Journal of Comparative Physiology A

, Volume 199, Issue 1, pp 1–16 | Cite as

Coding of abstract quantity by ‘number neurons’ of the primate brain

Review

Abstract

Humans share with nonhuman animals a quantification system for representing the number of items as nonverbal mental magnitudes. Over the past decade, the anatomical substrates and neuronal mechanisms of this quantification system have been unraveled down to the level of single neurons. Work with behaviorally trained nonhuman primates identified a parieto-frontal cortical network with individual neurons selectively tuned to the number of items. Such ‘number neurons’ can track items across space, time, and modality to encode numerosity in a most abstract, supramodal way. The physiological properties of these neurons can explain fundamental psychophysical phenomena during numerosity judgments. Functionally overlapping groups of parietal neurons represent not only numerable-discrete quantity (numerosity), but also innumerable-continuous quantity (extent) and relations between quantities (proportions), supporting the idea of a generalized magnitude system in the brain. These studies establish putative homologies between the monkey and human brain and demonstrate the suitability of nonhuman primates as model system to explore the neurobiological roots of the brain’s nonverbal quantification system, which may constitute the evolutionary foundation of all further, more elaborate numerical skills in humans.

Keywords

Single-neuron recordings Parietal cortex Prefrontal cortex Rhesus monkey Abstract categories 

Abbreviations

aITC

Anterior inferior temporal cortex

BOLD

Blood-oxygenation-level-dependent

BS

Broad spiking neuron

fMRI

Functional magnetic resonance imaging

IPS

Intraparietal sulcus

JND

Just noticable difference

LIP

Lateral intraparietal area

NS

Narrow spiking neuron

PFC

Prefrontal cortex

PPC

Posterior parietal cortex

SPL

Superior parietal lobule

VIP

Ventral intraparietal area

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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.Animal Physiology, Institute of NeurobiologyUniversity of TübingenTübingenGermany

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