Top-down regulation of default mode activity in spatial visual attention

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Imaging

Background:

• The task control network (TCN), including the dorsal anterior cingulate and anterior insula, manages cognitive set and sensorimotor regulation.
• The default mode network (DMN) is involved in introspection and self-referential thought.
• Interactions between TCN and DMN are known, but their functional impact on cognitive tasks is unclear.

Purpose of the Study:

• To investigate the functional implications of TCN-DMN interactions during a visual spatial attention task.
• To determine how directed causal influences between TCN and DMN affect behavioral performance and neural activity.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to record brain activity in human subjects performing a visual spatial attention task.
• Granger causality analysis was applied to fMRI data to assess directed influences between TCN and DMN.
• Correlations were examined between causal influences, behavioral performance, and blood oxygen level-dependent (BOLD) activity.

Main Results:

• Positive correlation found between TCN to DMN causal influences (TCN → DMN) and behavioral performance.
• Negative correlation found between DMN to TCN causal influences (DMN → TCN) and behavioral performance.
• Stronger DMN → TCN influences were associated with reduced TCN BOLD activity, suggesting interference with task control.

Conclusions:

• Top-down TCN signals to the DMN help regulate DMN activity, enhancing behavioral performance in attention tasks.
• Bottom-up DMN signals to the TCN may act as internal noise, disrupting task control and degrading performance.
• Understanding TCN-DMN interplay is crucial for explaining cognitive control and attention mechanisms.