Study Of Single Neuron Activity Helps Understand Abstract Thinking In Humans

Observing the activity of an individual brain cell in humans for the first time, scientists have found that neurons can differentiate objects or people regardless of the contexts in which they were encountered for the first time.

The findings can help understand how humans develop abstract thinking, the researchers, led by those at the Hospital del Mar Research Institute in Spain, said.

This behaviour of an individual neuron, described in a paper in the journal Cell Reports, allows for the forming of higher and abstract concepts in the brain, which constitutes the basis of human intelligence, they said.

Abstract thought, or perceiving an object in ways not physically visible, is a higher-order form of thinking, examples of which include using metaphors and analogies. The skill has varied applications, such as understanding the big picture.

The researchers explained that studies in animals have shown significant differences in how a neuron behaved in response to a concept — a specific place or object — when the context changed.

For example, neurons in a rat responded very differently if it found the same object in different locations. It was believed that such memories were stored in different groups of neurons.

The findings of the latest study, involving nine epilepsy patients in Argentina and the UK, contradicted the findings from the previous ones: the neurons were found to respond to a specific concept in the same manner when the context changed — such as remembering having seen a person in different locations.

"The basic principle of neuronal coding in humans is the opposite of what has been observed in other species, which has significant implications," lead researcher Rodrigo Quian Quiroga, a neuroscientist at the Hospital del Mar Research Institute, said.

"We observe similar single-neuron responses to the same concepts in different tasks," the authors wrote.

For the study, electrodes were implanted in the patients, who were being treated for refractory epilepsy, a drug-resistant form of the brain disorder marked by seizures.

The researchers thus tracked the individual behaviour of neurons and could obtain precise recordings of the neurons' responses.

The patients were presented with two stories featuring the same person in different contexts, supported by images. The team found that the response of a neuron remained the same in both the stories.

Further, as the patients recounted the stories, the same neurons were found to be activated seconds before they referred to the protagonist.

"Memories are stored in a much more abstract manner in humans compared to other animals. You can think of concepts or anything else in more abstract terms, independent of the context in which you learned them," Quian Quiroga said, suggesting that this could be one of the "foundations of human intelligence." "This ability allows us to make much more abstract and complex associations and inferences than if we were forced to think of each concept within a specific, concrete context," he said.

Previous studies in humans used fMRI (functional magnetic resonance imaging), which could not differentiate between individual neurons, the team said. PTI KRS RUK RUK

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