BIOL 3322: chapter 11 emotions

Components of emotion

Cognition, action, feeling, and physiological changes (they do not always stick together)

Autonomic arousal in emotion

Emotional situations arouse the autonomic nervous system; most evoke a combination of sympathetic and parasympathetic arousal

Pure autonomic failure

Autonomic output to the body fails; people report feeling the same emotions but less intensely

Right somatosensory cortex damage and emotion

Typical autonomic responses to emotional music but little subjective experience; suggests autonomic responses and subjective feelings are not always closely connected

Basic emotions vs. continuous dimensions

Biological evidence favors dimensions: heart rate and breathing increase with emotional intensity but do not distinguish fear from anger or any other pair; you can't identify emotion from autonomic activity alone

Limbic system

Located around the thalamus; central to emotional processing

Emotion most tied to a specific brain region

Disgust, tied to the right temporal-parietal junction (also remember the insular cortex's role in flavor perception)

PET and fMRI findings on emotion

Emotions activate multiple cortical areas, supporting dimensions (pleasure vs. displeasure, intensity, complexity) rather than discrete categories

Behavioral Activation System (BAS)

Left hemisphere (frontal and temporal lobes); approach behavior (happiness or anger); greater left frontal activity means happier, more extraverted people

Behavioral Inhibition System (BIS)

Right hemisphere (frontal and temporal lobes); inhibits impulses and resolves conflicts between drives; greater right activity means more withdrawn, cautious, and prone to negative emotions

Evidence for universal facial expressions

Expressions are similar across cultures; blind individuals show typical expressions (innate); people match expressions to emotions better than chance worldwide

Criticisms of the universal facial expression evidence

Use of posed faces, forced-choice methods, and better recognition of own-culture expressions

Does recognizing 6 facial expressions prove only 6 basic emotions?

No; people also identify contempt, pride, sleepiness, confusion, etc.; we rarely identify emotion from the face alone (body posture matters)

Individual differences in emotion recognition

Young adults > older adults; women > men; people with psychopathic traits perform worse than average

Adaptive functions of emotions

Fear alerts us to escape danger; anger directs us to attack an offender; disgust tells us to avoid illness-causing things; emotions guide quick decisions; the value of happiness, sadness, embarrassment is more speculative

Emotions and moral decisions

We attend to how outcomes will make us feel; decisions are seldom made rationally (one option 'feels' right and we rationalize afterward); people with strongest autonomic arousal are least likely to kill one to save five

Brain areas active in moral decisions

Prefrontal cortex and cingulate gyrus; ventromedial prefrontal cortex integrates utilitarian and emotional aspects

Effect of prefrontal cortex damage on moral decisions

Less emotional consideration and greater likelihood of choosing the utilitarian option (e.g., kill one to save five); also impulsivity, poor moral reasoning, risky behavior

Prefrontal cortex functions (review)

Judgment, impulse control, social decision making, and regulation/interpretation of emotion; can override emotional responses

Attack and escape behaviors

Closely related physiologically and behaviorally, with corresponding emotions anger and fear; depend on the individual and the situation

Hamster intruder example

Initial attack causes activity in the corticomedial amygdala and increases the victim's probability of attacking back for 30 minutes or more

Environmental influences on aggression

Abusive childhood, witnessing parental violence, violent neighborhood, lead and other harmful chemicals, heavy alcohol or drug use

Heredity and aggression

Twin studies show significant heritability (some debate about design); MAOA gene low-activity form is linked to aggression, especially with childhood maltreatment (gene-environment interaction)

Serotonin and aggression

Impulsiveness and aggression are linked to low serotonin release/turnover; the link is small and not predictive at the individual level

Serotonin turnover

Amount of serotonin neurons release, absorb, and replace; measured by 5-HIAA concentration in cerebrospinal fluid (blood measures correlate poorly with brain levels)

Serotonin and aggression findings

Social isolation reduces serotonin turnover in mice; juvenile rodents have lower serotonin and fight more; low turnover in humans is linked to violent behavior including arson and violent suicide

Testosterone and aggression (review)

Increases the likelihood of aggression but does not guarantee it; environment and learning also matter; amygdala is the trigger and hypothalamus the execution

Moro reflex

Newborn response to a sudden loud noise: arching the back, briefly extending arms and legs, and crying

Startle reflex

Extremely fast response to unexpected loud noises; pons commands tensing of neck and other muscles; more vigorous if already tense, so it is used as a behavioral measure of anxiety

Startle reflex timing

Information reaches the pons in 3-8 milliseconds; response occurs within two-tenths of a second

Amygdala (review)

Detects threat and fear; evaluates relevance of emotional information and directs attention to it; damage reduces fear and impairs threat detection

Amygdala learned fear pathway

Thalamus/auditory/visual cortex → basolateral (lateral) amygdala → central amygdala → central gray of midbrain → pons (startle); damage anywhere along the route interferes with learned fear

Bed nucleus of the stria terminalis (BNST)

Critical for long-term adjustments of anxiety, whereas the amygdala handles fear of individual items; connected to the amygdala by the stria terminalis

Amygdala response to faces

Strongest when the expression is difficult to interpret; stronger to an angry face directed away and a frightened face directed toward the viewer

Urbach-Wiethe disease

Rare genetic condition in which calcium accumulates in the amygdala until it wastes away; patient SM experiences fearlessness, has trouble drawing a fearful face, and doesn't look at people's eyes

Effects of amygdala damage on facial expressions

Impaired recognition of fear and disgust; recognized expressions are rated as less intense

Individual differences in anxiety and the amygdala

Anxiety tendency is fairly consistent over time; genes for reduced serotonin uptake increase threat responses; soldiers with high initial amygdala response had more combat stress; reappraisal is a coping mechanism

Panic disorder

Frequent anxiety with occasional attacks of rapid breathing, increased heart rate, sweating, and trembling; more common in women, adolescents, young adults; possible genetic component; linked to hypothalamus abnormalities (decreased GABA, increased orexin)

PTSD

Distressing recollections and nightmares about a traumatic event and vigorous reactions to noises/stimuli; smaller hippocampus may predispose; Vietnam veterans with amygdala damage had no PTSD vs. 40% with damage elsewhere

Benzodiazepines

Most commonly used anti-anxiety drugs (diazepam/Valium, alprazolam/Xanax); bind to the GABAA receptor (alpha sites) and facilitate GABA's effects in the amygdala, hypothalamus, midbrain, and other areas

GABAA receptor complex

GABA binds the beta site and twists the receptor open to let chloride ions into the neuron; benzodiazepines facilitate GABA binding

MDMA and the amygdala

Decreases the amygdala's response to unpleasant images (fMRI)

Alcohol and anxiety

Alcohol acts on GABA receptors for its anti-anxiety and intoxicating effects; experimental drug Ro-15-4513 blocks alcohol's effect on the GABAA complex

Behavioral medicine

Emphasizes effects of diet, smoking, exercise, stress, and other behaviors on health; emotions influence illness and recovery

Stress (Hans Selye, 1979)

The non-specific response of the body to any demand made upon it

General adaptation syndrome (GAS)

Threats to the body activate a general stress response with three stages: alarm, resistance, exhaustion

Two systems activated by stress

The sympathetic nervous system ('fight or flight') and the HPA axis (hypothalamus, pituitary gland, adrenal cortex)

HPA axis pathway

Hypothalamus induces pituitary to secrete ACTH → ACTH stimulates the adrenal cortex → cortisol released; cortisol mobilizes energy, elevates blood sugar, increases metabolism, and enhances alertness

GAS alarm stage

Increased sympathetic nervous system activity

GAS resistance stage

Sympathetic response declines; adrenal cortex keeps releasing cortisol and other hormones to prolong alertness

GAS exhaustion stage

After prolonged stress, the individual no longer has energy to sustain responses

Sapolsky (1998) on modern stress

Today's crises are more prolonged and inescapable, activating the GAS and causing widespread stress-related illness in industrial societies

Leukocytes

White blood cells of the immune system

B cells

Leukocytes that mature in bone marrow and secrete antibodies

Antibodies

Y-shaped proteins that attach to particular antigens

Antigens

Surface proteins that are antibody-generator molecules

T cells

Attack intruders directly and help other T cells or B cells multiply (helper T cells prompt B cells to divide and form memory cells)

Natural killer cells

Leukocytes that attack tumor cells and cells infected with viruses

Cytokines

Small proteins produced during infection that combat infection and tell the brain about illness; stimulate prostaglandins, causing fever, sleepiness, and lack of energy

Psychoneuroimmunology

Study of how experiences alter the immune system and how the immune system influences the central nervous system

Short-term stress and the immune system

Nervous system activates the immune system, increasing natural killer cells, leukocytes, and cytokines

Effects of prolonged stress

Symptoms similar to depression, a weakened immune system, and possible hippocampus damage (neurons more easily damaged or killed)

Enteric nervous system and stress

Neurons controlling digestion that react to brain input and stress hormones, causing digestive upset; gut bacteria cause variation (some produce IBS and visceral pain; some raise anxiety/depression risk)

Factors determining stress resilience

Genes, social support, physical health, and previous stressful experiences

Methods to control stress responses

Breathing routines, exercise, meditation, distraction, addressing issues, and social support (which reduces responses in brain areas including prefrontal cortex)