Systems neuroscience addresses how neural circuits are formed and function anatomically and physiologically. Sensory integration, motor coordination, circadian rhythms, emotional responses, and learning and memory are key physiological processes governing neural circuit functions and behavioral mechanisms. Neuroethology is the evolutionary and comparative approach to studying the underlying neurophysiological mechanisms of animal behavior. Neuroendocrinology is the study of how the nervous system and the endocrine system function, cooperatively. Psychoneuroimmunology examines various interactions of the nervous system and immune system.