title: No Effects of Bilateral tDCS over Inferior Frontal Gyrus on Response Inhibition and Aggression.
abstract: Response inhibition is defined as the capacity to adequately withdraw pre-planned responses. It has been shown that individuals with deficits in inhibiting pre-planned responses tend to display more aggressive behaviour. The prefrontal cortex is involved in both, response inhibition and aggression. While response inhibition is mostly associated with predominantly right prefrontal activity, the neural components underlying aggression seem to be left-lateralized. These differences in hemispheric dominance are conceptualized in cortical asymmetry theories on motivational direction, which assign avoidance motivation (relevant to inhibit responses) to the right and approach motivation (relevant for aggressive actions) to the left prefrontal cortex. The current study aimed to directly address the inverse relationship between response inhibition and aggression by assessing them within one experiment. Sixty-nine healthy participants underwent bilateral transcranial Direct Current Stimulation (tDCS) to the inferior frontal cortex. In one group we induced right-hemispheric fronto-cortical dominance by means of a combined right prefrontal anodal and left prefrontal cathodal tDCS montage. In a second group we induced left-hemispheric fronto-cortical dominance by means of a combined left prefrontal anodal and right prefrontal cathodal tDCS montage. A control group received sham stimulation. Response inhibition was assessed with a go/no-go task (GNGT) and aggression with the Taylor Aggression Paradigm (TAP). We revealed that participants with poorer performance in the GNGT displayed more aggression during the TAP. No effects of bilateral prefrontal tDCS on either response inhibition or aggression were observed. This is at odds with previous brain stimulation studies applying unilateral protocols. Our results failed to provide evidence in support of the prefrontal cortical asymmetry model in the domain of response inhibition and aggression. The absence of tDCS effects might also indicate that the methodological approach of shifting cortical asymmetry by means of bilateral tDCS protocols has failed.
authors.affiliation: Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center, Maastricht, The Netherlands.
authors.forename: Franziska
authors.initials: F
authors.lastname: Dambacher
authors.affiliation: Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center, Maastricht, The Netherlands.
authors.forename: Teresa
authors.initials: T
authors.lastname: Schuhmann
authors.affiliation: Department of Clinical Psychological Science, Maastricht University, Maastricht, The Netherlands.
authors.forename: Jill
authors.initials: J
authors.lastname: Lobbestael
authors.affiliation: Department of Clinical Psychological Science, Maastricht University, Maastricht, The Netherlands; Department of Clinical Psychology, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Arnoud
authors.initials: A
authors.lastname: Arntz
authors.affiliation: Department of Clinical Psychological Science, Maastricht University, Maastricht, The Netherlands.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Brugman
authors.affiliation: Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center, Maastricht, The Netherlands.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Sack
mesh_terms: D000374:Aggression / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009433:Neural Inhibition / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult