Clinical Neuroscience

[Spectral, phase-synchronization, and graph theoretical EEG changes related to mental arithmetics]

BOHA Roland1,2,3, TÓTH Brigitta1,2,3, GAÁL Zsófia Anna1, KARDOS Zsófia1,2, FILE Bálint4, MOLNÁR Márk1,2

MAY 30, 2013

Clinical Neuroscience - 2013;66(05-06)

[During mental arithmetic operations working memory playsan important role, but there are only few studies in which anattempt was made to separate this effect from the process ofarithmetics per se. In this study the effects of arithmetic onthe EEG of young adults (14 participants, six of themwomen, mean age 21.57 years, SD: 2.62) was investigatedduring a subtraction task in the θ(4-8 Hz) frequency band.Besides the power density spectrum analysis phasesynchrony based on recently developed graph theoreticalmethods were used and strength of local connections (clustercoefficient; C) and global interconnectedness of network(characteristic path length; L) were determined. Before thearithmetic task passive viewing (control situation) and anumber recognition paradigms were used. During the arith-metic task compared to the control situation significantlyincreasing phase synchrony and C values were found. L wassignificantly shorter (F(2, 26)=818.77, p<0.0001) only dur-ing the arithmetic task: this fact and the former two resultsimply that the network topology shifted towards the “smallworld” direction. Our findings concerning regionaldifferences confirm those reported earlier in the literature:compared to the control condition significant task-relatedincrease was found in C values in the parietal areas [moreexplicitly in the left side, (F(1, 13)=7.2020, p=0.0188)],which probably corresponds to stronger local connectionsand more synchronized (sub)networks. During the task con-dition significantly increased θband power; (F(1,13)=7.9708, p=0.0144) and decreased L values werefound in the left frontal region compared to the right side(F(1, 13)=6.0734, p=0.0284), which can also be interpret-ed as an indicator of optimized network topology ofinformation processing.]


  1. MTA, Természettudományi Kutatóközpont, Kognitív Idegtudományi és Pszichológiai Intézet, Budapest
  2. ELTE, PPK, Pszichológiai Intézet, Budapest
  3. ELTE, PPK, Pszichológiai Intézet, Pszichológiai Doktori Iskola, Budapest
  4. PPKE, Információs Technológiai Kar, Budapest



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