Neuronal codes for arithmetic rule processing in the human brain

Esther F Kutter,Jan Boström,Christian E Elger,Andreas Nieder,Florian Mormann

doi:10.1016/j.cub.2022.01.054

Esther F Kutter, Jan Boström + Show 3 more

Open Access

https://doi.org/10.1016/j.cub.2022.01.054

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Abstract

Arithmetic is a cornerstone of scientifically and technologically advanced human culture, but its neuronal mechanisms are poorly understood. Calculating with numbers requires temporary maintenance and manipulation of numerical information according to arithmetic rules. We explored the brain mechanisms involved in simple arithmetic operations by recording single-neuron activity from the medial temporal lobe of human subjects performing additions and subtractions. We found abstract and notation-independent codes for addition and subtraction in neuronal populations. The neuronal codes of arithmetic in different brain areas differed drastically. Decoders applied to time-resolved recordings demonstrate a static code in hippocampus based on persistently rule-selective neurons, in contrast to a dynamic code in parahippocampal cortex originating from neurons carrying rapidly changing rule information. The implementation of abstract arithmetic codes suggests different cognitive functions for medial temporal lobe regions in arithmetic.

Highlights

Mental arithmetic is an intricate skill and a hallmark of our scientifically advanced culture
Calculating with numbers requires temporary maintenance and manipulation of numerical information according to arithmetic rules
We explored the brain mechanisms involved in simple arithmetic operations by recording single-neuron activity from the medial temporal lobe of human subjects performing additions and subtractions

Summary

Introduction

Mental arithmetic is an intricate skill and a hallmark of our scientifically advanced culture. Mental arithmetic engages multiple brain systems, including those for the semantic representation of numeric values, the learning and memory of mathematical principles, and the cognitive control of mental operations.[1,2,3,4]. Arithmetically selective brain areas have been identified in the parietal cortex of patients using intracranial electrocorticography (ECoG) recordings that measure summed and synchronized postsynaptic potentials (bulk tissue mass potentials).[10,11] direct electrical stimulation studies in human patients have shown a specific arrest of counting and calculation performance during transient perturbation of parietal and frontal regions.[12,13,14] The latter investigations, in particular, suggest a causal involvement of parietal and frontal cortical regions in mental arithmetic

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