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Siva NK, Bauer C, Glover C, Stolin A, Chandi S, Melnick H, Marano G, Parker B, Mandich M, Lewis JW, Qi J, Gao S, Nott K, Majewski S, Brefczynski-Lewis JA. Real-time motion-enabling positron emission tomography of the brain of upright ambulatory humans. COMMUNICATIONS MEDICINE 2024; 4:117. [PMID: 38872007 PMCID: PMC11176317 DOI: 10.1038/s43856-024-00547-2] [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: 03/30/2022] [Accepted: 06/05/2024] [Indexed: 06/15/2024] Open
Abstract
BACKGROUND Mobile upright PET devices have the potential to enable previously impossible neuroimaging studies. Currently available options are imagers with deep brain coverage that severely limit head/body movements or imagers with upright/motion enabling properties that are limited to only covering the brain surface. METHODS In this study, we test the feasibility of an upright, motion-compatible brain imager, our Ambulatory Motion-enabling Positron Emission Tomography (AMPET) helmet prototype, for use as a neuroscience tool by replicating a variant of a published PET/fMRI study of the neurocorrelates of human walking. We validate our AMPET prototype by conducting a walking movement paradigm to determine motion tolerance and assess for appropriate task related activity in motor-related brain regions. Human participants (n = 11 patients) performed a walking-in-place task with simultaneous AMPET imaging, receiving a bolus delivery of F18-Fluorodeoxyglucose. RESULTS Here we validate three pre-determined measure criteria, including brain alignment motion artifact of less than <2 mm and functional neuroimaging outcomes consistent with existing walking movement literature. CONCLUSIONS The study extends the potential and utility for use of mobile, upright, and motion-tolerant neuroimaging devices in real-world, ecologically-valid paradigms. Our approach accounts for the real-world logistics of an actual human participant study and can be used to inform experimental physicists, engineers and imaging instrumentation developers undertaking similar future studies. The technical advances described herein help set new priorities for facilitating future neuroimaging devices and research of the human brain in health and disease.
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Affiliation(s)
- Nanda K Siva
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | | | - Colson Glover
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Alexander Stolin
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Sonia Chandi
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Helen Melnick
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Gary Marano
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Benjamin Parker
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - MaryBeth Mandich
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - James W Lewis
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Jinyi Qi
- Department of Biomedical Engineering, University of California, Davis, Davis, CA, USA
| | - Si Gao
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Kaylee Nott
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Stan Majewski
- Department of Biomedical Engineering, University of California, Davis, Davis, CA, USA
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Kashyap R, Bhattacharjee S, Bharath RD, Venkatasubramanian G, Udupa K, Bashir S, Oishi K, Desmond JE, Chen SHA, Guan C. Variation of cerebrospinal fluid in specific regions regulates focality in transcranial direct current stimulation. Front Hum Neurosci 2022; 16:952602. [PMID: 36118967 PMCID: PMC9479459 DOI: 10.3389/fnhum.2022.952602] [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: 08/11/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundConventionally, transcranial direct current stimulation (tDCS) aims to focalize the current reaching the target region-of-interest (ROI). The focality can be quantified by the dose-target-determination-index (DTDI). Despite having a uniform tDCS setup, some individuals receive focal stimulation (high DTDI) while others show reduced focality (“non-focal”). The volume of cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM) underlying each ROI govern the tDCS current distribution inside the brain, thereby regulating focality.AimTo determine the regional volume parameters that differentiate the focal and non-focal groups.MethodsT1-weighted images of the brain from 300 age-sex matched adults were divided into three equal groups- (a) Young (20 ≤ × < 40 years), (b) Middle (40 ≤ × < 60 years), and (c) Older (60 ≤ × < 80 years). For each group, inter and intra-hemispheric montages with electrodes at (1) F3 and right supraorbital region (F3-RSO), and (2) CP5 and Cz (CP5-Cz) were simulated, targeting the left- Dorsolateral Prefrontal Cortex (DLPFC) and -Inferior Parietal Lobule (IPL), respectively. Both montages were simulated for two current doses (1 and 2 mA). For each individual head simulated for a tDCS configuration (montage and dose), the current density at each region-of-interest (ROI) and their DTDI were calculated. The individuals were categorized into two groups- (1) Focal (DTDI ≥ 0.75), and (2) Non-focal (DTDI < 0.75). The regional volume of CSF, GM, and WM of all the ROIs was determined. For each tDCS configuration and ROI, three 3-way analysis of variance was performed considering- (i) GM, (ii) WM, and (iii) CSF as the dependent variable (DV). The age group, sex, and focality group were the between-subject factors. For a given ROI, if any of the 3 DV’s showed a significant main effect or interaction involving the focality group, then that ROI was classified as a “focal ROI.”ResultsRegional CSF was the principal determinant of focality. For interhemispheric F3-RSO montage, interaction effect (p < 0.05) of age and focality was observed at Left Caudate Nucleus, with the focal group exhibiting higher CSF volume. The CSF volume of focal ROI correlated positively (r ∼ 0.16, p < 0.05) with the current density at the target ROI (DLPFC). For intrahemispheric CP5-Cz montage, a significant (p < 0.05) main effect was observed at the left pre- and post-central gyrus, with the focal group showing lower CSF volume. The CSF volume correlated negatively (r ∼ –0.16, p < 0.05) with current density at left IPL. The results were consistent for both current doses.ConclusionThe CSF channels the flow of tDCS current between electrodes with focal ROIs acting like reservoirs of current. The position of focal ROI in the channel determines the stimulation intensity at the target ROI. For focal stimulation in interhemispheric F3-RSO, the proximity of focal ROI reserves the current density at the target ROI (DLPFC). In contrast, for intrahemispheric montage (CP5-Cz), the far-end location of focal ROI reduces the current density at the target (IPL).
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Affiliation(s)
- Rajan Kashyap
- Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
- School of Computer Science and Engineering, Nanyang Technological University, Singapore, Singapore
- *Correspondence: Rajan Kashyap,
| | - Sagarika Bhattacharjee
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences, Bengaluru, India
- Psychology, School of Social Sciences (SSS), Nanyang Technological University, Singapore, Singapore
| | - Rose Dawn Bharath
- Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Ganesan Venkatasubramanian
- InSTAR Program, Schizophrenia Clinic, Department of Psychiatry, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Kaviraja Udupa
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Shahid Bashir
- Neuroscience Center, King Fahad Specialist Hospital Dammam, Dammam, Saudi Arabia
| | - Kenichi Oishi
- The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - John E. Desmond
- The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - S. H. Annabel Chen
- Psychology, School of Social Sciences (SSS), Nanyang Technological University, Singapore, Singapore
- Centre for Research and Development in Learning (CRADLE), Nanyang Technological University, Singapore, Singapore
- Lee Kong Chian School of Medicine (LKC Medicine), Nanyang Technological University, Singapore, Singapore
- National Institute of Education, Nanyang Technological University, Singapore, Singapore
| | - Cuntai Guan
- School of Computer Science and Engineering, Nanyang Technological University, Singapore, Singapore
- Cuntai Guan,
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Applications of open-source software ROAST in clinical studies: A review. Brain Stimul 2022; 15:1002-1010. [PMID: 35843597 PMCID: PMC9378654 DOI: 10.1016/j.brs.2022.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 07/09/2022] [Accepted: 07/10/2022] [Indexed: 11/21/2022] Open
Abstract
Background: Transcranial electrical stimulation (TES) is broadly investigated as a therapeutic technique for a wide range of neurological disorders. The electric fields induced by TES in the brain can be estimated by computational models. A realistic and volumetric approach to simulate TES (ROAST) has been recently released as an open-source software package and has been widely used in TES research and its clinical applications. Rigor and reproducibility of TES studies have recently become a concern, especially in the context of computational modeling. Methods: Here we reviewed 94 clinical TES studies that leveraged ROAST for computational modeling. When reviewing each study, we pay attention to details related to the rigor and reproducibility as defined by the locations of stimulation electrodes and the dose of stimulating current. Specifically, we compared across studies the electrode montages, stimulated brain areas, achieved electric field strength, and the relations between modeled electric field and clinical outcomes. Results: We found that over 1800 individual heads have been modeled by ROAST for more than 30 different clinical applications. Similar electric field intensities were found to be reproducible by ROAST across different studies at the same brain area under same or similar stimulation montages. Conclusion: This article reviews the use cases of ROAST and provides an overview of how ROAST has been leveraged to enhance the rigor and reproducibility of TES research and its applications.
