Components of the Human Connectome Project
An important objective of the Human Connectome Project is to identify functionally distinct subdivisions (parcels, or nodes) of the human brain and to understand the relationships among these parcels.
Why is task fMRI useful?
There are a number of different ways that we could try to identify the different subdivisions of the human brain. One powerful approach is to examine brain regions whose activity changes when people are asked to (i) process different kinds of information (for example, words, pictures, sounds, letters, images); (ii) use different types of thinking skills (for example, memory, decision-making, language generation); or (iii) respond in different ways (for example, button presses, speaking aloud).
We are using Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) as an indirect and non-invasive measure of brain activity while individuals perform a variety of different tasks designed to activate and identify as many functional parcels as possible. We can use the information about which brain regions activate during which tasks to help understand how the brain is organized.
How are we using the task fMRI?
Task-related fMRI analyses will help us identify and characterize functionally distinct nodes in the human brain. In turn, this will help us guide, validate, and interpret the results of the connectivity analyses obtained using resting state fMRI and HARDI diffusion imaging. We have developed and are utilizing a core battery of tasks that each participant will perform.
These tasks have been selected and developed so that we can identify the location of nodes both in a group of participants, and in individual participants. The tasks assess as many different neural systems as it is feasible within the time that we have available to scan each participant. These “functional localizer” tasks include measures of primary sensory processes (e.g., vision, motor function) and as many different cognitive and affective processes as possible, including stimulus category representations, working memory, episodic memory, language processing, emotion processing, and decision-making.
We are using these functional localizers for three purposes:
- to aid in the identification of nodes that will be analyzed in the resting stating fMRI and HARDI diffusion data network graph analyses described in the Network Modeling project component.
- as one way to validate the location of functional areas identified in the resting state fMRI analyses described. Activations identified by the task-related fMRI analyses should fall within the same functional areas identified by resting-state fMRI functional analyses and should not cut across putative boundaries identified with such methods.
- as a comparative metric for analyses examining the relationship between individual differences in the behavioral and genetic measures and individual differences in the functional and structural connectivity measures.
We are also utilizing a subset of the same tasks with MEG to allow analyses of the flow of information among the nodes identified in key networks at a much finer timescale than possible with BOLD fMRI (see MEG and EEG).
How are we measuring behavior?
Click on the following link for a description of candidate paradigms for task fMRI. In phase 1, we are piloting these paradigms to determine which ones show robust and reliable activation within individual participants. After these pilot studies, we will decide how many paradigms it is feasible to use with each participant given the time that we will have available to scan each person.