How are our neurons organized to generate intelligence?

BarcelonaHuman memory is one of the most complex cognitive processes of our brain. We store memories that help shape our identity, and we are also able to distinguish objects and people regardless of their context. Now, and for the first time, a group of Catalan researchers from the Hospital del Mar Research Institute has observed in a study how the neurons in our brain collect these memories, which "allows us to establish higher and abstract relationships, which constitutes the basis of human intelligence," according to the authors of this research published this Thursday in the journal Cell Reports.

The study was led by Rodrigo Quian, coordinator of the research group on neuronal mechanisms of perception and memory at the centre, and is the first work "capable of observing this behaviour of neurons in humans". The study has used data from nine patients with epilepsy who do not respond to treatment and who had implanted electrodes to monitor the functioning of certain groups of neurons individually. This has allowed precise records of their responses to be obtained, unlike the studies carried out to date on humans, based on magnetic resonance images and without the capacity to differentiate individual neurons.

In terms of previous work with animals, findings showed major differences in the encoding of concepts – that is, how they distinguish places or objects when the context is changed. For example, neurons responded very differently if a rat found an object in one place or another, and so memories were thought to be stored in different groups of neurons.

Now this research has found "surprising answers that contradict the studies published to date," according to the center. The participants were told two stories, featuring the same person, in different contexts and with supporting images, and, thanks to monitoring, they checked which groups of neurons were activated. Specifically, they have shown how the response to the image of the person was the same and activated the same group of neurons in both stories. In addition, when it was the patients who told the story, they observed how, before referring to the protagonist, these neurons were already activated for both stories.

"Memories are stored in a much more abstract way in humans than in other animals. You can think of concepts, or whatever, in more abstract terms, independently of the context in which you learned them," explains Quian, who suggests that these findings may explain the "basis of human intelligence." "This fact allows us to make much more abstract and complex associations and inferences than if we were forced to think of each concept in a specific, concrete context," he says. That is, humans can decontextualize our memories to create more abstract thinking.