Introduction to Psychology

Introduction to Psychology of 97 Parts of the Brain-The structures of the brain’s core, which we share with all other vertebrates, govern the basic physiological functions that keep us alive, such as breathing and heart rate. Built upon these basic structures are newer systems that involve progressively more complex functions - sensing, wanting, thinking, and reasoning. Cortex- The cerebral cortex, a ¼ inch thick sheet of gray unmyelinated cells that form the outermost layer of the human brain, is the crowning achievement of brain evolution, and in humans constitutes 80 percent of brain tissue. The cerebral cortex is divided into the frontal, parietal, occipital, and temporal lobes. Some areas of the cerebral cortex receive sensory input, some control motor functions, and others (the association cortex) are involved in higher mental processes in humans. The frontal lobes are particularly important in such executive functions as planning, voluntary behavior, and self-awareness, perception, language, and thought. Medulla-The 1.5-inch medulla is the first structure above the spinal cord and plays an important role in vital body functions such as heart rate and respiration. Because of the medulla, these functions occur automatically. Damage to the medulla can result in death, or at best, the need to be maintained on a life support system. The medulla is also a two-way thoroughfare for all the sensory and motor nerve tracts coming up from the spinal cord and descending from the brain. Most of these tracts cross over within the medulla, so the left side of the brain receives sensory input from and exerts motor control over the right side of the body, and the right side of the brain serves the left side of the body. Corpus Callosum- The left and right hemispheres are connected by a broad white band of myelinated nerve fibers. The corpus callosum is a neutral bridge consisting of white myelinated fibers which act as a major communication link between the two hemispheres and allow them to function as a single unit. Pons- A word meaning bridge in Latin, lies just above the medulla and carries nerve impulses between higher and lower levels of the nervous system. The pons has clusters of neurons that help regulate sleep. Like the medulla, the pons helps control vital functions, especially respiration, and damage to it can produce death. Reticular Formation- Buried within the midbrain is a finger-shaped structure that extends from the hindbrain up into the lower portions of the forebrain. The reticular formation acts as a kind of sentry, both alerting higher centers of the brain that messages are coming and then either blocking those messages or allowing them to go forward. The reticular formation plays a vital role in consciousness, attention, and sleep. Activity of the ascending reticular formation excites higher areas of the brain and prepares them to respond to stimulation. The descending reticular formation acts as a gate, determining which stimuli enter into consciousness. Cerebellum- Attached to the rear of the brain stem is the little brain known as the cerebellum. Its wrinkled cortex or covering, consists mainly of gray cell bodies (gray matter). The cerebellum is concerned primarily with muscular movement coordination, but it also plays a role in learning and memory. © 2015 Achieve Page 22