STOP! The Neural Correlates of Impulsivity and Response Inhibition
INTRODUCTION
METHODS
1. Bari, A., & Robbins, T. W. (2013). Inhibition and impulsivity: Behavioral and neural basis of response control. Progress in Neurobiology, 108, 44–79. 2. Ethridge, L.E., Soilleux, M., Nakonezny, P.A., Reilly, J.L., Hill, S.K., Keefe, R.S.E., Gershon, E.S., Pearlson, G.D., Tamminga, C.A., Keshavan, M.S., & Sweeney, J.A. (2014). Behavioral response inhibition in psychotic disorders: diagnostic specificity, familiarity and relation to generalized cognitive deficit. Schizophrenia Research, 159, 491-498. 3. Lansbergen, M.M., Böcker, K.B.E., Bekker, E.M., & Kenemans, J.L. (2007). Neural correlates of stopping and self-reported impulsivity. Clinical Neurophysiology, 118, 2089–2103. 4. Messerotti Benvenuti, S., Sarlo, M., Buodo, G., Mento, G., & Palomba, D. (2015). Influence of impulsiveness on emotional modulation of response inhibition: An ERP study. Clinical Neurophysiology, 126(10), 1915–1925. 5. Ruchsow, M., Groen, G., Kiefer, M., Hermle, L., Spitzer, M., & Falkenstein, M. (2008). Impulsiveness and ERP components in a
Go/Nogo task. Journal of Neural Transmission, 115(6), 909–915. 6. Shen, I. H., Lee, D. S., & Chen, C. (2014). The role of trait impulsivity in response inhibition: Event-related potentials in a stop-signal task. International Journal of Psychophysiology, 91(2), 80–87. 6. Eagle, D.M., Wong, J.C., Allan, M.E., Mar, A.C., Theobald, D.E., & Robbins, T.W. (2011). Contrasting roles for dopamine D1 and D2 receptor subtypes in the dorsomedial striatum but not the nucleus accumbens core during behavioral inhibition in the stop-signal task in rats. The Journal of Neuroscience, 31, 7349–7356.
Marie-Anne Dussault Gomez, Theoretical and Applied Neuroscience Lab, University of Victoria – www.krigolsonlab.com – mdussaultgomez@gmail.com
Figure 5. Topographic maps for LI (left) and HI (right), at Pz, for successful Stop trials in the SSRT.
Figure 4. Topographic maps for LI (left) and HI (right), at Pz, for No-Go trials in the Go/No-Go task.
CONCLUSIONS
Figure 2. Visual representation of one trial in the SSRT. • 10 participants from the University of Victoria were split into high impulsivity (HI; n =
5) and low impulsivity (LI; n = 5) groups based on their Barratt Impulsiveness Scale (BIS-11) scores (mean HI = 86.4, LI = 46.8).
• In the Go/No-Go task (3 blocks of 100 trials), participants were required to respond to a coloured stimulus (i.e. a blue circle) on Go trials (75% of trials), and to not respond to a differently coloured stimulus (i.e. a green circle) on No-Go trials (25% of trials). • In the SSRT (5 blocks of 60 trials), participants were required to press a button in
reaction to a blue square (i.e. the stimulus) delivered in all trials, but to inhibit this
prepotent response when an auditory cue was delivered in “Stop” trials (30% of trials). • EEG was recorded from 32 electrodes during task completion.
• Response inhibition, defined as the capability to withhold from executing a pre-potent response, falls within the multilayered construct of impulsivity and has been implicated in obsessive
compulsive disorder, attention deficit hyperactivity disorder, substance abuse, schizophrenia, and bipolar disorder1,2
• Previous research investigating how impulsivity affects both performance and the P300
event-related potential component in two behavioural tasks, the Go/No-Go task and Stop Signal Response Task (SSRT), has offered inconsistent results and conclusions3,4,5,6
• The aim of this study was to use electroencephalography (EEG) to investigate how impulsivity modulates task performance and P300 amplitude in two response inhibition tasks.
• Individuals in the HI group had to exert greater inhibitory control than the LI group in successful SSRT Stop trials to obtain the same effect, similar to results found by Lansbergen and colleagues (2007).
• HI group had a larger P300 amplitude than the LI group in successful SSRT Stop trials. This is suggested to
represent an increase in the firing rate of noradrenergic neurons in the locus-coeruleus, which is related to
modulation of fast inhibitory processes (e.g. stimulus
detection, behavioral orienting, attentional shifting, and conflict detection) (Bari & Robbins, 2013).
• There was no difference in the number of commission errors (i.e. reacting to the auditory stop stimulus)
committed between both groups.
• Greater inhibitory control from individuals in the HI group is needed for action cancellation, which is necessary in the SSRT, but not for action restraint, which is needed in the Go/No-Go task.
• Eagle and colleagues (2008) have similarly suggested that the SSRT and Go/No-Go tasks involve different mechanisms of inhibition6
• There was no difference in P300 amplitude during
No-Go trials between HI and LI groups, whereas there was a difference in P300 amplitudes between groups on
successful SSRT Stop trials.
• Additional research with larger sample sizes is necessary in order to clearly define the neural processing and behavioural performance differences between high and low impulsivity individuals, which may assist in diagnosis, treatment, and prevention of conditions and disorders associated with heightened impulsivity.
RESULTS
Figure 3. Grand average ERP waveforms of HI and LI groups for successful SSRT Stop trials at channel Pz.
Figure 2. Grand average ERP waveforms of HI and LI groups for No-Go trials in the Go/No-Go task at chancel Pz.
