the effects of tES on neurovascular unit. Front Neurol 2023; 13:1038700. [PMID: 36698881 PMCID: PMC9868757 DOI: 10.3389/fneur.2022.1038700] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/28/2022] [Indexed: 01/11/2023] Open
Abstract
Transcranial electrical stimulation (tES) can modulate the neurovascular unit, including the perivascular space morphology, but the mechanisms are unclear. In this perspective article, we used an open-source "rsHRF toolbox" and an open-source functional magnetic resonance imaging (fMRI) transcranial direct current stimulation (tDCS) data set to show the effects of tDCS on the temporal profile of the haemodynamic response function (HRF). We investigated the effects of tDCS in the gray matter and at three regions of interest in the gray matter, namely, the anodal electrode (FC5), cathodal electrode (FP2), and an independent site remote from the electrodes (PZ). A "canonical HRF" with time and dispersion derivatives and a finite impulse response (FIR) model with three parameters captured the effects of anodal tDCS on the temporal profile of the HRF. The FIR model showed tDCS onset effects on the temporal profile of HRF for verum and sham tDCS conditions that were different from the no tDCS condition, which questions the validity of the sham tDCS (placebo). Here, we postulated that the effects of tDCS onset on the temporal profile of HRF are subserved by the effects on neurovascular coupling. We provide our perspective based on previous work on tES effects on the neurovascular unit, including mechanistic grey-box modeling of the effects of tES on the vasculature that can facilitate model predictive control (MPC). Future studies need to investigate grey-box modeling of online effects of tES on the neurovascular unit, including perivascular space, neurometabolic coupling, and neurovascular coupling, that can facilitate MPC of the tES dose-response to address the momentary ("state") and phenotypic ("trait") factors.
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Affiliation(s)
- Yashika Arora
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre, Gurugram, India
| | - Anirban Dutta
- School of Engineering, University of Lincoln, Lincoln, United Kingdom
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La Rocca M, Clemente L, Gentile E, Ricci K, Delussi M, de Tommaso M. Effect of Single Session of Anodal M1 Transcranial Direct Current Stimulation-TDCS-On Cortical Hemodynamic Activity: A Pilot Study in Fibromyalgia. Brain Sci 2022; 12:1569. [PMID: 36421893 PMCID: PMC9688269 DOI: 10.3390/brainsci12111569] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/09/2022] [Accepted: 11/15/2022] [Indexed: 07/23/2024] Open
Abstract
Transcranial direct current stimulation (TDCS) on the primary motor cortex (M1) has been reported to be effective in fibromyalgia (FM). Our previous works have shown hypometabolism of motor networks in FM using Functional Near Infrared Spectroscopy (fNIRS), which could contribute to pain symptoms. To investigate if a single Transcranial Direct Current Stimulation (TDCS) session can restore the reduced metabolism expected in FM patients, we compared metabolic activity in FM patients and controls during a finger-tapping task in basal condition, sham condition, and under anodal TDCS on M1. During the finger tapping task, a continuous wave 20 channel fNIRS system was placed across the bilateral central-frontal areas in 22 healthy controls and 54 FM patients. Subjects were randomly assigned to real TDCS or sham stimulation. The finger-tapping slowness did not change after real and sham stimulation. After real TDCS stimulation, FM patients showed an increased activation of cortical motor regions (t-statistic = -2.5246, p-value = 0.0125 for the stimulated hemisphere and t-statistic = -4.6638, p-value = 0.0001 for the non-stimulated hemisphere). The basal differences between FM and controls reverted after real TDCS, while this effect was not observed for sham stimulation. A single TDCS session of the cortical motor network seemed able to restore basic cortical hypometabolism in FM patients. Further studies could clarify the long-term effect of M1 stimulation on cortical metabolism, and its relevance in pain processing and clinical features.
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Affiliation(s)
- Marianna La Rocca
- Physics Department, Bari Aldo Moro University, 70121 Bari, Italy
- Laboratory of Neuro Imaging, USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA 90007, USA
| | - Livio Clemente
- DiBraiN Department, Bari Aldo Moro University, 70121 Bari, Italy
| | - Eleonora Gentile
- DiBraiN Department, Bari Aldo Moro University, 70121 Bari, Italy
| | - Katia Ricci
- DiBraiN Department, Bari Aldo Moro University, 70121 Bari, Italy
| | - Marianna Delussi
- DiBraiN Department, Bari Aldo Moro University, 70121 Bari, Italy
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Arora Y, Dutta A. Human-in-the-Loop Optimization of Transcranial Electrical Stimulation at the Point of Care: A Computational Perspective. Brain Sci 2022; 12:brainsci12101294. [PMID: 36291228 PMCID: PMC9599464 DOI: 10.3390/brainsci12101294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/05/2022] [Accepted: 09/18/2022] [Indexed: 11/17/2022] Open
Abstract
Individual differences in the responsiveness of the brain to transcranial electrical stimulation (tES) are increasingly demonstrated by the large variability in the effects of tES. Anatomically detailed computational brain models have been developed to address this variability; however, static brain models are not “realistic” in accounting for the dynamic state of the brain. Therefore, human-in-the-loop optimization at the point of care is proposed in this perspective article based on systems analysis of the neurovascular effects of tES. First, modal analysis was conducted using a physiologically detailed neurovascular model that found stable modes in the 0 Hz to 0.05 Hz range for the pathway for vessel response through the smooth muscle cells, measured with functional near-infrared spectroscopy (fNIRS). During tES, the transient sensations can have arousal effects on the hemodynamics, so we present a healthy case series for black-box modeling of fNIRS−pupillometry of short-duration tDCS effects. The block exogeneity test rejected the claim that tDCS is not a one-step Granger cause of the fNIRS total hemoglobin changes (HbT) and pupil dilation changes (p < 0.05). Moreover, grey-box modeling using fNIRS of the tDCS effects in chronic stroke showed the HbT response to be significantly different (paired-samples t-test, p < 0.05) between the ipsilesional and contralesional hemispheres for primary motor cortex tDCS and cerebellar tDCS, which was subserved by the smooth muscle cells. Here, our opinion is that various physiological pathways subserving the effects of tES can lead to state−trait variability, which can be challenging for clinical translation. Therefore, we conducted a case study on human-in-the-loop optimization using our reduced-dimensions model and a stochastic, derivative-free covariance matrix adaptation evolution strategy. We conclude from our computational analysis that human-in-the-loop optimization of the effects of tES at the point of care merits investigation in future studies for reducing inter-subject and intra-subject variability in neuromodulation.
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Affiliation(s)
- Yashika Arora
- Neuroimaging and Neurospectroscopy Lab, National Brain Research Centre, Gurgaon 122052, India
| | - Anirban Dutta
- Neuroengineering and Informatics for Rehabilitation and Simulation-Based Learning (NIRSlearn), University of Lincoln, Lincoln LN6 7TS, UK
- Correspondence:
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Hong KS, Khan MNA, Ghafoor U. Non-invasive transcranial electrical brain stimulation guided by functional near-infrared spectroscopy for targeted neuromodulation: A review. J Neural Eng 2022; 19. [PMID: 35905708 DOI: 10.1088/1741-2552/ac857d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/29/2022] [Indexed: 11/12/2022]
Abstract
One of the primary goals in cognitive neuroscience is to understand the neural mechanisms on which cognition is based. Researchers are trying to find how cognitive mechanisms are related to oscillations generated due to brain activity. The research focused on this topic has been considerably aided by developing non-invasive brain stimulation techniques. The dynamics of brain networks and the resultant behavior can be affected by non-invasive brain stimulation techniques, which make their use a focus of interest in many experiments and clinical fields. One essential non-invasive brain stimulation technique is transcranial electrical stimulation (tES), subdivided into transcranial direct and alternating current stimulation. tES has recently become more well-known because of the effective results achieved in treating chronic conditions. In addition, there has been exceptional progress in the interpretation and feasibility of tES techniques. Summarizing the beneficial effects of tES, this article provides an updated depiction of what has been accomplished to date, brief history, and the open questions that need to be addressed in the future. An essential issue in the field of tES is stimulation duration. This review briefly covers the stimulation durations that have been utilized in the field while monitoring the brain using functional-near infrared spectroscopy-based brain imaging.
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Affiliation(s)
- Keum-Shik Hong
- Department of Cogno-mechatronics Engineering, Pusan National University, 2 Busandaehak-ro, Geumgeong-gu, Busan, Busan, 609735, Korea (the Republic of)
| | - M N Afzal Khan
- Pusan National University, Department of Mechanical Engineering, Busan, 46241, Korea (the Republic of)
| | - Usman Ghafoor
- School of Mechanical Engineering, Pusan National University College of Engineering, room 204, Busan, 46241, Korea (the Republic of)
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Shao M, Zhong MC, Wang Z, Ke Z, Zhong Z, Zhou J. Non-Invasive Dynamic Reperfusion of Microvessels In Vivo Controlled by Optical Tweezers. Front Bioeng Biotechnol 2022; 10:952537. [PMID: 35910027 PMCID: PMC9331193 DOI: 10.3389/fbioe.2022.952537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 06/22/2022] [Indexed: 11/13/2022] Open
Abstract
Distributive shock is considered to be a condition of microvascular hypoperfusion, which can be fatal in severe cases. However, traditional therapeutic methods to restore the macro blood flow are difficult to accurately control the blood perfusion of microvessels, and the currently developed manipulation techniques are inevitably incompatible with biological systems. In our approach, infrared optical tweezers are used to dynamically control the microvascular reperfusion within subdermal capillaries in the pinna of mice. Furthermore, we estimate the effect of different optical trap positions on reperfusion at branch and investigate the effect of the laser power on reperfusion. The results demonstrate the ability of optical tweezers to control microvascular reperfusion. This strategy allows near-noninvasive reperfusion of the microvascular hypoperfusion in vivo. Hence, our work is expected to provide unprecedented insights into the treatment of distributive shock.