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Bhattacharjee S, Kashyap R, Goodwill AM, O’Brien BA, Rapp B, Oishi K, Desmond JE, Chen SHA. Sex difference in tDCS current mediated by changes in cortical anatomy: A study across young, middle and older adults. Brain Stimul 2022; 15:125-140. [PMID: 34826627 PMCID: PMC9041842 DOI: 10.1016/j.brs.2021.11.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 11/11/2021] [Accepted: 11/22/2021] [Indexed: 01/03/2023] Open
Abstract
INTRODUCTION The observed variability in the effects of transcranial direct current stimulation (tDCS) is influenced by the amount of current reaching the targeted region-of-interest (ROI). Age and sex might affect current density at target ROI due to their impact on cortical anatomy. The present tDCS simulation study investigates the effects of cortical anatomical parameters (volumes, dimension, and torque) on simulated tDCS current density in healthy young, middle-aged, and older males and females. METHODOLOGY Individualized head models from 240 subjects (120 males, 18-87 years of age) were used to identify the estimated current density (2 mA current intensity, 25 cm2 electrode) from two simulated tDCS montages (CP5_CZ and F3_FP2) targeting the inferior parietal lobule (IPL) and middle frontal gyrus (MFG), respectively. Cortical parameters including segmented brain volumes (cerebrospinal fluid [CSF], grey and white matter), cerebral-dimensions (length/width &length/height) and brain-torque (front and back shift, petalia, and bending) were measured using the magnetic resonance images (MRIs) from each subject. The present study estimated sex differences in current density at these target ROIs mediated by these cortical parameters within each age group. RESULTS For both tDCS montages, females in the older age group received higher current density than their male counterparts at the target ROIs. No sex differences were observed in the middle-aged group. Males in the younger age group had a higher current density than females, only for the parietal montage. Across all age groups, CSF, and grey matter volumes significantly predicted the current intensity estimated at the target sites. In the older age group only, brain-torque was a significant mediator of the sex difference. CONCLUSIONS Our findings demonstrate the presence of sex differences in the simulated tDCS current density, however this pattern differed across age groups and stimulation locations. Future studies should consider influence of age and sex on individual cortical anatomy and tailor tDCS stimulation parameters accordingly.
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Affiliation(s)
- Sagarika Bhattacharjee
- Psychology, School of Social Sciences, Nanyang
Technological University, Singapore,,Corresponding authors: Sagarika Bhattacharjee,
Psychology, School of Social Sciences, College of Humanities, Arts, & Social
Sciences, 48 Nanyang Ave, Singapore (639818).
or Prof SH Annabel Chen Psychology, School of
Social Sciences, College of Humanities, Arts, & Social Sciences, 48 Nanyang
Ave, Singapore (639818).
| | - Rajan Kashyap
- Centre for Research and Development in Learning (CRADLE),
Nanyang Technological University, Singapore
| | - Alicia M. Goodwill
- Centre for Research and Development in Learning (CRADLE),
Nanyang Technological University, Singapore,Physical Education and Sports Science Academic Group,
National Institute of Education, Nanyang Technological University, Singapore
| | - Beth Ann O’Brien
- Centre for Research in Child Development (CRCD), National
Institute of Education, Singapore
| | - Brenda Rapp
- The Johns Hopkins University, Krieger School of Arts and
Sciences, Baltimore, United States
| | - Kenichi Oishi
- The Johns Hopkins University School of Medicine, Baltimore,
United States
| | - John E. Desmond
- The Johns Hopkins University School of Medicine, Baltimore,
United States
| | - SH Annabel Chen
- Psychology, School of Social Sciences, Nanyang
Technological University, Singapore,,Centre for Research and Development in Learning (CRADLE),
Nanyang Technological University, Singapore,Lee Kong Chian School of Medicine (LKC Medicine), Nanyang
Technological University, Singapore,Corresponding authors: Sagarika Bhattacharjee,
Psychology, School of Social Sciences, College of Humanities, Arts, & Social
Sciences, 48 Nanyang Ave, Singapore (639818).
or Prof SH Annabel Chen Psychology, School of
Social Sciences, College of Humanities, Arts, & Social Sciences, 48 Nanyang
Ave, Singapore (639818).
