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

NCT04600531 | Completed

• 1 other identifier: B1432020000011
• Study Type: interventional
• Target: 90
• Locations: 1 country
• Sites: 1

Brief 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

Keywords

Healthy; Healthy Young Adults; Transcranial Direct Current Stimulation; tDCS; Serial Reaction Time Task; SRT Task; Sequence Learning; Procedural Learning; Implicit Learning; Implicit Motor Sequence Learning

Outcome Measures

Primary Outcomes (2)

• Sequence-Specific Learning Effect (during and following active tDCS)

  In a typical SRT task, a target (e.g. black dot) is presented in one of four horizontal locations on a computer screen. Participants are asked to react to the target location by pressing a spatially compatible response key. Participants are not informed that the order of target locations follows a sequence predetermined by the experimenter. Participants are trained on the sequence in several blocks of trials, e.g.: 7 blocks of 100 trials. Typically, reaction times (RTs) decrease with practice, which is referred to as a general learning effect and constitutes the non-sequence-specific learning component of IMSL. Crucially, RTs increase when the sequence is inconspicuously replaced by a random sequence and decrease again when the predetermined sequence is reintroduced. The latter is referred to as the sequence-specific learning effect and is calculated by subtracting the mean RTs of the adjacent sequel blocks.

  Changes in Sequence-Specific Learning Effect will be assessed between: (baseline) during active tDCS; (short-term) 5-minutes post active tDCS; (long-term) 1 week post active tDCS

• Sequence-Specific Learning Effect (during and following sham tDCS)

  In a typical SRT task, a target (e.g. black dot) is presented in one of four horizontal locations on a computer screen. Participants are asked to react to the target location by pressing a spatially compatible response key. Participants are not informed that the order of target locations follows a sequence predetermined by the experimenter. Participants are trained on the sequence in several blocks of trials, e.g.: 7 blocks of 100 trials. Typically, reaction times (RTs) decrease with practice, which is referred to as a general learning effect and constitutes the non-sequence-specific learning component of IMSL. Crucially, RTs increase when the sequence is inconspicuously replaced by a random sequence and decrease again when the predetermined sequence is reintroduced. The latter is referred to as the sequence-specific learning effect and is calculated by subtracting the mean RTs of the adjacent sequel blocks.

  Changes in Sequence-Specific Learning Effect will be assessed between: (baseline) during sham tDCS; (short-term) 5-minutes post sham tDCS; (long-term) 1 week post sham tDCS

Secondary Outcomes (2)

• General Learning Effect (during and following active tDCS)

  Changes in General Learning Effect will be assessed between: (baseline) during active tDCS; (short-term) 5-minutes post active tDCS; (long-term) 1 week post active tDCS

• General Learning Effect (during and following sham tDCS)

  Changes in General Learning Effect will be assessed between: (baseline) during sham tDCS; (short-term) 5-minutes post sham tDCS; (long-term) 1 week post sham tDCS

Study Arms (4)

Group 1a - Conventional tDCS - Anodal first

EXPERIMENTAL

Half of all subjects will receive Conventional tDCS (randomly assigned). Within this Conventional tDCS condition, half of the subjects will receive active (anodal, real) tDCS in the first session. Following cross-over and a three-week washout-period, this half of the subjects will receive sham (placebo) tDCS.

Device: 1x1 Low Intensity Transcranial Direct Current Stimulation (tDCS)

Group 1b - Conventional tDCS - Sham first

SHAM COMPARATOR

Half of all subjects will receive Conventional tDCS (randomly assigned). Within this Conventional tDCS condition, half of the subjects will receive sham (placebo) tDCS in the first session. Following cross-over and a three-week washout-period, this half of the subjects will receive active (anodal, real) tDCS.

Device: 1x1 Low Intensity Transcranial Direct Current Stimulation (tDCS)

Group 2a - HD tDCS - Anodal first

EXPERIMENTAL

Half of all subjects will receive High Definition (HD) tDCS (randomly assigned). Within this HD tDCS condition, half of the subjects will receive active (anodal, real) tDCS in the first session. Following cross-over and a three-week washout-period, this half of the subjects will receive sham (placebo) tDCS.

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

Group 2b - HD tDCS - Sham first

SHAM COMPARATOR

Half of all subjects will receive High Definition (HD) tDCS (randomly assigned). Within this HD tDCS condition, half of the subjects will receive sham (placebo) tDCS in the first session. Following cross-over and a three-week washout-period, this half of the subjects will receive active (anodal, real) tDCS.

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

Interventions

1x1 Low Intensity Transcranial Direct Current Stimulation (tDCS) DEVICE

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.

Group 1a - Conventional tDCS - Anodal first; Group 1b - Conventional tDCS - Sham first

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

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).

Group 2a - HD tDCS - Anodal first; Group 2b - HD tDCS - Sham first

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• no history of neurological and/or recent musculoskeletal diseases that could hamper the execution of the SRT-task.

You may not qualify if:

• any of the following tDCS contra-indications: deep brain stimulator; pacemaker; head wound; skin condition of the scalp; a history of epilepsy.

Sponsors & Collaborators

• Vrije Universiteit Brussel: lead

Study Sites (1)

Vrije Universiteit Brussel

Brussels, Brussels Capital, 1050, Belgium

Location

Study Officials

• Kris Baetens, PhD

  Vrije Universiteit Brussel - Brain Body and Cognition Research Group

  STUDY CHAIR

• Chris Baeken, PhD, MD

  University Ghent

  STUDY CHAIR

• Frank Van Overwalle, PhD

  Vrije Universiteit Brussel - Brain Body and Cognition Research Group

  STUDY CHAIR

• Eva Swinnen, PhD

  Vrije Universiteit Brussel - Rehabilitation Research Group

  STUDY CHAIR

• Natacha Deroost, PhD

  Vrije Universiteit Brussel - Brain Body and Cognition Research Group

  STUDY DIRECTOR

• Mahyar Firouzi, MSc

  Vrije Universiteit Brussel - Brain Body and Cognition Research Group

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principle Investigator (Doctoral Researcher)

Model Details: sham-controlled, counterbalanced study

Study Record Dates

• First Submitted: October 16, 2020
• First Posted: October 23, 2020
• Study Start: October 15, 2020
• Primary Completion: October 15, 2021
• Study Completion: November 15, 2021
• Last Updated: November 19, 2021

Record last verified: 2021-11

Locations

BE (1)