Basic Brain Anatomy

Richard Edelson, Ph.D.

Explaining brain illness and injuries is easier when one has a basic understanding of brain anatomy. The brain has two halves, called hemispheres, and is divided down the middle by a long groove, called the Central Sulcus. Information flows from one half to the other across a set of nerve fibers called the Corpus Callosum. In right-handed people, the right hemisphere controls/mediates visuospatial (i.e., perceptual), eye-motor-hand types of activities. These include visual reasoning, construction, and memory. It also controls the motor and sensory skills on the left side of the body. The left hemisphere controls verbal skills (i.e., those involving words or language). These include verbal reasoning, reading, writing, talking, and understanding what people say, and remembering what is said or read. It also controls the motor and sensory skills on the right side of the body.

There are four sections, or lobes, in each half. The entire forward half is called the Frontal lobes. They control reasoning, judgment, attention/concentration, multi-tasking, organization, language production, motor skills, personality, and emotional regulation. Behind the frontal area are the Parietal lobes. On the left they mediate understanding language, word knowledge, and feeling sensation from the right side of the body. The right Parietal lobe directs visual attention (where the eyes go), visual perception and praxis (seeing and knowing how parts fit together to form a whole), and feeling sensation from the left side of the body.

The Temporal lobes sit behind and under the parietal lobes. Their primary cognitive function is memory. Memory can be divided into types such as immediate, short-term, and long-term, entailing verbal and/or visual information. This area also involves smell and sound and particularly pairing sounds with letters. Finally, the Occipital lobes, in the back of the brain, control some aspects of vision; the left occipital the right field of vision, and the right occipital the left field of vision.

Other brain areas to be discussed later include the Basal Ganglia/subcortex, the Limbic system, and the Cerebellum, as well as the flow of information into and out of the brain. Stay tuned.