Neural and cognitive mechanisms of predictive coding and their interactions for perception and action

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In daily life we seldom marvel at abilities such as grabbing a cup of coffee, recognizing a friend's face, or jogging through a park. But these tasks are enormously challenging: we have to deal with overwhelming amounts of ambiguous and incomplete information entering our eyes and other senses. Why then don't we always spill coffee, ignore our friends or crash into trees? There is growing evidence that to deal with these challenges the brain behaves much like a detective who makes smart inferences. The brain uses not only available sensory "evidence," but also prior knowledge about the world to predict what the world should be like. The underlying principle is called predictive coding and recent computer models have proposed that the visual cortex may implement the principle in a hierarchy of so-called prediction modules. It is unclear, however, whether the same hierarchical system can explain any form of prediction mechanisms based on unconscious, implicit expectations as well as conscious or explicit expectations about the world, or whether different mechanisms apply. It is also unclear how visual process-es tie in with visuomotor functions. Therefore, I propose to study visual perception together with several forms of expectations, as well as vision in the context of hand and eye movements. Leading a research team of graduate and undergraduate students I will test object perception in healthy human participants using an `expected feature perception paradigm' while recording electrophysiological signals from their brain or while stimulating brain functions with magnetic pulses. ***Theme 1 will test whether effects of explicit expectations (i.e., attention to colours or shapes) and implicit expectations (e.g., transient plasticity due to repeated presentation of stimuli) interact at specific times of electrophysiological brain signals as predicted by predictive coding models or whether more complex models are required. ***Theme 2 will investigate in depth predictive effects of attention in terms of attentional capacity and stimulus similarities. ***Theme 3 will examine predictive coding principles during visually guided grasp movements. ***Theme 4 will investigate predictive coding during eye movements. ***In sum, this research will pursue a new, comprehensive approach to investigating vision. This research can be expected to give us a more complete understanding of the different forms of predictive coding in the brain. Such understanding would constitute a significant step towards a unifying theory of the visual brain as a dynamic system embedded in a complex world with important benefits for technical applications such as augmented reality.**