Pace yourself: Neural activation and connectivity changes over time vary by task type and pacing

Area of Science:

• Cognitive Neuroscience
• Neuroimaging

Background:

• Performance deterioration over time, or time-on-task (TOT) effects, are common but poorly understood regarding neural mechanisms.
• Previous research has not adequately explored how task pacing and cognitive demands influence TOT-related brain activity.

Purpose of the Study:

• To investigate the impact of task pacing (self-paced vs. externally paced) and cognitive demands on brain activity and network connectivity during time-on-task effects.
• To examine how the dorsal attention network (DAN) and default-mode network (DMN) are modulated by these task parameters.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) to measure brain activation and functional connectivity.
• Employed three closely related tasks with varying pacing conditions (self-paced vs. externally paced).
• Analyzed neural activity and network interactions over short (~2-3 min) and long (~10 min) time scales.

Main Results:

• Self-paced tasks showed increased DAN activation and connectivity over short time scales, correlating with pronounced reaction time slowing.
• No significant pacing effects were observed for TOT-related changes in DMN activity, DAN-DMN anti-correlations, or pupil diameter.
• Over longer time scales (~10 min), task-positive activation and connectivity decreased across all task paradigms.

Conclusions:

• The brain dynamically allocates resources, with the DAN showing increased engagement in self-paced tasks over short durations.
• Task pacing and time scale are critical factors influencing neural resource allocation during sustained cognitive performance.
• Findings challenge previous assumptions and highlight novel patterns of brain activity modulation related to task control and duration.