Comparison of local activation, functional connectivity, and structural connectivity in the N-back task

Front Neurosci. 2024 Mar 4:18:1337976. doi: 10.3389/fnins.2024.1337976. eCollection 2024.


The N-back task is widely used to investigate working memory. Previous functional magnetic resonance imaging (fMRI) studies have shown that local brain activation depends on the difficulty of the N-back task. Recently, changes in functional connectivity and local activation during a task, such as a single-hand movement task, have been reported to give the distinct information. However, previous studies have not investigated functional connectivity changes in the entire brain during N-back tasks. In this study, we compared alterations in functional connectivity and local activation related to the difficulty of the N-back task. Because structural connectivity has been reported to be associated with local activation, we also investigated the relationship between structural connectivity and accuracy in a N-back task using diffusion tensor imaging (DTI). Changes in functional connectivity depend on the difficulty of the N-back task in a manner different from local activation, and the 2-back task is the best method for investigating working memory. This indicates that local activation and functional connectivity reflect different neuronal events during the N-back task. The top 10 structural connectivities associated with accuracy in the 2-back task were locally activated during the 2-back task. Therefore, structural connectivity as well as fMRI will be useful for predicting the accuracy of the 2-back task.

Keywords: N-back task; diffusion tensor imaging; functional MRI; local activation; structural connectivity.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The assessment conducted in the laboratory of TT was supported by Grant-in-Aid for Challenging Research (Exploratory) (Grant number 21 K19464).