title: When problem size matters: differential effects of brain stimulation on arithmetic problem solving and neural oscillations.
abstract: The problem size effect is a well-established finding in arithmetic problem solving and is characterized by worse performance in problems with larger compared to smaller operand size. Solving small and large arithmetic problems has also been shown to involve different cognitive processes and distinct electroencephalography (EEG) oscillations over the left posterior parietal cortex (LPPC). In this study, we aimed to provide further evidence for these dissociations by using transcranial direct current stimulation (tDCS). Participants underwent anodal (30min, 1.5 mA, LPPC) and sham tDCS. After the stimulation, we recorded their neural activity using EEG while the participants solved small and large arithmetic problems. We found that the tDCS effects on performance and oscillatory activity critically depended on the problem size. While anodal tDCS improved response latencies in large arithmetic problems, it decreased solution rates in small arithmetic problems. Likewise, the lower-alpha desynchronization in large problems increased, whereas the theta synchronization in small problems decreased. These findings reveal that the LPPC is differentially involved in solving small and large arithmetic problems and demonstrate that the effects of brain stimulation strikingly differ depending on the involved neuro-cognitive processes.
authors: Research on Learning and Instruction, Institute for Behavioral Sciences, ETH Zurich, Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), University of Zurich and ETH Zurich, Zurich, Switzerland.
authors: Bruno
authors: B
authors: Rütsche
authors: Neuroscience Center Zurich (ZNZ), University of Zurich and ETH Zurich, Zurich, Switzerland; Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom; University Clinics for Child and Adolescent Psychiatry (UCCAP), University of Zurich, Zurich, Switzerland.
authors: Tobias U
authors: TU
authors: Hauser
authors: Division Neuropsychology, Institute of Psychology, University of Zurich, Zurich, Switzerland; International Normal Aging and Plasticity Imaging Center (INAPIC), University of Zurich, Zurich, Switzerland; Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; University Research Priority Program (URPP), Dynamic of Healthy Aging, University of Zurich, Zurich, Switzerland; Department of Special Education, King Abdulaziz University, Jeddah, Saudi Arabia.
authors: Lutz
authors: L
authors: Jäncke
authors: Section of Educational Neuroscience, Department of Psychology, University of Graz, Graz, Austria; Department of Educational Psychology, Institute of Psychology, Georg-August-University of Göttingen, Göttingen, Germany.
authors: Roland H
authors: RH
authors: Grabner
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D010296:Parietal Lobe / Q000502:physiology*; D011340:Problem Solving / Q000502:physiology*; D011930:Reaction Time; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult