Proactive Interhemispheric Disinhibition Supports Response Preparation during Selective Stopping

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Psychology

Background:

• Response inhibition is crucial for halting unwanted actions.
• Stopping only part of a bimanual action can cause delays in the non-stopped limb (stopping-interference).
• Proactive cueing can mitigate this interference, suggesting improved selective control.

Purpose of the Study:

• To investigate the role of interhemispheric primary motor cortex (M1-M1) communication in selective response inhibition with proactive cueing.
• To test the hypothesis that increased stopping certainty, cued proactively, reduces stopping-interference via interhemispheric modulation.

Main Methods:

• Twenty-three participants performed a bimanual response inhibition task with varying stop-signal likelihood cues.
• Dual-coil transcranial magnetic stimulation assessed corticomotor excitability (CME), interhemispheric inhibition (IHI), and facilitation (IHF) in the left primary motor cortex.
• Measurements were taken at rest and during response preparation.

Main Results:

• Stopping-interference decreased as stopping certainty increased.
• Proactive inhibition involved faster electromyographical cancel times.
• Interhemispheric inhibition (IHI) was released during response preparation, but not CME. An effector-specific CME reduction occurred when one hand was cued to stop, without IHI reinstatement.

Conclusions:

• Proactive cueing enhances stopping speed and selectivity in bimanual actions.
• Interhemispheric M1-M1 pathways adjust inhibitory tone for response preparation but are not directly engaged in proactive stopping.
• Improvements in selective stopping with cues do not appear to rely on advance engagement of interhemispheric motor cortex influences.