Probability effects in the stop-signal paradigm: the insula and the significance of failed inhibition

Brain Res. 2006 Aug 11;1105(1):143-54. doi: 10.1016/j.brainres.2006.02.091. Epub 2006 Apr 17.


In the present randomized, mixed-trial event-related fMRI study, we examined the neural mechanisms underlying inhibitory control using a stop-signal paradigm in which stop-signal frequency was manipulated parametrically across blocks. As hypothesized, presenting stop signals less frequently was accompanied by a stronger set to respond to the go stimuli as subjects were faster in responding to go stimuli on no stop-signal trials and made more commission errors (i.e., were less successful in inhibiting the go response) on stop-signal trials. When response inhibition was successful, having to inhibit responses more frequently compared to less frequently was associated with greater activation in occipital areas. This presumably reflects enhanced visual attention to the stop signal. When response inhibition failed, greater activity was observed in bilateral insula when stop signals were presented less compared to more frequently. The insula may thus play a role in processing the significance of inhibitory failure.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Analysis of Variance
  • Brain Mapping*
  • Cerebral Cortex / anatomy & histology
  • Cerebral Cortex / blood supply
  • Cerebral Cortex / physiology*
  • Choice Behavior / physiology
  • Female
  • Functional Laterality / physiology
  • Humans
  • Inhibition, Psychological*
  • Magnetic Resonance Imaging / methods
  • Male
  • Oxygen / blood
  • Photic Stimulation / methods
  • Probability*
  • Reaction Time / physiology*


  • Oxygen