Chapter 07 - Anatomy and Physiology of Personality

How is personality relate to physiology?

Psychologists study brain anatomy and biochemistry (neurotransmitters and hormones) to understand personality

Hypothalamus

Underneath the thalamus, connected to most everything else, and secretes several hormones

Amygdala

Plays a central role in emotion, including learning what objects to fear

Hippocampus

Important in processing memories

Nucleus accumbens

Implicated in responsiveness to reward - contains receptors for dopamine

Cortex

Outer layer of the brain

Neocortex

The outermost layer of the cortex and the most distinctive part of the human brain

Frontal cortex

Large; crucial for uniquely human aspects (planning, anticipating consequences, and emotional experience)

Neurotransmitters

Chemicals that travel across the synapse between neurons; cause excitatory or inhibitory effect through a chemical-electrical process

Hormones

Travel through the blood to affect body other than where they are produced; produced in pituitary gland and adrenal cortex

Pituitary glad

Located below the hypothalamus and secretes hormones that play important roles in bodily functions

Adrenal cortex

Located atop the kidneys and secretes behaviorally important hormones

How do we know what we know about the brain?

Observation and surgery, as well as brain injuries - first studied people who suffered from head injuries, and how damage relates to functioning

Brain stimulation

Stimulating the brain directly w/ electrodes, can cause temporary lesions to target different areas of the brain linked to different behaviors or emotions

Deep brain stimulation (DMS)

Sending electrical impulses into certain areas of the brain

Transcranial magnetic stimulation (TMS)

Applying a strong magnet to a part of the brain - used in research and clinical practice; can be used to treat major depressive disorder

Brain functioning and imaging

Used to observe functioning directly, detecs when the brain is working

Electroencephalography (EEG)

Electrodes are placed on the scalp to pick up electrical signals

Magnetoencephalography (MEG)

Uses delicate sensors to detect magnetic indications of brain activity

Computed tomography (CT) scan

Generates images of very thin slices of the brain; can access small structures

Positron emission tomography (PET)

Maps brain activity according to blood flow by injecting a radioactive tracer into bloodstream

Functional magnetic resonance imaging (fMRI)

Maps brain activity using magnetic impulses from blood oxygen (BOLD)

Functioning and imaging - Difficulties

All brain parts always active to some degree, brain activity in response to stimulus doesn’t always mean same psychological process occurs when that area is active, most researchers only look at small areas, expensive

Assays and injections

Can measure levels of neurotransmitters and hormones; can inject neurotransmitters or hormones

Assays

Samples of blood, saliva, urine, or spinal fluid

Dopamine

Turns motivation into action, allows brain to control body movements, affects response to reward, approach tendency, affects behavioral activation system (BAS)

Dopamine - associations

Extraversion and openness (plasticity), Parkinson’s (low levels), Bipolar disorder (high levels)

Serotonin

When higher, people tend to be more organized, agreeable, and emotional stable - foundation of stability

Serotonin - associations

Reduces feelings of fear and anxiety (reduced degree of amygdala reactions to threatening stimuli), prozac (changes personality), MDMA

Epinephrine

Neurotransmitter/hormone in the brain released by adrenal gland in a response to stress; also called adrenaline, found throughout the body

Norepinephrine

Neurotransmitter in brain associated w/ responses to stress; also called noradrenaline, found primarily in the brain

Fight-or-flight response

Triggered by the release of epinephrine and noreprinephrine; epinephrine is release, heart rate speeds up, digestion stops, muscles tense (adrenaline rush), simultaneously the brain becomes fully alert and concentrated (norepinephrine)

Tend-and-befriend response

Women may respond more commonly in this way - calm others down, and work together

Cortisol

Released in response to stress (physical or psychological), helps prepare body for action

Cortisol - associations

High among ppl who experience severe stress, anxiety, and depression; Low among those w/ PTSD or high sensation seeking

Testosterone

Male sex hormone, 10x higher in men than women

Testosterone - men

Associated w/ higher aggression and other problematic behavior; those w/ high levels are not always aggressive

Testosterone - women

Produced mainly by adrenal cortex, associated w/ higher sociability, impulsivity, lack of inhibition, and conformity

Big Five and Brain - Stability

Emotional stability, conscientiousness, agreeableness; able to moderate emotions, control impulses, compromise; serotonin

Big Five and Brain - Plasticity

Extraversion and openness, happier, more active, interested in exploring, dopamine

Extraversion - Brain areas

Midbrain (Nucleus accumbens, amygdala, substantia niagra) - produce more dopamine and more endorphins

Extraversion - brain chemistry

Dopaminergenic system - causes release of endorphins (opiates body produces) - makes people feel pleasure and want to repeat a behavior which can lead to addiction

Neuroticism - Brain areas

Amygdala (+hypothalamus, insula, dorsolateral prefrontal cortes, hippocampus) - more active in shy people, people who experience panic attacks, or those w/ PTSD diagnoses

Neuroticism - brain chemistry

Hypothalamus releases cortisol (stress hormone; relevance depends on stress and social support), less serotonin

Conscientiousness - brain areas

Frontal cortex (dorsolateral prefrontal cortex, lateral orbitofrontol cortex + insula) - people have self-control and pursue goals

Agreeableness - brain areas

Thicker cortex, bigger insula

Agreeableness - brain chemistry

high serotonin + low testosterone

Openness - brain areas

Prefrontal cortex

Openness - brain chemistry

Dopamine levels

Intellect - openness to experience

Tendency to be interested in abstract ideas, theory, positively associated w/ IQ test performance

Openness - openness to experience

Tendency to respond to aesthetic stimuli and even private fantasies

Psychosurgery

Neurosurgery to alter personality - current day these techniques are replaced w/ drugs

Prefrontal leucotomy

Damage to small areas of white matter behind each frontal lobe to make an individual less emotional, more rational, and calmer

Prefrontal lobotomy

Remove whole sectors of frontal lobe, results in horrible consequences

Drugs

don’t have isolated effects, can have serious side effects, aren’t necessarily better than therapy, environmental changes