Timed magnetic stimulation to change connections between brain areas
Physiology of Human Brain Connectivity
We will test whether pairs of very brief, timed magnetic pulses to two brain areas can change how those areas communicate in healthy adults.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 80 (estimated) |
| Ages | 18 Years to 64 Years |
| Sex | All |
| Sponsor | Massachusetts General Hospital Academic / other |
| Locations | 1 site (Boston, Massachusetts) |
| Trial ID | NCT06246942 on ClinicalTrials.gov |
What this trial studies
This interventional study will apply cortico-cortical paired associative stimulation (ccPAS) using brief transcranial magnetic stimulation (TMS) pulses to two brain regions with millisecond-scale timing offsets while recording EEG. About 80 healthy, right-handed adults aged 18–64 will undergo MRI (structural, functional, diffusion) and repeated TMS-EEG visits to measure source-resolved cortico-cortical evoked potentials (ccEPs) as the primary outcome. The protocol varies the inter-pulse asynchrony across conditions to test whether longer or shorter delays relative to conduction time selectively increase or decrease effective connectivity. Results will be interpreted alongside MRI-derived structural and functional connectivity to map timing-dependent modulation mechanisms.
Who should consider this trial
Good fit: Healthy, right-handed adults aged 18–64 who can undergo MRI and TMS and have no neurological diagnoses, seizure history, or implanted metal/electronic devices are ideal candidates.
Not a fit: People with epilepsy or other neurological disorders, those with implanted metal or electronic devices, pregnant individuals, or anyone unable to have MRI/TMS would not benefit because they are excluded from participation.
Why it matters
Potential benefit: If successful, this work could help clinicians fine-tune noninvasive brain stimulation by identifying timing patterns that strengthen or weaken connections between targeted regions.
How similar studies have performed: Previous animal studies and some human experiments have shown that paired magnetic pulses can alter interregional connectivity, but the exact timing rules and mechanisms are still being clarified.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Age from 18 to 64 years * Right-handed * Normal hearing and (corrected) vision * Able to understand and give informed consent Exclusion Criteria: * Cardiac pacemaker or pacemaker wires; neurostimulators; implanted pumps * Metal in the body (e.g., rods, plates, screws, shrapnel, dentures that cannot be removed during the recordings, IUD) * Suspected metallic particles in the eye * Surgical clips in the head or previous neurosurgery * Any magnetic particles in the body * Cochlear implants * Prosthetic heart valves * Epilepsy or any other type of seizure history * Any neurological diagnoses or medications influencing brain function * History of significant head trauma (i.e., extended loss of consciousness, neurological sequelae) * Known structural brain lesion * Significant other disease (heart disease, malignant tumors, mental disorders) * Significant claustrophobia; Ménière's disease * Pregnancy (ruled out by urine ß-HCG if answers to screening questions suggest that pregnancy is possible), breast feeding * Non prescribed drug use * Failure to perform the behavioral tasks or neuropsychological evaluation tests * Prisoners
Where this trial is running
Boston, Massachusetts
- Massachusetts General Hospital — Boston, Massachusetts, United States (Recruiting)
Study contacts
- Principal investigator: Tommi Raij, MD, PhD — Massachusetts General Hospital
- Study coordinator: Netri Pajankar, MS
- Email: npajankar@mgh.harvard.edu
- Phone: 617-726-2000
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.