Neural processes for action observation

Abstract

Through actions we explore the world around us, we express ourselves, achieve goals and interact with others. We are thinking about actions, planning, executing, imitating, observing, and understanding them. In other words, our life is filled with motor cognition. Yet our knowledge of the brain processes underlying these tasks is limited.Based on extensive literature we know that action observation and production share common neural mechanisms and a common neural network. Throughout the studies in this thesis, I use this connection to explore neural processes related to motor cognition.In the first chapter, I examine current theories on action observation and identify key concepts investigated in the later experiments. I review a wide range of literature from the fields of neural disorders and healthy participants tested on various tasks, such as visual illusions, motor expertise, and conscious and unconscious visual processing. Focusing on the bidirectional information flow between motor and perceptual areas, I examine how well the common coding theory, the direct matching hypothesis, and predictive coding models fit the current experimental results. I argue that, while predictive coding theories are best to explain the wide variety of results related to motor cognition, there are still important questions unanswered in the literature. There is a relative lack of studies investigating motor cognition in close-tonatural settings, and attentional modulation is often ignored. Furthermore, more research is needed to explore the spatial and temporal dynamics of how observed and executed actions present on the neural level.In the first experiment, I investigate how the brain processes actions when they are not consciously attended. I recorded brain activity related to action observation under an attentionally demanding visual task. Data indicate that even when our attention is directed away from actions both the motor and perceptual systems -as part of the action observation network-show a systematic change depending on the novelty of action properties. The results of this experiment also suggest that action related information is prioritised even when attentional resources are limited. In the second experiment, I examined how attention on specific action representations, such as kinematics, goals and agency, influences brain response during the processing of actions. The results of this experiment suggest that, even though novelty-related 3 changes are very strong throughout in the action observation network, attention can specifically modulate neural activity to enhance the processing of task-specific information.Finally, in the third experiment, I investigated how a common system can deal with the parallel processing of action execution and observation. I aimed to give a comprehensive picture of neural activity related to motor cognition, and thus analysed event-related magnetic field activity and power changes in theta, alpha and beta frequency bands. Data indicated that neural processes are sensitive to ...