Ch 17: Emotion, Stress & Health

Fear Biopsychological research on emotions has concentrated mainly on fear because it has 3 important qualities The easiest emotion to infer from behavior in a variety of species Plays an adaptive function in motivating the avoidance of threatening situations Chronic fear induces stress

Phineas Gage In 1848, Phineas Gage had a terrible accident when a 3-foot iron rod was blasted into his face, going through this brain and out the other side of his skull

Phineas Gage He survived!!! He was as able-bodied & intellectually capable as before But his personality & emotional life changed drastically

Phineas Gage While he was originally a pious, respectful & reliable man; after his injury he was rude, impulsive, undependable, cursed a lot, lost his job After his death, his skull was studied to determine the brain areas that were likely damaged Both medial prefrontal lobes Known to be involved in planning & emotion

Darwin’s Theory of the Evolution of Emotion Observed that members of a species have the same behavioral responses to specific emotional states (ex: human facial expressions) So the behavioral expressions of emotion are the product of evolution Expressions of emotion evolve from behaviors that indicate what an animal is likely to do next Over time the signals may lose their original meaning, remaining only communicative Threat displays Opposite messages are often signaled by opposite movements/postures (ex: aggression/submission)

James-Lange Theory Emotion-inducing sensory stimuli are received by the cortex & trigger bodily changes via the autonomic & somatic nervous system, which trigger the experience of emotion in the brain

Cannon-Bard Theory Emotional stimuli have 2 independent excitatory effects: The feeling of emotion in the brain The physical expression of emotion in the autonomic & somatic nervous systems The emotional experience & physiological expression of the emotion are parallel processes (no causal relationship)

J-L vs C-B J-L: C-B: So which is right? Emotional experience depends entirely on feedback from the ANS/SNS activity C-B: Emotional experience is independent of the ANS/SNS activity (yet simultaneous) So which is right? Both wrong!

Modern Biopsychological View of Emotion Each of the 3 factors of an emotional response… Perception of emotion-inducing stimuli Autonomic & somatic nervous system responses Experience of the emotion …can influence the other 2.

Comparing the Theories of Emotion

Limbic System A circuit of interconnected nuclei & tracts around the thalamus that are involved in emotional expression Amygdala, mammilary body, hippocampus, fornix, cortex of the cingulate gyrus, septum, olfactory bulb & hypothalamus

Emotions & Facial Expression The human facial expressions of the major emotions are universal People from all different cultures can identify the emotion just from pictures of facial expressions And they are very similar to those made by primates And now I need a volunteer! http://www.nbb.cornell.edu/neurobio/land/oldstudentprojects/cs490-95to96/hjkim/emotions.html

Emotions & Facial Expression There are 6 primary emotions & corresponding facial expressions Surprise Anger Sadness Disgust Fear Happiness All other facial expressions of genuine emotion are some combination of these 6

Facial Feedback Hypothesis Your facial expression can influence your emotional experience If you smile, it can actually cause you to feel happy!

Voluntary Control of Facial Expressions Because we can voluntarily control our facial muscles, we can inhibit true facial expressions & create false ones But the details show differences between real & fake expressions Microexpressions Millisecond long expressions of your true emotion that intermittently break through the fake face you are making Slow-mo video review can show them

Voluntary Control of Facial Expressions Real vs. fake smiles Both involve lifting the corners of your mouth But only real smiles (Duchenne smiles) also involve the muscles at the outside corners of your eyes

Skip 17.2 & 17.3

Stress & Health Stress is the body’s physiological response to threat Stressors (experiences that cause stress) can be physical or psychological Chronic psychological stress has been frequently implicated in poor health The stress response is adaptive in the short term because it causes the animal to respond to the stressor, but in the long term it produces changes that are maladaptive

Stress Response Stressors stimulate the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary, which then triggers the release of glucocorticoids from the adrenal cortex, which results in the stress response Stressors also activate the sympathetic nervous system, which increases the amount of epinephrine and norepinephrine released from the adrenal medulla

Stress Response

Psychosomatic Disorders Medical disorders with psychological causes Stress can cause a number of medical disorders Heart disease, asthma, skin disorders, gastric ulcers, etc So many medical maladies can be caused by stress that almost any medical disorder could be classified as psychosomatic Stress can increase one’s susceptibility to infectious diseases

Stress & the Immune System Psychoneuroimmunology: the study of interactions among psychological factors, the nervous system & the immune system The effects of stress on the immune system depend on the kind of stress Acute (less than 100min) stressors improve immune function Ex: public speaking Eustress: stress that improves health Chronic stressors negatively impact the immune system Ex: caring for a sick loved one, a period of unemployment Distress: stress that disrupts health

Stress & Health Stress can also affect your behaviors which in turn decrease your immune system function Ex: not sleeping, not eating healthy, not exercising, drug use The behavior of a stressed person can produce stress & illness in others Ex: stressed mother & the health of her child Early exposure to stress can have many negative effects on development (especially brain & endocrine system) Including prenatal stress

Stress & the Hippocampus Exposure to stress can negatively affect the brain The hippocampus is particularly susceptible to the negative impacts of stress Likely because of the high concentration of glucocorticoid receptors in the hippocampus

Brain Mechanisms of Emotion Scans have shown that brain activity associated with each human emotion is diffuse i.e. no sadness center of the brain Experiencing emotion or empathizing almost always results in activity in motor & sensory cortical areas There is similar brain activity when someone experiences an emotion, imagines that emotion, or sees someone else experiencing that emotion Think back to mirror neurons!

Brain Mechanisms of Emotion The amygdala is involved in the perception of fear & other negative emotions, not so much its experience The medial prefrontal lobes are active when emotional reactions are being cognitively supressed or reevaluated

Asymmetry of Facial Expressions In most people, a facial expression is more pronounced on the left side of the face So we pay more attention to that side to get emotional info Even dogs have picked up on this!! Monkeys also have asymmetrical left-biased facial expressions!

Asymmetry of Facial Expressions