Physiology of Human Brain Connectivity

Part of paid clinical trials in Boston, Massachusetts.

Sponsor
Massachusetts General Hospital
Study ID
NCT06246942
Status
Recruiting
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Conditions

  • Healthy

Eligibility Criteria

Sex
ALL
Age
18 Years - 64 Years
Healthy Volunteers
Accepted

Interventions

  • Single-pulse transcranial magnetic stimulation (spTMS) — DEVICE
    Single-pulse TMS (spTMS) will be delivered with a TMS stimulator (MagPro X100 w/ MagOption, MagVenture, Farum, Denmark) and a figure-of-eight TMS coil. 80 spTMS will be repeated at 0.2 Hz. An MRI-based TMS navigation system will be used to navigate the TMS coil (Localite, Bonn, Germany).
  • Paired associative stimulation (PAS) — DEVICE
    Paired associative stimulation (PAS) will be applied with two TMS stimulators (MagPro X100 w/ MagOption, MagVenture, Farum, Denmark) and two TMS coils. The pulses from each stimulator/coil will be repeated at 0.2 Hz, duration of run 15 minutes (180 pulses for each stimulator/coil). In different sessions, we will deliver PAS with different asynchrony values to examine their effects on effective connectivity. Coils will be navigated using an MRI-based TMS navigation system (Localite, Bonn, Germany).
  • Magnetic resonance imaging (MRI) — DIAGNOSTIC_TEST
    Structural, diffusion, and functional MRI with a 3-Tesla Siemens scanner

Study Details

The purpose of this study is to investigate the effective connectivity between different regions of the human brain in healthy participants, and the mechanisms which influence and modulate its development. Specifically, the investigators will examine the effects of cortico-cortical paired associative stimulation (ccPAS) which is induced by the application of brief (\< 1 ms) transcranial magnetic stimulation (TMS) pulses separated by a short millisecond-level time intervals ("asynchrony") to two different areas of the brain. All techniques are non-invasive and considered safe in humans: TMS, electroencephalography (EEG), and magnetic resonance imaging (MRI). Based on previous animal and human studies, it is hypothesized that ccPAS will increase or decrease effective connectivity between the stimulated areas depending on the asynchrony value. The main outcome measure is source-resolved EEG cortico-cortical evoked potentials (ccEPs) elicited by single-pulse TMS.

Key Dates

Start date
Dec 13, 2024
Status verified
Nov 2025
Primary completion
Apr 15, 2027
Completion
Apr 15, 2027

Study Design

Enrollment
80 participants (estimated)
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE

Arms

  • Experimental: Healthy Participants
    All participants will be scheduled for a minimum of four separate visits. The first visit will consist of MRI scanning sessions (including T1 and T2 structural MRI, diffusion MRI, and resting-state fMRI), followed by a single-pulse TMS session to determine the participant's resting motor threshold. The remaining three visits consist of a series of TMS-EEG runs using the paired associative stimulation (PAS) methodology. Each visit will be restricted to a single asynchrony condition with every participant receiving all three conditions over the course of the three visits. Participants will not be informed of which asynchrony condition they are receiving on any given visit. Some subjects may be invited for additional sessions for the purposes of optimizing TMS, EEG, or MRI parameters, and to assess test-retest reliability.

Primary Outcome Measure

Changes in EEG effective connectivity [ Time Frame: Within-session (Before PAS, 5 minutes after PAS, 60 minutes after PAS) ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
Massachusetts General HospitalBostonMassachusetts02129-

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Massachusetts General Hospital· Boston, MA

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