Modulation of the Parieto-frontal Communication
Modulation of the Parieto-frontal Communication
Background:

 Research shows that the parietal and prefrontal areas of the brain are involved in short-term
 memory. Researchers want to look at the effects of transcranial magnetic stimulation (TMS) of
 these areas on short-term memory and brain activity. They will use functional magnetic
 resonance imaging (fMRI) to look at brain activity.

 Objective:

 To look at the effects of TMS on brain pathways involved in memory.

 Eligibility:

 Healthy, right-handed adults ages 18-50

 Design:

 Participants will have 3 or 4 visits at least 1 week apart. They cannot drink alcohol for at
 least 48 hours before each visit.

 The screening visit lasts about 1 (Omega) hours. It can be combined with the first testing
 visit. Screening includes:

 -  Medical history

 -  Physical exam

 -  Neurological exam

 -  Urine tests

 -  Questionnaires about being left or right handed and about their ability to imagine
 physical activities.

 The first testing visit lasts about 1 (Omega) hours and includes an MRI. For the MRI,
 participants lie on a table that slides into a machine. They will lie still or perform simple
 memory tasks on a computer screen.

 The second and third testing visits last about 3 hours. Participants will have:

 -  2 MRIs

 -  TMS: A wire coil is held to the scalp. A brief electrical current passes through the
 coil to create a magnetic pulse that affects brain activity. They will perform simple
 memory tasks.

 -  EMG: Small electrodes are taped to the skin to record muscle activity while they rest.

 After the study, participants will complete a questionnaire about any discomfort they
 experienced during the study.

 ...
Objective: This study aims to identify whether repetitive dual-site transcranial magnetic
 stimulation (TMS) can modulate the functional connectivity between the parietal and
 dorso-lateral prefrontal cortices.

 Study population: The study involves 26 healthy volunteers.

 Design: This controlled study comprises 3 main visits for each subject: (1) a baseline,
 evaluation visit during which fMRI will be acquired during a visual short memory task along
 with diffusion tensor imaging and structural MRI; (2) a visit during which resting state fMRI
 (rsfMRI) will be acquired, followed by paired-associative stimulation (PAS) with pulses
 delivered over the parietal and then over the dorso-lateral prefrontal cortex, in order to
 induce a temporary plastic change in the interaction between the parietal and prefrontal
 cortices; the PAS will be followed by another rsfMRI and task fMRI; (3) a visit identical to
 #2 during which the PAS will be delivered with pulses in reverse order of previous visit.

 Outcome measures: The effects of PAS will be quantified with rsfMRI and a short working
 memory task, considered as a proxy for complex motor and cognitive control.

 -  The primary outcome will be to investigate the resting state functional connectivity
 changes induced by each PAS intervention

 -  The secondary outcome #1 will be to evaluate the difference in visual angle error
 between sessions 2 and 3 in a working memory task during which the subjects will be
 asked to remember the position of a bar presented on the screen at different time
 intervals before the inquiry.

 -  The secondary outcome #2 will be to build an fMRI-DTI analysis pipeline for generation
 of TMS targets individually customized for each subject and a given task.
-  INCLUSION CRITERIA:

 -  Age between 18-50 years.

 -  Right-handed (handedness questionnaire will be part of the initial evaluation)

 -  Able to give informed consent.

 -  Have a normal neurological exam within the last year and MoCA>27

 -  Willing and able to abstain from alcohol for at least 48 hours prior to the study.

 -  Willing to not participate in other rTMS studies in the week preceding visits for the
 current protocol.

 EXCLUSION CRITERIA:

 -All participants must be able to undergo MRI and TMS, for which the MRI- and TMS-safety
 checklists will be part of the initial evaluation, and reconfirmed at the beginning of
 every visit. It will constitute as exclusion criteria if the participant:

 -  has metal in his/her body which would make having an MRI scan unsafe, such as
 pacemakers, stimulators, pumps, aneurysm clips, metallic prostheses, artificial heart
 valves, cochlear implants or shrapnel fragments, or if he/she was a welder or metal
 worker, since small metal fragments may be found in the eyes.

 -  is uncomfortable in small closed spaces (claustrophobia) so that he/she would feel
 uncomfortable in the MRI machine.

 -  is not able to lie comfortably on the back for up to 2 hours

 has hearing loss.

 --is pregnant.

 -  Self-reported consumption of >14 alcoholic drinks/week for a man and >7 alcoholic
 drinks/week for a woman.

 -  History of or current brain tumor, stroke, head trauma with loss of consciousness,
 epilepsy or seizures.

 -  Taking medications that act directly on the central nervous system such as
 anti-epileptics, anti-histamines, anti-parkinsonian medication, medication for
 insomnia, anti-depressants, anti-anxiety medication.