Saccade suppression exerts global effects on the motor system.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Motor Control

Background:

• Cognitive control enables focused attention by inhibiting inappropriate actions.
• The stop-signal task models the ability to suppress voluntary movements.
• Previous studies show stopping limb or speech actions globally suppresses unrelated motor systems.

Purpose of the Study:

• To investigate if stopping eye movements (saccades) also induces global motor suppression.
• To examine the temporal dynamics of this effect using transcranial magnetic stimulation (TMS).

Main Methods:

• Participants performed a saccade task with a stop-signal.
• Corticospinal excitability (CSE) of the hand was measured using TMS during saccade initiation and attempted stopping.
• High temporal precision was used to analyze CSE changes relative to saccade stopping time.

Main Results:

• Reduced CSE in the hand (a task-unrelated effector) was observed approximately 50 ms before successful saccade stopping.
• This indicates that inhibiting eye movements recruits a global motor suppression mechanism.

Conclusions:

• Rapidly stopping saccades, similar to limb movements, results in widespread motor suppression.
• This global effect may involve the basal ganglia and thalamocortical pathways.
• This mechanism could underlie distractibility, as abrupt stimuli might trigger broad motor and non-motor suppressive effects.