Comparing the efficacy of anodal transcranial direct current stimulation at two locations: EEG and TMS-derived hotspot

• Grant number: 15/16744-4
• Support type: Scholarships abroad - Research Internship - Doctorate (Direct)
• Effective date (Start): November 01, 2015
• Effective date (End): October 31, 2016
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal researcher: Tania de Fatima Salvini
• Grantee: Maíra Carolina Lixandrão
• Supervisor abroad: Bernadette Gillick
• Home Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Research place: University of Minnesota (U of M), United States
• Associated to the scholarship: 14/00200-2 - 3-D scapular kinematics and eletromiography during arm elevation in chronic hemiparesis: implications for upper limb rehabilitation, BP.DD

Abstract

Introduction: Non-invasive brain stimulation (NIBS) is a technique to influence the excitability of the brain and has been combined with rehabilitation interventions to augment outcomes in post stroke patients. One technique, transcranial direct current stimulation (tDCS), involves the use of electrodes placed on the target cortical area such as the primary motor cortex (M1). Two methods exist to determine the location of the electrodes: International 10/20 electroencephalogram (EEG) Coordinates and Transcranial Magnetic Stimulation (TMS)-derived motor hotspot. A consistent methodology for electrode placement to guide intervention has not been determined in the literature. The results of this study will provide evidence on the efficacy of stimulation at the different locations. These findings can guide electrode placement in future studies involving tDCS application in neurologic population. Aims: Determine the efficacy of tDCS at the location of the motor cortex through two means: 1) The International 10/20 EEG system of measurement and 2) TMS testing of cortical excitability in healthy adults as measured by cortical excitability and behavioral outcomes. Methods: 20 healthy adults between 18-40 years old with no neurologic disorders, indwelling metal in proximity of stimulation near head or neck, pregnancy, acquired brain injury, or history of seizures will be included in the study. The participant will be comfortably seated in a reclining chair and a surface EMG electrode will be attached over the first dorsal interosseous muscle serving the dominant hand, which will record the motor evoked potentials (MEPs) resulting from the magnetic stimulation to the contralateral M1. Next, the threshold for TMS activation of the target muscle will be determined. It will be used a 70-mm figure-eight TMS coil connected to a Magstim 200 machine. Baseline TMS pre-testing will include short intracortical inhibition (SICI) and MEP amplitude. These measurements will inform investigators on motor performance. Experiment 1 will involve 20 minutes of anodal tDCS intervention to the dominant hemisphere primary motor cortex as located by the 10/20 EEG system. The 10/20 EEG system localization of the primary motor cortex will be achieved using a measuring tape. Experiment 2 will involve 20 minutes of anodal tDCS intervention to the dominant hemisphere primary motor cortex as located by TMS threshold testing. The Soterix 1x1 device will be used for the tDCS. Electrodes will be secured with an elastic headband. Stimulation intensity will be 1.0 mA. TMS measures of SICI and MEP amplitude will be repeated following the tDCS intervention. Vitals and subject report of symptoms will be included to develop a safety profile for each participant. Statistical analysis: Descriptive statistics will be used for baseline, demographic and safety data. Mean (Standard Deviation) will be reported for continuous variables and frequency (%) for categorical variables. Confidence intervals (95%) will be computed and reported along with means and proportions for evaluating safety. Hypothesis: In healthy adults, use of TMS-derived stimulation will results in greater cortical excitability and motor performance than the 10/20 EEG location. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

LIXANDRAO, MAIRA C.; STINEAR, JAMES W.; RICH, TONYA; CHEN, CHAO-YING; FEYMA, TIM; MEEKINS, GREGG D.; GILLICK, BERNADETTE T. EMG breakthrough during cortical silent period in congenital hemiparesis: a descriptive case series. BRAZILIAN JOURNAL OF PHYSICAL THERAPY, v. 24, n. 1, p. 20-29, JAN-FEB 2020. Web of Science Citations: 0.

CHEN, MO; LIXANDRAO, MAIRA C.; PRUDENTE, CECILIA N.; SUMMERS, REBEKAH L. S.; KIMBERLEY, TERESA J. Short Interval Intracortical Inhibition Responses to Low-Frequency Repetitive Transcranial Magnetic Stimulation Under Multiple Interstimulus Intervals and Conditioning Intensities. NEUROMODULATION, v. 21, n. 4, p. 368-375, JUN 2018. Web of Science Citations: 0.

LIXANDRAO, MAIRA CAROLINA; CAMARGO, PAULA REZENDE; NEVES SCARPA, CAROLINE EVELIN; PRADO-MEDEIROS, CHRISTIANE LANATOVITZ; SALVINI, TANIA FATIMA. Bilateral changes in 3-D scapular kinematics in individuals with chronic stroke. CLINICAL BIOMECHANICS, v. 47, p. 79-86, AUG 2017. Web of Science Citations: 0.