Components and Theories of Emotion and Stress

Components of emotion process

Cognition (interpretation), Action (behavioral/physiological), Feeling (subjective experience)

Facial feedback hypothesis

Emotions are partially generated by perception of bodily responses and actions

Behavioral Activation System (BAS)

Motivated by rewards; energizes action

Behavioral Inhibition System (BIS)

Sensitive to punishment; inhibits behavior

Broaden‑and‑Build Theory

Positive emotions broaden attention and build lasting personal resources

ANS activation in emotion

Emotional states activate the autonomic nervous system

Emotion‑specific ANS arousal

Different emotions correspond to different mixes of sympathetic & parasympathetic activity

vmPFC damage effects

Impaired decision‑making, blunted guilt, excessive indecision

PFC lesion effect

Impaired anticipation of emotional consequences

Limbic system key node

Amygdala

PFC role in emotion

Regulates and controls emotional responses

Left hemisphere emotion

Approach behaviors (BAS): happiness or anger

Right hemisphere emotion

Avoidance/withdrawal behaviors (BIS): fear, disgust, guilt

Selye's stress definition

Non‑specific bodily response to any demand (General Adaptation Syndrome)

McEwen's stress definition

An interpreted threat that triggers physiological & behavioral responses

General Adaptation Syndrome (GAS)

Phase 1 alarm (SNS), Phase 2 adaptation (HPA); nonspecific stress response

SNS in stress

Fast branch; releases epinephrine & norepinephrine; dilates pupils, increases heart rate

HPA axis in stress

Slower branch; CRH→ACTH→cortisol release from adrenal cortex

Hypothalamus in HPA negative feedback

Inhibits further CRH and ACTH release to return system to baseline

Stress‑signal origins

Amygdala, locus coeruleus, dorsal raphe nucleus activate medulla (SNS) & PVN (HPA)

Acetylcholine in ANS

Neurotransmitter for preganglionic autonomic fibers

Norepinephrine in ANS

Neurotransmitter for postganglionic sympathetic fibers

Vagus nerve function

Reports peripheral arousal state back to the brain

Cortisol functions

Mobilizes energy, suppresses nonessential functions; chronic high cortisol lowers BDNF

DHEA function

Buffers cortisol effects; supports immune & cognitive performance

Oxytocin in stress

Promotes "tend‑and‑befriend": reduces SNS reactivity & builds social bonds

Psychoneuroimmunology

Study of how psychological factors (e.g., stress) affect immune responses

Cytokines & sickness behavior

Psychological stress raises cytokines, triggering fatigue, fever, low energy

Tend‑and‑befriend response

Oxytocin‑mediated affiliative stress response, especially in females

MDD diagnostic criteria

≥5 symptoms over 2 weeks including depressed mood or loss of pleasure

Depression structural changes

↓ volume in hippocampus, OFC, ACC

Depression functional changes

Amygdala hyperactivity; dmPFC hypoactivity; weakened amygdala-vmPFC/dmPFC connectivity

Reward dysfunction in MDD

Nucleus accumbens less responsive to reward

Evolutionary role of negative emotions

Signal need to change environment/behavior; conserve energy; withdraw from conflict

Evolutionary definition of disorder

Failure to activate when needed, activate inappropriately, or coordinate with other systems

MAOI mechanism

Block monoamine oxidase to prevent breakdown of monoamines

Tricyclic antidepressants

Block reuptake of 5‑HT, NE, and DA; many side effects

SSRI mechanism

Block serotonin reuptake; fewer side effects than tricyclics

Atypical antidepressants

Varying mechanisms (DA or glutamate); examples: Wellbutrin, ketamine

Neuroplasticity hypothesis of recovery

Antidepressants ↑ BDNF → increased neurogenesis, synaptic growth, learning capacity

BDNF role

Supports neuronal health, growth, and connectivity; low BDNF → reduced plasticity

BDNF‑related treatments

SSRIs, ECT, rTMS, exercise, ketamine, psychedelics all ↑ BDNF or neuroplasticity

Anxiolytic drug class

GABA‑A receptor agonists increase inhibitory signaling in the brain

Benzodiazepine mechanism

Bind GABA‑A receptors to enhance GABA's calming effects

Common benzodiazepines

Xanax (alprazolam), Ativan (lorazepam), Klonopin (clonazepam), Valium (diazepam)

Neurotransmitter imbalance theory issues

Serotonin levels not reliably low; depleting 5‑HT doesn't induce depression; SSRIs act slowly

Psychedelics & DMN

Psilocybin ↓ activity in mPFC, ACC, PCC (Default Mode Network) to reduce rumination

Psilocybin vs SSRI trials

Psilocybin showed greater improvement than escitalopram, independent of treatment expectancy

Trait suggestibility effect

Psilocybin outcomes correlated with suggestibility, indicating increased psychological flexibility