Probability effects in the stop-signal paradigm: the insula and the significance of failed inhibition.
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.
Ramautar
Jennifer R
JR
Faculty of Social and Behavioral Sciences, Department of Psychology, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands. J.R.Ramautar@uva.nl <J.R.Ramautar@uva.nl>
Slagter
Heleen A
HA
Kok
Albert
A
Ridderinkhof
K Richard
KR
D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D011336:Probability; D011930:Reaction Time / Q000502:physiology*
D010100:Oxygen