Structural or functional abnormalities of brain

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Structural or functional abnormalities of brain structures are involved in various forms of abnormal behavior. For example, investigators have found abnormalities in parts of the cerebral cortex and limbic system in patients with schizophrenia (discussed in Chapter 11). The hypothalamus is implicated in certain types of sleep disorders (see Chapter 9), and deterioration of the basal ganglia is associated with Huntington's disease-a degenerative disease that can lead to disturbances of mood, paranoia, and even dementia (see Chapter 14). These are but a few of the brain-behavior relationships we shall discuss in later sections of this text. ------ Central Fissure Motor Area (B)
46 Chapter 2 Watch HOW THE BRAIN WORKS, PART 2 Watch the video Ho w the Brain Work s, Part 2 to learn how the nervous system is divided and how it processes information, the significance of each of the different brain structures, and how neuronal transmission works. TRUTH or FICTION Peripheral Nervous System The peripheral nervous system is a network of neurons con- necting the brain to our sense organs-our eyes, ears, and so on-as well as our glands and mus- cles. These neural pathways allow us to both sense the world around us and act on it by using our muscles to move our limbs. The peripheral nervous system consists of two main parts or divisions, called the somatic n ervous system and the autonomic nervous system (see Figure 2.3). The somatic nervous syst em transmits mes- sages from our sensory organs to the brain for processing, leading to the experience of visual, auditory, tactile, and other sensations. Commands emanating from the brain pass downward through the spinal cord to nerves of the somatic nervous system that connect to our muscles, allowing us to voluntarily control our movements, such as when raising an arm or walking. Psychologists are especially interested in the workings of the autonomic nervous syst em (ANS) because of its role in emotional processing. Autonomic means automatic. The ANS regulates the glands and involuntary processes such as heart rate, breathing, digestion, and dilation of the pupils of the eyes, even when we are sleeping. The ANS has two branches, the sym path etic nervous system and the parasympathetic nervo us sy st em . These branches have mostly opposing effects. Many organs and glands are served by both branches of the ANS. The sympathetic division is most involved in pro- cesses that mobilize the body's resources during physical exertion or responses to stress, such as when drawing energy from stored reserves to prepare a person to deal with impos- ing threats or dangers (see Chapter 4). When we face a threatening or dangerous situation, the sympathetic branch of the ANS kicks in by accelerating our heart rate and breathing rate, thereby preparing our body to either fight or flee from a threatening stressor. Sympathetic activation in the face of a Anxiety can give you indigestion.

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