Personality Neuroscience Lecture Notes PDF

(and its transformations) Lecture 10: Personality Neuroscience Dr. William S. Ryan (Will)  Announcements No class or office hours on Thursday! Listen to podcast. Pre-registration due before class Tuesday October 15th Midterm grades will be posted...

(and its transformations) Lecture 10: Personality Neuroscience Dr. William S. Ryan (Will)  Announcements No class or office hours on Thursday! Listen to podcast. Pre-registration due before class Tuesday October 15th Midterm grades will be posted October 17th Midterm viewing sessions (SS 514a, “ground floor”) ○ Thurs Oct 17th 4:30-6 pm ○ Friday Oct 18th 1:45-3:15 pm ○ Thurs Oct 24th 1:00-2:30 pm 01 (Intentional) Personality Change (wrap up) Lecture 02 What is personality Neuroscience? Overview 03 Early Theories 04 Key Neurotransmitters & Hormones 05 Biological Correlates of the Big 5  01. (Intentional) Personality Change (wrap up)  Life Experiences Exercise, starting university or a job, beginning a serious relationship, travel, trying drugs, other intentional choices The text also talks about non-intentional experiences here too Life Experiences- Adversity & Reactions to Stress  Obstacles t0 personality Change Not seeing a reason for change Takes effort! Blaming negative experiences and failures on external forces rather than their own personality People like consistency and predictability. Overcoming Obstacles t0 personality Change Principles of Personality Change/Stability Cumulative Personality traits increase in rank-order consistency as people get older Continuity People become better equipped to deal with the demands of Maturity life as they acquire experience and skills Plasticity Personality can change at any time (but may not be easy) Taking on roles consistent with one’s personality may explain Role Continuity stability Principles of Personality Change/Stability Identity People seed to develop a stable sense of who they are and then stive to act Development consistently with that Social Changing social roles at different stages of Investment life drive personality change Person-environment transactions can Corresponsive cause personality traits to remain consistent or can magnify existing traits Summary: “Personality is characterized by stability over the life span, and also by significant change” -Funder, pg. 257  02. Personality Neuroscience  What is personality Neuroscience? Personality neuroscience is the study of persistent psychological individual differences (typically in the general population) using neuroscientific methods. The key presumption of personality neuroscience is that a person cannot be understood without understanding their brain (DeYoung, 2010)  From Traits to Biology Interested in mapping traits onto brain structure and function Finding biological correlates of personality is not causal itself, but is an essential step in linking personality to genetics and environmental influences Answers getting more complex as our methods improve and get more complex  03. Early Theories Early Theories of Brain Structure: Phrenology Eysenck’s Big 3 Traits Eysenck: Big Three Traits Theory based approach ○ Reviewed existing personality theories and identified common elements Posited a neurobiological basis of traits Used factor analysis to confirm this structure of traits. Ultimately emerged with three basic traits, but started with two review Eysenck’s P-E-N Model Psychoticism (vs. superego control)- unconstrained? ○ Aggression, creativity, impulsivity Added this third trait later ○ Psychological detachment from others ○ Enjoy danger, Disregard social conventions Extraversion (vs. introversion) ○ Outgoing; Like being around people; Enjoy excitement Neuroticism (vs. emotional stability) ○ Greater reactions to stress; Touchy, restless, moody, anxious review Ascending Reticular Activating System (ARAS) Area that controls how much nervous system stimulation enters the brain ○ Keeps you awake (or not) in class ○ Arousal activity and activation of brain ○ Lets in or filters out information The center of Eysenck’s theory of introversion – extraversion Eysenck’s Arousal Hypothesis Underlying idea: people seek optimal level of arousal The ARAS of introverts is open and lets in a lot of sensory information ○ Introverts: higher resting levels of arousal because ARAS lets in too much stimulation thus, engage in behaviors to minimize or avoid stimulation The ARAS of extraverts is more closed and lets in less sensory information ○ Extraverts: lower resting levels of arousal because ARAS lets in too little stimulation thus, engage in behaviors to increase stimulation Eysenck’s Theory Optimal 100 90 Stimulation Arousal Level seeking 80 70 Stimulation 60 seeking 50 40 Brain arousal 30 20 Brain 10 arousal 0 Introverts Extroverts Revision to Eysenck’s original theory Introverts and extraverts do not differ in baseline (resting) levels of arousal ○ Same level of arousal in quiet environment