When problem size matters: differential effects of brain stimulation on arithmetic problem solving and neural oscillations

Bruno Rütsche; Tobias U Hauser; Lutz Jäncke; Roland H Grabner

doi:10.1371/journal.pone.0120665

When problem size matters: differential effects of brain stimulation on arithmetic problem solving and neural oscillations

PLoS One. 2015 Mar 19;10(3):e0120665. doi: 10.1371/journal.pone.0120665. eCollection 2015.

Authors

Bruno Rütsche¹, Tobias U Hauser², Lutz Jäncke³, Roland H Grabner⁴

Affiliations

¹ 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.
² 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.
³ 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.
⁴ 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.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Electroencephalography
Female
Humans
Male
Mathematics*
Parietal Lobe / physiology*
Problem Solving / physiology*
Reaction Time
Transcranial Direct Current Stimulation*
Young Adult

Grants and funding

This study was funded by a grant awarded to TUH and RHG by the Swiss National Science Foundation (100014_140515 / 1; http://www.snf.ch). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.