The ability to change our beliefs about our actions and their outcomes in a constantly changing environment is a key part of advanced thinking. However, disruptions to this ability can have a negative impact on how we think and behave, leading to feelings of paranoia, or the belief that others want to harm us. In a recent study, researchers have discovered how a specific area of the brain could be responsible for causing these feelings of paranoia. Their new method, which involved comparing data collected from monkeys with human data, also provides a new way for scientists to better understand human behavior across different species.Cognition through the study of other species.
The ability to modify beliefs about one’s actions and their outcomes in an ever-changing environment is a key element of advanced cognition. However, disruptions to this ability can have a negative impact on cognition and behavior, resulting in mental states such as paranoia, where individuals believe that others have harmful intentions.
In a recent study, researchers at Yale have discovered how a specific region of the brain may be responsible for causing these feelings of paranoia.
Their innovative approach involved analyzing data collected from The paper presented in Cell Reports discusses how researchers have been able to gain insights into human cognition by studying monkeys. The researchers at Yale University used a cross-species approach to analyze data from previous studies on paranoia, shedding new light on the neural underpinnings of this condition. Although previous studies have identified some brain regions associated with paranoia, there is still limited understanding in this area. By analyzing data from both humans and monkeys, the researchers were able to offer a fresh perspective on this topic.The task measures how unstable a participant perceives their environment to be. In each study, participants were presented with three options on a screen, each associated with different probabilities of getting a reward. If they chose the option with the highest probability, they would receive the reward with fewer clicks. The option with the lowest probability required more clicks. The third option was in between. Participants didn’t know the probability of the reward and had to figure it out on their own.Best option by trial and error. After a set number of trials and without warning, the highest and lowest reward probability options flip. “So participants have to figure out what’s the best target, and when there’s a perceived change in the environment, the participant then has to find the new best target,” said Steve Chang, associate professor of psychology and of neuroscience in Yale’s Faculty of Arts and Sciences and co-senior author of the study. Participants’ clicking behavior before and after the flip could reveal information about how volatile they view their environment to be and how adaptive their behavior is with”In the ever-changing environment, we not only utilized data from monkeys and humans performing the same task, but also applied the same computational analysis to both datasets,” stated Philip Corlett, an associate professor of psychiatry at Yale School of Medicine and co-senior author of the study. “The computational model consists of a series of equations that we can use to interpret behavior, and in this case, it acts as the common language between the human and monkey data, allowing us to compare and understand the relationship between the two.” Previous studies have shown that some monkeys had small, specific lesions.The study focused on two specific areas of the brain: the orbitofrontal cortex, linked to decision-making based on rewards, and the mediodorsal thalamus, responsible for relaying environmental information to the brain’s decision-making centers. Among the human participants, some had reported high levels of paranoia while others did not.
The researchers discovered that lesions in both of these brain regions had a negative impact on the monkeys’ behavior, but in different ways.
Monkeys with lesions in the orbitofrontal cortex tended to stick with the same choices even when they did not receive a reward.Those with damage to the mediodorsal thalamus showed unpredictable behavior even after being rewarded, suggesting that they perceived their surroundings as particularly unstable, similar to the behavior seen in humans with high levels of paranoia. This research provides insight into the role of the mediodorsal thalamus in paranoia and opens up new avenues for studying complex behaviors in simpler animals. It also allows researchers to explore how findings in simpler animals can be applied to understanding human behavior.Corlett, along with Chang, are part of Yale’s Wu Tsai Institute, which is focused on advancing human cognition. This method will also enable scientists to investigate how medications impacting conditions such as paranoia function in the brain. Chang also suggested that in the future, this approach could potentially lead to the development of new methods to alleviate paranoia in people. The study was primarily conducted by Praveen Suthaharan, a graduate student in Corlett’s lab, and Summer Thompson, an associate research scientist at Yale’s De.The research was conducted by the Department of Psychiatry in collaboration with Jane Taylor, who holds the Charles B.G. Murphy Professor of Psychiatry position at Yale School of Medicine.
