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Chapter 7 notes.docx

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Connie Boudens

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Chapter 7: The Neuroscience of Personality Evidence suggests that the regular practice of mindfulness meditation makes people more receptive to positive emotions, decreases anxiety, and strengthens the immune system WHAT IS NEUROSCIENCE AND HOW DO WE STUDY IT? The nervous system:  Central nervous system  Brain  Spinal cord  Peripheral nervous system  Somatic nervous system- controls movement of the muscles  Autonomic nervous system- regulates smooth muscle (inner organs), cardiac muscle & glands:  Sympathetic division- mobilizes energy (for flight or fight)  Parasympathetic division- replenishes the body’s energy stores (salivation, digestion…) The brain is protected by a bath of cerebrospinal fluid (CSF) that cushions the delicate brain and also flows through spaces in the brain called ventricles. CSF is similar to blood plasma, and is continually produced, circulated, and reabsorbed thru the brain and the ventricles Researchers hypothesize that differences in bodily responses, brain structures, brain activity, and biochemical activity are all related to individual differences in personality Bodily Responses:  When aroused the sympathetic system responds by increasing heart rate, blood pressure, blood flow to the extremities, respiration, sweating, and muscle activity  Galvanic skin response (GSR)- measure of skin conductance or how quickly a slight electrical current passes thru 2 points on the skin. The faster the conductance of the current, the more moisture is present that indicates greater arousal. (measures sweating)  Electromyography (EMG)- (myoelectric activity) estimates the electrical impulses of the muscles during contraction and relaxation. Often used in biofeedback to train people to perceive muscle contractions so that they can learn to relax their muscles Brain Structure:  Researchers look for differences among people in the relative size & weight of specific parts of the brain, or even in the kinds and # of cells found in various parts of the nervous system  Computerized tomography (CT)- takes a high-resolution x-ray picture of the brain; by looking at thin cross section of the brain (often less than a millimetre) we can detect abnormalities or differences in brain tissue. This technique was once called Computer axial tomography (CAT)  Magnetic resonance imaging (MRI)- radio frequency waves are used instead of x-rays. First a strong magnetic field causes the nuclei of some atoms to resonate. Then radio frequency waves are used to detect the activity of these atoms. Because hydrogen atoms are present in all tissues but in varying concentrations, the pattern of resonance formed by the hydrogen forms a multidimensional pic of the brain Brain Activity:  Measures of brain activity are ways of looking for differences in brain structures while the brain is stimulated  often participants are given a mental task to work on or other stimuli to react to while measures of brain activity are taken  An early technique of studying brain activity is cortical stimulation- using either electrodes implanted in the brain or direct electrical stimulation of parts of the brain, the patient is awake and can report on sensations as various parts of the brain are being stimulated  Electroencephalogram (EEG)- electrodes are put on scalp to monitor electrical activity of brain  Evoked potential (EP)- when electrical activity of the brain or other part of the nervous system is measured in response to a specific stimulus  Positron emission tomography (PET)- slightly radioactive glucose like substance with a very short half-life is injected into the brain & the person is placed in a scanner (like a CT scanner). Active regions of the brain use up more glucose than inactive regions & with the aid of computer enhancement, scans of these regions appear in different colors related to their activity level  Functional magnetic resonance imaging (fMRI)- brain activity levels are monitored over time by tracing blood oxygen levels in the brain. The more active areas use up more oxygen and this activity is translated into different color scans of the brain. Patient is often engaged in some cognitive activity or viewing stimuli Problems:  Timing of response- when viewing a stimulus our thoughts react within milliseconds whereas blood flow takes about 2 seconds (this makes it difficult to find a reliable and significant effect)  Procedure is time intensive and equipment is expensive so experiments often only use a small number of participants  Nonindependence error- researchers may unintentionally bias their results by not independently selecting which brain areas to correlate with  Confounds such as time of day and nervousness of participants can also affect the results of neuroimaging studies  Transcranial magnetic stimulation (TMS)- a brief electrical current passes thru a coil placed on the head. The magnetic field disrupts the regular activity of the neurons, sometimes impairing and sometimes enhancing function. Essentially it mimics a brain lesion, which allows researcher to draw inferences about cause and effect Biochemical Activity:  Physiological differences may appear as differences in how the brain and body process various chemicals including neurotransmitters, hormones, and drugs  Depending on how and where these chemicals function, we might analyze cerebrospinal fluid saliva, blood, or urine to monitor levels of these chemical substances  Neurotransmitters- chemicals released by neurons to inhibit or excite the next neuron into action, they help transmit signals thru the nervous system some important neurotransmitters are:  norepinephrine & epinephrine- stress hormones, they help the body deal with threat by increasing blood flow to the muscles which increases heart rate and blood pressure  dopamine- related to feelings of pleasure, and helps regulate movement, learning, attention, and rewards  serotonin- involved with mood regulation, arousal, the control of sleeping and eating, and pain regulation (depression, anxiety, and other mood disorders are related to how the body processes serotonin)  The enzyme monoamine oxidase (MAO) regulates, to some degree, the availability of dopamine, norepinephrine, and epinephrine in the system  Challenge test- researchers administer a drug that is known to either increase or decrease a neurotransmitter’s functioning and monitor the impact of this new substance on reactions presumed to be related to the neurotransmitter Many brain-imaging studies will use scatterplots to illustrate their results. Each point represents a participant in the study NEUROLOGICAL THEORIES OF PERSONALITY Temperament:  Relatively stable across the life span  Expressed thru general energy level  Present from early childhood  Similar in other species of animals  Present at birth, at least in a general way  Determined by genetic factors  Changeable with maturation and experience 3 Primary Temperaments:  Extraversion- positive emotion, reward sensitivity, social rewards, sociability, approach  Neuroticism- negative emotion, anxiety, punishment sensitivity, withdrawal  Impulsivity- psychoticism, lack of constraint, sensation seeking, novelty seeking, lack of conscientiousness, lack of agreeableness Eysenck’s PEN Model:  Eysenck’s 3 dimensions: 1. Extraversion  how outgoing people are, to both the social and the physical environments  tend to be sociable, popular, optimistic, and somewhat unreliable  those low in extraversion (introverts) tend to be quiet, introspective, reserved, and reliable, and have a few close friends 2. Neuroticism  People high in this factor tend to be distressed, insecure, and upset in many areas of life, they are chronically worried, nervous, and moody, hold a low opinion of themselves, and find it difficult to get back on an even keel after an upsetting experience  In contrast, emotionally stable people are even-tempered, calm, relaxed, carefree, unworried, and somewhat unemotional, and return to their natural state quickly after an emotional experience 3. Psychoticism  Might think of psychoticism as being antisocial and contrast it with ego control  People high in psychoticism tend to be loners, ego-centric, troublesome, manipulative, impulsive, uncooperative, hostile, withdrawn, & don’t fit in  People low in psychoticism tend to be altruistic, socialized, empathetic, and conventional, they care about others and are able to control their impulses to a greater extent than those high in psychoticism  Responses and habits might change over time and situations, but traits do not. This consistency suggests a strong biological component to these traits  Eysenck thought that introverts had greater cortical arousal than extraverts, particularly in the ascending reticular activating system (ARAS)- a pathway transmitting signals from the limbic system and the hypothalamus to the cortex  activation in the ARAS can make a person alert and mentally sharp or sluggish and mentally dull  introverts act more restrained and inhibited, to avoid conditions that would aggravate their already overstimulated condition  extraverts lets in too little stimulation so tha
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