PI: Paul Sauseng
Our visual perception is strongly influenced by expectancies we have about incoming sensory information. Anticipated information is more efficiently processed than unexpected input. It is assumed that mental templates of expected sensory input are created that can be applied if matching sensory information is received. In this project the neural signatures of this matching process shall be investigated. It has been suggested that the matching of visual input with mental templates is reflected by transient phase synchronization between theta (oscillatory brain activity around 5 Hz) and gamma (>30Hz) frequencies in posterior brain areas, reflecting the interplay between top-down and bottom-up processing, respectively. Here we plan to run a series of experiments in which electroencephalogram (EEG) is recorded in healthy human volunteers. It will be investigated (i) how predictability of visual stimuli are influencing phase synchronization between theta and gamma brain oscillations, (ii) whether transient theta:gamma synchronization in the ongoing EEG indicates identification of a target in visual search tasks, (iii) how semantic knowledge (i.e. pre-existing knowledge about stimulus categories) influences matching between expectations and visual input reflected by theta:gamma phase synchronization, and (iv) what the dynamics of these processes are while expectations are developed.