Abstract
Arithmetic requires complex and fast processes orchestrated within a large-scale network spanning multiple brain regions. However, reports on the network’s temporal dynamics are scarce. Here, we present data from intracranial EEG (iEEG) of 20 subjects (epilepsy surgery candidates) performing a sequential three-operand arithmetic task. Utilizing the high temporal and spatial resolution of iEEG, we analysed changes in high-gamma band (HGB; 52–120 Hz) activity and functional connectivity assessed by phase-locking value (PLV) in the delta (0.1–3 Hz) and theta (3–7 Hz) frequency bands. Strong and transient HGB activations peaked first in the ventral occipito-temporal cortex, followed by a more gradual increase in the lateral parietal, sensorimotor, and frontal cortices, accompanied by deactivations in default mode network areas. The connectivity patterns were more extensive during calculation than number recognition, with the theta PLV peaking ~ 150 ms earlier than the delta PLV. Earliest connectivity appeared, surprisingly, between ventral temporal and frontal regions at ~ 100–200 ms, evolving into a robust pattern among key network nodes at ~ 200–400 ms after the presentation of each operand. The presented results elucidate information flow within the putative arithmetic network during calculation in the human brain, offering high-temporal-resolution insights into its functional architecture.
Data availability
The raw iEEG data that support the findings of this study are publicly available (https://zenodo.org/records/16778665) https://zenodo.org/records/18245516. Further data are available from the corresponding authors upon reasonable request.
Code availability
Code is publicly available for the iEEG data analysis (https://github.com/JiriHammer/SEEG_dataAnalysis).
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Acknowledgements
Motol University Hospital is a full member of ERN EpiCARE. All authors are members of the Epilepsy Research Centre Prague - EpiReC consortium. The authors would like to thank the patients for their participation in this study and CESNET for access to their data storage facility.
Funding
The research was supported by ERDF-Project Brain Dynamics, No. CZ.02.01.01/00/22_008/0004643, and Grant Agency of Charles University (GA UK, Grant No. 272221).
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M.K.: Methodology, investigation, formal analysis, writing—original draft, visualization. A.K.: Investigation, data curation, writing—review & editing. B.K.: Writing—review & editing. V.P.: Investigation, writing—review & editing. J.A.: Writing—review & editing. R.J.: Methodology, writing—review & editing. P.J.: Data curation. D.K.: Investigation, data curation. M.K.: Investigation, writing—review & editing. P.K.: Investigation, writing—review & editing. P.M.: Conceptualization, resources, writing—review & editing, supervision, funding acquisition. J.H.: Conceptualization, methodology, investigation, formal analysis, writing – original draft, visualization, supervision, funding acquisition.
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Kalinova, M., Kerkova, B., Kalina, A. et al. Temporal order of activations and interactions during arithmetic calculations measured by intracranial electrophysiological recordings in the human brain. Sci Rep (2026). https://doi.org/10.1038/s41598-026-36122-z
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DOI: https://doi.org/10.1038/s41598-026-36122-z
