Cognitive Stimulation Study
Condition: Healthy
Study type: Interventional

Summary: 
      This study will evaluate the influence of non-invasive brain stimulation on different
      elements of cognitive function in healthy persons between the ages of 18-90 years. It will
      specifically use transcranial direct current stimulation (tDCS) to evaluate the relationship
      between certain brain structures and cognitive abilities, like attention, working memory,
      visual search, etc.
    

Detailed description: 
      The research team conducting the research procedures will perform several tests.
      Investigators will ask participants if participants are right or left handed, how far
      participants went in school, their job, and a medical history including brain and nervous
      system disorders, psychiatric disorders, heart related disorders, and other significant
      disorders. Investigators will ask participants for their current medications. Investigators
      will ask participants about their history of cognitive function. If participants are a woman
      of child bearing potential, Investigators will perform a pregnancy test and the result must
      be negative to receive stimulation. Prior to stimulation, Investigators will have
      participants complete pre-stimulation computerized cognitive tests involving tasks where
      participants are asked to respond to images or sounds presented by a computer. Investigators
      will also collect measures of physiological function during the testing session, specifically
      heart rate, blood pressure, skin conductance, respiration rate, and pupillary response. These
      will be measured using recording electrodes attached to the fingertip, arm, and chest and a
      respiration band around the chest. A small camera will record changes in their pupil size.
      Investigators will also collect measures of brain structure and function using magnetic
      resonance imaging. Investigators will also ask participants to fill out a questionnaire
      describing their experience during each study session.

      If participants decide to take part in this study, participants will be asked to participate
      in up to four different testing sessions separated by at least 24 hours. In each of these
      testing sessions, participants will be asked to receive either electrical stimulation or
      placebo stimulation during different testing sessions. Placebo stimulation looks like and is
      performed in the same way as electrical stimulation, but stimulation is stopped before it can
      have an effect. Placebo stimulation is used in research studies to show what effect a
      treatment has compared with receiving a lower level of stimulation or nothing at all. Studies
      have shown, however, that about 1 in 3 persons who take a placebo have an effect, if only for
      a short time. Participants will not know whether participants are receiving placebo
      stimulation or electrical stimulation, but that information is available if it is needed. In
      the remainder of the description of what will be done, both the electrical stimulation and
      the placebos stimulation will be called "stimulation."

      Stimulation will be completed with a Transcranial Direct Current Stimulator. This is an
      experimental device that is not currently approved by the Food and Drug Administration (FDA)
      for any treatment. Participants will receive stimulation for up to 20 minutes. To perform the
      stimulation, Investigators will either apply two salt-water soaked sponges to their head or
      five smaller gel covered disk electrodes. Gel-covered disk electrodes are placed in specially
      designed holders held in a cap that fits on their head. Caps are fitted to their head size
      for comfort. Following the stimulation, Investigators will remove the sponges or electrodes
      and have participants perform a series of computerized tests to assess their cognitive
      ability. These involve tasks where participants will have to respond to images or sounds
      presented by a computer screen or headphones.

      Participants may also be asked to undergo magnetic resonance imaging (MRI) of their brain
      before, during, and after undergoing transcranial direct current stimulation. Investigators
      will use an MRI safe Transcranial Direct Current Stimulator to perform stimulation and
      evaluate how their brain responds to stimulation. Magnetic resonance imaging (MRI) is a
      procedure that allows doctors to look inside the body by using a scanner that sends out a
      strong magnetic field and radio waves. This procedure is used routinely for medical care and
      is very safe for most people, but participants will be monitored during the entire MRI scan
      in case any problems occur. The risks of MRI are:

      The MRI scanner contains a very strong magnet. Therefore, participants may not be able to
      have the MRI if participants have any type of metal implanted in their body, for example, any
      pacing device (such as a heart pacer), any metal in their eyes, or certain types of heart
      valves or brain aneurysm clips. Someone will ask participants questions about this before
      participants have the MRI.

      There is not much room inside the MRI scanner. Participants may be uncomfortable if
      participants do not like to be in close spaces ("claustrophobia"). During the procedure,
      participants will be able to talk with the MRI staff through a speaker system, and, in the
      event of an emergency, participants can tell them to stop the scan.

      The MRI scanner produces a loud hammering noise, which has produced hearing loss in a very
      small number of patients. Participants will be given earplugs to reduce this risk.
    

Intervention name(s): Transcranial Direct Current Stimulation
Intervention type(s): Device
Intervention description(s): Application of a weak electrical current to the scalp
Other intervention name(s): Soterix DC Stimulator; Neuroconn DC Stimulator MR
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Normal cognition in healthy adults; Cognitive function; Transcranial direct current stimulation; Structural Magnetic Resonance Imaging; Functional Magnetic Resonance Imaging