Is the human brain unique among animals? New study suggests an evolving answer

Man is unrivalled in the realm of knowledge. After all, no other species has sent probes to other planets, made life-saving vaccines, or written poetry. How information is processed in the human brain to make this possible is a question that draws endless fascination but lacks definitive answers.

Our understanding of brain function has changed over the years. However, current theoretical models describe the brain as a “distributed information-processing system”. This means that it has various components that are tightly connected through the wiring of the brain. In order to interact with each other, regions exchange information through a system of input and output signals.

However, this is only a small part of a more complex picture.

What’s new – In a study published in nature neuroscienceUsing evidence from multiple species and multiple neuroscientific disciplines, we show that there is more than one way of processing information in the brain. How information is processed also differs between humans and other primates, which could explain why our species’ cognitive abilities are so superior.

We borrowed concepts from the so-called mathematical framework of information theory — the study of the measurement, storage, and transmission of digital information critical to technologies like the internet and artificial intelligence — to trace how the brain processes information. We found that different brain regions actually use different strategies to interact with each other.

Some brain regions exchange information with others in very stereotypical ways, using input and output. This ensures that signals arrive reproducibly and reliably. This is the case for areas specialized in sensory and motor functions (e.g. processing of sound, image and movement information).

To go into detail – Take the eyes, for example, which send signals to the back of the brain for processing. The majority of the information sent is duplicated and provided by each eye. In other words, half of this information is not needed. Therefore we call this type of input-output information processing “redundant”.

But the redundancy provides robustness and reliability – it allows us to still see with just one eye. This skill is essential for survival. In fact, it’s so crucial that the connections between these brain regions are anatomically hardwired in the brain, a bit like a landline phone.

However, not all information provided by the eyes is redundant. The combination of information from both eyes ultimately allows the brain to process depth and distance between objects. This is the basis for many types of 3D glasses in cinemas.

This is an example of a fundamentally different way of processing information in a way that is greater than the sum of its parts. We call this type of information processing – when complex signals from different brain networks are integrated – “synergistic”.

How people process a lot of information

Synergistic processing is most prevalent in brain regions that support a wide range of more complex cognitive functions, such as B. attention, learning, working memory and social and numerical cognition. It’s not hardwired in the sense that it can change in response to our experiences, connecting different networks in different ways. This makes it easier to combine information.

Such areas where many synergies take place—mostly in the front and middle cortices (the outer layer of the brain)—integrate various sources of information from across the brain. They are therefore broader and more efficiently connected to the rest of the brain than the regions dealing with primary sensory and movement-related information.

Areas of high synergy that support the integration of information also typically have many synapses, the microscopic connections that allow nerve cells to communicate.

Is synergy what defines us?

We wanted to know whether this ability to gather and construct information through complex networks in the brain differs between humans and other primates, which are evolutionarily close relatives of ours.

To find out, we looked at brain imaging data and genetic analyzes of different species. We found that synergistic interactions account for a higher proportion of the total flow of information in the human brain than in the macaque brain. In contrast, the brains of both species are the same when it comes to how much they rely on redundant information.

However, we also looked specifically at the prefrontal cortex, an area in the front part of the brain that supports more advanced cognitive functions. In macaques, redundant information processing is more prevalent in this region, while in humans it is a synergy-heavy area.

The prefrontal cortex has also expanded significantly over the course of evolution. When we examined data from chimpanzee brains, we found that the more a region of the human brain had enlarged over the course of evolution compared to its chimpanzee counterpart, the more that region relied on synergy.

Rhesus macaque monkeys at Swayambhunath Temple in Nepal.Shutterstock

We also looked at genetic analysis of human donors. This indicated that brain regions associated with synergistic information processing are more likely to express genes that are uniquely human and involved in brain development and function, such as brain function. B. intelligence related.

This led us to conclude that additional human brain tissue acquired through evolution may be primarily destined for synergy. In turn, it’s tempting to speculate that the benefits of greater synergy might partially explain our species’ additional cognitive abilities. Synergy could add an important piece that was previously missing to the puzzle of human brain evolution.

Ultimately, our work shows how the human brain navigates the trade-off between reliability and integration of information – we need both. Importantly, the framework we have developed promises critical new insights into a wide range of neuroscientific questions, from those on general cognition to specific diseases.

This article was originally published on The conversation by Emmanuel A Stamatakis, Andrea Luppi and David Menon at the University of Cambridge. Read the original article here.

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