Problem 4: Personality and the Brain

Question 1

Neurotransmitters

Answer 1

= biochemical substances involved in the communication among nerve cells, or neurons

–> can act in such a ways as to speed up the communication of messages from one neuron to the next, or to slow down that communication

–> the “firing” of neurons is the basis of our emotions, our thoughts, and our behaviors

Question 2

Dopamine

Answer 2

Facilitates response to pleasurable, exciting stimuli

–> associated with Extraversion and Openness
–> involved in motivation, emotion, and reward
–> involved in higher cognition (PFC)

Question 3

Serotonin

Answer 3

Inhibits response to harmful, unpleasant stimuli

–> associated with Neuroticism, Agreeableness, or Conscientiousness
–> low levels: aggression, poor impulse control, and depression

Question 4

Norepinephrine

Answer 4

Inhibits response to stimuli that have previously been associated with pleasure –> inhibits signals of conditioned reward

Question 5

Tridimensional Personality Model - Cloninger

Dopamine and Novelty Seeking

Answer 5

Individuals whose dopamine system is very active will tend to have high levels of “Novelty Seeking”
–> the tendency to seek pleasure and excitement

Individuals whose dopamine system is very inactive will den to be low in Novelty Seeking
–> they will not be particularly motivated to find fun and variety

Question 6

Tridimensional Personality Model - Cloninger

Serotonin and Harm Avoidance

Answer 6

Individuals whose serotonin system is very inactive will tend to have high levels of “Harm Avoidance”
–> the tendency to avoid pain and anxiety

Individuals whose serotonin system is very active will tend to be low in Harm Avoidance
–> they will not be particularly motivated to avoid pain and anxiety

Question 7

Tridimensional Personality Model - Cloninger

Norepinephrine and Reward Dependence

Answer 7

Individuals whose norepinephrine system is very inactive tend to have high levels of “Reward Dependence”
–> the tendency to develop strong sentimental attachments

Individuals whose norepinephrine system is very active will tend to be low in Reward Dependence
–> they will tend not to develop strong sentimental attachments

Question 8

Reinforcement Sensitivity Theory - Gray

Behavioral Activation System (BAS)

Answer 8

= regions from the brain that are responsible for receiving signals from the nervous system which indicate that rewards are being experienced (or are about to be experienced)

–> “go” system - encourages the pursuit of rewards, by transmitting signals within the brain to communicate the pleasurable and exciting nature of those rewards

–> similar to Cloninger’s Novelty Seeking

Question 9

Reinforcement Sensitivity Theory - Gray

Behavioral Inhibition System (BIS)

Answer 9

= regions of the brain that are responsible for receiving signals from the nervous system which indicate that punishments are being experienced (or may soon be experienced)

–> “stop” system - encourages the avoidance of punishments, by transmitting signals within the brain to communicate the painful and frightening nature of those punishments

–> similar to Cloninger’s Harm Avoidance

Question 10

Reinforcement Sensitivity Theory - Gray

Fight-or-Flight System

Answer 10

= regions of the brain that are responsible for motivating extreme reactions - fighting and/or fleeing - in response to extremely threatening situations

Question 11

Theory of Personality - Eysenck

Extraversion

Answer 11

= strength of people’s reactions to stimulation of their senses –> arousability of their brains

–> very extraverted people tend to seek stimulation, and therefore enjoy bright colors, loud noises, other sensations, and meeting and interacting with lots of people

–> very introverted people tend to avoid stimulation, quieter surroundings, and prefer to be alone or with a few others

Ascending reticular activation system (ARAS):
- a filter that regulates the amount of stimulation that is admitted to the brain from the nervous system, which receives stimulation from the environment
- little stimulation: under-aroused, stimulation-seeking, extraverted personality
- great stimulation: over aroused, stimulation-avoiding, introverted personality

–> related to Gray’s Behavioral Activation System

Question 12

Theory of Personality - Eysenck

Neuroticism

Answer 12

= the strength of people’s reactions to stressful stimuli

–> very neurotic people feel a great deal of worry and nervousness in response to life’s problems

–> emotionally stable people feel little of the negative emotions that are caused by life’s distresses

Limbic System:
- regulate responses to stress
- overwhelmed by stressors: neurotic personality
- handle stressors: stable personality

–> related to Gray’s Behavioral Inhibition System

Question 13

Theory of Personality - Eysenck

Psychoticism

Answer 13

= traits such as aggressiveness, manipulation, tough-mindedness, risk-taking, irresponsibility, and impulsivity versus their opposites

–> high levels of Psychoticism were associated with criminal behavior, various mental illnesses, and creativity

–> persons high in Psychoticism tended to have high levels of the hormone testosterone and low levels of monoamine oxidase (MOA)

Question 14

Zuckerman’s Model

Answer 14

Five factors are believed to represent the basic dimensions of personality/temperament:

Activity
Sociability
Impulsive Sensation-Seeking
Aggression
Neuroticism- Anxiety

–> each of the personality dimensions is caused by its own set of complex interactions among brain structures, neurotransmitters, and hormones, and not by a single one of these

