Neuronal codes for arithmetic rule processing in the human brain

• Published in: Current biology Vol. 32; no. 6; pp. 1275 - 1284.e4
• Main Authors: Kutter, Esther F., Boström, Jan, Elger, Christian E., Nieder, Andreas, Mormann, Florian
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 28.03.2022
• Subjects: arithmetic; Brain - physiology; Brain Mapping; dynamic code; hippocampus; Humans; Mathematics; medial temporal lobe; Neurons - physiology; numbers; parahippocampal cortex; single-unit recordings; static code; symbolic competence; Temporal Lobe - physiology; single-unit recordings; medial temporal lobe; hippocampus; parahippocampal cortex; static code; dynamic code; numbers; arithmetic; symbolic competence; humans
• ISSN: 0960-9822; 1879-0445; 1879-0445
• DOI: 10.1016/j.cub.2022.01.054

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. [Display omitted] •Single neurons in the human MTL show abstract codes for addition and subtraction•Time-resolved decoding analysis shows a dynamic code in the parahippocampal cortex•The hippocampus shows a static code based on persistently rule-selective neurons•Different codes suggest different cognitive functions of MTL regions in arithmetic Kutter et al. demonstrate abstract and notation-independent codes for addition and subtraction in neuronal populations in the human medial temporal lobe (MTL). A dynamic code in the parahippocampal cortex contrasts with a static code in the hippocampus, suggesting different cognitive functions for these MTL regions in arithmetic.