Recent advance in brain science has revealed some mechanisms of knowledge processing in the human brain. We study the knowledge processing about how the visual and auditory systems acquire and process knowledge derived from the external environment, how the memory system retains such knowledge, how the multimodal knowledge processing is achieved, and so on, from a neuroscience point of view. In parallel, they learn anatomical brain structures and pathways, and experience peripheral and central illusions to understand knowledge processing phenomenologically.