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Affiliation(s)
- Meng Shao
- Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronics Engineering, Hefei University of Technology, Hefei, China
| | - Min-Cheng Zhong
- Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronics Engineering, Hefei University of Technology, Hefei, China
- *Correspondence: Min-Cheng Zhong, ; Jinhua Zhou,
| | - Zixin Wang
- School of Biomedical Engineering, Anhui Medical University, Hefei, China
| | - Zeyu Ke
- School of Biomedical Engineering, Anhui Medical University, Hefei, China
| | - Zhensheng Zhong
- School of Biomedical Engineering, Anhui Medical University, Hefei, China
| | - Jinhua Zhou
- School of Biomedical Engineering, Anhui Medical University, Hefei, China
- *Correspondence: Min-Cheng Zhong, ; Jinhua Zhou,
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Short periods of bipolar anodal TDCS induce no instantaneous dose-dependent increase in cerebral blood flow in the targeted human motor cortex. Sci Rep 2022; 12:9580. [PMID: 35688875 PMCID: PMC9187751 DOI: 10.1038/s41598-022-13091-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 05/20/2022] [Indexed: 12/03/2022] Open
Abstract
Anodal transcranial direct current stimulation (aTDCS) of primary motor hand area (M1-HAND) can enhance corticomotor excitability, but it is still unknown which current intensity produces the strongest effect on intrinsic neural firing rates and synaptic activity. Magnetic resonance imaging (MRI) combined with pseudo-continuous Arterial Spin Labeling (pcASL MRI) can map regional cortical blood flow (rCBF). The measured rCBF signal is sensitive to regional changes in neuronal activity due to neurovascular coupling. Therefore, concurrent TDCS and pcASL MRI may reveal the relationship between current intensity and TDCS-induced changes in overall firing rates and synaptic activity in the cortical target. Here we employed pcASL MRI to map acute rCBF changes during short-duration aTDCS of left M1-HAND. Using the rCBF response as a proxy for regional neuronal activity, we investigated if short-duration aTDCS produces an instantaneous dose-dependent rCBF increase in the targeted M1-HAND that may be useful for individual dosing. Nine healthy right-handed participants received 30 s of aTDCS at 0.5, 1.0, 1.5, and 2.0 mA with the anode placed over left M1-HAND and cathode over the right supraorbital region. Concurrent pcASL MRI at 3 T probed TDCS-related rCBF changes in the targeted M1-HAND. Movement-induced rCBF changes were also assessed. Apart from a subtle increase in rCBF at 0.5 mA, short-duration aTDCS did not modulate rCBF in the M1-HAND relative to no-stimulation periods. None of the participants showed a dose-dependent increase in rCBF during aTDCS, even after accounting for individual differences in TDCS-induced electrical field strength. In contrast, finger movements led to robust activation of left M1-HAND before and after aTDCS. Short-duration bipolar aTDCS does not produce consistant instantaneous dose-dependent rCBF increases in the targeted M1-HAND at conventional intensity ranges. Therefore, the regional hemodynamic response profile to short-duration aTDCS may not be suited to inform individual dosing of TDCS intensity.
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Optical Modalities for Research, Diagnosis, and Treatment of Stroke and the Consequent Brain Injuries. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12041891] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Stroke is the second most common cause of death and third most common cause of disability worldwide. Therefore, it is an important disease from a medical standpoint. For this reason, various studies have developed diagnostic and therapeutic techniques for stroke. Among them, developments and applications of optical modalities are being extensively studied. In this article, we explored three important optical modalities for research, diagnostic, and therapeutics for stroke and the brain injuries related to it: (1) photochemical thrombosis to investigate stroke animal models; (2) optical imaging techniques for in vivo preclinical studies on stroke; and (3) optical neurostimulation based therapy for stroke. We believe that an exploration and an analysis of previous studies will help us proceed from research to clinical applications of optical modalities for research, diagnosis, and treatment of stroke.
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Im C, Shin J, Lee WR, Kim JM. Machine learning-based feature combination analysis for odor-dependent hemodynamic responses of rat olfactory bulb. Biosens Bioelectron 2022; 197:113782. [PMID: 34814029 DOI: 10.1016/j.bios.2021.113782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 10/19/2021] [Accepted: 11/08/2021] [Indexed: 11/29/2022]
Abstract
Rodents have a well-developed sense of smell and are used to detect explosives, mines, illegal substances, hidden currency, and contraband, but it is impossible to keep their concentration constantly. Therefore, there is an ongoing effort to infer odors detected by animals without behavioral readings with brain-computer interface (BCI) technology. However, the invasive BCI technique has the disadvantage that long-term studies are limited by the immune response and electrode movement. On the other hand, near-infrared spectroscopy (NIRS)-based BCI technology is a non-invasive method that can measure neuronal activity without worrying about the immune response or electrode movement. This study confirmed that the NIRS-based BCI technology can be used as an odor detection and identification from the rat olfactory system. In addition, we tried to present features optimized for machine learning models by extracting six features, such as slopes, peak, variance, mean, kurtosis, and skewness, from the hemodynamic response, and analyzing the importance of individuals or combinations. As a result, the feature with the highest F1-Score was indicated as slopes, and it was investigated that the combination of the features including slopes and mean was the most important for odor inference. On the other hand, the inclusion of other features with a low correlation with slopes had a positive effect on the odor inference, but most of them resulted in insignificant or rather poor performance. The results presented in this paper are expected to serve as a basis for suggesting the development direction of the hemodynamic response-based bionic nose in the future.
