How Our Brain Works

The attributes of the human brain that produce human intelligence are the focus of this book. This book is about the real you. Not the reflected image you see in the mirror, the shape of your face and body and the coloration of your skin, hair, and eyes. That’s a machine. A set of moveable connected bones driven by muscles and covered with skin and hair. You control the machine that you see in the mirror. The real you is contained within your brain. At this very moment, your brain is building neural representations of every object you currently perceive and a neural representation of the space around you. These perceptions of objects and space, contained in different areas of your brain, are brought together to build your virtual world. That neural virtual world is your reality. The most important object in your virtual world is you. Your neural representation of yourself is much larger and more complicated than what you see in the mirror. In our conversations about the human brain, we will treat a very complex subject in a simple manner. The words simple and complex are terms that often describe our understanding of things rather than descriptions of the things themselves. Things we understand, we tend to describe as simple; things we do not understand, we tend to describe as complex. The brain is commonly referred to as the most complex structure in the known universe. This description is a reflection of our current lack of understanding as well as a tribute to the vast numbers of microscopic neuron cells, each with multiple thousands of interconnections to other neurons, that make up the brain. Most of your neural system is inherited. The neural circuits that comprise this portion of you are genetically determined, are identical in all humans, and remain static throughout your entire life. A few neural components, the cerebellum, basal ganglia and cerebral cortex, contain large arrays of identical neural circuits that modify their wiring with learning. It is these modified by experience neural components that enable human intelligence. I am going to assume that your familiarity with neurons and neural components is limited. This assumption creates an immediate problem. It is very difficult to discuss any aspect of human brain function without an understanding of neuron functionality and basic brain structure. An in depth discussion requires a great deal of prior knowledge. We will therefore divide our time together into two parts, an introductory journey through your brain followed by an in depth discussion and analysis. We will begin each of our two explorations with a discussion of neurons in chapters one and four. Neurons are the basic elemental building material from which brains are constructed. It is necessary to understand what they do and perhaps as importantly, what they don’t do. Neurons do not store data. Neurons do not perform computations. Performing computations on stored data are computer like functions. You cannot utilize neurons to build a computer. We are going to examine how neurons build a brain. Neurons are complex living cells that perform one function, pattern detection. What neurons are, how they work, and what they do is the purview of chapter one. Chapter four examines the attributes of neurons that enable learning and the need for, and capability of, neurons to support synchronous activity. Human intelligence is facilitated by a vast array of neurons performing various pattern detection tasks. The neural components that make up your nervous system will be introduced in chapter two. Your neural structure will be compared to the more familiar architectural structure of a five-story building. The various components that comprise the floors of that building will be discussed in some detail. After we have examined and understood these floors, we will re-examine each of the various neural components within actual brain architecture in chapter five, exploring their functions and how they accomplish those functions. The first floor of your brain building contains the elevator shaped spinal cord. Spinal cords have been around for over four hundred million years. Every spinal cord on earth today is just like yours. The second floor contains the brain stem, your reptilian brain. The brain stem is mostly a maintenance service center controlling temperature, blood pressure, heart rate and other functions necessary to keep the body alive and functioning. The second floor also contains a movement-learning center called the cerebellum. The cerebellum is where you store the patterns for “How to ride a bike”. There are two main rooms on the third floor that contain your chemistry lab, the hypothalamus, and your main switchboard, the thalamus. The hypothalamus is the master component of your limbic system. The limbic system controls behavior through the release of hormones. Quite specific, behaviorally correct, complicated behaviors are turned on and off by the limbic system’s control of the chemical state of the body. Watch a pair of birds perform an intricate, beautiful mating dance or feed their young to witness this type of chemically controlled behavior. An output control center called the basal ganglia completely occupies the fourth floor. The fourth floor controls your behavior. The fifth floor houses your executive level functions contained within your cerebral cortex. The storage of all the neural patterns that drive the higher-level neural capabilities that make you human are contained on the fifth floor. This is where memory patterns are recognized. Memory recognition in the cerebral cortex is enabled by large pyramidal neurons that have an average of 60,000 inputs and 20,000 outputs. A pyramidal neuron monitors its 60,000 inputs and signals to 20,000 other neurons its level of pattern recognition. Morphing this description to be more human friendly, 60,000 inputs can be represented as a black and white TV with a 245 by 245 pixel array. Not great resolution but a 245 by 245 array can display quite complicated patterns. Risking a giant anthropomorphic distortion of reality, the pyramidal neuron “watches” its black and white TV screen and signals to 20,000 other pyramidal neurons the level of pattern recognition it has for the current image. There are approximately fifteen billion pyramidal neurons in your cerebral cortex. The pattern complexity that can be represented by fifteen billion low-resolution black and white TV sets is staggering. There are numerous examples in the animal kingdom of one, two and three story brains. Each of these fewer floor brain-building architectures represent complete functioning neural systems sustaining the animals they serve. Brains have evolved to add more floors and enlarge existing floors. All mammals have five floors and all of these floors are very similar in all mammals. It is the fifth floor cerebral cortex and interconnected neural components that have expanded in size to enable the mental capacity that makes you human. The aspects of human intelligence we are trying to understand, memory, learning, intelligence, and behavior, will be introduced in chapter three. Each is presented and dissected. A highly speculative discussion of human brain evolution is also presented in chapter three. The human nervous system was not designed, it was grown. New structures that enabled new capabilities were added on top of existing neural systems through evolution. Each new evolutionary stage of neural development represents a complete, operational nervous system. Neural subsystems were not discarded and replaced by new designs. After around 500 million years of this process, human intelligence emerged. The sixth and final chapter ties all of the neural components together into a complete architectural model of your brain. Based on this architectural model and the sum total of all our prior deliberations, explanations of memory, learning, and behavior are presented. This book contains a great deal of s