Method Article

Non-Invasive Modulation and Robotic Mapping of Motor Cortex in the Developing Brain

DOI:

10.3791/59594

⸱

July 1st, 2019

 ,  ,  ,  ,  ,  , 
1Department of Neurosciences, University of Calgary, 2Hotchkiss Brain Institute, University of Calgary, 3Cumming School of Medicine, University of Calgary, 4Department of Pediatrics, University of Calgary, 5Alberta Children's Hospital Research Institute, University of Calgary, 6Faculty of Medicine and Dentistry, University of Alberta, 7Department of Clinical Neurosciences, University of Calgary

In This Article

Summary

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We demonstrate protocols for the modulation (tDCS, HD-tDCS) and mapping (robotic TMS) of the motor cortex in children.

Abstract

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Mapping the motor cortex with transcranial magnetic stimulation (TMS) has potential to interrogate motor cortex physiology and plasticity but carries unique challenges in children. Similarly, transcranial direct current stimulation (tDCS) can improve motor learning in adults but has only recently been applied to children. The use of tDCS and emerging techniques like high–definition tDCS (HD-tDCS) require special methodological considerations in the developing brain. Robotic TMS motor mapping may confer unique advantages for mapping, particularly in the developing brain. Here, we aim to provide a practical, standardized approach for two integrated methods capable of simultaneously exploring motor cortex modulation and motor maps in children. First, we describe a protocol for robotic TMS motor mapping. Individualized, MRI-navigated 12x12 grids centered on the motor cortex guide a robot to administer single-pulse TMS. Mean motor evoked potential (MEP) amplitudes per grid point are used to generate 3D motor maps of individual hand muscles with outcomes including map area, volume, and center of gravity. Tools to measure safety and tolerability of both methods are also included. Second, we describe the application of both tDCS and HD-tDCS to modulate the motor cortex and motor learning. An experimental training paradigm and sample results are described. These methods will advance the application of non-invasive brain stimulation in children.

Introduction

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Non-invasive brain stimulation can both measure and modulate human brain function1,2. The most common target has been the motor cortex, due in part to an immediate and measurable biological output (motor evoked potentials) but also the high prevalence of neurological diseases resulting in motor system dysfunction and disability. This large global burden of disease includes a high proportion of conditions affecting children such as cerebral palsy, the leading cause of lifelong disability affecting some 17 million persons worldwide3. Despite this clinical relevance and the diverse and inc....

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Protocol

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All the methods described in this protocol have been approved by Conjoint Health Research Ethics Board, University of Calgary (REB16-2474). The protocol is described in Figure 1.

1. Non-invasive brain stimulation contraindications

  1. Screen all participants for contraindications for TMS15 and tDCS1 prior to recruitment.

2. Transcranial magnetic stimulation motor mapping

  1. Preparing MRI for navigated TMS
    1. Obtain each participant’s structural MRI (T1). If an MRI is unobtainable, use a template MRI from Mo....

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Results

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Using the methods presented here, we completed a randomized, sham-controlled interventional trial8. Right-handed children (n = 24, ages 12-18) with no contraindications for both types of non-invasive brain stimulation were recruited. Participants were specifically excluded in this study if on neuropsychotropic medication or if they were not naïve to tDCS. There were no dropouts.

Robotic TMS motor maps wer.......

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Discussion

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TMS has also been explored in clinical pediatric populations, including perinatal stroke22 and cerebral palsy, where TMS motor maps were successfully created in children with cerebral palsy to explore mechanisms of interventional plasticity. Using an established protocol8, TMS motor maps were successfully collected in typically developing children, and are currently being collected in an ongoing multicenter clinical trial for children with perinatal stroke and hemiplegic ce.......

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Disclosures

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The authors have no disclosures.

Acknowledgements

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This study was supported by the Canadian Institutes of Health Research.

....

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
1x1 SMARTscan StimulatorSoterix Medical Inc.https://soterixmedical.com/research/1x1/tdcs/device
4x1 HD-tDCS AdaptorSoterix Medical Inc.https://soterixmedical.com/research/hd-tdcs/4x1
Brainsight NeuronavigationRoge Resolutionhttps://www.rogue-resolutions.com/catalogue/neuro-navigation/brainsight-tms-navigation/
Carbon Rubber ElectrodeSoterix Medical Inc.https://soterixmedical.com/research/1x1/accessories/carbon-ruber-electrode
EASYpad ElectrodeSoterix Medical Inc.https://soterixmedical.com/research/1x1/accessories/1x1-easypad
EASYstrapsSoterix Medical Inc.https://soterixmedical.com/research/1x1/accessories/1x1-easystrap
EMG AmplifierBortec Biomedicalhttp://www.bortec.ca/pages/amt_16.htm
HD1 Electrode HolderSoterix Medical Inc.https://soterixmedical.com/research/hd-tdcs/accessories/hd1-holderStandard Base HD-Electrode Holder for High Definition tES (HD-tES)
HD-ElectrodeSoterix Medical Inc.https://soterixmedical.com/research/hd-tdcs/accessories/hd-electrodeSintered ring HD-Electrode.
HD-GelSoterix Medical Inc.https://soterixmedical.com/research/hd-tdcs/accessories/hd-gelHD-GEL for High Definition tES (HD-tES)
Micro 1401 Data Acquisition SystemCambridge Electronics http://ced.co.uk/products/mic3in
Purdue PegboardLafayette Instrument Company
Saline solutionBaxterhttp://www.baxter.ca/en/products-expertise/iv-solutions-premixed-drugs/products/iv-solutions.page
Soterix Medical HD-CapSoterix Medical Inc.https://soterixmedical.com/research/hd-tdcs/accessories/hd-cap
TMS RobotAxilium Roboticshttp://www.axilumrobotics.com/en/
TMS Stimulator and CoilMagstim Inchttps://www.magstim.com/neuromodulation/

References

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  1. Woods, A. J., et al. A technical guide to tDCS, and related non-invasive brain stimulation tools. Clinical Neurophysiology. 127 (2), 1031-1048 (2016).
  2. Nitsche, M. A., et al.

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Tags

Robotic TMS Motor MappingTranscranial Magnetic StimulationTranscranial Direct Current StimulationHigh Definition tDCSMotor Evoked PotentialNeuronavigation MRI IntegrationEMG Data Acquisition3D Motor Map AnalysisPediatric Brain StimulationMotor Cortex Plasticity

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