But, introverts have more arousability than extraverts ○ Introverts respond to stimulation more quickly and strongly ○ Overwhelmed more easily by stimulation The ARAS alone is not responsible for this difference Evidence for (Revision of) Eysenck’s Theory Introverts get used to sensory stimuli (like unusual sounds) slower than extroverts Explanation: Introverts more sensitive to new auditory stimuli When lemon juice is dripped onto the tongue… ○ introverts salivate more than extroverts. Explanation: Introverts experience the sour taste more, thus respond more strongly to it When given caffeine and asked to complete difficult tasks… ○ Introverts had stronger brain activity than extroverts Explanation: introverts more sensitive to the caffeine thus are more affected by it BiS/BAS Theory developed by Jeremy Gray in the 1970s & 80s building on and revising Eysenck's work Also called reinforcement sensitivity theory (RST) Proposed two brain systems that explain individual differences in emotional response, motivation, and behavior (aka personality!) ○ BIS (Behavioural Inhibition System) - sensitivity to punishment, threat, movel stimuli ○ BAS (Behavioural Activation System)- sensitivity to rewards A model of approach and avoidance  BiS/BAS Sensitivity to rewards (BAS) links to extraversion Sensitivity to punishment (Dopamine) (Serotonin) (BIS) with neuroticism Extraversion Neuroticism  04. Key hormones & Neurotransmitters Neurotransmitters and Personality Chemical messengers; communication between neurons Levels vary across situations and people Dopamine “Motivation to action” Reward sensitivity, control of body movements Pleasure, sociability, activity level, novelty-seeking Low levels can lead to alcoholism, drug abuse, gambling, etc. (Impulsivity) Very low levels can lead to symptoms of Parkinson’s disease Big 5 Correlates: Extraversion & Openness Neurotransmitters and Personality Serotonin Important for inhibiting emotional impulses Low levels associated with rejection sensitivity, chronic anxiety Selective serotonin reuptake inhibitors (SSRIs; Prozac) thought to improve mood by increasing available serotonin Psilocybin and MDMA act similarly to serotonin Recent evidence suggesting long covid is associated with reduced serotonin levels and increased anxiety! More serotonin sensitivity and function related to less neuroticism, more conscientiousness, more agreeableness Neurotransmitters, Hormones, and Personality Hormones are also chemical messengers Produced in one location and act in another (unlike neurotransmitters which are produced and act in the brain) Can be measured in many ways (saliva, blood, urine, hair) Epinephrine & Norepinephrine (aka adrenaline and noradrenaline)* ○ Reactivity to stress (“adrenaline rush”) ○ Fight-or-flight response ○ Elevated among highly anxious individuals ○ Higher on average among those high in neuroticism *These are hormones AND neurotransmitters Hormones and Personality Cortisol Released in response to physical or psychological stress Prepares body for sustained action Beneficial in short durations, but not chronically Higher resting levels and greater reactivity associated with neuroticism Low levels can also be problematic (too much risk-taking, psychopathy) Both genetics and early life history are related to cortisol levels  05. Biological Correlates of the Big 5  DeYoung (2010) The Structure of Personality Stability Plasticity Agreeable- Conscientiousn Openness/Intel Neuroticism Extraversion ness ess lect Withdrawal Volatility Industrious Intellect Openness Orderliness ness Com- Assertive- Politeness Enthusiasm ness passion  DeYoung (2010) The Structure of Personality Serotonin Dopamine Cortisol & Stability Plasticity norepinephrine Endorphins (endogenous opiates) testosterone Agreeable- Conscientiousn Openness/Intel Neuroticism Extraversion ness ess lect Withdrawal Volatility Industrious Intellect Openness Orderliness ness Com- Assertive- Politeness Enthusiasm ness passion  Biological Bases of the Big 5 Stability Plasticity Emotional Agreeableness Conscientious- Extraversion Openness Stability ness Neurotransmitter Serotonin Serotonin Serotonin Dopamine Dopamine Hormone Cortisol & Testosterone Endorphins Norepinephrine Brain Structures Amygdala Insula Dorsolateral Nucleus Left pre-frontal prefrontal cortex accumbens cortex (don’t need to Hypothalamus know these!) Lateral Amygdala Posterior medial Insula orbitofrontal pre-frontal cortex cortex Substantia nigra Medial and dorsolateral prefrontal cortex Hippocampus What do we mean by correlates? If we know what brain mechanisms relate to different personality traits, does this mean the brain is the cause of personality? ○ Correlation does not equal causation ○ Caution: Biological determinism Thought Questions: Do you think if research methods improved sufficiently, scientists would be able to look at someone’s brain and know their personality? How would we know if they are correct? Thank you!