Effects of Connectivity-based rTMS and State-Dependency on Amygdala Activation
Phase: NA
Conditions: Amygdala Activation
Sponsor: Duke University

 
 
 
 
 
 
 
Effects of Connectivity-based rTMS and State-Dependency 
on Amygdala Activation 
NCT03746405 
 
 
 
Study Protocol 
 
 
 
 
 
Date of Approval: February 14th, 2019  
 
 
 
 
 
 
 
 
 
 

This blinded, sham-controlled trial will feature a between-subject design with active or sham rTMS 
applied over the medial prefrontal cortex, while subjects will be viewing fearful video-clips to engage the 
stimulated network. Study experimental design is illustrated in Figure 1A. Twenty five healthy subjects 
(18 - 35 years old) will participate. In the initial session, which will last about 2 hours, participants will be 
consented and screened for eligibility. Resting motor threshold (rMT), defined as the TMS pulse intensity 
producing on average a 50μV peak-to-peak amplitude motor evoked potential, will be assessed using a 
maximum likelihood method. A 1-hour MRI session that includes a T1-weighted anatomical image and 
BOLD signal acquisition during passive viewing of fearful and neutral faces in an event-related design, will 
be performed. Psychophysiological interaction (PPI) or diffusions weighted analyses will be conducted by 
selecting a seed in the amygdala and defining the spot within the mPFC with the strongest task-related 
correlation with amygdala activation, or the strongest structural connection with amygdala (Figure 1B). 
 
 
Figure 1: A) Illustration of the experiment design. B) Illustration of the psychophysiological 
interaction (PPI) analysis using the right amygdala as the seed to define a TMS target in the medial 
prefrontal cortex. 
During the second visit, participants will receive active or sham rTMS, counterbalanced across 
sessions between subjects. 5Hz rTMS will be applied over the mPFC at an intensity up to 120% rMT, 
replicating parameters used in a promising recent PTSD study. The optimal coil placement during 
stimulation will be controlled by a neuronavigation system. An electrical sham coil that produces the same 
auditory and somatosensory stimulations, without a significant magnetic field, will be used as an active 
control. Participants will view fearful video-clips during rTMS to engage amygdala activation, which we 
hypothesize will lead to a stronger rTMS effect. Heart rate variability and skin galvanic response will be 
acquired with the BioPack system during rTMS and will be analyzed as moderators of rTMS efficacy. 
To evaluate rTMS-induced changes, MRI will be acquired before and after rTMS, with the 
acquisition of anatomical scans, resting-state, and task-related functional connectivity, as well as diffusion 
tensor imaging. These acquisitions will be used to evaluate target engagement within the amygdala and 
its connectivity with the prefrontal cortex. 
  
  

Subject Screening: 
Twenty-five healthy subjects (18 - 35 years old) will be recruited from the community (to get 19 
completers). At the beginning of their first visit to BIAC, they will be screened for the study with a physical 
examination, the MINI, a handedness questionnaire, and a urine test. If they pass the screening 
procedure, they will have a short session of TMS (about 0.5 hour), in order to acclimate them to TMS and 
to obtain right or left hand resting motor thresholds for future dosing of rTMS. 
Resting Motor Threshold Determination: 
All procedures will occur in Duke Brain Imaging and Analysis Center (BIAC). Resting motor 
threshold (rMT) is defined as the TMS pulse intensity producing on average a 50μV peak-to-peak 
amplitude motor evoked potential, will be assessed using a maximum likelihood method. rMT is the 
standard in the field for determining the intensity of rTMS for each individual to reduce seizure risk. The 
motor evoked potentials (MEP) for the contralateral first dorsal interosseus (FDI) will be measured with 
EMG. The scalp region producing the largest amplitude MEP will be identified. At that scalp location, the 
lowest TMS intensity able to elicit 5 MEP's of ≥50µV in peak-to-peak amplitude will be determined, using 
a using a maximum likelihood estimator (TMS Motor Threshold Assessment Tool, MTAT 2.0, 
http://www.clinicalresearcher.org/software.html). rMT will be determined for one or both hemispheres 
with the muscle at rest (verified by baseline EMG). Individual MT will be used to determine the intensity 
of stimulation for each individual, as recommended by safety guidelines. 
MRI/fMRI Procedure: Localizer: 
At BIAC, after obtaining a T1-weighted anatomical image, fMRI data will be acquired during 
passive viewing of fearful and neutral faces in an event-related design. Stimuli will be back-projected onto 
a screen located at the head of the MRI bed using an LCD projector. Subjects will view the screen via a 
mirror system located in the head coil. Task onset will be electronically synchronized with the MRI 
acquisition computer. Task administration will be computer controlled. The scanning session will take 
about 1 hr. 
Application of rTMS During Fearful video-clips viewing 
rTMS will be applied out of the scanner. Subjects will be seated comfortably in a chair, facing a 
computer screen positioned in front of the subject for visual stimulus presentation. Earplugs will be worn 
to protect hearing. The participant's head will be held steady by a frame with a chin rest and the rTMS coil 
holder frame. A figure-of-eight magnetic coil will be placed on the scalp and held in place with a coil fixing 
system supplied by MagVenture. This will be paired with a neuronavigation system (BrainSight) which 
provides precise fMRI-guided rTMS coil placement for basic, translational, and clinical applications of 
rTMS. The neuronavigation system enables to the coil to be placed at precise cortical targets (the spot 
within the mPFC showing the strongest task-related correlation with amygdala activation, obtained from 
the first visit) on the individual’s 3-dimensionally rendered brain MRI with less than one millimeter error, 
and enables to dynamically move the coil to account for slight head movements. 
5Hz rTMS will be applied at an intensity up to 120% rMT, stimulation will be applied during 4 
seconds separated by 12 seconds of inter-train interval. Sham rTMS will be administered with a sham coil 
equipped with shielding to block magnetic field output but retain the auditory and some of the tactile 
aspects of active stimulation. rTMS administration will be controlled by an external computer and will be 

time-locked relative to the presentation of fearful video-clips. Heart rate variability and skin galvanic 
response acquisition will be acquired with a BioPack system during rTMS application and will be analyzed 
as moderators of rTMS efficacy. 
MRI/fMRI Procedure: Evaluation of rTMS-induced changes: 
To evaluate rTMS-induced changes, MRI will be acquired before and after rTMS, with the 
acquisition of anatomical scans, resting-state, and task-related functional connectivity, as well as diffusion 
tensor imaging. These acquisitions will be used to evaluate target engagement within the amygdala and 
its connectivity with the prefrontal cortex. 
Side effects monitoring: 
            Subjects’ side-effects will be monitored closely. An rTMS side effect rating scale will be 
administered at the end of each session. Subjects are instructed during the consent process and during 
the rTMS sessions about all known side effects. They are further instructed during consenting and 
additionally at the conclusion of the rTMS session to contact the principal investigator or study physician 
with any questions or concerns (including those that may arise after the experimental session has ended).