Priming of visual cortex by temporal attention? The effects of temporal predictability on stimulus(-specific) processing in early visual cortical areas

In recent studies it has been shown that temporal predictability of expected events alters processing in perception and action. Yet, the neural mechanism(s) by which temporal predictability biases this processing is to date little understood. Therefore, in the present fMRI study we investigated how temporal predictability affects neural processing in visual cortical areas. For this, thirty-four participants either categorized the gender or the movement direction of vertically or horizontally moving faces in different blocks of trials. Temporal predictability of stimulus onset was manipulated by the presence or absence of an auditory alerting signal validly predicting stimulus onset. The behavioral data revealed a clear performance benefit for the presence of an alerting signal. Neuroimaging results showed that irrespective of the currently performed task temporal predictability significantly reduced activation in the primary visual cortex. This activation reduction correlated with the alerting signal-related performance benefit. Furthermore, we did not find a selective influence of increased temporal predictability on target-specific visual processing (faces or movement) in the respective material-specific visual brain areas. Together, these findings suggest an increased task-unspecific readiness by the alerting signal that might result in more efficient transmission of stimulus codes into response codes.