Tale of Two n-Backs: Diverging Associations of Dorsolateral Prefrontal Cortex Activation With n-Back Task Performance

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Investigating neural correlates of working memory (WM) using functional magnetic resonance imaging (fMRI) often lacks reporting of brain activation-task performance associations.
• The influence of specific WM task designs on these activation-performance relationships remains unclear.

Purpose of the Study:

• To demonstrate how different working memory task variations impact brain-behavior correlations.
• To analyze fMRI data from two large, independent cohorts performing distinct n-back tasks.

Main Methods:

• Utilized between-participant analyses on task-based fMRI data from the Human Connectome Project (HCP) and the Queensland Twin Imaging (QTIM) Study.
• Examined activation-performance relationships ([2-back - 0-back] contrast vs. 2-back % correct) in prefrontal cortex regions and the whole cortex across datasets.

Main Results:

• Global brain activation patterns were consistent across datasets.
• Opposite activation-performance associations were found in the pre-supplementary motor area and left middle frontal gyrus.
• The Human Connectome Project cohort showed a stronger activation-performance relationship in the middle frontal gyrus compared to the QTIM Study cohort.

Conclusions:

• Divergent activation-performance relationships observed between variations of the n-back task highlight the critical impact of task selection.
• Researchers should exercise caution when interpreting neural activation in response to working memory tasks and consider task design implications.