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Affiliation(s)
- Changkyun Im
- Bio & Medical Health Division, Korea Testing Laboratory, Seoul, 08389, Republic of Korea
| | - Jaewoo Shin
- Hurvitz Brain Sciences Research Program, Biological Sciences, Sunnybrook Research Institute, Toronto, ON, M4N 3M5, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S 1A8, Canada; Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Woo Ram Lee
- Department of Electronic Engineering, Gyeonggi University of Science and Technology, Siheung, 15073, Republic of Korea.
| | - Jun-Min Kim
- Department of Mechanical Systems Engineering Electronics, Hansung University, Seoul, 02876, Republic of Korea.
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Neurovascular-modulation: A review of primary vascular responses to transcranial electrical stimulation as a mechanism of action. Brain Stimul 2021; 14:837-847. [PMID: 33962079 DOI: 10.1016/j.brs.2021.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The ubiquitous vascular response to transcranial electrical stimulation (tES) has been attributed to the secondary effect of neuronal activity forming the classic neurovascular coupling. However, the current density delivered transcranially concentrates in: A) the cerebrospinal fluid of subarachnoid space where cerebral vasculature resides after reaching the dural and pial surfaces and B) across the blood-brain-barrier after reaching the brain parenchyma. Therefore, it is anticipated that tES has a primary vascular influence. OBJECTIVES Focused review of studies that demonstrated the direct vascular response to electrical stimulation and studies demonstrating evidence for tES-induced vascular effect in coupled neurovascular systems. RESULTS tES induces both primary and secondary vascular phenomena originating from four cellular elements; the first two mediating a primary vascular phenomenon mainly in the form of an immediate vasodilatory response and the latter two leading to secondary vascular effects and as parts of classic neurovascular coupling: 1) The perivascular nerves of more superficially located dural and pial arteries and medium-sized arterioles with multilayered smooth muscle cells; and 2) The endothelial lining of all vessels including microvasculature of blood-brain barrier; 3) Astrocytes; and 4) Neurons of neurovascular units. CONCLUSION A primary vascular effect of tES is highly suggested based on various preclinical and clinical studies. We explain how the nature of vascular response can depend on vessel anatomy (size) and physiology and be controlled by stimulation waveform. Further studies are warranted to investigate the mechanisms underlying the vascular response and its contribution to neural activity in both healthy brain and pathological conditions - recognizing many brain diseases are associated with alteration of cerebral hemodynamics and decoupling of neurovascular units.
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Paik SH, Lee SH, Kim JH, Kang SY, Phillips V Z, Choi Y, Kim BM. Multichannel near-infrared spectroscopy brain imaging system for small animals in mobile conditions. NEUROPHOTONICS 2021; 8:025013. [PMID: 34179215 PMCID: PMC8230091 DOI: 10.1117/1.nph.8.2.025013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 05/19/2021] [Indexed: 06/13/2023]
Abstract
Significance: We propose a customized animal-specific head cap and an near-infrared spectroscopy (NIRS) system to obtain NIRS signals in mobile small animals. NIRS studies in mobile small animals provide a feasible solution for comprehensive brain function studies. Aim: We aim to develop and validate a multichannel NIRS system capable of performing functional brain imaging along with a closed-box stimulation kit for small animals in mobile conditions. Approach: The customized NIRS system uses light-weight long optical fibers, along with a customized light-weight head cap to securely attach the optical fibers to the mouse. A customized stimulation box was designed to perform various stimuli in a controlled environment. The system performance was tested in a visual stimulation task on eight anesthetized mice and eight freely moving mice. Results: Following the visual stimulation task, we observed a significant stimulation-related oxyhemoglobin (HbO) increase in the visual cortex of freely moving mice during the task. In contrast, HbO concentration did not change significantly in the visual cortex of anesthetized mice. Conclusions: We demonstrate the feasibility of a wearable, multichannel NIRS system for small animals in a less confined experimental design.
