Individual differences in stop-related activity are inflated by the adaptive algorithm in the stop signal task

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatric Disorders

Background:

• Individuals with ADHD, OCD, and substance use disorders often exhibit impaired inhibitory control on the Stop Signal Task.
• Deficits in inhibitory control are associated with reduced neural activity in brain regions critical for stopping.
• Adaptive algorithms in the Stop Signal Task can introduce performance-related difficulty variations, potentially confounding neural activity measurements.

Purpose of the Study:

• To investigate the impact of algorithm-induced objective task difficulty on neural activity measures during the Stop Signal Task.
• To determine if controlling for task difficulty alters observed group differences in stop-related neural activity.

Main Methods:

• Compared fMRI data from 210 subjects with differing inhibitory abilities using standard and difficulty-controlled analyses.
• Resampled trials to isolate the effects of inhibitory ability from objective task difficulty.

Main Results:

• Objective task difficulty significantly influences between-group differences in stop-related neural activity.
• Controlling for task difficulty attenuated differences in neural activity between superior and poor inhibitors in regions like the inferior frontal gyrus.
• Exaggerating task difficulty effects led to the emergence of group differences in other brain regions associated with stopping.

Conclusions:

• The adaptive algorithm's manipulation of task difficulty can confound interpretations of neural activity differences related to inhibitory control.
• Researchers should account for objective task difficulty when analyzing fMRI data from the Stop Signal Task to accurately assess individual differences in inhibitory networks.