The pre-supplementary motor area achieves inhibitory control by modulating response thresholds

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Computational Neuroscience

Background:

• The pre-supplementary motor area (pre-SMA) is crucial for initiating and inhibiting voluntary actions.
• Its role in action execution involves optimizing choice decisions by adjusting evidence thresholds.
• The precise contribution of the pre-SMA to action inhibition remains incompletely understood.

Observation:

• A patient with a focal pre-SMA lesion exhibited prolonged stop-signal reaction times, indicating impaired action inhibition.
• The same patient showed faster go reaction times.
• Computational modeling was used to analyze performance on a stop/no-go task in the patient and 52 controls.

Findings:

• The patient's impaired ability to inhibit actions was linked to a significantly lower response threshold for action initiation compared to controls.
• This suggests the patient required less evidence to commit to an action.
• A similar deficit was observed in the patient's ability to decide which action to choose.

Implications:

• Dynamic threshold modulation by the pre-SMA appears to be a general mechanism for controlling voluntary action.
• These findings shed light on the neural basis of action control and decision-making.
• Understanding pre-SMA function is vital for conditions involving impaired voluntary control.