Conventional or High Definition tDCS to Enhance Implicit Motor Sequence Learning in Healthy Young Adults?

Summary

Implicit motor sequence learning (IMSL) is a form of cognitive function that is known to be directly associated with motor function. This hallmark motor skill enables humans to perform multiple single movements in a specific sequential order and is involved in many of our daily activities (e.g. reaching, dressing, typing). One promising tool that has been shown to improve this type of learning in healthy young individuals, is transcranial direct current stimulation (tDCS). This non-invasive brain stimulation technique entails the administration of a weak electrical current at the scalp between two electrodes. To date, studies have almost exclusively investigated effects of conventional tDCS. Recently, however, novel High Definition (HD) tDCS devices have been commercialised. Whereas conventional tDCS uses two rather large electrodes, likely including adjacent cortical areas in the stimulation, HD-tDCS uses multiple smaller electrodes, allowing for stimulation of the targeted cortical region with higher resolution/specificity. The aim of the present study is to confirm previous findings suggesting beneficial effects of conventional tDCS, delivered over the primary motor cortex (M1) in healthy young adults. Additionally, the investigators will be the first to investigate potential effects of HD tDCS on IMSL in this population and to make a comparison between these two devices. The investigators will determine immediate effects that may occur concurrently with the application of tDCS but also short-term (five minutes post-tDCS) and long-term (one week post-tDCS) consolidation effects, as previous studies suggest that tDCS exerts its beneficial effects on IMSL in a consolidation phase rather than in an acquisition phase.

Conditions

• Healthy

Interventions

DEVICE

1x1 Low Intensity Transcranial Direct Current Stimulation (tDCS)

tDCS will be delivered through a pair of identical square rubber electrodes (size 35 cm2), placed in rectangular saline-soaked sponges. For the stimulation of M1, electrodes will be placed over C3 or C4 according to the 10-20 EEG system, matching with the M1 contralateral to the performing dominant hand. The reference electrode will be positioned on F1 or F2, ipsilateral to the dominant hand. The current stimulation will be slowly ramped up from 0 mA to 2 mA in one minute. For the anodal tDCS condition, this intensity will be maintained for the duration of the SRT-task (approximately 20 minutes). This will result in a current density of 0,057 mA/cm2. For the sham tDCS condition - unbeknown to the subject - stimulation will be gradually decreased towards 0 mA immediately after the one-minute ramp-up. During the last block of the SRT-task, this gradual ramping-up and -down of the current stimulation will be repeated to optimize the process of blinding of participants.

DEVICE

4x1 Multichannel Stimulation Adapter for High Definition Transcranial Direct Current Stimulation (HD tDCS)

HD tDCS will be delivered over M1. By connecting the conventional tDCS device (described above) to this "adapter", the direct current is delivered along the 4x1 HD tDCS configuration, allowing for more specific neuromodulation. Stimulation is delivered by means of one central gel-electrode and four return-electrodes placed in plastic encasings embedded in an EEG cap. Stimulation of left M1 (right hand = performing): delivered via the central electrode corresponding with C3 and held in place using a synthetic cap to hold the HD-tDCS electrodes on the head. Return-electrodes are positioned at Cz, F3, T7 and P3 (10-20 EEG system). Stimulation of right M1 (left hand = performing): central electrode will be positioned at C4 with the return-electrodes at Cz, F4, T8 and P4. Strategies for anodal and sham stimulation are identical to the ones described above (conventional tDCS).

Sponsors & Collaborators

• Vrije Universiteit Brussel

  lead OTHER

Principal Investigators

• Kris Baetens, PhD · Vrije Universiteit Brussel - Brain Body and Cognition Research Group

• Chris Baeken, PhD, MD · University Ghent

• Frank Van Overwalle, PhD · Vrije Universiteit Brussel - Brain Body and Cognition Research Group

• Eva Swinnen, PhD · Vrije Universiteit Brussel - Rehabilitation Research Group

• Natacha Deroost, PhD · Vrije Universiteit Brussel - Brain Body and Cognition Research Group

• Mahyar Firouzi, MSc · Vrije Universiteit Brussel - Brain Body and Cognition Research Group

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

35 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2020-10-15

Primary Completion

2021-10-15

Completion

2021-11-15

Countries

• Belgium

Study Locations