Though often dismissed as irrational or over-inflated concerns, delusions stem from a very rational ability to remain calm in a chaotic environment.
Being able to adapt quickly to changing circumstances can help you survive. But in extreme cases, a delusional belief in the ill intentions of others can be a real problem. May be socially isolatedIt robs people of their ability to maintain healthy relationships and hold down jobs.
To better understand why some brains metaphorically jump into the shadows more than others, a research team led by Yale psychiatrists Praveen Suthaharan and Summer Thompson analyzed the results of a simple test in a group of male rhesus monkeys and human volunteers.
This is called stochastic reversal learning (PRL) The task centered on a test in which participants had to select a symbol for the chance to win a reward (food for the monkeys, points for the humans).
Because different symbols had different chances of success, three options were presented on the screen, giving subjects the opportunity to learn which symbol was most likely to earn them a reward.
Just when subjects thought they had it all figured out after completing half the test, the results of the trials were reversed, with the luckiest symbols paying rewards less frequently and the unluckiest symbols becoming the optimal choice.
“Participants have to figure out what the optimal target is, and when they perceive a change in the environment, they have to find a new optimal target.” To tell Steve Chang, a psychologist at Yale University.
Six of the 20 macaques had previously undergone neurological procedures in another study. Dorsal thalamic nucleus – areas thought to play a role in planning, abstract thinking, and organization – or Areas of the prefrontal cortex Be involved in decision making.
Meanwhile, human volunteers were asked to complete a Thought Scale questionnaire to assess their level of delusions, and a second survey to determine signs of depression.
By analysing the monkeys’ and humans’ behaviour before and after the switch occurred, and comparing the results with their findings, the team was able to determine which of the disturbed brain regions might affect the monkeys’ ability to calmly navigate a volatile game environment.
“Not only did we use data from monkeys and humans performing the same tasks, but we also applied the same computational analyses to both data sets.” To tell Yale University psychiatrist Philip Corlett.
The data showed that both the magnocellular medial dorsal thalamus (MDmc) within the dorsal thalamic nucleus and the orbitofrontal cortex (known as Walker areas 11, 13, and 14) influenced the monkeys’ behavior following the test switch in subtly different ways.
Among the monkeys whose Walker area was inhibited, the sudden disappearance of the reward had little effect on their decision to switch: They continued to tap recklessly on what they thought was a “winning” ticket.
Those with damaged MDmc exhibited the exact opposite behavior, going back and forth even after discovering that the new “high probability” symbols were paying rewards, as if they suspected the system was being rigged against them personally.
This was similar to behavior observed in humans whose survey responses indicated higher levels of delusion.
While delusions and paranoia are undoubtedly complex behaviors that involve diverse thinking and different regions of the brain, tracing the lines between specific areas and erratic decision-making could inform future research, leading to new treatments and helping us better understand how certain behaviors increase the risk of psychosis.
“In the future, we may be able to use this to find new ways to reduce delusions in people.” To tell Chan.
This study Cell Report.