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Affiliation(s)
- Seung-Ho Paik
- Korea University, College of Health Science, Global Health Technology Research Center, Seoul, Republic of Korea
- KLIEN Inc., Seoul, Republic of Korea
| | - Seung Hyun Lee
- Korea University, College of Health Science, Global Health Technology Research Center, Seoul, Republic of Korea
| | - Ju-Hee Kim
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
| | - Shin-Young Kang
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
| | - Zephaniah Phillips V
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
| | - Youngwoon Choi
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
| | - Beop-Min Kim
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
- Korea University, Interdisciplinary Program in Precision Public Health, Seoul, Republic of Korea
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Boonzaier J, Straathof M, Ardesch DJ, van der Toorn A, van Vliet G, van Heijningen CL, Otte WM, Dijkhuizen RM. Activation response and functional connectivity change in rat cortex after bilateral transcranial direct current stimulation-An exploratory study. J Neurosci Res 2021; 99:1377-1389. [PMID: 33511664 PMCID: PMC8048424 DOI: 10.1002/jnr.24793] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/14/2020] [Accepted: 01/11/2021] [Indexed: 12/13/2022]
Abstract
Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique implicated as a promising adjunct therapy to improve motor function through the neuromodulation of brain networks. Particularly bilateral tDCS, which affects both hemispheres, may yield stronger effects on motor learning than unilateral stimulation. Therefore, the aim of this exploratory study was to develop an experimental model for simultaneous magnetic resonance imaging (MRI) and bilateral tDCS in rats, to measure instant and resultant effects of tDCS on network activity and connectivity. Naïve, male Sprague‐Dawley rats were divided into a tDCS (n = 7) and sham stimulation group (n = 6). Functional MRI data were collected during concurrent bilateral tDCS over the sensorimotor cortex, while resting‐state functional MRI and perfusion MRI were acquired directly before and after stimulation. Bilateral tDCS induced a hemodynamic activation response, reflected by a bilateral increase in blood oxygenation level‐dependent signal in different cortical areas, including the sensorimotor regions. Resting‐state functional connectivity within the cortical sensorimotor network decreased after a first stimulation session but increased after a second session, suggesting an interaction between multiple tDCS sessions. Perfusion MRI revealed no significant changes in cerebral blood flow after tDCS. Our exploratory study demonstrates successful application of an MRI‐compatible bilateral tDCS setup in an animal model. Our results indicate that bilateral tDCS can locally modulate neuronal activity and connectivity, which may underlie its therapeutic potential.
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Affiliation(s)
- Julia Boonzaier
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
| | - Milou Straathof
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
| | - Dirk Jan Ardesch
- Connectome Lab, Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Annette van der Toorn
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
| | - Gerard van Vliet
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
| | - Caroline L van Heijningen
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
| | - Willem M Otte
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands.,Department of Pediatric Neurology, UMC Utrecht Brain Center, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
| | - Rick M Dijkhuizen
- Biomedical Magnetic Resonance Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht and Utrecht University, Utrecht, The Netherlands
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14
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Turner DA, Degan S, Galeffi F, Schmidt S, Peterchev AV. Rapid, Dose-Dependent Enhancement of Cerebral Blood Flow by transcranial AC Stimulation in Mouse. Brain Stimul 2020; 14:80-87. [PMID: 33217607 DOI: 10.1016/j.brs.2020.11.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 10/18/2020] [Accepted: 11/12/2020] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Transcranial electrical stimulation at an appropriate dose may demonstrate intracranial effects, including neuronal stimulation and cerebral blood flow responses. OBJECTIVE We performed in vivo experiments on mouse cortex using transcranial alternating current [AC] stimulation to assess whether cerebral blood flow can be reliably altered by extracranial stimulation. METHODS We performed transcranial AC electrical stimulation transversely across the closed skull in anesthetized mice, measuring transcranial cerebral blood flow with a laser Doppler probe and intracranial electrical responses as endpoint biomarkers. We calculated a stimulation dose-response function between intracranial electric field and cerebral blood flow. RESULTS Stimulation at electric field amplitudes of 5-20 mV/mm at 10-20 Hz rapidly increased cerebral blood flow (within 100 ms), which then quickly decreased with no residual effects. The time to peak and blood flow shape varied with stimulation intensity and duration, showing a linear correlation between stimulation dose and peak blood flow increase. Neither afterdischarges nor spreading depression occurred from this level of stimulation. CONCLUSIONS Extracranial stimulation amplitudes sufficient to evoke reliable blood flow changes require electric field strengths higher than what is tolerable in unanesthetized humans (<1 mV/mm), but less than electroconvulsive therapy levels (>40 mV/mm). However, anesthesia effects, spontaneous blood flow fluctuations, and sampling error may accentuate the apparent field strength needed for enhanced blood flow. The translation to a human dose-response function to augment cerebral blood flow (i.e., in stroke recovery) will require significant modification, potentially to pericranial, focused, multi-electrode application or intracranial stimulation.
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Affiliation(s)
- Dennis A Turner
- Neurosurgery, Duke University, USA; Neurobiology, Duke University, USA; Biomedical Engineering, Duke University, USA; Surgery and Research Branches, Durham VAMC, Durham, NC, 27710, USA.
| | - Simone Degan
- Neurosurgery, Duke University, USA; Surgery and Research Branches, Durham VAMC, Durham, NC, 27710, USA
| | - Francesca Galeffi
- Neurosurgery, Duke University, USA; Surgery and Research Branches, Durham VAMC, Durham, NC, 27710, USA
| | - Stephen Schmidt
- Neurosurgery, Duke University, USA; Biomedical Engineering, Duke University, USA
| | - Angel V Peterchev
- Neurosurgery, Duke University, USA; Psychiatry & Behavioral Sciences, Duke University, USA; Biomedical Engineering, Duke University, USA; Electrical & Computer Engineering, Duke University, USA
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15
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Liu X, Gao Q, Zhang Y, Li Y, Li B. In Vivo Optofluidic Switch for Controlling Blood Microflow. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2001414. [PMID: 32714772 PMCID: PMC7375249 DOI: 10.1002/advs.202001414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/12/2020] [Indexed: 05/13/2023]
Abstract
Control of blood microflow is crucial for the prevention and therapy of blood disorders, such as cardiovascular diseases and their complications. Conventional control strategies generally implant exogenous synthetic materials into blood vessels as labeling markers or actuating sources, which are invasive and incompatible with biological systems. Here, a label-free, noninvasive, and biocompatible device constructed from natural red blood cells (RBCs) for controlling blood microflow in vivo is reported. The RBCs, optically manipulated, arranged, and rotated using scanning optical tweezers, can function as an optofluidic switch for targeted switching, directional enrichment, dynamic redirecting, and rotary actuation of blood microflow inside zebrafish. The regulation precision of the switch is determined to be at the single-cell level, and the response time is measured as ≈200 ms using a streamline tracking method. This in vivo optofluidic switch may provide a biofriendly device for exploring blood microenvironments in a noncontact and noninvasive manner.
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Affiliation(s)
- Xiaoshuai Liu
- Institute of NanophotonicsJinan UniversityGuangzhou511‐443China
| | - Qing Gao
- Institute of NanophotonicsJinan UniversityGuangzhou511‐443China
| | - Yao Zhang
- Institute of NanophotonicsJinan UniversityGuangzhou511‐443China
| | - Yuchao Li
- Institute of NanophotonicsJinan UniversityGuangzhou511‐443China
| | - Baojun Li
- Institute of NanophotonicsJinan UniversityGuangzhou511‐443China
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16
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Jung YJ, Lee YS, Choi GY, Hwang HJ. Development of a transcranial direct current stimulation device based on current limiter for simultaneous measurement of electroencephalography: A feasibility study. Technol Health Care 2020; 28:123-130. [PMID: 32333570 PMCID: PMC7369038 DOI: 10.3233/thc-209013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND: Electroencephalography (EEG) measured during transcranial direct current stimulation (tDCS) can help understand the accurate impact of tDCS on the brain, but this has been hindered due to significant inflow of tDCS-induced electrical artifacts. OBJECTIVE: In this study, we introduce a novel tDCS device developed based on current limiter, which can prevent the generation of significant electrical artifacts. METHODS: To verify the feasibility of our developed tDCS device, we performed simultaneous measurement of EEG during tDCS application with five different current intensities (0, 500, 1,000, 1,500, and 2,000 μA). Changes in EEG power spectral density (PSD) and correlation between the PSD of non-stimulation and tDCS condition were investigated to see whether our tDCS device can be used for simultaneous EEG recording without significant inflow of tDCS-induced electrical artifacts. RESUTLS: The mean EEG-PSD differences between non-stimulation and tDCS condition were not significant for all stimulation current intensities. Furthermore, EEG-PSDs estimated during non-stimulation and tDCS application showed statistically high correlation for all comparison cases. CONCLUSION: Based on the results, we could demonstrate the feasibility of our tDCS device based on current limiter for simultaneous EEG measurement, which could potentially provide a way to investigate the impact of tDCS on the brain more accurately.
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Affiliation(s)
- Young-Jin Jung
- Department of Radiological Science, Dongseo University, Busan, Korea.,Center for Radiological Environment and Health Science, Dongseo University, Busan, Korea
| | - Yun-Sung Lee
- Department of Electronics and Information Engineering, Korea University, Sejong, Korea
| | - Ga-Young Choi
- Department of Electronics and Information Engineering, Korea University, Sejong, Korea
| | - Han-Jeong Hwang
- Department of Electronics and Information Engineering, Korea University, Sejong, Korea
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17
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Han CH, Hwang HJ, Lim JH, Im CH. Assessment of user voluntary engagement during neurorehabilitation using functional near-infrared spectroscopy: a preliminary study. J Neuroeng Rehabil 2018; 15:27. [PMID: 29566710 PMCID: PMC5865332 DOI: 10.1186/s12984-018-0365-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 03/05/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Functional near infrared spectroscopy (fNIRS) finds extended applications in a variety of neuroscience fields. We investigated the potential of fNIRS to monitor voluntary engagement of users during neurorehabilitation, especially during combinatory exercise (CE) that simultaneously uses both, passive and active exercises. Although the CE approach can enhance neurorehabilitation outcome, compared to the conventional passive or active exercise strategies, the active engagement of patients in active motor movements during CE is not known. METHODS We determined hemodynamic responses induced by passive exercise and CE to evaluate the active involvement of users during CEs using fNIRS. In this preliminary study, hemodynamic responses of eight healthy subjects during three different tasks (passive exercise alone, passive exercise with motor imagery, and passive exercise with active motor execution) were recorded. On obtaining statistically significant differences, we classified the hemodynamic responses induced by passive exercise and CEs to determine the identification accuracy of the voluntary engagement of users using fNIRS. RESULTS Stronger and broader activation around the sensorimotor cortex was observed during CEs, compared to that during passive exercise. Moreover, pattern classification results revealed more than 80% accuracy. CONCLUSIONS Our preliminary study demonstrated that fNIRS can be potentially used to assess the engagement of users of the combinatory neurorehabilitation strategy.
