Prefrontal iTBS on Working Memory

Overview

Our previous pilot study showed that the brain remained activated after 3 minutes of intermittent theta burst stimulation (iTBS). Therefore, an open question remains that how long the effects will last and when the maximum effects will be achieved. In addition, many pioneering works showed the positive effects of repetitive transcranial magnetic stimulation (rTMS) on working memory. Intermittent theta burst stimulation (iTBS) is a patterned form of rTMS, it has shown a non-inferior efficacy in depression but with a much shorter time (approximately 3 mins) than traditional rTMS (approximately 40 mins). As discussed above, this study aims to investigate the effects of prefrontal iTBS on working memory using concurrent iTBS/fNIRS and to explore the duration of the effects.

Full Title of Study: “Exploring the Effects of Prefrontal iTBS on Working Memory in Healthy Participants: a Concurrent TMS/fNIRS Study”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Basic Science
    • Masking: Single (Participant)
  • Study Primary Completion Date: August 31, 2023

Detailed Description

Please refer to the full proposal

Interventions

  • Device: intermittent theta burst stimulation (iTBS)
    • Intermittent TBS (iTBS) will be applied to the left DLPFC at 80% of the resting motor threshold (rMT) (Hoy et al., 2016). A stimulation, where 3-pulse at 50 Hz will be given, will repeat every 10 s for a total of 190 s (600 pulses in total) (Huang et al., 2005). The left DLPFC stimulation site will be determined using the neuronavigator system (lDLPFC, x-38, y+44, z+26). Sham stimulation will be applied by placing the coil perpendicular to the left DLPFC at the same intensity as the active stimulation.

Arms, Groups and Cohorts

  • Active Comparator: Active iTBS on working memory
    • Participants will receive active 80% rMT iTBS over the left DLPFC in this arm. The working memory assessments will be performed pre-stimulation and at 0-, 10-, 20-, 30-, and 40-min post-stimulation. The working memory assessment is measured using a 2-minute 3-back task. The fNIRS will monitor the prefrontal hemoglobin change throughout the whole procedure.
  • Sham Comparator: Sham iTBS on working memory
    • Participants will receive sham 80% rMT iTBS over the left DLPFC (by putting the coil perpendicular to the left DLPFC) in this arm. The working memory assessments will be performed pre-stimulation and at 0-, 10-, 20-, 30-, and 40-min post-stimulation. The working memory assessment is measured using a 2-minute 3-back task. The fNIRS will monitor the prefrontal hemoglobin change throughout the whole procedure.

Clinical Trial Outcome Measures

Primary Measures

  • N-back
    • Time Frame: before and post iTBS, up to 3 months
    • The accuracy number of each n-back task
  • N-back
    • Time Frame: before and post iTBS, up to 3 months
    • The response time of each n-back task

Secondary Measures

  • Hemoglobin change
    • Time Frame: before and post iTBS, up to 3 months
    • The hemoglobin change throughout whole procedure.

Participating in This Clinical Trial

Inclusion Criteria

  • right-handed participants – normal or corrected-to-normal vision Exclusion Criteria:

  • a current or past diagnosis of any neurological or psychiatric disorder – any severe medical conditions, seizure, and pregnancy – contraindication to TMS (e.g., with mental implants)

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 35 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • The Hong Kong Polytechnic University
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Contact(s)
    • Georg Kranz, PhD, 2766, georg.kranz@polyu.edu.hk

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