Neurochemistry is the study of the chemical processes and substances in the nervous system. It focuses on neurotransmitters, neuromodulators, and other molecules that influence brain function and neural communication. By investigating how these chemicals affect mood, cognition, and behavior, neurochemistry helps to understand the biochemical basis of neurological disorders and mental health conditions. This field plays a crucial role in developing treatments for diseases like Parkinson's, Alzheimer's, and depression, as well as in uncovering the underlying mechanisms of brain function.