Dose dependent effects of 

non-invasive brain stimulation (NIBS)

Study Purpose: To better understand how NIBS alters brain function, and how it can be used to improve a person’s ability to make hand movements necessary for daily life activities such as eating, dressing, tool-use and writing.

Who is eligible: Healthy, right-handed, English-speaking adults between the ages of 18 and 50 years OR 65 and 80 years with no history of neurological disorder can take part in this study. 

What to expect: two sessions scheduled at least48 hours apart lasting approximately 4 hours each. In each session participants will undergo one of two forms of NIBS [cortical paired associative stimulation (cPAS), a form of repetitive transcranial magnetic stimulation (rTMS), or Transcranial direct current stimulation (tDCS)] followed by neurophysiological assessments with TMS.

Time commitment: two sessions over the course of 1-2 weeks. Each session lasts approximately 4 hours and sessions will be scheduled at least 48 hours apart.

Compensation: ~$160.

Recruitment status: Recruiting now! Please complete our pre-screening application and we will be in touch soon.

IRBMED HUM00196773Date of approval: 7/13/2022 

What are TMS and tDCS?

Transcranial magnetic stimulation (TMS) and Transcranial direct current stimulation (tDCS) are both forms of non-invasive brain stimulation (NIBS). This process is considered non-invasive because it does not involve placing anything under your skin or inside your body. 


TMS involves sending magnetic fields into a person’s brain to stimulate nerve cells. Using TMS to stimulate the brain and measure brain activity is not currently FDA-approved for healthy people and is considered experimental.


Before testing, we will place electrodes on the skin of your hands. These electrodes will record muscle activity from your hands. A device called a coil will rest on your head, as shown here in the picture. We will send an electric current through the coil to create a magnetic field. The magnetic field will pass through your skin and skull and into your brain. You will not feel the magnetic field, and it will not hurt or damage your body. During this part of the experiment, you will hear a click, and it may feel like someone has lightly tapped your head. We will determine the intensity of stimulation needed for you; this is because everyone’s brain is different.

You will be seated in a chair with your arms placed in molded hand rests during the experiment. We will place one coil over the part of your brain called the motor cortex.  We will place a second coil over a different part of your brain involved in planning voluntary hand movements. During the TMS procedure, you will experience slight twitching and muscle contractions in your arm and hand. During stimulation, we will measure your hand muscle activity through the electrodes. We will use TMS to study the excitability of the two parts of your brain and how different regions of your brain send commands to your hand muscles. 


tDCS involves sending a weak electrical current through the brain via electrodes attached to the scalp. The tDCS device used in this study has not received FDA approval and is limited to investigational use in the US.


We will apply tDCS using a battery-operated stimulator delivered through a pair of saline soaked surface sponge electrodes or gelled electrodes placed in holes of a neoprene cap (see picture) for ~20 minutes. You might feel a slight itch under the electrode.  This is normal, and it will not hurt or damage your body. During the tDCS procedure, you likely will experience a tingling sensation on the scalp where electrodes are attached; this tingling sensation usually diminishes after several seconds. The goal of the tDCS portion of our study is to determine the roles of brain regions used to control hand movement, by measuring behavior and brain activity during stimulation.


When we remove the electrodes, a small amount of gel may remain in your hair; this generally comes out easily with water and shampoo.

Brain Behavior Lab

Kinesiology Building


at the Kinesiology Building

Functional MRI Laboratory

Bonisteel Building