This document provides an overview of basic brain anatomy and functions. It is divided into multiple parts. Part 1 discusses the early development of the human embryo's brain within the first 6 weeks. It also covers the basic units of the brain - neurons and synapses. Additionally, it compares the size of human and animal brains. The brain is described as having three main parts: the reptilian brain for instinct, the limbic system for emotion, and the neocortex for higher-level thought. The reptilian brain and limbic system are the evolutionarily older parts of the brain. The document notes that part 2 will provide more details on brain functioning.