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CHAPTER 7.docx

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University of Toronto Scarborough
Connie Boudens

CHAPTER 7: THE NEUROSCIENCE PERSONALITY - Group that learned meditation showed less anxiety, and showed differences in how their brain responded to emotional stimuli o Greater activation on left prefrontal cortex at rest and in response to positive and negative emotional events, and also showed better immune functioning - Best way to think of our physiologies is as a package of potentialities for personality What is Neuroscience and How Do We Study It? - Nervous system made up of: o Central Nervous System (CNS):Include brain and spinal cord o Peripheral Nervous System (PNS): Includes  Somatic Nervous System: controls movements of muscles  Autonomic Nervous System: regulates smooth muscle, cardiac muscle, and glands. Is further divided into:  Sympathetic Division: mobilizes energy (fight or flight)  Parasympathetic Division: supports systems that replenish the body’s energy store - Brain protected by cerebrospinal fluid (CSF) that cushions brain, and flows through spaces in the brain called ventricles - Researches hypothesize differences in bodily responses, brain structure, brain activity and biochemical activity are all related to individual differences in personality Bodily Responses - It is the autonomic nervous system that responses to arousing events in the environment o When aroused the sympathetic division responds by increasing heart rate, blood pressure, blood flow to extremities, respiration, sweating and muscle activity - Sweating measured by Galvanic Skin Response (GSR) – skin conductance test - Muscle activity measured by Elecrtomyography – estimates electrical impulses of muscles during contraction and relaxation Brain Structure - Computerized Tomography (CT) Scan: takes a high resolution x-ray picture of the brain. By looking at thin cross sections of the brain, we can detect abnormalities or differences in brain tissue - Magnetic Resonance Imaging (MRI): radio frequency waves are used instead of x-rays. Strong magnetic field causes nuclei of some atoms to resonate, then waves used to detect activity of the atoms - Since hydrogen atoms are present in all tissues but in varying concentrations the pattern of resonance formed by hydrogen atoms forms a multidimensional picture of the brain Brain Activity - Electroencephalogram (EEG): electrodes placed on scalp to monitor electrical activity of the brain. When electrical activity of brain or other part of nervous system is measured in response to specific stimulus it is called Evoked Potential - Positron Emission Tomography (PET): slightly radioactive glucose substance with short half-life injected into brain and person is placed in a scanner. Active regions use up more glucose than inactive regions - Functional MRI (fMRI): works same as an MRI but brain activity levels are monitored over time by tracing blood oxygen levels in the brain o Notable problems with fMRI:  Timing of response: when viewing stimulus our thoughts react within milliseconds, but blood flow takes 2 seconds  Small samples make it difficult to find a reliable and significant effect  Non-Independence Error: researches may unintentionally bias their results by not independently selecting which brain areas to correlate with variables  Confounds such as tie of day and nervousness of participant affect results of neuroimaging studies - Transcranial Magnetic Stimulation: brief electric current passes through coil placed on head, the magnetic field disrupts the regular activity of those neurons Biochemical Activity - Physiological differences may appear as differences in how the brain and body process various chemicals including neurotransmitters, hormones and drugs - Neurotransmitters: chemicals released by neurons to inhibit or excite the next neuron into action (i.e. norepinephrine, epinephrine, dopamine, and serotonin) o Norepinephrine (noradrenaline) and epinephrine (adrenaline) are considered stress hormones – help body deal with threat by increasing blood flow to muscles which increases heart rate and blood pressure o Dopamine related to feelings of pleasure and helps regulate movement learning, attention and rewards o Serotonin is involved with mood regulations, arousal, control of sleeping and eating, and pain regulation  Depression, anxiety and other mood disorders related to how body processes serotonin - Monoamine oxidase (MAO): regulates availability of dopamine, norepinephrine and epinephrine in the system - Norepinephrine and serotonin may also be related to symptoms of depression – some anti-depressant drugs work by blocking their reuptake so they stay in spaces between neurons longer - Anti-Anxiety drugs work by mimicking neurotransmitter Gamma-Aminobutryic Acid (GABA), an inhibitory neurotransmitter - Challenge Test: researchers administer a drug that is known to either increase or decrease a neurotransmitter functioning and monitor the impact of this new substance on reactions presumed to be related to the neurotransmitter Neurological Theories of Personality - Scientists are not able to find consistent physiological differences that relate in a clear way to differences in personality characteristics - Maybe biology has biggest impact at a broader, more general level of personality called temperament: set of personality characteristics that are: o Relatively stable across life span o Expressed through general energy level o Present from early childhood o Similar in other species of animals o Present at birth at least in a general way o Determined by genetic factors o Changeable with maturation and experience - All major personality typologies converge on three primary temperaments: o Extraversion: Positive emotion, reward sensitivity, social rewards, sociability, approach o Neuroticism: Negative emotion, anxiety, punishment sensitivity, withdrawal o Impulsivity: Psychoticism, lack of constraint, sensation seeking, novelty seeking, lack of conscientiousness, lack of agreeableness Eysenck’s PEN Model (Psychoticism, Extraversion, Neuroticism) - Extroverts tend to be sociable, popular, optimistic, and somewhat unreliable - People high in Neuroticism 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 - People high in Psychoticism tend to be loners, egocentric, troublesome, manipulative, impulsive, uncooperative, hostile, withdrawn and don’t fit in anywhere - Eysenck drew on at least pieces of evidence to support the view that these are genetic and biological o Cross cultural universality in traits implies a strong biological component o People show tremendous consistency in these three traits over time, despite changing environments o Each of the three traits have moderate heritability Neurology of Extraversion - Thought the main difference between extraverts and introverts was arousal - Introverts had greater cortical arousal than extraverts, particularly in the ascending reticular activating system (ARAS): a pathway transmitting signals from the limbic system and hypothalamus to the cortex o Activation in the ARAS can make a person alert and mentally sharp or sluggish and mentally dull o According to this Introverts avoid over stimulation, while extraverts seek more stimulation o If this were the case though, there would be differing arousal levels even when sleeping or resting, but this is not the case o This suggests the key difference is in the arousability, or sensor reactivity Neurology of Neuroticism - Thought physiological arousal could also account for differences in neuroticism - Eysenck thought Neuroticism had to do with the stability or instability of the sympathetic nervous system (parts involved with emotion regulation (hippocampus, amygdale, cingulum, septum, hypothalamus) o This is to say that the vulnerability of people high in Neuroticism to negative emotions is due to an extrasensitive emotional or drive system - While extraversion and neuroticism both deal with arousal, the key difference is extraversion deals with positive arousal (excitement, energy) whereas neuroticism is marked by negative arousal (fear, anxiety) - People high in neuroticism are sensitive to negative emotions in particular o If this is true, it would be d
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