Neurobiological mechanisms of response inhibition in humansTitle: Modulation of response inhibition: a combined TMS-fMRI study in healthy individuals

• Applicant: Professor Dr. Norbert Brüggemann
• Subject Area: Human Cognitive and Systems Neuroscience
• Term: from 2011 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 209458435

Effective inhibition of inappropriate motor activities crucially depends on the integrity and effective interaction of frontal and parietal brain areas. The right frontal inferior gyrus (IFG) and the rostral part of the supplementary motor cortex (pre-SMA) are specifically involved in the maintenance of this important executive function. The proposed project aims to determine the causal contribution of both areas to the voluntary inhibition of inappropriate activities using a perturb-and-measure approach.Twenty healthy probands will undergo 1Hz repetitive transcranial magnetic stimulation (rTMS) to induce a transient focal lesion to the right IFG or the pre-SMA (perturb). Subsequently, the probands are asked to perform a newly developed Go/NoGo task during functional magnetic resonance imaging (fMRI). Apart from the established Go and NoGo cues, the task includes an Alternative Go cue to assess the combined ability of the brain to inhibit a planned motor response and to switch to an alternative motor reaction. Event-related fMRI will unravel the effects of rTMS on the functional activation of brain regions in comparison with a control group that underwent sham rTMS (measure). We hypothesize that perturbation of the right IFG or pre-SMA will: (i) result in a compensatory increase in activation of the non-stimulated region (e.g. increased activation after rTMS of the right IFG) and (ii) strengthen the functional connectivity of the non-stimulated cortical region with the ipsilateral subthalamic nucleus and putamen. The ability to inhibit inappropriate responses following rTMS will correlate with the extent of this compensatory activation pattern. The presented project will shed light on the functional interaction between IFG and pre-SMA with respect to response inhibition and will significantly expand the knowledge of cerebral mechanisms of voluntary inhibition of motor activities.

• DFG Programme: Research Fellowships
• International Connection: Denmark
• Host: Professor Dr. Hartwig Roman Siebner