Chapter 12. Emotional Behaviors and Stress
Essay questions:
1. Describe the three components of emotion and theories of emotion
2. Describe how acute stress activates the sympathetic-adrenal medulla-axis
3. Describe how prolonged stress activates the hypothalamic-anterior pituitary-adrenal cortex-axis
4. List the main organs of immune system and define cellular immunity and humoral immunity.
5. Describe symptoms of anxiety, chemical pathogenesis of anxiety, and neuropharmacological mechanisms of benzodiazepines (anxiety-reducing drugs)
Chapter 12. Emotional Behaviors and Stress
1. Autonomic nervous system (ANS) and emotion
1.1. Review of ANS
See Transparency Overhead 80 (see Fig. 12.14)
(1). Sympathetic nerves: prepare the body for intense, vigorous, emergency activity, such as see a bear in the wood
(2). Parasympathetic nerves: increases digestion and other processes associated with relaxation
1.2. Three components of emotion
(1). Sympathetic arousal: increases in heart rate, respiration, blood pressure, galvanic skin conductance, and pupil size
(2). Subjective experience: happiness, sadness, angry, fear, phobia, euphoria
(3). Behavioral responses: facial expressions of emotions, bodily postures and gestures, tones of voice vary with angry, fear, joy, sorrow, fear, and so on.
1.3. Polygraph testing: Lie detection
Principle: the lie detector (polygraph) does not detect lies, it detects the arousal of sympathetic nervous system
Example: (Susan Smith drowned her two sons and lied to police by saying a stranger kidnapped her kids)
(1). The control-question technique: increase false positive
Ex: what is your name? (control question)
Did you kill your two sons? (target question)
Problems: innocent subjects may show arousal to target questions
(2). The guilt-knowledge technique: increase false negative
Ex: What is your name? (control question)
Are your sons still alive? (quilt-knowledge question: she drowned her
two sons by herself)
Advantage: only Susan will response to the question because only she knew they are dead.
(3). Problems with polygraph testing
1). Experienced criminal can fool the machine by conducting self-induced pain or imagining fear scenes. If I were tested by lie detector, I will beat the machine easily
Pain induction technique can fool the polygraph: by biting tongue or stepped on a tack hidden in the shoe while being asked "control questions"
2). There is no unique physiological response to deception, the reaction may result from the individual's concern or fear of the questions
3). Psychopathic individuals experiance little emotional reaction to their crimes
1.4. Theories of emotion
See Transparency Overhead 70
(1). James-Lange theory
Emotions depend on feedback from the body.
We feel fear because our heart palpitates
We feel sorry because we cry
Steps: Perception of emotion-provoking stimuli (see a bear)
Body reposes (heart palpitation)
Emotion occurs (fear)
(2). Cannon-Bard theory
Physiological responses and experience of emotion occurs simultaneously
Steps: Perception of emotion-provoking stimuli (see a bear)
Both body reposes (heart palpitation)and emotion occurs (fear) simultaneously
(3). Cognitive labeling theory
An individual's interpretation for physiological arousal determines the emotion experiences
Cognitive thinking, subjective evaluation, and physiological arousal components are all necessary to emotional experiences
Steps: Perception of emotion-provoking stimuli (see a bear)
Body responses (heart palpitates) and brain labels body response Then emotion occurs (fear)
(4). Facial feedback hypothesis
See Transparency Overhead 116, 117
Changes in facial expression provide information about what emotion is being felt. When you smile, you must be happy. Movements of the facial muscles produces or intensify emotional reactions
Steps: Perception of emotion-provoking stimuli (see a bear)
Facial expressions change (eye widen)
Emotion occurs (fear)
(5). Contemporary model of emotion
Emotional stimulus triggers the cognitive appraisal which in turn induces ANS arousal, behavioral changes, emotional expression, and emotional feelings
1.5. Brain areas associated with emotion
(1). Limbic system is critical for emotion
"limbus" = "border" in Latin)
1). Major structures of limbic system
See Transparency Overhead 79 (Fig. 12.13)
A forebrain area (which forms a border around the brainstem), Amygdala, hippocampus, cingulate cortex (gyrus of the cerebral cortex), fornix, mamillary body, parts of the hypothalamus and thalamus
2). Major functions of limbic system
Regulating emotions, memory, aggression, pleasure, sexual enjoyment, and cooperative social behavior
Ex: damage to various parts of the amygdala can make an animal excessive tame and less aggressive
(2). Medial frontal cortex is important for identifying angry expressions
(3). The insular cortex is necessary for emotional experience of disgust
(4). The right hemisphere appears to be more responsive to emotional stimuli than the left.
(5). The right hemisphere is especially activated by unpleasant emotions.
(6). Pleasure and self-stimulation of the brain
See Transparency Overhead: Extra
1). Priming: the animal does not rush to the lever as soon as it is available, but once it starts pressing, it persists for long period. Like cocaine abusers
2). Extremely high response rate: 2000 times per hour and continues for hours until collapsing from exhaustion
3). Why? for pleasure? not clear.
If it is true, we can treat depression by implanting an electrode into brain then push the button to feel happy
4). Neural structures that mediate reinforcement (self-stimulation)
see Fig. 16-7
Main ascending dopamine pathway: by stimulating these areas, dopamine secretion increases, which increases the self-stimulation for pleasure
2. Acute stress (relatively short period, few seconds to few hours) activates sympathetic-adrenal medulla-axis
Steps: Seeing a bear (stress)
Feel fear (activation of CNS)
Fight or flight (cortex's decision)
CNS activates autonomic nervous system through direct nerve connection to hypotjalamus and medulla
increase sympathetic activity inhibit parasympathetic
splanchnic nerve vagus nerve
adrenal medulla direct connection inhibits GI system
release EP and NE with heart by releasing activity
to increase HR EP and NE to increase
and BP HR and BP
(DOUBLED EFFECT)
See Transparency Overhead 142
3. Prolonged stress (relatively a prolonged period, few weeks to months) activates hypothalamic-anterior pituitary-adrenal cortex-axis
See Transparency Overhead 55
Steps: Fear to be dumped by girlfriend or boyfriend
CNS perceives chronic anxiety
Hypothalamus releases corticotropin-releasing factor (CRF)
Anterior pituitary releases ACTH
Adrenal cortex secretes cortisol and other hormones
The increase sugar level and metabolic rate
The decrease of immune system functions
Sickness: flu, or cancer
See Transparency Overhead 141
Note: The 2-system model of the response to stress
4. Stress and immune system
The fight-or flight response through sympathetic-adrenal medulla-axis is the protection against threats from the outside. However, if the danger is come from the inside of the body, such as bacteria, HIV virus, etc... your body has a defense system to protect you, this is immune system
4.1. Antigens (antibody generator)
When the body recognizes something as a "not self" invader, the immune system mobilizes body resources and attacks the invader. Any substance that can trigger an immune response is called an antigen
(1). Bacteria
Bacteria exists in river, ocean, air, plants, animals, decaying organic matter, their activity is essential to the life, such as in the large intestine which helps the bowel movement
(2). Fungi
Fungi are organisms, such as molds and yeasts, they attach to an organic host and absorb nutrients from the host. Some cause skin diseases. Penicillin is derived from molds
(3). Protozoa
Protozoa are one-celled animals, such as amoebas. They live primary in water and insects. Drinking contaminated water can cause amoebic dysentery, an intestinal illness, and being bitten by an infected mosquito can cause malaria
Be careful when you travel in some area
(4). Viruses
Virus is the tiniest of these antigens. They are particles of proteins that are smaller than cells. Strictly speaking, they are not even alive
They responsible to a variety of diseases: flu, herpes, measles, polio, and AIDS
(5). Organ transplants
Normally the body rejects the transplant by immune system.
