Temporal expectation is the ability to make predictions and to use temporal information to anticipate the occurrence of future events. This capacity is associated with highly efficient perceptual and motor behaviors. However, how cognitive systems use temporal information to optimize behavior and what brain structures are engaged during these processes remains largely unknown. Neurophysiological and recent neuroimaging data have suggested that temporal expectations modulate activity not only in parietal and motor-related frontal regions, but also in occipital visual cortex, when the expected stimulus is a simple visual object. Here we investigate crossmodal properties and category selectivity of temporal expectations examining activity in visual cortex during expectation of auditory stimuli (the sound of hand-clapping or of a hammer-hammering). We found that activity in occipital cortex changed over time, reflecting the subject's temporal expectations about the upcoming auditory event. This modulatory effect included extrastriate visual areas known to process body-parts and tools, despite these were never presented visually during the experiment. However activity in these areas was not specific for the expected sound category, but it was rather related to the overall probability of the auditory target to occur. We conclude that crossmodal associations can influence activity in sensory-specific visual areas in an anticipatory manner, consistent with temporal expectations affecting activity in a distributed system of motor-related and sensory-related brain regions.
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