Can Animals Count? Scientists Unveil the Neural Basis of Number Sense in Rats

The concept of numbers and the ability to count are a vital component of human nature. These skills are part of our everyday lives, from calendars, weekly shops, and even in humanity's greatest achievements.

Experts believe that number sense appears in humans in early childhood development. In a recent study, it was also found that this ability is also present in other animals, but is poorly understood.

What Is Number Sense?

Number sense refers to the capability of an individual to compare, estimate, and manipulate nonsymbolic numerical quantities rather than associated magnitudes. The latter includes continuous dimensions inherent in a group of items, like the duration of sound pulses or the area of visual objects.

Number sense is a basic ability in animals' perception of the world which helps them increase their chances of survival. It is also a vital cognitive ability which is very important for mathematical aptitude, a sign of human intelligence.

Almost 3% to 7% of people suffer from dyscalculia, a learning disability which affects the ability of a person of normal intelligence to learn arithmetic and mathematics. One of the major symptoms of dyscalculia is a deficit in number sense.

There have been challenges whether number sense can be measured apart from the influence of continuous magnitudes. There also has been an ongoing debate on whether the sense of magnitude or the sense of number is more fundamental.

Numerical Abilities in Animals

In a recent study, a team of experts has made a remarkable discovery about number sense in animals when they confirmed the existence of discrete number sense in rats. The details of the research is described in the paper "Disparate processing of numerosity and associated continuous magnitudes in rats."

The study is led by neuroscientists Professor Ke Ya from The Chinese University of Hong Kong (CUHK) Faculty of Medicine and Professor Yung Wing-Ho from City University of Hong Kong (CityUHK). Their findings provided a crucial animal model for investigating the neural basis of numerical ability and disability in humans.

The team has developed an innovative approach which uses brain manipulation techniques, a novel numerical learning task, and artificial intelligence modeling. This strategy resolves an ongoing dispute about whether rats exhibit a sense of numbers.

The study authors also minimized the influence of continuous magnitudes in numerical tests and conducted complex quantitative analyses to determine the respective contributions of numbers and magnitudes. They made an algorithm for generating stimuli which enable animals to focus only on numbers, minimizing other distracting factors. Such an approach helped them understand how animals perceive and quantify numbers.

It was found that rats without any prior knowledge of numbers were able to develop a sense of numbers when trained with sounds that represent two or three numbers. Although there is influence from continuous magnitudes, the rats consistently focused on the number of sounds when making choices for food rewards.

The research presents the relationship between magnitude and numerosity processing. The scientists discovered that when the posterior parietal cortex in the rat's brain is blocked, the rodent's ability to understand numbers was affected, but not their sense of magnitude. This means that the brain has a specific area for dealing with numbers.