They are two ways to increase transplant acceptance:
1). To select the transplant carefully so that the tissue of the donor and recipient are as similar as possible (identical twins);
2). To suppress the immune system with drugs like cortisol (this low immune function will cause the patientto be susceptible to infectious diseases and cancer)
4.2. The organs of the immune system
See Transparency Overhead: Immune System
(1). Lymphatic fluid circulating system
Blood - aorta - arteries - arterioles (small arteries) - capillaries - fluids(lymph) leak from capillary diffusion - lymph travels in the lymph vessels - fluids (lymph) returning to vein - to heart - aorta
(2). Lymph node
They are a series of round or oval capsules spaced throughout the lymphatic system
(3). Lymphocytes (also called leukocyte)
Types of white blood cell found in the lymph. They are T cells, B cells, and Natural killer cells
(4). Bone marrow
Lymphocytes arise in the bone marrow. Leukemia patients need bone marrow transplantation
(5). The spleen
Spleen is one site of lymphocyte maturation as a holding station for lymphocytes
(6). The thymus
Thymus is involved in the maturation and differentiation of lymphocytes
(7). Tonsils
Tonsils are masses of lymphatic tissue located in the throat containing lymphocytes
(8). Macrophage
They destroy bacteria, parasites (non specific, and act slowly)
(9). Granulocyte
They kill bacteria and act rapidly
4.3. Cellular immunity
See Transparency Overhead 56 and two extra oveheads
Cellular immunity: a variety of T lymphocytes, natural killer cells, and macrophages destroy unwanted cells through cell to cell interaction
4.4. Humoral immunity
Humoral immunity is composed of B lymphocytes that recognize specific antigens and produce molecules called antibodies. These antibodies are also called immunoglobulin, which cause the destruction or deactivations of the pathogen
4.5. The hormones, nervous system, and Immune system
(1). Adrenal corticosteroid can move T cells out of peripheral circulation, inhibit T cells proliferation, block T cells activity, and reduce B cells' ability to produce antibodies
(2). Destruction of portions of the hypothalamus impairs immune function
(3). Thalamus, spleen, bone marrow, lymph nodes, tonsils receive nerve fibers from autonomic nervous system
Ex: destruction of sympathetic nerve distributions, immune activity is enhanced, suggesting an inhibitory role for the sympathetic nervous system
4.6. Effects of stress on the immune system
(1). Immune responses to bereavement (death of spouse)
Reduced T lymphocytes, lower natural killer cell activity
(2). Immune responses to divorce
Recent separated women and men have lower cellular immune activity
(3). Immune responses to final examination
Herpes virus activity increased
Natural killer cells' activity decreased (for those students who reported very anxious during the final week)
5. Aggression and attack behaviors
5.1. Types of aggressive behavior
(1). Defensive aggression: self-defense for survival
(2). Predatory aggression: predation for food by killing others
(3). Social aggression: to establish a social dominance hierarchy
5.2. Heredity and environment in violence
(1). Studies of twins and adoptees have found genetic contributions to agreession, antisocial, and criminal behavior
(2). Monozygotic twins were more likely to resemble each other in adult crimes and aggressive behaviors than were dizygotic twins
(3). Adopted children, who had biological parents with criminal records and a troubled adoptive home, were more likely to exhibit aggressive behaviors and conduct discorders.
(4). The more a woman smoked cigarettes during preganancy, the more likely her son was to be arrested for criminal activities in adlolescence and early adulthood.
See Transparency: Figure 12.9
5.3. Hormones: Testosterone and aggression
(1). Male animals tend to be more aggressive than females
Reason: male hormone-testosterone
(2). British scientists reported that men who has large testes are more aggressive, having more extra-marrital affairs, and more successful in careers (3 times larger than average)
(3). Castration of male animals reduces their tendency to be aggressive
(4). The aggressive behavior of castrated animals can be restored by injections of testosterone
(5). Human studies:
See Transparency: Figure 12.10 from Kalat's book
1). The male aggressiveness and internal fighting show a marked increase during pubescence in the early teens when testosterone levels increase significantly
2). Inmates in the prison convicted of violent crimes tend to have high testosterone levels than other prisoners
5.4. Psychosurgery and aggression
(1). Hypothesis: violent people have excessive activity in the structures of the brain (amygdala) which causes the violent behavior. By destroying these structures can reduce violent behavior
(2). Electrical stimulation: stimulation of amygdala (part of the temporal lobe) and the ventralmedial nuceus of the hypothalamus increases attack behavior
(3). Amygdalectomy often reduces the average level of aggressive behavior in animals (See Transparency 57: Figure 12.9)
(4). Human practice: people with focal epileptic seizures in the temporal lobe often have a history of violent toward others and themselves. Amygdalectomy reduced the violent behavior
Mostly, these people are treated successfully with antiepileptic drugs, such as, dilantin.
