Bonn and Tübingen researchers uncover how the brain processes zero in both symbolic and nonsymbolic forms.

October 2024 – Zero is a fundamental concept in mathematics, but how does the human brain represent it? A new study from researchers at the Universities of Bonn and Tübingen has provided groundbreaking insights into how neurons in the brain process zero, both in its symbolic form (as the numeral “0”) and in nonsymbolic form (such as an empty set).

Using single-neuron recordings from neurosurgical patients, the researchers found that individual neurons respond either to symbolic zero or nonsymbolic zero, but not both. This suggests that different neuronal networks are involved depending on how zero is represented—whether as a concept of “nothing” or as a numerical symbol integrated into the number system.

The study also revealed a numerical distance effect, where neurons responded more strongly when zero was compared with nearby numbers, like 1 or 2. This indicates that zero is treated as part of the mental number line. However, a boundary was found in how nonsymbolic zero (empty set) is coded compared to small positive numbers, reflecting the difficulty humans experience in distinguishing zero from “something small.” In contrast, symbolic zero did not show this boundary, suggesting it integrates more smoothly into the number system.

These findings offer new insights into how our brains handle abstract numerical concepts, particularly the unique nature of zero, and how it evolves from a concept of “nothing” into an integral part of symbolic mathematics.

For more details, read the full publication https://doi.org/10.1016/j.cub.2024.08.041

Publication: Esther F. Kutter, Gert Dehnen, Valeri Borger, Rainer Surges, Andreas Nieder, Florian Mormann; Single-neuron representation of nonsymbolic and symbolic number zero in the human medial temporal lobe, Current Biology, 2024.

Scientific contact: Prof. Florian Mormann
Department of Epileptology- Cognitive and Clinical Neurophysiology
Bonn University Hospital
E-Mail:  fmormann@yahoo.de

Written by: Dr Michela Barboni, Ph.D