MEG responses over right inferior frontal gyrus during stop-signal task performance
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1
Swinburne University of Technology, Brain and Psychological Sciences Centre, Australia
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2
University of Newcastle, School of Psychology, Australia
Background: The stop-signal paradigm (Logan, 1984) probes the ability to inhibit on-going responses (stopping). This involves occasional inhibition of a trained response upon presentation of a countermanding stop-signal. Stop-signal task performance can be accounted for by a 'race model' that depicts the attempt to inhibit the go response as a race between stop-signal task processes and go task processes - the winner determines whether a response is inhibited (signal-inhibit trial) or executed (signal-respond trial). This model affords estimation of the stop-signal reaction time (SSRT) which is the finishing time of stopping processes. Neuroimaging and cortical deactivation studies have shown that right inferior frontal gyrus (IFG) is critical for stopping by demonstrating relationships between the function of right IFG and SSRT. Here we used magnetoencephalography (MEG) to explore the link between right IFG and SSRT.
Methods: MEG data were recorded on an ELEKTA Neuromag TRIUX machine while a participant responded to stop-signal paradigm stimuli. Go task stimuli (Go) were left and right pointing arrows and stop-signals were auditory tones presented on 25% of trials. All trials began with a fixation cross (500ms) and stop-signal delays were varied dynamically to yield a 50% inhibition rate. The participant performed 4 blocks of stimuli (160 trials per block). After artifact rejection, trial type averages time-locked to the fixation cross were computed.
Results: Mean go task RT was 361 ms and the inhibition rate was 50%. Mean stop-signal delay was 123 ms and SSRT was 238 ms. The time-frequency plot from a sensor over right IFG reveals a broad spectrum response beginning about 60 ms before SSRT on signal-inhibit trials that is not present during either signal-respond or go task trials.
Conclusions: These data show that right IFG becomes active between stop-signal onset and estimated SSRT. This is the first MEG evidence indicating that right IFG is critical for stopping.
Keywords:
Magnetoencephalography,
response inhibition,
Stop-signal reaction time,
right inferior frontal gyrus
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Cognition and Executive Processes
Citation:
Hughes
M,
Woods
W,
Thomas
N,
Michie
P and
Rossell
S
(2015). MEG responses over right inferior frontal gyrus during stop-signal task performance.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00138
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Dr. Matthew Hughes, Swinburne University of Technology, Brain and Psychological Sciences Centre, Hawthorn, Australia, matthewhughes@swin.edu.au