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Affiliation(s)
- Chang-Hee Han
- Department of Biomedical Engineering, Hanyang University, Seoul, 04763, South Korea
| | - Han-Jeong Hwang
- Kumoh National Institute of Technology, Department of Medical IT Convergence Engineering, Gumi, 38530, South Korea
| | - Jeong-Hwan Lim
- Department of Biomedical Engineering, Hanyang University, Seoul, 04763, South Korea
| | - Chang-Hwan Im
- Department of Biomedical Engineering, Hanyang University, Seoul, 04763, South Korea.
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18
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Giovannella M, Ibañez D, Gregori-Pla C, Kacprzak M, Mitjà G, Ruffini G, Durduran T. Concurrent measurement of cerebral hemodynamics and electroencephalography during transcranial direct current stimulation. NEUROPHOTONICS 2018; 5:015001. [PMID: 29392156 PMCID: PMC5784784 DOI: 10.1117/1.nph.5.1.015001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/20/2017] [Indexed: 05/05/2023]
Abstract
Transcranial direct current stimulation (tDCS) is currently being used for research and treatment of some neurological and neuropsychiatric disorders, as well as for improvement of cognitive functions. In order to better understand cerebral response to the stimulation and to redefine protocols and dosage, its effects must be monitored. To this end, we have used functional diffuse correlation spectroscopy (fDCS) and time-resolved functional near-infrared spectroscopy (TR-fNIRS) together with electroencephalography (EEG) during and after stimulation of the frontal cortex. Twenty subjects participated in two sessions of stimulation with two different polarity montages and twelve also underwent a sham session. Cerebral blood flow and oxyhemoglobin concentration increased during and after active stimulation in the region under the stimulation electrode while deoxyhemoglobin concentration decreased. The EEG spectrum displayed statistically significant power changes across different stimulation sessions in delta (2 to 4 Hz), theta (4 to 8 Hz), and beta (12 to 18 Hz) bands. Results suggest that fDCS and TR-fNIRS can be employed as neuromonitors of the effects of transcranial electrical stimulation and can be used together with EEG.
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Affiliation(s)
- Martina Giovannella
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
- Address all correspondence to: Martina Giovannella, E-mail:
| | | | - Clara Gregori-Pla
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - Michal Kacprzak
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | | | - Giulio Ruffini
- Starlab, Barcelona, Spain
- Neuroelectrics Barcelona, Barcelona, Spain
| | - Turgut Durduran
- ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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19
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20
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Kim HY, Seo K, Jeon HJ, Lee U, Lee H. Application of Functional Near-Infrared Spectroscopy to the Study of Brain Function in Humans and Animal Models. Mol Cells 2017; 40:523-532. [PMID: 28835022 PMCID: PMC5582298 DOI: 10.14348/molcells.2017.0153] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 08/03/2017] [Indexed: 01/26/2023] Open
Abstract
Functional near-infrared spectroscopy (fNIRS) is a noninvasive optical imaging technique that indirectly assesses neuronal activity by measuring changes in oxygenated and deoxygenated hemoglobin in tissues using near-infrared light. fNIRS has been used not only to investigate cortical activity in healthy human subjects and animals but also to reveal abnormalities in brain function in patients suffering from neurological and psychiatric disorders and in animals that exhibit disease conditions. Because of its safety, quietness, resistance to motion artifacts, and portability, fNIRS has become a tool to complement conventional imaging techniques in measuring hemodynamic responses while a subject performs diverse cognitive and behavioral tasks in test settings that are more ecologically relevant and involve social interaction. In this review, we introduce the basic principles of fNIRS and discuss the application of this technique in human and animal studies.
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Affiliation(s)
- Hak Yeong Kim
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988,
Korea
| | - Kain Seo
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988,
Korea
| | - Hong Jin Jeon
- Department of Psychiatry, Depression Center, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul 06351,
Korea
| | - Unjoo Lee
- Department of Electronic Engineering, Hallym University, Kangwon 24252,
Korea
| | - Hyosang Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988,
Korea
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21
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Ha U, Lee Y, Kim H, Roh T, Bae J, Kim C, Yoo HJ. A Wearable EEG-HEG-HRV Multimodal System With Simultaneous Monitoring of tES for Mental Health Management. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2015; 9:758-766. [PMID: 26742142 DOI: 10.1109/tbcas.2015.2504959] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A multimodal mental management system in the shape of the wearable headband and earplugs is proposed to monitor electroencephalography (EEG), hemoencephalography (HEG) and heart rate variability (HRV) for accurate mental health monitoring. It enables simultaneous transcranial electrical stimulation (tES) together with real-time monitoring. The total weight of the proposed system is less than 200 g. The multi-loop low-noise amplifier (MLLNA) achieves over 130 dB CMRR for EEG sensing and the capacitive correlated-double sampling transimpedance amplifier (CCTIA) has low-noise characteristics for HEG and HRV sensing. Measured three-physiology domains such as neural, vascular and autonomic domain signals are combined with canonical correlation analysis (CCA) and temporal kernel canonical correlation analysis (tkCCA) algorithm to find the neural-vascular-autonomic coupling. It supports highly accurate classification with the 19% maximum improvement with multimodal monitoring. For the multi-channel stimulation functionality, after-effects maximization monitoring and sympathetic nerve disorder monitoring, the stimulator is designed as reconfigurable. The 3.37 × 2.25 mm(2) chip has 2-channel EEG sensor front-end, 2-channel NIRS sensor front-end, NIRS current driver to drive dual-wavelength VCSEL and 6-b DAC current source for tES mode. It dissipates 24 mW with 2 mA stimulation current and 5 mA NIRS driver current.
