A Study of the Effects of Brain Stimulation on Higher-Order Cognition

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For questions and more information about this study, please contact the team using the information below.
Study coordinator
Name - Megan Boudewyn
Email - maboudewyn@ucdavis.edu
Phone - 916-734-4149

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"Volunteer for research at UC Davis and contribute to discoveries that may improve health care for you, your family, and your community!"
Age: 18 to 35 years old
Healthy Volunteers: No
Keywords: Transcranial Direct Current Stimulation, EEG, brain stimulation, cognition
Type: Device study
155 Participants
The purpose of this research study is to learn more about how the brain functions during higher-order cognition. “Higher-order cognition” refers to processes like language comprehension and reasoning. Specifically we hope to learn whether stimulating an area of the brain called the prefrontal cortex can improve these processes. We are doing this research because understanding how the brain functions during these processes, including how it responds to stimulation, will provide important new scientific information relevant to mental health disorders including schizophrenia, and could eventually lead to the development of new treatments.
This study requires

If you choose to participate in this study you will complete up to four sessions.

Interview Session: During the interview session we will ask you questions about your personality, speech, mood, living situation, medical history, and any past or present drug or alcohol use. We will also ask you about experiences such as hearing voices, seeing visions or having trouble with your thinking. You may skip any question on the questionnaire or in the interview that you do not wish to answer. If you are female, you will be given a urine pregnancy test to determine that you are not pregnant. If you are found to be pregnant you will be not be able to participate in the study. This is because it is unknown whether the study device may harm a fetus. This session will last about 1 hour.

tDCS/EEG Sessions: At the beginning of each tDCS/EEG session you will complete a urine drug screen. This is to check for any drugs (e.g., marijuana, cocaine) that may be in your body that could affect the study results. We will not tell anyone the results of your drug screen without your permission. The results will not become part of your medical record. It is your choice if you wish to tell someone the results from this drug screen. Results from this drug screen will not prevent you from doing the study. If your drug screen is positive we will ask you to reschedule your appointment. Next you will get 20 minutes of tDCS stimulation. tDCS is “transcranial direct current stimulation”. This is a safe method of applying a small electrical current to your brain using small electrodes. We will place two tDCS electrodes on your head. The electrodes apply a low electrical current to stimulate your brain. You will receive either “active” or “sham” tDCS stimulation at each session.

Active stimulation is when the electrical current is applied for the 20 minutes. The electrical current strength will be a maximum of 2 milliamperes (mA). This is similar to the output of a 9-volt battery. Sham stimulation is when the electrical current is applied for the first minute and then switched off. We will not tell you which type of stimulation you are receiving. This is to prevent biased performance on the task.

The type of stimulation you get during a given session will be chosen by chance, like flipping a coin. Neither you nor the researchers will choose what type of stimulation you get during a session. Over the course of the study, you will complete all types of stimulation (active and sham), in randomized order. Neither you nor the researchers will know which type of stimulation you are getting at a given session.

We will ask about your mood before and after stimulation. We will monitor you until your mood has returned to normal. During stimulation you will complete a short cognitive task. We will also ask you about any physical sensations that you are experiencing. If you experience unpleasant physical sensations we will stop stimulation. After stimulation you will complete the brain wave recording (EEG). Several locations on your head and face will be cleansed (alcohol may be used) and tin or silver and plastic disks (electrodes) will be attached to those locations with either a sticker or an elastic cap that you will wear. Between your skin and the electrodes, a small amount of electrode jelly will be applied to make good contact.

During EEG recording, you will sit in a comfortable chair and your brain waves will be recorded while you complete cognitive tasks. These tasks will involve looking at a computer screen where different types of stimuli will be presented. These will be figures, symbols, numbers, letters, words or sentences. You will be asked to respond to these by pressing a button, reading aloud what you see on screen or generating your own verbal responses, or picking from among a group of answers on the screen.

At the conclusion of EEG recording, the electrodes and elastic cap will be removed and the area where the electrodes were located will be cleansed. Preparation of the sensors typically takes about 30 minutes, and recording time will take up to 1.5 hours.

MRI Scan: At the end of the last tDCS/EEG session, you may complete an MRI magnetic resonance imaging) recording after the EEG recording. The MRI machine uses magnetic waves to take pictures inside the body. The waves are not harmful. The MRI machine is a large hollow round tube. In an MRI, you will lie comfortably on your back on a table inside the machine while pictures are taken of your brain. The MRI images allow us to see how well your brain functions while you are responding to the computer tasks. You will hear noises during the scan, and wear earplugs so the noises aren’t too loud. You will always be able to talk with the operator or technologist during the study. The MRI session includes 15 minutes of preparation before getting in the scanner. The actual time you will be in scanner will be about 1 hour.

Who can participate

Inclusion criteria:

  • Participants must be able to sufficiently speak and understand English so as to be able to understand and complete cognitive tasks.
  • All subjects must have the ability to give valid informed consent. Inclusion Criteria for Patients with Schizophrenia Only:
  • Diagnosis of schizophrenia, schizophreniform or schizoaffective disorder
  • No medication changes in the prior month
  • No medication changes anticipated in the upcoming month
  • Stable outpatient or partial hospital status
  • Normal IQ (>70; IQ will be measured by administering the Wechsler Abbreviated Scale of Intelligence (WASI) test)
  • Must not be currently taking the antipsychotic clozapine

Exclusion criteria:

  • Pacemakers
  • Implanted electrical (brain and spinal) stimulators
  • Implanted defibrillator
  • Metallic implants
  • Skin damage or skin conditions such as eczema at the sites where electrodes will be placed
  • Hair styles hindering the placement of electrodes
  • Cranial pathologies
  • Head trauma
  • Epilepsy
  • Mental retardation
  • Any known history of neurological disorders (including epilepsy, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), stroke, cerebral palsy, any DSM-5 axis I psychiatric disorder (for healthy control subjects), autism)
  • Uncorrected vision problems that would hinder cognitive testing (this also pertains to subjects with color blindness in tasks where discriminating colored objects/items is necessary for successful performance)
  • Pregnancy
  • Substance dependence in the past six months
  • Substance abuse in the past month
Benefits and risks of participating

We cannot promise any benefits to you as a result of taking part in this research study.


The study doctor will discuss the risks associated with taking part in this research study.
We will pay you $25 for completing the interview session, and $15 per hour for all other study sessions. If you complete all study sessions, you will receive another $50 for completing this study.
Study duration and period
If you agree, you will be in this study for about 1 month and will need to visit the research site about 4 times.
Recruitment period
From Dec. 17, 2018
UC Davis Medical Center
2315 Stockton Boulevard
Sacramento, CA 95817
Megan Boudewyn
Research Topic
  • Schizophrenia

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