Similar brain regions are involved in imagination and perceiving reality
Naeblys / Alamy
How do you say if something is real or imaginary? We have now discovered a brain path that seems to help you decide – and the observation could improve treatments for hallucinations caused by conditions such as Parkinson’s disease.
We already knew that the parts of the brain that are activated when we imagine that something visual is similar to those involved in the perception of real visual stimuli, but we do not know how we distinguish both. “How does our brain know which of these signals reflects our imagination or what is reality?” said Nadine Dijkstra at the University College of London.
To find out, Dijkstra and his colleagues asked 26 people to carry out a visual task while their brain activity was recorded via MRI analyzes. Participants had to see a static gray block on a screen for 2 seconds, in a repeated process more than 100 times. They were also invited to imagine seeing diagonal lines on each block, although half of the blocks have really had diagonal lines.
After viewing each block, the participants were invited to assess how much they saw the lines on a scale of 1 to 4 and say if they thought that the lines were real or imaginary.
By analyzing the brain recordings, the researchers found that an area called the Fusiform gyrus was more active when people saw lines more strongly, that the lines are really there.
“We know in previous studies that this area is activated during perception and imagination, but now we have shown that it actually follows to what extent you live very well visual imagery,” explains Dijkstra.
Above all, when the activity of the Fusiform gyrus exceeded a certain threshold, it led to a leap in activity in an area called anterior insula, bringing people to judge something as real. “You have this other region which connects with the Fusiform gyrus – perhaps it receives signals and gives signals – and it makes a more binary decision: real or not real,” explains Dijkstra.
Although it is unlikely that these brain regions are the only ones involved in the decision of what is real in relation to the imagination, a more in -depth exploration of this path could deepen our understanding of how to treat visual hallucinations caused by conditions such as schizophrenia and Parkinson’s disease.
“Perhaps in people who experience visual hallucinations, there is too much activity in the fusiform gyrus when they imagine, or their previous insula does not monitor the signals correctly,” explains Dijkstra.
“I think this work will be informative of clinical cases,” said Adam Zeman at the University of Exeter, in the United Kingdom. “But there is a big step between deciding if a small fluctuation in your sensory experience is due to something that happens in the real world and to see a fully formed hallucination – which you remain for a convinced time,” he said.
To help fill this gap, the Dijkstra team now explores the way for people with Parkinson’s disease.
Subjects:
