Set 7 - Action inhibition and STN

Action inhibition

Canceling or preventing an action that is already prepared or strongly elicited.

Stop-signal task

A speeded go response occasionally followed by a cue instructing the participant to stop.

Go trial

A trial in which the participant must execute the usual speeded response.

Stop trial

A trial in which a later signal instructs the participant to cancel the response.

Stop-signal delay

Time between the go cue and the stop cue; longer delays make stopping harder.

Stop-signal reaction time (SSRT)

Estimated time required by the covert stopping process; longer values imply slower stopping.

Horse-race model of stopping

Go and stop processes race; whichever finishes first determines the response outcome.

Successful inhibition

The stop process finishes before the prepared response is executed.

Failed inhibition

The go process finishes before stopping can prevent movement.

Right inferior frontal gyrus (rIFG)

Right frontal region involved in detecting or initiating the need to stop an action.

rIFG lesion study — design

Compare stop-signal performance in individuals with versus without damage to right IFG.

rIFG lesion study — finding

Damage prolonged stopping time, showing impaired action cancellation.

Stop-task fMRI comparison — finding

rIFG responds to stop cues even when stopping fails, consistent with signaling “stop”.

Motor cortex during failed stopping

Motor execution signals remain stronger when the prepared response escapes inhibition.

Subthalamic nucleus (STN)

Basal-ganglia nucleus involved in rapid, relatively global suppression of actions.

Frontal–STN stopping pathway

Frontal control can recruit STN-mediated braking of ongoing or planned actions.

Deep brain stimulation (DBS)

Electrical stimulation of a brain target used clinically to alter network function.

STN DBS — motor effect

Can improve Parkinsonian motor symptoms by modulating basal-ganglia activity.

STN DBS — cognitive side effect

Can alter impulse control or produce disinhibition as stopping-related networks are affected.