A new study has uncovered the processes occurring in the brain that help an individual distinguish between what’s real and what they might be imagining.
The findings published in the journal Neuron could help understand how cognitive processes go haywire in psychosis — a mental state in which one loses touch with reality.
Psychosis is a symptom of mental illness such as schizophrenia and the mania phase of bipolar disorder, according to researchers.
‘Fusiform gyrus’ — part of the visual cortex, located behind one’s temples and involved in processing visuals — helps the brain determine whether what we are seeing is from the external world or generated by our imagination, the researchers from University College London said.
The team asked 26 participants to look for a specific faint pattern of a grating in images of staircases and indicate whether it was present or not. The pattern was presented only half the time.
The participants were also asked to simultaneously imagine a grating pattern that was either the same or different to the one they were looking for and indicate how vividly they were able to produce mental images.
When the presented pattern and the one imagined were the same, and the participants reported being able to produce vivid mental images, they were more likely to say they saw a real pattern, even in experiments when it was not presented, the researchers said.
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The result meant that the participants mistook their mental images for reality.
“Imagine an apple in your mind’s eye as vividly as you can. During imagination, many of the same brain regions activate in the same manner as when you see a real apple. Until recently, it remained unclear how the brain distinguishes between these real and imagined experiences,” lead author Nadine Dijkstra, from the University College London, said.
Using functional magnetic resonance imaging (fMRI), the researchers monitored the participants’ brain activity as they engaged in the tasks.
When activity in the fusiform gyrus was strong, people were more likely to indicate that the pattern was there, the team said.
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They added that the brain region is less active during imagination than in perception, which helps the brain keep the two apart.
However, the study showed that, sometimes, when participants imagined very vividly, the fusiform gyrus was strongly activated and the participants confused their imagination for reality.
“The brain activity in this area of visual cortex matched the predictions from a computer simulation on how the difference between internally and externally generated experience is determined,” senior author Steve Fleming, professor of cognitive neuroscience at the University College London, said.
Here’s what to consider (Photo: Freepik)
The authors show that “judgments of reality are underpinned by the combined strength of sensory activity generated by either imagery or perception in the fusiform gyrus.” “Activity fluctuations in this region predict confusions between imagery and perception on a trial-by-trial basis and interact with a frontal brain network encoding binary judgments of reality,” they wrote.
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Additionally, the study found that the fusiform gyrus collaborates with other brain areas, including the anterior insula in the prefrontal cortex, to help one decide what is real and what is imagined.
The prefrontal cortex helps with complex tasks such as decision-making, problem solving and planning.
Activity in the anterior insula increased in line with that in the fusiform gyrus when participants said something was real, even if it was imagined, the researchers said.
“These areas of the prefrontal cortex have previously been implicated in metacognition — the ability to think about our minds. Our results indicate that the same brain areas are also involved in deciding what is real,” Fleming said.
