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The COVID-19 pandemic has plunged all of us into a state of uncertainty. In a rapidly changing situation where it is difficult to know what will happen next, making decisions can be difficult. Researchers from the University of Cambridge and University College London have created a simplistic model of this uncertain situation in the laboratory to understand how our brains respond.
They found that when situations seem stable, we tend to rely on our previous experiences to help us anticipate what will happen in the future. But when the world is unstable, our brains can let go of these expectations and allow for rapid learning. The balance between the two approaches is moderated by the brain chemical norepinephrine. The study was published today in the journal Current Biology.
“Adapting to uncertain situations helps us survive. When something unexpected happens, we have to decide if it’s a one-off and ignore it, or if it will continue to happen – in which case we could benefit from doing things differently, “said Dr Rebecca Lawson, researcher at the university. of Cambridge Department of Psychology and lead author of the study.
The study tested the effects of propranolol, a drug used to reduce anxiety and blood pressure, on how people responded to stable and changing situations. Propranolol blocks the action of noradrenaline.
Participants in the experiment – who did not suffer from anxiety – heard a sound and then an image of a house or a face was shown. They quickly learned to predict the image they would see depending on the sound they would hear before it appeared. The association between particular sounds and images was then changed at random intervals, increasing uncertainty and requiring participants to quickly learn new associations.
The reaction times of participants who received a placebo drug slowed as the associations became more unexpected. Those who received propranolol relied on sound to a greater extent when uncertainty was high. This suggests that the drug makes people more likely to rely on their expectations, based on previous experience, in the face of uncertainty, which may be how it works to reduce feelings of anxiety.
Using a computational model, the researchers showed that the Propranolol group was slower than the placebo group in learning to use new information to adjust their expectations of what might happen next when a situation is very uncertain.
“We found that a brain chemical called norepinephrine plays a role in our inability to predict the future when the state of the world is volatile,” Lawson said.
When a situation is stable – represented in the experiment by a fixed link between sounds and images – we can rely on our past experiences as a good guide for what will happen next. But when a situation is changing, we need to be more receptive to new information to try to understand what is going on and how to respond.
“Faced with uncertainty, people taking the anti-anxiety drug Propranolol showed a greater reliance on past experience to inform their behavior – they were less affected by changes in their environment that contradicted that experience,” Lawson said. .
Difficulty in balancing expectations with new information is believed to underlie many conditions including autism and anxiety. The team plans to extend their research to try to understand how people with these conditions learn under uncertainty. In the long run, this could help people with autism and anxiety recognize the source of their anxiety and manage it better.
This research was funded by Wellcome. Dr. Lawson is a Fellow of the Lister Institute and an Autistic Future Leaders Fellow.
Reference
Lawson, RP et al: “The computational, pharmacological and physiological determinants of sensory learning under conditions of uncertainty”. Current Biology, November 2020 DOI: 10.1016 / j.cub.2020.10.043
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