The Effect of Repetitive Transcranial Magnetic Stimulation on Brain Activity in Healthy Human Volunteers
Condition: Changes in EEG During and After Magnetic Stimulation
Study type: Interventional

Summary: 
      The proposed study is designed to determine whether small changes in the positioning of a
      transcranial magnetic stimulation coil over the frontal parts of the brain cause different
      patterns of brain activation measured by electroencephalography (EEG) and quantitative EEG
      (QEEG).
    

Detailed description: 
      A previously recorded MRI will be loaded into Brainsight, a stereotactic neuronavigation
      system specifically designed to be used with rTMS, and the scalp surface site overlying the
      centre of Brodmann area 46 in the dorsolateral prefrontal cortex (DLPFC) of both the left and
      right hemisphere will be identified and marked on a spandex swim cap placed on the subjects
      head over 31 EEG electrodes (notched to prevent eddy currents) placed at international 10-20
      locations . Three trains of true 10 Hz (110% motor threshold (MT)] rTMS (one train each with
      duration=2,4, and 8 seconds) and 6 similar trains of sham rTMS (3 of active sham and 3 of
      inactive sham) will be delivered to the left hemisphere in Brodmann area 46 in random order.
      Eyes-closed QEEG power will be recorded across all leads over 10 second "blocks" for 1 minute
      after each 10 Hz stimulus to determine the distribution and time course of any changes in
      electrical potential and QEEG spectrum. The subjects will be asked to rate their mood and
      anxiety by placing a mark along 100 mm long Visual Analogue Scales for depression and anxiety
      after each stimulus train. We will also measure ERPs after 1 Hz stimulation to the right
      DLPFC (centre of Brodmann area 46). We will administer three 60-second trains of true 1 Hz
      rTMS (at 90%, 100% and 110% motor threshold), and six 60-second trains of sham rTMS (3 of
      "active" sham and 3 of "inactive" sham) with device intensity setting of 10 %, 30% and 50%
      motor threshold and coil tilted at 90 degrees away form the head. Part 2 (location testing):
      Twenty four to 48 hours later, the swim hat will be placed on the subject's head and the
      neuroanatomical landmarks reconfirmed using Brainsight. One true train and 1 inactive sham
      train of 10 Hz rTMS (10 Hz, 110% MT) will be delivered in random order to Brodmann area 46
      and two other sites (in Brodmann areas 9 and 10). The rTMS train duration will be 8 seconds.
      The subjects will be asked to rate their mood and anxiety by placing a mark along 100 mm long
      Visual Analogue Scales for depression and anxiety after each stimulus train. The same
      procedure will be done over the right hemisphere using 1 Hz stimulation set at 110% motor
      threshold. True rTMS pulses at 1 Hz, or inactive sham rTMS pulses will be delivered in 60
      second trains to the 3 sites as described above, but marked over the right DLPFC. QEEG
      activity will be recorded for 1 minute after each stimulus train. The subjects will be asked
      to rate their mood and anxiety by placing a mark along 100 mm long Visual Analogue Scales for
      depression and anxiety after each stimulus train. Diffusion Tensor Imaging: The 15 healthy
      subjects (18-65 years old) will also undergo diffusion tensor imaging (DTI) along with the
      MRI, which will add approximately 10 minutes to the MRI procedure. Following a routine brain
      imaging protocol whole brain DTI measurements will be conducted in each subject using a
      single shot spin echo EPI diffusion tensor imaging sequence.
    

Intervention name(s): true left high frequency; Passive sham left high frequency
Intervention type(s): Device; Device
Intervention description(s): 10 Hz stimulation will be given at 110% motor threshold for 8 seconds to Brodmann areas 46, 9 and 10 in the left hemisphere. The coil will be held flat over the skull surface with the coil handle held at approximately 45 degrees to the floor; 10 Hz stimulation will be given at 110% motor threshold for 8 seconds to Brodmann areas 46, 9 and 10 in the left hemisphere. The passive (inactive) coil will be held flat over the skull surface with the coil handle held at approximately 45 degrees to the floor. An active coil will be held vertically in a mechanical holder 50 cm behind the subject head and run at 10 Hz with an intensity set to 150% of motor threshold.
Other intervention name(s): Magstim super rapid left true 10 Hz; Magstim super rapid left passive sham 10 Hz
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Repetitive Transcranial Magnetic Stimulation (rTMS); Electroencephalography (EEG); Magnetic Resonance Imaging; Quantitative EEG (QEEG)