5 Steps to a 5 AP Psychology, 2010-2011 Edition by Laura Lincoln Maitland Page B

of people. An EEG (electroencephalogram) is an amplified tracing of brain activity produced when electrodes positioned over the scalp transmit signals about the brain’s electrical activity (“brain waves”) to an electroencephalograph machine. The amplified tracings are called evoked potentials when the recorded change in voltage results from a response to a specific stimulus presented to the subject. EEGs have been used to study the brain during states ofarousal such as sleeping and dreaming, to detect abnormalities (such as deafness and visual disorders in infants), and to study cognition. Another technology, positron emission tomography (PET) produces color computer graphics that depend on the amount of metabolic activity in the imaged brain region. When neurons are active, an automatic increase in blood flow to the active region of the brain brings more oxygen and glucose necessary for respiration. Blood flow changes are used to create brain images when tracers (such as radioactively tagged glucose) injected into the blood of the subject emit particles called positrons, which are converted into signals detected by the PET scanner. Functional MRI (fMRI) shows the brain at work at higher resolution than the PET scanner. Changes in oxygen in the blood of an active brain area alters its magnetic qualities, which is recorded by the fMRI scanner. After further computer processing, a detailed picture of that local brain activity emerges. With new brain imaging technology, psychologists can explore far more about our abilities than ever before, from well-known systems like perception to less understood systems like motivation and emotion.
Organization of Your Nervous System
    Your patterns of behavior generally involve masses of neural tissue rather than a few neurons. All of the neurons in your body are organized into your nervous system. Your nervous system has subdivisions based on location and function. The two major subdivisions are your central nervous system and your peripheral nervous system. Your central nervous system consists of your brain and your spinal cord. Your peripheral nervous system includes two major subdivisions: your somatic nervous system and your autonomic nervous system. Your peripheral nervous system lies outside the midline portion of your nervous system carrying sensory information to and motor information away from your central nervous system via spinal and cranial nerves. Your somatic nervous system has motor neurons that stimulate skeletal (voluntary) muscle. Your autonomic nervous system has motor neurons that stimulate smooth (involuntary) and heart muscle. Your autonomic nervous system is subdivided into the antagonistic sympathetic nervous system and parasympathetic nervous system . Sympathetic stimulation results in responses that help your body deal with stressful events including dilation of your pupils, release of glucose from your liver, dilation of bronchi, inhibition of digestive functions, acceleration of heart rate, secretion of adrenalin from your adrenal glands, acceleration of breathing rate, and inhibition of secretion of your tear glands. Parasympathetic stimulation calms your body following sympathetic stimulation by restoring digestive processes (salivation, peristalsis, enzyme secretion), returning pupils to normal pupil size, stimulating tear glands, and restoring normal bladder contractions. Your spinal cord , protected by membranes called meninges and your spinal column of bony vertebrae, starts at the base of your back and extends upward to the base of your skull where it joins your brain. The cord is composed mainly of interneurons and glial cells, which are all bathed by cerebrospinal fluid produced by your glial cells.
The Brain
    Your brain , which has the consistency of soft-serve yogurt, is covered by protective membranes called meninges, and is housed in your skull. The evolutionary approach describes the brain’s evolution from more primitive organisms, reasoning