What is a connectome? The new maps of the brain

These representations of neural connectivity can help us understand ourselves better.

The human brain is one of the most complex natural systems known. This is not simply because it is only relatively recently that technological development has enabled the creation of measurement tools suitable for studying this set of organs, not because the average human brain of an adult person contains approximately 80,000,000 neurons. The key is how these nerve cells are connected.

As we will see in this article, the concept of the connectome is born to help us understand the internal logic of something as complicated as a brain.

What is the connectome?

As we have seen, the human brain contains an overwhelming number of nerve cells. But, in addition, each neuron is capable of connecting with hundreds, thousands of other neurons.. These connections can change and develop over time.

It can be said that if our nervous system functions, it is because neurons are capable of sending millions of nerve impulses to each other through these contacts, called synapses. Each neuron, individually, is not capable of performing any of the functions that allow us to think, feel or even stay alive.

A connectome, then, is a mapping of the neuronal connections that exist in a nervous system or part of a nervous system, usually a brain.usually a brain. In recent years, several projects have appeared through which attempts have been made to understand the functioning of various parts of the nervous system thanks to these representations.

Structural connections and functional connections

When designing connectomes, it is possible to describe both structural and functional connections. The former reveal general and macro-anatomical patterns of connectivityThe former reveal general and macroanatomical patterns of connectivity, usually embodied in bundles of axons that run from one part of the nervous system to another region of the nervous system. The latter focus on smaller details related to the probability that a group of neuronal connections sends certain nerve impulses to another group, a connection that is usually made in a more unpredictable and interrupted manner.

The Human Connectome Project

The concept of the connectome is often compared to that of the genome, a word that in turn refers to the information contained in another type of Biological structure: DNA. In the same way that in the 20th century biology and related scientific disciplines saw great hope in the possibility of unraveling the inner logic of the human genome, in recent years neuroscience and psychology, as well as computational science, have begun to look at thehave begun to set their sights on the possibility of understanding the typical connectome of the members of our species.

That is why in 2009 the Human Connectome Project was born, funded by members of the National Institutes of Health of the United States of America. The link between this initiative and health is evident: it is possible to map the connections of a healthy human brain, but also of one associated with a specific mental illness. one associated with a particular mental illnessThe link with health is obvious: it is possible to map the connections of a healthy human brain, but also of one associated with a particular mental illness, in order to locate significant differences in the way nerve cells communicate with each other in each case.

It is reasonable to look for the causes of certain disorders in this connectivity pattern, since there is currently an important consensus around the idea that mental processes are more likely to have functional problems if the groups of neurons that drive them are far apart, given that working with these distances involves assuming a greater metabolic cost. If the distance between groups of neurons in a brain is abnormally large, this could lead to alterations in perception or behavior. To date, the Human Connectome Project is still underway.

A photograph of the brain?

As we have seen, the connectome is a sort of map of the brain, and its existence can facilitate the understanding of its functioning.. However, by its very nature, it is a tool with limited power.

This is because the nervous system, especially the brain, is a constantly changing system. This is a phenomenon known as neuronal plasticity, whereby any experience, regardless of its importance in psychological terms, causes the connectivity and activity patterns of our neurons to change.

Thus, a connectome can give an approximate idea of the functioning of certain behavioral logics, of the effects of some mental illnesses and brain injuries, and can even be used to create neural network learning systems in computers. In fact, promising achievements have already been made, such as recreating the connectome of the brain of a type of worm, creating a simulation with it, and making it learn certain behaviors as one of these animals would without programming a single line of code.

But a connectome cannot accurately predict the behavior of an organism with a brain like the human brain or one of similar complexity, since it is constantly changing. If we are able to reach that level of knowledge, it seems that there is still a long way to go.