Humans are unparalleled in perception, the ability to gain knowledge through sensory perception and then process that information through thought. After all, no other species has sent tentacles to other planets, produced life-saving vaccines or created art. What makes us smarter than other animals in the human brain?
Our understanding of brain function has changed over the years. But current theoretical models describe the brain as a “distributed information processing system”. This means that it contains many components that are closely related to the wiring of the brain. In order to communicate with each other, regions in the brain exchange information through a system of input and output signals.
However, this is only a small part of a more complex picture, according to a study published in Nature Neuroscience. The way we process information also differs between humans and other primates, which may explain why our species has superior cognitive abilities.
The researchers found that different areas of the brain actually use different strategies to interact with each other. Some areas of the brain exchange information with others in a very modular way, using inputs and outputs. This ensures that the signals appear repeatable and reliable. This is the case for areas specialized in sensory and motor functions (such as processing sound and visual information and movement).
This allows us to see with one eye
Take the eyes, for example, which send signals to the back of the brain for processing. Most of the information sent is duplicate and is provided by each eye. In other words, half of this information is not necessary.
But the system guarantees durability and reliability – this is what allows us to see with one eye. This ability is necessary for survival. In fact, it is very important that the connections between these brain regions are anatomically wired, like a landline phone.
However, not all the redundant information provided by the eyes is redundant. The combination of information from both eyes eventually allows the brain to process depth and distance between objects. It 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 combined – ‘synergistic’.
Is synergy what makes us special?
Synergistic processing is most common in areas of the brain that support a wide range of more complex cognitive functions, such as attention, learning, and working memory as well as social and numerical cognition. The system is not “fixed” in the sense that it can change in response to our experiences and connect different networks in different ways. This makes it easier to combine information.
Such areas where there is a great deal of synergy – usually in the front and center of the cerebral cortex (the outer layer of the brain) – integrate different information sources from across the brain. Therefore, they are connected more broadly and more efficiently to the rest of the brain than the areas that deal with primary sensory information related to movement.
The areas of high synergy that support information integration typically contain many synapses, the microscopic connections that allow neurons to communicate.
The difference between the brains of monkeys and humans
The researchers wanted to see if this ability to gather and build information through the complex networks in the brain differs between humans and other primates, which are our evolutionary relatives.
To find out, they studied brain imaging data and genetic analyzes of several species. They found that synergistic interactions are responsible for a greater proportion of the overall information flow in the human brain than in macaques. In contrast, the brains of both species are similar in the degree to which they rely on redundant information.
However, the scientists also looked specifically at the prefrontal cortex, an area in the front of the brain that supports more advanced cognitive functions. In macaques, hyperinformation processing is more common in this region, while in humans it is a synergistic heavy region.
The prefrontal cortex has also experienced significant expansion with development. When the researchers examined chimpanzee brain data, they found that as a region of the human brain expanded in size during evolution compared to that of a chimpanzee, that region became more dependent on synergy in humans.
The researchers also looked at genetic analyzes of human donors. This showed that brain regions associated with synergistic information processing are more likely to express unique human genes related to brain development and function, such as intelligence. This led them to conclude that additional human brain tissue obtained as a result of evolution could be devoted primarily to synergy.