However, they are able to recreate the picture with their left hand, which is also controlled by the right hemisphere. For instance, a split-brain patient is unable to name a picture that is shown in the patient’s left visual field because the information is only available in the largely nonverbal right hemisphere. After surgery, these split-brain patients show a variety of interesting behaviors. While this is an effective treatment option, it results in individuals who have split brains. In some cases of severe epilepsy, doctors elect to sever the corpus callosum as a means of controlling the spread of seizures (Figure 2). Normally, we are not aware of the different roles that our two hemispheres play in day-to-day functions, but there are people who come to know the capabilities and functions of their two hemispheres quite well. The corpus callosum allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side. The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum, consisting of about 200 million axons. What we do know is that the left hemisphere controls the right half of the body, and the right hemisphere controls the left half of the body. Beyond that, however, the differences that have been found have been minor (this means that it is a myth that a person is either left-brained dominant or right-brained dominant). There is evidence of some specialization of function-referred to as lateralization-in each hemisphere, mainly regarding differences in language ability. (credit: modification of work by Bruce Blaus) A deep sulcus is called a fissure, such as the longitudinal fissure that divides the brain into left and right hemispheres. The surface of the brain is covered with gyri and sulci. The most prominent sulcus, known as the longitudinal fissure, is the deep groove that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere.įigure 1. These gyri and sulci form important landmarks that allow us to separate the brain into functional centers. The surface of the brain, known as the cerebral cortex, is very uneven, characterized by a distinctive pattern of folds or bumps, known as gyri (singular: gyrus), and grooves, known as sulci (singular: sulcus), shown in Figure 1. Therefore, the lower on the spine damage is, the fewer functions an injured individual loses. When the spinal cord is damaged in a particular segment, all lower segments are cut off from the brain, causing paralysis. The spinal cord is protected by bony vertebrae and cushioned in cerebrospinal fluid, but injuries still occur. In matters of survival, the spinal reflexes allow the body to react extraordinarily fast. Seconds are saved, because messages don’t have to go the brain, be processed, and get sent back. The signal passes from the sensory nerve to a simple processing center, which initiates a motor command. When a sensory message meets certain parameters, the spinal cord initiates an automatic reflex. Withdrawal from heat and knee jerk are two examples. Some sensory messages are immediately acted on by the spinal cord, without any input from the brain. Messages travel to and from the brain through every segment. Sensory nerves bring messages in motor nerves send messages out to the muscles and organs. Nerves branch out from the spine at each vertebra. Each segment is connected to a specific part of the body through the peripheral nervous system. The spinal cord is functionally organized in 30 segments, corresponding with the vertebrae. In the opposite direction, the spinal cord ends just below the ribs-contrary to what we might expect, it does not extend all the way to the base of the spine. The top of the spinal cord merges with the brain stem, where the basic processes of life are controlled, such as breathing and digestion. It not only routes messages to and from the brain, but it also has its own system of automatic processes, called reflexes. The spinal cord is like a relay station, but a very smart one. It can be said that the spinal cord is what connects the brain to the outside world. Each lobe is associated with certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviors. It is a bilateral, or two-sided, structure that can be separated into distinct lobes. The brain is a remarkably complex organ comprised of billions of interconnected neurons and glia. The central nervous system (CNS), consists of the brain and the spinal cord. Identify the location and function of the lobes of the brain.Explain the two hemispheres of the brain, lateralization and plasticity.
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