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Focality-Oriented Selection of Current Dose for Transcranial Direct Current Stimulation. J Pers Med 2021; 11:jpm11090940. [PMID: 34575717 PMCID: PMC8466113 DOI: 10.3390/jpm11090940] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/18/2021] [Accepted: 09/18/2021] [Indexed: 11/30/2022] Open
Abstract
Background: In transcranial direct current stimulation (tDCS), the injected current becomes distributed across the brain areas. The objective is to stimulate the target region of interest (ROI) while minimizing the current in non-target ROIs (the 'focality' of tDCS). For this purpose, determining the appropriate current dose for an individual is difficult. Aim: To introduce a dose-target determination index (DTDI) to quantify the focality of tDCS and examine the dose-focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of the average current density at the target ROI to the ROI with a maximum value (the peak region). Ideally, target ROI should be the peak region, so DTDI shall range from 0 to 1. The higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups: (a) young adults (20 ≤ x ˂ 40 years), (b) mid adults (40 ≤ x ˂ 60 years), and (c) older adults (60 ≤ x ˂ 80 years). DTDI's were evaluated for the frontal montage with electrodes at F3 and the right supraorbital for three current doses of 1 mA, 2 mA, and 3 mA, with the target ROI at the left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals depending on the relationship (nonlinear or linear) between the injected tDCS current and the distribution of current density in the target ROI. The nonlinearity is predominant in older adults with a decrease in focality. The decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. The recommended DTDI dose should be prioritized based on the age (>40 years) and sex (especially for males) of an individual. The toolbox i-SATA(MNI) is freely available.
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Bhattacharjee S, Kashyap R, O'Brien BA, McCloskey M, Oishi K, Desmond JE, Rapp B, Chen SHA. Reading proficiency influences the effects of transcranial direct current stimulation: Evidence from selective modulation of dorsal and ventral pathways of reading in bilinguals. BRAIN AND LANGUAGE 2020; 210:104850. [PMID: 32890855 PMCID: PMC8103814 DOI: 10.1016/j.bandl.2020.104850] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 08/11/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
INTRODUCTION tDCS can modulate reading which is processed by lexical (ventral) and sub-lexical (dorsal) pathways. Previous research indicates that pathway recruitment in bilinguals depends on a script's orthographic depth and a reader's proficiency with it. The effect of tDCS on each reading pathway has not been investigated in bilinguals. We stimulated the left dorsal and ventral pathways separately in Chinese-English (C-E) bilinguals to understand whether pathway-specific modulation by tDCS is possible and, if so, how it is influenced by orthographic depth and script proficiency. METHODS A double-blind, sham-controlled, within-subject experiment was designed wherein 16 balanced bilinguals received anodal tDCS in dorsal, ventral and sham sessions. Two tDCS montages of electrode sizes 5 × 5 cm2 with 1) anode at CP5 and cathode at CZ, and 2) anode at TP7 and cathode at nape of the neck, were applied for stimulating the dorsal and ventral pathways respectively. Bilinguals were asked to read word lists for each language before and after stimulation. RTs for accurate trials were analysed using linear mixed-effect modelling that included proficiency scores for reading English pseudo-words (PW) and Chinese pinyin. RESULTS For both languages, word reading RTs were faster following dorsal pathway stimulation. The dorsal stimulation effect (change in RT) was negatively correlated with pseudoword reading and pinyin proficiency. Stimulation of the ventral pathway decreased RTs only for Chinese reading. CONCLUSION Dorsal and ventral reading pathways can be selectively modulated by tDCS in bilingual readers with dorsal (sub-lexical) pathway stimulation affecting reading in both scripts and ventral (lexical) pathway stimulation selectively affecting Chinese reading. Dorsal pathway tDCS effects are modulated by sub-lexical reading proficiency.
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Affiliation(s)
| | - Rajan Kashyap
- Centre for Research and Development in Learning (CRADLE), Singapore
| | - Beth Ann O'Brien
- Centre for Research in Child Development (CRCD), National Institute of Education, Singapore
| | - Michael McCloskey
- Cognitive Science, Johns Hopkins University, Baltimore, United States
| | - Kenichi Oishi
- The Johns Hopkins University School of Medicine, Baltimore, United States
| | - John E Desmond
- The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Brenda Rapp
- Cognitive Science, Johns Hopkins University, Baltimore, United States.
| | - S H Annabel Chen
- Psychology, School of Social Sciences, Nanyang Technological University, Singapore; Centre for Research and Development in Learning (CRADLE), Singapore; Lee Kong Chian School of Medicine (LKC Medicine), Nanyang Technological University, Singapore.
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