Study
Neurons selective to the number of visual items in the corvid songbird endbrain
Ditz, Helen M.; Nieder, Andreas
Proceedings of the National Academy of Sciences, 2015
Carrion crows were trained to judge how many dots appeared on a screen while the activity of individual neurons in a forebrain region was recorded.
- Studied in
- Corvus corone
- Sample size
- 2 trained carrion crowsSingle-neuron recording studies typically use very few, heavily trained animals.
Individual neurons responded most strongly to a preferred quantity — some to one item, others to two, three or four — with responses tapering off for neighbouring numbers.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Crows possess number-selective neurons functionally equivalent to those found in the primate prefrontal cortex, despite an independently evolved brain organisation.
How NatureHQ reads it
This is about as direct as evidence for animal number sense gets: not "the bird chose the larger pile", but "this cell fires for three". The convergence with primates matters because bird and mammal forebrains are built differently, so similar solutions arose twice. Two birds is a small number of animals, which is normal for this method and still a real constraint.
- Two heavily trained individuals.
- Numerosities tested were small; the finding does not extend to counting in the human sense.
- Training regimes shape what neurons are recruited, so the result describes a trained brain.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Proceedings of the National Academy of SciencesPublished in PNAS.
doi.org/10.1073/pnas.1504245112
This reference was resolved automatically against Crossref and OpenAlex on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-09.