Chapter 17 Biopsychology of Emotion, Stress, and Health

Fear, the Dark Side of Emotion This multimedia product and its contents are protected under copyright law. The following are prohibited by law: • any public performance or display, including transmission of any image over a network; • preparation of any derivative work, including the extraction, in whole or in part, of any images; • any rental, lease, or lending of the program.

Copyright © 2006 by Allyn and Bacon

Phineas Gage

• Why would a tamping iron through the skull lead to dramatic changes in personality?

• Damage to the medial prefrontal lobes Copyright © 2006 by Allyn and Bacon

Darwin’s Theory of the Evolution of Emotional Expression • Expressions of emotion evolve from behaviors that indicate what an animal is likely to do next.

• If emotional signals are beneficial, they will evolve to more effectively communicate and may lose their original meaning.

Theories of Emotion

• James-Lange – Stimulus > autonomic/skeletal response > emotion – Autonomic/skeletal response necessary for emotion – I run therefore I am afraid • Cannon-Bard – Stimulus > autonomic/skeletal response & emotion – Autonomic/skeletal response independent of emotion – Can be interpreted as Parallel emotion/response • Both are wrong

Theories of Emotion

Bard – Sham Rage

• Decorticated cats exhibit extreme and unfocused aggressive responses • Hypothalamus must be intact • Perhaps hypothalamus is needed for expression of aggression and cortex serves to inhibit and direct responses • Papez proposed emotional circuit – limbic system, that includes hypothalamus

Kluver-Bucy Syndrome

• Rare cerebral neurological disorder • Major symptoms - urge to put objects into mouth, memory loss, extreme sexual behavior, placidity, visual distractibility. • Bilateral temporal lobes.

Emotions and the Autonomic Nervous System (ANS) • Which patterns of ANS activity are associated with specific emotions?

• There is

NOT

a separate ANS profile for each emotion.

Emotions and Facial Expression

• The meanings of facial expressions appear to be universal • 6 primary emotions – all others are a mixture of these

• 6 primary emotions – Surprise – Anger – Disgust – Fear – Sadness – Happiness

Facial Expressions

• Facial Feedback Hypothesis – Smiling does make you happier – facial muscles may feedback and influence emotional experience • Microexpressions – brief facial expressions that reveal true feelings often break through false ones • Different muscles involved in fake and real smiles

Fear, Defense, and Aggression

• Fear – emotional reaction to threat • Defensive behaviors – designed to protect from threat or harm, motivated by fear • Aggressive behaviors – function to threaten or harm

Aggression and Testosterone (T) • Nonprimates – relationship between T and aggression is clear • Human males – aggression does not increase at puberty, is not eliminated by castration, and not increased by T injection • But – violent male criminals and aggressive male athletes have slightly elevated T levels • Aggressive encounters may increase T, rather than vice versa

Stress and Health

• Stress – reaction to harm to threat • Stressors – stimuli that cause stress • Chronic psychological stress – most clearly linked to ill health • In the short-term stress is adaptive, in the long-term it is maladaptive

Selye and the Stress Response

• Activation of the anterior-pituitary adrenal-cortex system • Selye neglected the role of the sympathetic nervous system • All common psychological stressors are associated with high levels of glucocorticoids, epinephrine, and norepinephrine

Effects of Stress

Stress and Immune Function

• If stress affects immune function, how might it do so?

• Why is stress initially adaptive and then, when chronic, harmful?

Meta-Analysis of Stress Studies

• Effects of stress on immune function depend on the kind of stress – Acute stressor improve immune function – Chronic stressor impair • Many ways that stress could impact immune function

Stress and the Hippocampus

• Hippocampus has many glucocorticoid receptors • Following stress – Dendrites of pyramidal cells are shorter and less branched – Adult neurogenesis of granule cells reduced • Effects blocked with adrenalectomy, produced with corticosteroids • Effects seen with only a few hours of stress

Stress and the Hippocampus

• Natural stressors produce more pathology than artificial ones • Effects are severe enough to disrupt behaviors mediated by the hippocampus • Effects of stress tend to be greater in males (estradiol protects – promotes neurogenesis and recovery)

Fear Conditioning

• Auditory fear conditioning blocked with medial geniculate nucleus (MGN) lesions – not affected by auditory cortex lesions • Critical pathways: MGN to amygdala • Amygdala lesion blocks fear conditioning

Auditory Fear Conditioning

Brain Mechanisms of Human Emotion • Neuropsychological studies of the brain damaged • Functional imaging of the healthy • Amygdala and prefrontal cortex clearly play a role

Emotion

• What unique challenges must be overcome in the study of emotion?

• Why is it important to develop an understanding of the brain mechanisms that underlie emotion?