title: Induction and quantification of prefrontal cortical network plasticity using 5 Hz rTMS and fMRI.
abstract: Neuronal plasticity is crucial for flexible interaction with a changing environment and its disruption is thought to contribute to psychiatric diseases like schizophrenia. High-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive tool to increase local excitability of neurons and induce short-time functional reorganization of cortical networks. While this has been shown for the motor system, little is known about the short-term plasticity of networks for executive cognition in humans. We examined 12 healthy control subjects in a crossover study with fMRI after real and sham 5 Hz rTMS to the right dorsolateral prefrontal cortex (DLPFC). During scanning, subjects performed an n-back working memory (WM) task and a flanker task engaging cognitive control. Reaction times during the n-back task were significantly shorter after rTMS than after sham stimulation. RTMS compared with sham stimulation caused no activation changes at the stimulation site (right DLPFC) itself, but significantly increased connectivity within the WM network during n-back and reduced activation in the anterior cingulate cortex during the flanker task. Reduced reaction times after real stimulation support an excitatory effect of high-frequency rTMS. Our findings identified plastic changes in prefrontally connected networks downstream of the stimulation site as the substrate of this behavioral effect. Using a multimodal fMRI-rTMS approach, we could demonstrate changes in cortical plasticity in humans during executive cognition. In further studies this approach could be used to study pharmacological, genetic and disease-related alterations.
authors.affiliation: Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, University of Heidelberg, Mannheim, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Esslinger
authors.forename: Nadja
authors.initials: N
authors.lastname: Schüler
authors.forename: Carina
authors.initials: C
authors.lastname: Sauer
authors.forename: Dagmar
authors.initials: D
authors.lastname: Gass
authors.forename: Daniela
authors.initials: D
authors.lastname: Mier
authors.forename: Urs
authors.initials: U
authors.lastname: Braun
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ochs
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Schulze
authors.forename: Marcella
authors.initials: M
authors.lastname: Rietschel
authors.forename: Peter
authors.initials: P
authors.lastname: Kirsch
authors.forename: Andreas
authors.initials: A
authors.lastname: Meyer-Lindenberg
mesh_terms: D001931:Brain Mapping; D003071:Cognition / Q000502:physiology; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult