Our brain is highly complex with billions of neurons; how do neurons work together to produce adaptive & flexible behaviors? Systems neuroscience studies this question at the systems level. Using various animal models, it aims to provide quantitative and causal links between neural circuits/networks and perception, behavior, and cognition. Through this course, you will learn about the popular animal models with simpler brains and interpret the neural mechanisms from multiple perspectives, to acquire a quantitative understanding. Particularly, this course will emphasize interdisciplinary technology, such as large-scale optical neural recording and computational tools. Knowledge gained will provide insights into understanding mental disorders and artificial intelligence.