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How the brain makes a difficult decision

Two publications from SISSA track the perceptual decision making process

New research conducted in the Cognitive Neuroscience group of SISSA shows that a perceptual decision – recognizing an object and taking the appropriate action – is triggered as soon as the brain’s processing networks accumulate the exact right quantity of sensory information. Our sensory receptors continuously collect information from the outside world, allowing us to understand what surrounds us and to behave accordingly. Recognizing the identity of an object often seems almost instantaneous. However, sometimes information enters the sensory system more gradually, in fits and starts, and an immediate percept is not possible. How, then, are signals accumulated over time?

When does the nervous system decide that “enough is enough: it’s time to act”? Two new publications in Current Biology by Yanfang Zuo and Mathew E. Diamond (director of SISSA’s Tactile Perception and Learning Lab) show that the brain compares the incoming sensory evidence in favor of competing percepts and expresses a decision as soon as the total acquired evidence for one choice reaches a fixed boundary. The studies uncover fundamental brain mechanisms underlying decision making in an uncertain world.