Finding neuromechanisms of decision making

Xingjie Chen stands at MRI scanner

The Neuro-Learning and Performance Lab combines fMRI and EEG techniques for the first time at UMass Amherst

What areas of our brain are activated when we make decisions? Xingjie Chen, developmental science doctoral student advised by Youngbin Kwak, is striving to uncover the neuromechanisms behind this action. She is studying what happens when people process decision making-related variables and make a final choice, such as when we opt to take a risk or play it safe. Her dissertation research will incorporate both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) technologies used simultaneously to gather data from human subjects. Chen’s project is the first at UMass Amherst to combine these two techniques.

MRI images of brain with highlighted areasfMRI is a non-invasive experimental technique which measures brain activation using the blood-oxygen-level dependent (BOLD) signal. It can capture an area of the brain about 2mm on all sides; recording a signal that averages over the responses of numerous individual neurons in the brain. The BOLD signal can tell you many things, such as which parts of the brain are reacting during a task.

When people make decisions it happens very quickly, sometimes within 500 milliseconds. fMRI has a disadvantage in terms of real-time recording of images, due to a low temporal resolution of the BOLD signal. That is, the BOLD signal change in our brain doesn’t happen very fast, which differs greatly from the extremely fast speed of neurons firing.

EEG cap on human subjectEEG is able to record the brain’s electrical activity in time intervals as small as 1 millisecond. The technique involves recording various surfaces of the scalp using electrodes. In Chen’s project, she will measure exactly when a brain signal change happens in response to an event—you see, hear, feel, or think something. By combining EEG and fMRI data, her research team can identify both when and where decision making happens.

“We are trying to build up the connection between MRI and EEG to know more about what areas of the brain contribute to EEG signals,” says Chen. If these two types of signals show a high correlation, researchers can be more certain that a particular electrode can reflect the activity of a specific brain region.

colored areas of the brain showing activation Many decision-making studies in the past have focused on the prefrontal cortex of the brain. In a previous EEG study from the Neuro-Learning and Performance Lab, the team found that an area in the motor region, which controls body movement, could also contribute to the decision-making process. The team also knows that the subcortical regions, a group of neural formations deep within the brain, play a role. The addition of fMRI technology will help the team gather more exact data about what is occurring in these other areas of the brain.

For more information or to participate in this study, contact the Neuro-Learning and Performance Lab at kwaknlpgroup@gmail.com.