Emotion and Mood Disorders

What is the main idea of the James-Lange Theory of emotion?

Conscious emotion arises from the perception of specific bodily changes; stimulus → bodily response → perceived emotion.

How did Walter Cannon critique the James-Lange Theory?

He argued the thalamus sends parallel signals that produce both the subjective feeling of emotion and the bodily responses simultaneously, making peripheral feedback unnecessary.

What modern evidence supports the James-Lange view that bodily states shape emotion?

Distinct autonomic patterns for emotions, body-map studies (e.g., Nummenmaa et al.), facial-feedback experiments, and blunted emotions in patients with autonomic failure.

According to the Somatic Marker Hypothesis, how are decisions guided?

Bodily (somatic) signals arising from prior emotional experiences bias decision-making via regions such as the ventromedial prefrontal cortex, amygdala, and insula.

What did the Iowa Gambling Task reveal about somatic markers in VMPFC patients?

Healthy participants developed anticipatory bodily responses and avoided risky decks, whereas VMPFC-lesioned patients lacked those responses and kept choosing disadvantageous decks.

How do personal moral dilemmas illustrate emotion-based decision making?

They activate emotional brain regions, reducing utilitarian choices; damage to VMPFC lessens this emotional influence, increasing utilitarian responses.

What role does the amygdala play in the fear response?

It detects threats and coordinates behavioral, autonomic, and endocrine fear reactions through downstream pathways such as the periaqueductal gray.

What did studies of patient SM (bilateral amygdala damage) demonstrate about fear?

She showed severely impaired recognition and experience of fear, underscoring the amygdala’s necessity for normal fear processing.

Which hormones modulate aggression and how?

Testosterone and vasopressin tend to increase aggression; serotonin and oxytocin decrease it; cortisol modulates aggression depending on context and levels.

What was Paul MacLean’s triune brain theory?

He proposed the brain consists of a reptilian complex (instinct), a paleomammalian or limbic system (emotion), and a neomammalian cortex (cognition).

Why is the classic limbic system concept criticized today?

Modern evidence shows emotion and cognition are highly integrated with no clear anatomical boundary separating a discrete limbic system from the rest of the brain.

According to DSM-5, what constitutes Major Depressive Disorder (MDD)?

Depressed mood or anhedonia plus at least four additional symptoms (e.g., sleep disturbance, fatigue, feelings of worthlessness) lasting two weeks or more.

What are the main pharmacological classes of antidepressants?

Monoamine oxidase inhibitors (MAOIs), tricyclics (TCAs), selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs), and norepinephrine–dopamine reuptake inhibitors (NDRIs).

What does the monoamine hypothesis claim, and what are its limitations?

It posits that depression stems from low levels of monoamine neurotransmitters, yet drug effects are delayed and empirical evidence for simple monoamine deficiency is mixed.

How does chronic stress biologically contribute to depression?

Persistent cortisol elevation causes excitotoxicity, lowers BDNF, and leads to atrophy in the hippocampus and prefrontal cortex, impairing mood regulation.

In what ways is inflammation implicated in depression?

Pro-inflammatory cytokines can cross the blood–brain barrier, alter neurotransmission and neuroplasticity, and produce depressive-like symptoms in humans and animals.

What are key evidence-based treatment strategies for depression?

Pharmacotherapy (e.g., SSRIs, ketamine), psychotherapy, brain-stimulation methods (ECT, TMS), and lifestyle interventions such as exercise or herbal supplements like St. John’s Wort.