Behavioral and Neuronal Representation of Numerosity Zero in the Crow

Area of Science:

• Cognitive Neuroscience
• Comparative Psychology
• Neurobiology

Background:

• Numerosity discrimination is observed across various animal species.
• The neural basis of numerical representations has been studied, but the concept of zero remains underexplored.
• The empty set (numerosity zero) is crucial for human number theory but lacks investigation in non-primate brains.

Purpose of the Study:

• To investigate the behavioral and neuronal representation of the empty set in carrion crows.
• To determine if crows can discriminate numerosity zero and if it's integrated into their numerical cognition.
• To explore the neural mechanisms underlying the representation of zero in the avian brain.

Main Methods:

• Behavioral experiments training crows to discriminate numerosities, including the empty set.
• Single-cell recordings in the nidopallium caudolaterale (NCL) to identify neurons responsive to numerosity zero.
• Neuronal population analysis using statistical classifiers to assess predictive power of neural representations.

Main Results:

• Crows exhibited a numerical distance effect for the empty set, indicating its place on a mental number line.
• A significant proportion of NCL neurons were tuned to numerosity zero, showing distance and size effects.
• Neuronal representations predicted task success, confirming their role in numerical cognition.

Conclusions:

• Carrion crows can cognitively represent the empty set as a numerical quantity.
• The avian brain, specifically NCL neurons, implements a neural number line that includes zero.
• This suggests that the cognitive precursor to a zero-like concept is not exclusive to primate brains and evolved convergently in birds.