We use many different tools to learn more about brain and behavior development across the lifespan. All of them are safe and non-invasive. Many, such as fMRI, are also used for medical purposes and may already be familiar to you. Read on for more information about the various methods we use and what they help us to discover!
A game of peekaboo
Several of our studies, such as the Infant Sibling Project, use standardized cognitive tests to learn about how infants and children develop. Using such tests, we can learn more about developmental timelines for particular cognitive processes, and also assess whether individual children are meeting certain developmental milestones.
Some of these testing methods are play based--we can learn a great deal about things like motor and social development from watching how children play. Some studies also use more paper or interview-based tests for older children, with which we can measure things like IQ and reading or pre-reading skills.
To learn about the development of cognitive and perceptual processes such as memory and face-processing, we sometimes use an eye tracker. This is simply a set of infrared cameras mounted on top of a computer screen; the cameras allow us to track where a viewer is looking on the screen and for how long. By analyzing these "looking patterns," we can learn more about typical development as well as how development of certain processes may differ in children diagnosed with particular developmental disorders.
This tool is particularly useful in studying infants, as it allows us to make inferences about memory and face-processing abilities before babies can say, "Yes, I remember that picture!" But how exactly do we tell if babies can remember an object or tell the difference between two faces? Infants consistently show a novelty preference, which means that they will look longer at something that is new, rather than something they have seen before. So, we start by familiarizing a baby with one face or picture and then present them with that familiar stimulus next to a new one of the same type. We can infer that infants who look longer at the new picture are not only remembering the first picture, but they are successfully discriminating between the two (one is new and exciting, the other is old and boring). Conversely, if they look equally at the old and the new picture, we can infer that they do not remember the first one.
Eye tracking is also useful in learning more about certain developmental disorders, such as autism. We know that children with an autism spectrum disorder tend to look at faces differently than typically developing children. For example, they tend to look at the mouth or the edges of the face more than the eyes. By learning more about looking patterns in children diagnosed with or at risk for autism, we aim to create tools for better interventions and earlier diagnosis.
In many of our studies, we aim to take a direct measure of brain activity, using tools such as EEG (electroencephalography). Similar to when you get an EKG at the doctor's office to measure the heart's activity, the EEG sensors in our caps (pictured at right) pick up on electrical activity that's present on the scalp all day long as the result of normal brain activity. When we look at brain activity in response to a particular stimulus--a technique known as event-related potentials, or ERPs--we can identify the neural signatures, or wave forms, that correspond to certain perceptual and cognitive processes, such as face recognition and attention.
The ability to identify these neural signatures helps us to learn not only about typical development, but also to identify specific differences in these signatures among children diagnosed with or at risk for certain developmental disorders. Ultimately, identifying these differences may help to create more targeted interventions and new tools for diagnosis.
Many of you may be familiar with MRI as a medical tool. Like MRI, fMRI (functional magnetic resonance imaging) uses a magnet to take pictures of the brain. But, in addition to getting a picture of physical anatomy, fMRI can also take images of the brain's activity by measuring changes in blood flow. Just like a muscle, when you use part of your brain, blood flow increases to that area; by measuring those changes, we can see which parts of the brain are being used. In our studies, children are given games and activities designed to measure brain activity during particular cognitive processes such as attention and reading development. As with EEG, we can track brain activity in response to these tasks in order to learn more about these processes in both typical children and children diagnosed with or at risk for developmental disorders such as ADHD and dyslexia.
For those of you who may have had previous experience with MRI, we are happy to report that MRI technology has improved dramatically over the last several years. The scanners we use now are much quieter and larger than previous scanners, changes which make them much more comfortable for children and adults alike! We also have special child friendly techniques to help make our youngest participants comfortable. You can learn more about them here.
Like fMRI, NIRS (near-infrared spectroscopy) makes use of a common medical tool in order to help us learn more about the brain. Whereas fMRI uses a magnet to create images of the brain, NIRS uses light in order to monitor changes in blood oxygen. This method works just like the "pulse ox"--short for pulse oximeter--that you may have had on your finger while at the hospital. The pulse oximeter shines light into the finger and can read how much oxygen is in the blood based on how much light comes back. The light that's used is comparable to that experienced from sunlight. We've adopted the same concept to help us learn more about brain development, putting the NIRS sensors on the head instead of the finger. By monitoring changes in blood oxygen while children look at pictures of faces or objects, we can learn more about how children process these images.