Imagine picking up a glass of what you think is apple juice, only to take a sip and discover that it’s actually ginger ale. Even though you usually love the soda, this time it tastes terrible. That’s because context and internal states, including expectation, influence how all animals perceive and process sensory information, explained Alfredo Fontanini, a neurobiologist at Stony Brook University in New York. In this case, anticipating the wrong stimulus leads to a surprise, and a negative response.
But this influence isn’t limited to the quality of the perception. Among other effects, priming sensory systems to expect an input, good or bad, can also accelerate how quickly the animal then detects, identifies and reacts to it.
Years ago, Fontanini and his team found direct neural evidence of this speedup effect in the gustatory cortex, the part of the brain responsible for taste perception. Since then, they have been trying to pin down the structure of the cortical circuitry that made their results possible. Now they have. Last month, they published their findings in Nature Neuroscience: a model of a network with a specific kind of architecture that not only provides new insights into how expectation works, but also delves into broader questions about how scientists should think about perception more generally. Moreover, it falls in step with a theory of decision making that suggests the brain really does leap to conclusions, rather than building up to them.
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