Higher Brain Functions
.... Last scene of all, That ends this strange eventful history, Is second childishness, and mere oblivion, Sans teeth, sans eyes, sans taste, sans everything.
This chapter presents an overview of normal brain functions with emphasis on higher brain (cortical) functions. It will describe in general terms how brain systems function and how Alzheimer's disease impairs these systems. This basic description should help prepare the reader for subsequent chapters on the effects and management of Alzheimer's disease.
People have known for centuries that the human brain is the primary organ of thought (cognition) and emotion. The brain grows to weigh approximately 3 pounds by the time a person reaches age 30, and then it slowly begins to lose tissue. By using the brain's capacity for complex planning, problem solving, and communicating, humans have been able to travel to the moon, solve medical mysteries, and build elaborate computer networks, but much still needs to be learned about how the brain actually works. A great deal of what people have already learned about the brain has come through the study of brain lesions caused by injuries or diseases such as Alzheimer's disease, Parkinson's disease, and others that affect the nervous system.
The central nervous system is composed of the spinal cord and the brain. The brain is structurally divided into two cerebral hemispheres that correspond to the left and right sides of the body. The hemispheres are connected by a large