Scientists suggest that the brain may work better with 7 senses, not just 5

“Our conclusion is of course highly speculative when applied to human senses, although you never know: it is possible that humans in the future will develop a sense of radiation or magnetic fields. But in any case, our findings may be of practical importance for robotics and the theory of artificial intelligence,” said study co-author Professor Nikolai Brilyantov from Skoltech AI. “It seems that when each concept held in memory is described in terms of seven features — versus, say, five or eight — the number of distinct things held in memory reaches a ceiling.”

In keeping with a well-established approach that arose in the early 1900s, the team modeled the basic building blocks of memory: memory “engrams.” The engram can be viewed as a dispersed collection of neurons across multiple regions of the brain that fire together. The conceptual content of an engram is an ideal abstract object characterized by multiple features. In the context of human memory, features correspond to sensory input, such that the idea of ​​banana corresponds to the visual image, smell, taste of banana, etc. This results in a five-dimensional object that exists and develops in a five-dimensional space inhabited by all other concepts stored in memory.

The development of engrams suggests that concepts become more focused or blurred over time, depending on how often the engrams are activated by a stimulus acting from the outside world via the senses, triggering a memory of the object in question. This is a model of learning and forgetting as a result of interaction with the environment.

“We have mathematically proven that engrams in conceptual space tend to evolve towards a steady state, which means that after a transient period, a ‘mature’ distribution of engrams appears, which then persists over time,” commented Briliantov. “As we consider the ultimate capacity of a conceptual space of a given number of dimensions, we find somewhat surprisingly that the number of distinct engrams stored in memory in the steady state is largest for a seven-dimensional conceptual space. Hence the claim of the seven senses.”

In other words, let things in the world be described by a finite number of features corresponding to the dimensions of some conceptual space. Suppose we want to maximize the capacity of the conceptual space, expressed as the number of distinct concepts associated with these objects. The larger the conceptual space, the deeper the comprehensive understanding of the world becomes. It turns out that the maximum is achieved when the dimension of the conceptual space is seven. From this, researchers conclude that seven is the optimal number for the senses.

According to the researchers, this number does not depend on the details of the model – the properties of the conceptual space and the stimuli that provide sensory impressions. The number seven seems to be a strong and persistent feature of memory engrams as such. One caveat is that multiple engrams of different sizes located around a common center are considered to represent similar concepts and are therefore treated as one when calculating memory capacity.

The memory of humans and other living beings is a mysterious phenomenon linked to the property of consciousness, among other things. Developing theoretical models of memory will be useful in gaining new insights into the human mind and recreating human-like memory in AI agents.