Effect of Transcranial Magnetic Stimulation to the Frontoparietal Attention Network on Anxiety Potentiated Startle

Not Applicable

Completed

Conditions: Healthy Volunteers

Interventions: Drug: Transcranial Magnetic Stimulation Sham
Device: Transcranial Magnetic Stimulation

Registration Number: NCT03027414

Lead Sponsor: National Institute of Mental Health (NIMH)

Brief Summary: Background:

Researchers want to better understand brain processes related to fear and anxiety. They want to find out if transcranial magnetic stimulation (TMS), a type of brain stimulation, can reduce anxiety.

Objective:

To see how TMS affects fear and anxiety through memory and attention tasks.

Eligibility:

Healthy people ages 18-50 who are right-handed

Design:

Participants will be screened through another protocol.

Participants in the pilot study will have 1 visit. This includes:

Urine tests

Questionnaires about mood and thinking

Shock and startle workup: Electrodes are taped to the wrists or fingers. Participants will be shocked to find out what level of shock is uncomfortable but tolerable. They will hear loud, sudden noises through headphones.

TMS: A coil is held on the scalp. A magnetic field stimulates the brain. Sometimes they might receive fake TMS. This feels the same as real TMS. They will perform simple tasks. Participants in the main study will have 2 visits within 2 weeks.

The first visit includes:

Urine tests

Questionnaires about mood and thinking

MRI: Participants lie on a table that slides into a scanner. They will be in the scanner about 1 hour. A computer screen in the scanner will tell them to perform simple tasks.

The second visit includes:

Shock and startle workup

TMS

Detailed Description: Objective: To determine the effect of non-invasive brain stimulation on anxiety and anxiety-cognition interactions in healthy subjects. Toward this aim we will test the effect of transcranial magnetic stimulation (TMS) on two outcome measures: 1) Fear and anxiety during the threat of predictable and unpredictable shock (NPU threat test; Substudies 1 and 3), and 2) Working memory (WM) related anxiety downregulation while performing the Sternberg WM task under threat of shock (Substudy 2).

Study population: The study population will consist of up to 184 healthy volunteers between the ages of 18-50.

Design: This study will consists of two (sub-studies 1 and 2) or three (sub-study 3) outpatient visits (1 MRI, 1 or 2 TMS visits \[2 for sub-study 3\]). In this protocol we will explore the effect of TMS in three sub-studies in the TMS study visit. The sub-studies will contain either the NPU or the Sternberg task during the TMS visits. The first visit (MRI) will consist of the same procedures for all sub-studies. Each subject will be assigned to only one of the sub-studies.

Sternberg Task: Expose subjects to active or sham TMS to a region of the frontoparietal attention network during the Sternberg WM task. Subjects will have to maintain a series of letters in WM for a brief interval during blocks of safety and threat of shock.

NPU Task: Expose subjects to active or sham TMS to a region of the frontoparietal attention network during the NPU threat test. Subjects will be exposed to blocks in which they are either 1) safe from shock (neutral), 2) at risk of shock delivered only during a cue (predictable), or 3) at risk of shock presented randomly (unpredictable).

Outcome measures: In both studies the primary outcome measure will be anxiety-potentiated startle (APS), which is the increase in startle magnitude during periods of threat compared to periods of safety. We expect active, but not sham TMS to increase activity in the dlPFC, and therefore reduce APS in both studies

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 61

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Substudy 3 Active and Sham	Transcranial Magnetic Stimulation	HVs will receive offline TMS to the lest IPS (FPN)
Substudy 2 Active and Sham	Transcranial Magnetic Stimulation Sham	HVs that receive TMS over the right dlFPC
Substudy 1 Active and Sham	Transcranial Magnetic Stimulation Sham	HVs that receive TMS over the right dlPFC
Substudy 1 Active and Sham	Transcranial Magnetic Stimulation	HVs that receive TMS over the right dlPFC
Substudy 2 Active and Sham	Transcranial Magnetic Stimulation	HVs that receive TMS over the right dlFPC
Substudy 3 Active and Sham	Transcranial Magnetic Stimulation Sham	HVs will receive offline TMS to the lest IPS (FPN)

Primary Outcome Measures

Name	Time	Method
Anxiety-potentiated Startle	Pre and post stimulation	Electromyography Facial electromyography (EMG) startle responses were recorded from the left orbicularis oculi muscle at 2000 Hz using a Biopac MP160 unit (Biopac; Goleta, CA) via 15 × 20 mm hydrogel coated vinyl electrodes (Rhythmlink #DECUS10026; Columbia, SC). Startle EMG was bandpass filtered from 30 to 300 Hz, rectified, and smoothed using a 20-ms sliding window. Startle responses were scored as the peak (max during the 20 ms to 120 ms post-noise window) - the baseline (50 ms pre-noise window), and converted to t-scores with a mean of 50 and a standard deviation of 10 (tx = \[Zx × 10\] + 50). Greater t-scores mean larger blinks, which could be associated with greater anxiety, however there is no clinically relevent threshold. Noisy trials (baseline SD \> 2x run SD) were excluded, and "no blink" (peak \< baseline range) trials were coded as 0. To calculate APS, we subtracted the response during the neutral ITI from the response during the unpredictable ITI.
Working Memory (WM) Related Anxiety Downregulation While Performing the Sternberg WM Task Under Threat of Shock.	Pre and post stimulation	Sternberg Task: Expose subjects to active or sham TMS to a region of the frontoparietal attention network during the Sternberg WM task. Subjects will have to maintain a series of letters in WM for a brief interval during blocks of safety and threat of shock. Electromyography Facial electromyography (EMG) startle responses are recorded from the left orbicularis oculi muscle at 2000 Hz. Startle EMG is bandpass filtered from 30 to 300 Hz, rectified, and smoothed using a 20-ms sliding window. Startle responses are scored as the peak (max during the 20 ms to 120 ms post-noise window) - the baseline (50 ms pre-noise window), and converted to t-scores (tx = \[Zx × 10\] + 50). Noisy trials (baseline SD \> 2x run SD) are excluded, and "no blink" (peak \< baseline range) trials are coded as 0. These t scores are then averaged across trials within each condition, and threat-safe contrasts are calculated independently for each level of load (low vs. high) and timing (maintenance vs. ITI).