Human brain functional areas of unitary pooled activity discovered with fMRI

Abstract

We report the discovery of human brain functional areas of unitary pooled activity (FAUPAs) using fMRI. A FAUPA is defined as an area in which the temporal variation of the activity is the same across the entire area. This dynamically unitary activity implies a perfect temporal correlation everywhere within the FAUPA for the activity-induced BOLD response, i.e., the corresponding Pearson correlation coefficient (R) is 1 for the BOLD responses of any two locations within the FAUPA. A novel method was developed to identify the FAUPA. In this study, nine subjects had a resting-state (rs) fMRI and a task-fMRI. FAUPAs have been identified for both rs- and task-fMRI, and their determination was objective and automatic, with no a-priori knowledge. The group mean of R was 0.952 ± 0.004 for the rs-fMRI and 0.950 ± 0.002 for the task-fMRI, showing the dynamically unitary activity within each FAUPA. For the finger-tapping (FT) task, the group-mean BOLD signal time course of the FT-associated FAUPAs in the primary motor cortex was almost perfectly correlated with the FT-induced ideal response (R = 0.9330, P = 1.8 × 10⁻⁵⁶), confirming the association of the FAUPA with the task. A task-associated FAUPA may play the role of a functional unit for a particular neural computation.