The representation of erroneously perceived stimuli in the primary visual cortex

In order to attain a correct interpretation of an ambiguous visual stimulus , the brain may have to elaborate on the sensory evidence. Are the neurons that carry the sensory evidence also involved in generating an interpretati on? To address this question, we studied the activity of neurons in the pri mary visual cortex of macaque monkeys involved in a task in which they have to trace a curve mentally, without moving their eyes. On a percentage of t rials, the monkeys made errors and traced the wrong curve. Here, we show th at these errors are predicted by activity in area V1. Thus, neurons in the primary visual cortex do not only represent sensory events, but also the wa y in which they are interpreted by the monkey.