Brain circuit keeps tabs on what just happened to aid judgment of what's happening now
A brain must constantly cope with the highly variable, fast-paced nature of the world when trying to judge what's going on around it. On the one hand, it has to be open to whatever new sensory information may come its way, but on the other hand, just to keep up, it has to try to leverage prior experience to make predictions about what seems to be happening. In a new study in Science, MIT…
In a recent study published in Science, MIT neuroscientists have identified a brain circuit that helps animals and humans evaluate the present sensory information in relation to their recent experiences. The circuit connects a sensory decision-making region with one that assesses how much sensory information has changed. This allows them to make predictions about what is happening in the sensory world and take appropriate actions.
Led by senior author Mriganka Sur, a Newton Professor at the Picower Institute for Learning and Memory, and lead author Ning Leow, the research sheds light on the role of the pulvinar thalamus and the anterior cingulate cortex (ACC) in the brain. The pulvinar, traditionally known for its role in attention and visual filtering, is also crucial for comparing current sensory information with the immediate past.
Sur and Leow trained mice to play a video game where they had to discern patterns in the movement of dots on a screen. By measuring the mice's performance over successive trials, they found that the mice relied on both the present sensory information and their recent experiences to make decisions. When the cues were similar to the previous ones, the mice were more likely to repeat their previous guesses, while different cues led to more variable responses.
To confirm that the pulvinar-ACC circuit was responsible for this comparison process, the researchers used optogenetics to manipulate the circuit's activity. This manipulation altered the mice's decision-making, showing that the circuit was causally involved in integrating recent sensory history when interpreting new evidence.
The findings have implications for understanding autism, as many patients with the condition exhibit difficulties in filtering out recurring stimuli and making predictions about the sensory world. The study offers insights into the fundamental functioning of the brain and its ability to adapt to a constantly changing environment.
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