The smooth, well-coordinated yet complex functioning of the brain is truly a marvel of nature. Like a well-organized corporate office, your brain is divided up into different sections, each with its own set of responsibilities and tasks. The brain is comprised of several main parts:
The cerebrum is the largest part of the brain and is made up of the right and left hemispheres. The cerebrum contains your gray matter, which gives its outside surface a grayish-brown hue. It is the center of most of your cognitive processes—efforts like thinking, analyzing, organizing, and decision-making in large part take place here.
On the outer layer of the cerebrum is the cerebral cortex. Higher brain functions, like pondering a complicated calculus problem or deciding which is the quickest route to a destination, take place in this part of the brain. It is here that the brain processes the barrage of sensory information it receives, controls our movements, and regulates thoughts and mental activity.
At the center of the two hemispheres is a thick band of nerve cell fibers called the corpus callosum. The corpus callosum links all the billions of neurons between the two hemispheres.
Scientists believe that each hemisphere processes information somewhat differently. The left hemisphere appears to focus in on details, while the right deals with background, or the big picture.
Each hemisphere is made up of four lobes:
• The frontal lobe. Located just behind your forehead, the frontal lobe is largely responsible for your personality. It handles problem solving, abstract thinking and skilled movement.
• The parietal lobe. Just behind the frontal lobe is the parietal lobe. Here is where the brain receives sensory information, such as taste, smells, and textures. It also helps you determine your location in space using visual and spatial cues and allows you to navigate your surroundings.
• The temporal lobe. At the side of your forehead, just behind your temple is the temporal lobe. This lobe is responsible for hearing, some aspects of language comprehension, perception, and essential memory functions.
• The occipital lobe. Behind each hemisphere is the occipital lobe, which contains the visual cortex. This lobe handles vision.
The Limbic System
At the center of the cerebral hemispheres is an area known as the limbic system. The limbic system regulates your emotions, instincts, and motivation. It connects your brain stem to the regions of the cerebral cortex.The limbic system houses several other important parts of the brain:
• The hippocampus is a key player in your ability to memorize, store, sort, and retrieve information. Scientists believe that it is here that short-term memories are converted into long-term memories and sent to be stored elsewhere in the brain.
• The hypothalamus acts as the body’s internal regulation system, where hormones, food intake, and body temperature are controlled.
• The amygdala houses the body’s fight or flight response system and governs powerful emotions such as fear and anger.
Like the cerebrum, the cerebellum is made up of two hemispheres. But the cerebellum is considerably smaller, occupying just slightly more than ten percent of the brain. The job of the cerebellum is to coordinate balance and movement. A steady flow of information about your environment helps the cerebellum determine your movements—the dash across the street just before a traffic light changes, stooping to retrieve a dropped object without falling, or turning to greet someone who’s just tapped you on the back.
The Brain Stem
At the base of the brain sits the brain stem, which connects the spinal cord to the brain. As the smallest part of the brain, the brain stem controls our body’s autonomic processes, such as our heart rate and breathing. Information transmitted between the brain and the spinal cord takes place in the brain stem, too. In addition, the brain stem controls our sleep and dreaming.
On its way to the cerebral cortex, all sensory information passes through the thalamus. There, information is processed, prioritized and sent elsewhere in the brain.