An MRI is a specialized examination of the head which will create pictures of the structure and function of the brain. The MRI scan involves lying on a table, then being slid into a large tunnel. The participant's head and shoulders lie in a plastic rounded tray (picture) which makes it more comfortable and easier to lie still. The MRI scan uses a magnet to make images (picture) of the brain. No X rays or radiation is involved. Except for a loud noise, there is typically no sensation of any kind, and it is not harmful. The hardest part of the scan is the need to lie still for this amount of time.

The purpose of the research MRI scan is to answer a very specific research question, which is different than the purpose of a clinical MRI scan.  Therefore, the way the research scan is acquired and analyzed is very different from the clinical scan.  For one thing, there are more restrictions on who can participate in a research scan.  Also, the research scan cannot be used for typical clinical purposes, and vice-versa. Finally, the strength of the magnet on a research MRI scan might be stronger than that of a clinical scan. 


The purpose of a structural neuroimage scan is to view the anatomy of the brain.  The purpose of a functional neuroimage scan is to determine when different parts of the brain are active and how they communicate with one another.  Some functional neuroimaging scans look at the metabolism of glucose (sugar) in the brain (such as an 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scan, see below). 

Another type of functional neuroimaging scan is a function MRI scan (fMRI), which uses blood flow in different parts of the brain to determine where neurons are activated during various tasks (such as tapping a finger or remembering a list of words).  During the fMRI portion of the scan, a projection device will be set up on a table to provide visual stimulation while you are in the magnet.  Simple letters, words, or pictures will be projected onto a mirror above your head.  You will be asked simple questions relating to these letters, words, or pictures.  Your responses to these questions will be recorded using high-speed MRI imaging provided by the radio frequency coil.  There will be nothing during the study to startle you or cause any discomfort. We will provide earplugs or ear phones that you will be required to wear.  Finally, you will have a hand-held control box to manually respond to stimuli.
The Poston Lab uses both of these functional neuroimaging techniques in various research studies.


The PET scanner is a large, donut-shaped machine that detects a special radioactive substance in your body to create detailed images. The whole procedure lasts no more than one hour. Participants undergoing a PET scan will have a small plastic tube (intravenous line) inserted into the arm. A radioactive substance called 18F-FDG will be injected through the tube in the arm. The FDA has approved the PET scan device for diagnostic purposes.

The PET Scans, which include CT transmission scans, will expose participants to radiation during the research; however, if there is any risk from this exposure, it is too small to be measured.

However, while participating in any studies using a PET scan, you should not take part in any other research project without approval from all of the investigators.  This is to protect you from possible injury arising from such things as extra blood drawing, extra x-rays, interaction of research drugs, or similar hazards.


Participation of people without Parkinson’s disease (control participants) is just as important as participation of people with Parkinson’s disease!  Many studies seek controls participants who are in the same age range as participants who have Parkinson’s disease.  Contact us to discuss which studies you might be interested in.


An LP is a medical procedure to obtain cerebrospinal fluid (CSF), which is the fluid that surrounds the brain and spinal cord.

An LP provides scientists with CSF, a crucial bodily specimen for Parkinson’s disease research

  • Examining CSF is a key part of research regarding conditions that affect the brain such as Parkinson disease. CSF supplies nutrients to the cell of the brain. CSF contains many of the proteins and other chemicals important for brain health. It may also contain chemical particles indicating a disease process, such as Parkinson disease.

Overview of the procedure:

  • A small needle is inserted between the vertebrae (bones in the back) and below the level of the spinal cord to obtain the fluid.
  • Lidocaine, which is a numbing medicine is provided before the needle is inserted to decrease any discomfort.
  • The average person has about 150cc of spinal fluid and we will be obtaining about 24 cc, which is the equivalent to two teaspoons of fluid. This amount of fluid re-accumulates in the body quickly – generally over a period of 2-3 hours.

The procedure is routine and will be conducted by someone who performs these regularly

  • Many neurologists perform LPs multiple times a week and are quite practiced at this procedure.

There are some minor risks associated with an LP

  • Subjects may experience minor pain when the needle is inserted. About 5-10% of subjects experience a headache after the LP. Such a headache is usually mild and lasts from a few hours to 2 days and is relieved by increased fluid intake and lying flat. There is a very small risk for infection, which is similar to that of getting a blood draw.

There are a few precautions that should be taken after an LP

  • You will be asked to rest for a short period (about 30 minutes) after the procedure. After that, most people are able to drive home. You will be instructed to drink plenty of fluids for about 12 hours following the LP. You will also be asked to avoid strenuous physical activity for about 48 hours. All subjects will be given a contact number to call if new symptoms occur or if questions arise following the LP.


Contact Us

To make a clinic appointment with Dr. Poston, please visit Stanford Hospital Movement Disorders Clinic.