Question 15

Testosterone

Answer 15

= a hormone that is responsible for many of the physical characteristics of men

–> testosterone levels can be influenced by events: competitive situations; increase after victory
–> higher levels of testosterone: wilder, more unruly, more rambunctious, more violent crimes

–> women do naturally have some testosterone, but men’s levels are typically at least 10 x higher

–> triggers the development of male reproductive sex organs and male secondary sex organs

Question 16

Cortisol

Answer 16

= a hormone that is released by the adrenal cortex in response to physical or psychological stress

–> function: prepare the body for action in response to stress - increase in blood pressure, blood sugar, and suppression of the immune system

–> cortisol levels might be an indicator (at least in boys) of overall emotional reactivity
–> little cortisol release: emotionally insensitive

Question 17

Oxytocin

Answer 17

= a hormone that is produced in the hypothalamus and released by the pituitary gland

–> in women, released when giving birth, breastfeeding, having an orgasm

–> associated with emotional bonding: establishing attachments between persons, cooperative relationships, facilitates tendencies to be trusting and trustworthy

Question 18

Oxytocin administration

Answer 18

Exogenous administration of synthetic OXT includes subtle changes in social behaviors
–> tendencies toward increased sociality, including trust, empathy, approach, and altruism
–> targets reward-related and fear-related neurocircuits
–> potential treatment for psychiatric conditions ranging from anxiety to autism spectrum disorders
–> the effects of OXT on prosocial behavior are highly susceptible due to individual and contextual variables
–> OXT may interact with other hormonal and neurotransmitter systems
–> interacts with person-specific factors related to trust and affiliation

Question 19

Intranasal OXT administration

Answer 19

= the most direct and non-invasive way to assay the central actions of OXT in humans

–> bypasses the blood-brain barrier (BBB)

Question 20

OXT-system and prosocial behavior

Answer 20

prosocial = a wide range of positive social behaviors, including trust, cooperation, care, empathy, and altruism - all of which are mainstays of forming and maintaining adaptive human social relationships

altruism = non-reciprocal prosocial acts which are aimed at improving the welfare of another individual at a personal cost to the altruist

–> the OXT-system is involved in both the formation and maintenance of social relationships, in part through its central involvement in orchestrating altruism and associated prosocial behaviors

–> effects are mediated by the amygdala, the anterior insula, and the anterior cingulate cortex

Question 21

Oxytocin and therapeutic potential

Answer 21

Oxytocin enhances social salience rather than social behavior, and for oxytocin administration to be therapeutic and influence behavior, it must be paired with an appropriate social context.

–> oxytocin changes the way in which incoming social stimuli are perceived and processed, which can influence behavior and social learning in various ways
–> oxytocin is a powerful neuromodulator: it makes the brain more attentive to social stimuli, promotes synaptic plasticity, and facilitates social learning by modulating neural circuits
–> oxytocin should be used as a tool to prime the brain for receiving, processing, and learning social information during cognitive and behavioral therapy interventions
–> future clinical studies must explore the potential of pairing oxytocin with therapeutic contexts

Question 22

Personality Neuroscience

Answer 22

= the use of neuroscience methods to study individual differences in behavior, emotion, and cognition

aim: understand both the biological systems that are responsible for the states associated with traits and the parameters of those systems that cause them to function differently in different individuals

Question 23

The structure of personality traits

Answer 23

1. Hierarchical arrangement - correlated groups of
   more specific traits are categorized together
2. Metatraits (higher-order factor structure)
   
   • Stability: shared variance of Neuroticism,
     Agreeableness, and Conscientiousness
   • Plasticity: shared variance of Extraversion and
     Openness
3. Facets - shared variance of lower-level traits
4. Aspects - two separable but correlated aspects
   of which each Big Five factor is comprised

Question 24

Meta-traits

Answer 24

Stability represents a general tendency to regulate or restrain potentially disruptive emotion and behavior
–> related to serotonin

Plasticity represents a general tendency to explore and engage with possibilities
–> related to dopamine

Question 25

Trait Theory

Answer 25

1. Trait theory views traits as orthogonal and
   dimensional constructs that allow for each
   individual to be positioned in a multidimensional
   trait space
2. A person scoring at the upper end of a given
   trait will respond consistently stronger to
   relevant stimuli than a person with lower scores
   on the respective trait
3. Trait theory posits that these neural substrates
   are characterized by the same trait-like
   properties as behavioral traits such as
   invariance across situations and time
4. Each situation is characterized by a unique
   brain state consisting of (a) a neural reaction
   elicited by the physical aspect of the stimulus
   and (b) an idiosyncratic component associated
   with the individual trait level

Question 26

Psychometrics

Answer 26

= a psychological discipline focused on theories and techniques to measure psychological constructs

internal consistency: a technical term from psychometrics that reflects how reliable an instrument measures a psychological construct

Question 27

Personality Network Neuroscience (PNN)

Answer 27

The goal of PNN is to identify and integrate neural systems (or biophysical entities) associated with psychological trait conceptions within an integrated framework for human personality