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22
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Dutta A. Bidirectional interactions between neuronal and hemodynamic responses to transcranial direct current stimulation (tDCS): challenges for brain-state dependent tDCS. Front Syst Neurosci 2015; 9:107. [PMID: 26321925 PMCID: PMC4530593 DOI: 10.3389/fnsys.2015.00107] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 07/13/2015] [Indexed: 12/04/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has been shown to modulate cortical neural activity. During neural activity, the electric currents from excitable membranes of brain tissue superimpose in the extracellular medium and generate a potential at scalp, which is referred as the electroencephalogram (EEG). Respective neural activity (energy demand) has been shown to be closely related, spatially and temporally, to cerebral blood flow (CBF) that supplies glucose (energy supply) via neurovascular coupling. The hemodynamic response can be captured by near-infrared spectroscopy (NIRS), which enables continuous monitoring of cerebral oxygenation and blood volume. This neurovascular coupling phenomenon led to the concept of neurovascular unit (NVU) that consists of the endothelium, glia, neurons, pericytes, and the basal lamina. Here, recent works suggest NVU as an integrated system working in concert using feedback mechanisms to enable proper brain homeostasis and function where the challenge remains in capturing these mostly nonlinear spatiotemporal interactions within NVU for brain-state dependent tDCS. In principal accordance, we propose EEG-NIRS-based whole-head monitoring of tDCS-induced neuronal and hemodynamic alterations during tDCS.
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Affiliation(s)
- Anirban Dutta
- INRIA (Sophia Antipolis) - CNRS: UMR5506 - Université Montpellier Montpellier, France ; Laboratoire d'Informatique de Robotique et de Microélectronique de Montpellier (LIRMM), CNRS: UMR5506 - Université Montpellier Montpellier, France
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23
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Pulgar VM. Direct electric stimulation to increase cerebrovascular function. Front Syst Neurosci 2015; 9:54. [PMID: 25870543 PMCID: PMC4378276 DOI: 10.3389/fnsys.2015.00054] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/13/2015] [Indexed: 12/23/2022] Open
Affiliation(s)
- Victor M Pulgar
- Biomedical Research and Infrastructure Center, Faculty of Natural and Physical Sciences, Winston-Salem State University Winston-Salem, NC, USA ; Hypertension and Vascular Research Center, Wake Forest School of Medicine Winston-Salem, NC, USA ; Department of Obstetrics and Gynecology, Wake Forest School of Medicine Winston-Salem, NC, USA
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24
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McKendrick R, Parasuraman R, Ayaz H. Wearable functional near infrared spectroscopy (fNIRS) and transcranial direct current stimulation (tDCS): expanding vistas for neurocognitive augmentation. Front Syst Neurosci 2015; 9:27. [PMID: 25805976 PMCID: PMC4353303 DOI: 10.3389/fnsys.2015.00027] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 02/14/2015] [Indexed: 12/02/2022] Open
Abstract
Contemporary studies with transcranial direct current stimulation (tDCS) provide a growing base of evidence for enhancing cognition through the non-invasive delivery of weak electric currents to the brain. The main effect of tDCS is to modulate cortical excitability depending on the polarity of the applied current. However, the underlying mechanism of neuromodulation is not well understood. A new generation of functional near infrared spectroscopy (fNIRS) systems is described that are miniaturized, portable, and include wearable sensors. These developments provide an opportunity to couple fNIRS with tDCS, consistent with a neuroergonomics approach for joint neuroimaging and neurostimulation investigations of cognition in complex tasks and in naturalistic conditions. The effects of tDCS on complex task performance and the use of fNIRS for monitoring cognitive workload during task performance are described. Also explained is how fNIRS + tDCS can be used simultaneously for assessing spatial working memory. Mobile optical brain imaging is a promising neuroimaging tool that has the potential to complement tDCS for realistic applications in natural settings.
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Affiliation(s)
- Ryan McKendrick
- Center of Excellence in Neuroergonomics, Technology, and Cognition (CENTEC), George Mason University Fairfax, VA, USA
| | - Raja Parasuraman
- Center of Excellence in Neuroergonomics, Technology, and Cognition (CENTEC), George Mason University Fairfax, VA, USA
| | - Hasan Ayaz
- School of Biomedical Engineering, Science and Health Systems, Drexel University Philadelphia, PA, USA
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