Brain Imaging Information for Students

• MRI Information
• Dartmouth's Brain Imaging Center
• Brain Imaging Techniques
• Brain Imaging Comparison Chart

As we're sure you know, adolescence is a time of change. The changes in your social, academic, and emotional lives can be exciting and fun, but can also be really hard and confusing at times. Your body grows; school gets more complicated (more teachers, changing classes, more homework, etc.), and your friendships change and become more important. You begin to rely on and spend more time with your friends. In short, adolescence is a really big deal.

What we want to know is how you, a teenager, deal with and respond to all of these changes in your body and environment. We believe that all these changes mean your brain has to do a lot of growing and maturing to figure out how to cope with the different pressures and expectations in your life. These changes allow you to learn skills that will help you navigate your social, emotional, and academic worlds.

Right now our lab is conducting several studies to help us understand how your brain changes throughout adolescence. Using Magnetic Resonance Imaging, a really cool and safe way to look at the brain in study participants, we can measure the growth and connections of different areas of the brain in teenagers just like you. We are particularly interested in the areas of the brain that help us with skills you develop in middle school like planning, organization, goal-setting, inhibition, and emotional control.

If you'd like to learn more about what MRI is or what it’s like to have an MRI, read on!

And if you think you might be interested in taking part in our study and want to find out more, contact us.

What is an MRI?

MRI (magnetic resonance imaging) is a machine that lets us see inside people's bodies by using a large magnet, radio waves, and powerful computers. The MRI images let us see body tissues in a different way. It is almost like taking cuts or slices of the body but in a "virtual" (yet highly accurate) way on the computer. By using very new MR technologies, we are able to look at both structure and function within the brain.

What is it like to have an MRI?

MRI machines have a magnet that goes around the tube where a person lies. Study participants lie face-up on a sliding table, and are moved into the tube. You can still talk to us while you're in the tube, using an intercom system. Cameras also let us see you at all times. While the magnet is operating, it makes a loud banging noise. For this reason, we give you headphones to help muffle the noise.

Each study may ask different questions about the brain, so participants are often asked to perform different tasks while in the MRI machine. Our laboratory generally asks participants to perform a few tasks by viewing pictures (or stimuli) and pressing certain buttons depending on their thoughts or feelings about the stimuli.

Here are a few examples of what you might be asked to do during an MRI at our lab:

• Study one: You'll see a number of human faces with different facial expressions. We ask you to identity certain expressions such as happiness or fear.
• Study two: We ask you either to remember or forget different pictures.
• Study three: You'll see two pictures simultaneously. We will ask you to make rapid decisions (by pressing a button) about which picture you like better, or think is cooler.

Are there any risks to me in getting an MRI?

MRI does not use any radiation (like x-rays do). There are no risks to having an MRI unless you have any metal objects implanted in your bodies (for example, if you wear braces, we won't let you go in the scanner). To ensure your safety, we ask you a number of questions before you can have an MRI scan. As well, you'll be required to wear protective headphones to help muffle the noise generated by the scanner.

The Brain Imaging Center at Dartmouth recently received a make over!

This summer, we got a new fMRI machine at Dartmouth College in the Psychological & Brain Sciences department. The magnet in this machine is twice as powerful as our old one!

Brain Imaging Techniques

• X-ray
• Nuclear (PET, SPECT)
• Magnetic Resonance (MRI, fMRI, DTI)
• Surface electrical activity (EEG, MEG, ERP)
• Near-infrared (NIRS)
• Computed Tomography (CT)
• Ultrasound

In the 1970s, scientists began using computers to put together information from brain x-rays to make a single image of the whole brain. These were the first pictures of normal brains in living humans.

PET: Positron Emission Tomography

PET measures emissions from radioactively labeled chemicals that have been injected into the bloodstream, and uses the data to produce two- or three-dimensional images of the chemicals in the brain.

 

SPECT: Single Photon Emission Computed Tomography

Similar to PET, SPECT also uses radioactive tracers and a scanner to record data that a computer then uses to construct two- or three-dimensional images of active brain regions.

MRI: Magnetic Resonance Imaging

MRI uses magnetic fields and radio waves to produce high-quality two- or three-dimensional images of brain structures without injecting radioactive tracers.

fMRI: Functional Magnetic Resonance Imaging

Functional MRI (fMRI) uses the magnetic parts of blood to let scientists see images of blood flow in the brain as it occurs. Researchers can make "movies" of changes in brain activity as subjects perform tasks or are exposed to different stimuli.

DTI: Diffusion Tensor Imaging

Diffusion Tensor Imaging (DTI) is a technique that measures the movement of water in the brain along "myelinated" white matter tracts. DTI will allow scientists to see activity in the brain on an even smaller scale.

Surface Electrical Activity Monitoring

EEG: Electroencephalography

Electroencephalography uses electrodes placed on the scalp to measure patterns of electricity coming from the brain.

MEG: Magneto-encephalography

Magnetoencephalography (MEG) measures the magnetic fields caused by the brain's electrical activity.

ERP: Event-Related Potential

An event-related potential (ERP) is used to investigate the activity measured by electroencephalography (EEG) as a response to a certain event.

Near-infrared Spectroscopy (NIRS)

Near infrared spectroscopy (NIRS) is a noninvasive technique that uses certain wavelengths of light to illuminate tissue and activity below the skin (in our case, inside the brain).

Computed Tomography (CT)

Computed tomography (CT), sometimes called a CAT scan, uses special x-ray equipment to get many images from different angles, and then join them together to show a cross-section of body tissues and organs.

Ultrasound

Ultrasonography is another procedure for viewing areas inside the body. High-frequency sound waves that cannot be heard by humans enter the body and bounce back. Their echoes produce a picture called a sonogram. While the use of ultrasound technologies in brain scanning and brain surgery has only begun to be developed in the past few years, there are exciting possibilities for applying these technologies to brain imaging.