For some people who are not responsive to Dilantin, surgeons use selective destruction of specific structures in the brain, such as amygdala
5.5. Serotonin turnovers (metabolites) and aggression
(1). Mice with low serotonin turnover is associated with increased aggressive behavior
(2). People with a history of violent behavior have lower than normal serotonin turnovers (release less or synthesis less)
(3). Serotonin is significantly decreased in people who committed suicide by violent means
(4). Serotonin turnover is also decreased in people convicted of arson and other violent crimes
(5). The murder rate is highest in those countries that consume the most corn. Corn contains very little tryptophan, the precursor to serotonin. That is, eating a lot of corn decreases serotonin synthesis
Warning: do not eat popcorns while watching violent movies
6. Anxiety and escape behaviors
6.1. Symptoms of anxiety:
(1). An unpleasant state accompanied by apprehension, worry, fear, nervousness and sometimes conflict.
(2). An increase of sympathetic nervous system arousal with increased blood pressure, heart beat, respiratory rate. Dry mouth and gastrointestinal discomfort may occur
6.2. Chemical pathogenesis of anxiety
Two neurotransmitters are involved in anxiety disorders
(1). High levels of noradrenaline (norepinephrine):
Yohimbine blocks noradrenergic autoreceptors (e.g. on cell bodies and nerve terminals) and then enhance noradrenaline release. The drug can cause fear and anxiety in both man and animals
Clonidine which stimulates noradrenergic autoreceptors can relieve anxiety state
(2). Low levels of GABA:
GABA is one of the most widely distributed neurotransmitters in the mammalian brain, occupying some 40% of all synapses. GABA is an inhibitory transmitter and reduces firing of brain cells.
The facilitation of GABAergic activity is associated with the reduction in anxiety. GABA antagonists delete the effects of benzodiazepines
6.3. Anxiety-reducing drugs
(1). Barbiturates: induce sleep, addictive, overdose is fatal
(2). Benzodiazepines: relieving anxiety, relax muscles, induce sleep (valium, xanax)
Classifications of Benzodiazipines
A. Long-acting benzodiazepines - once or twice per day
1). Valium (Diazepam)
2). Librium (Chlordiazepoxide)
Same as Valium but less potent then Valium
B. Intermediate-acting benzodiazepines - three or four times daily
3). Restoril (Temazepam)
4). Xanax (Alprazolam)
C. Short-acting benzodiazepines - three or four times daily
5). Serax (Oxazepam)
6). Ativan (Lorazepam)
Same as Serax
7). Halcion (Triazolam)
6.4. Neuropharmacological mechanisms of benzodiazepines
See Figure 12.10 of Kalat book, page 435
The benzodiazepine receptor and GABA function
Within the brain, benzodiazipine receptors are specially located in the cerebral cortex, the limbic system, midbrain and the brain stem and spinal cord
(1). Benzodiazepine binding site is located next to the site where GABA binds.
(GABA is one of the most important inhibitory neurotransmitter in the brain).
(2). Benzodiazepine first bind to benzodiazepine receptors and then potentiates GABA-induced increase in chloride conductance, which in tern, inhibits synaptic action
Conclusion: benzodiazepine reduces anxiety by increasing GABA-receptor-coupled chloride conductance
Benzodiazepines do not directly act on GABA receptors.
The brain has two GABA receptors: GABAa and GABAb
GABAa sites decrease anxiety. Benzodizepines facilitate binding of GABA to the GABAa receptors and then help to reduce anxiety
The heart of the GABAa receptor complex is a chloride channel. When open, it permits chloride ions (CL-) to cross the membrane into a neuron, and hyperpolarizing the cell (inhibitory effect)
Changes in benzodiazepine receptor function following chronic administration of benzodiazepines
It is well-established biological phenomenon that receptors adapt to the prolonged presence or absence of an agonist by changing their sensitivity.
Example 1: high doses of diazepam, lorazepam, and flurazepam causes a decrease in benzodiazepine receptors in the cortex of the brain, but the number of receptors rapidly returns to normal following the abrupt cessation of drug treatment.
Exam 2: There is also electrophysiological evidence to show that the functional activity of the GABA receptors is also decreased following prolonged treatment with chlozodiazepoxide.
6.5. Excess anxiety: panic disorder
(1). Symptoms: A person with panic disorder suffers occasional attacks of extreme fear, breathlessness, heart palpitations, fatigue, and dizziness.
(2). Explanations:
1). Chronically high levels of norepinephrine (drugs that increase the release of norepinephrine can produce anxiety even in normal people)
2). Many people prone to panic disorders have an overresponsive sympathetic nervous system
(3) Conclusion:
The symptoms of anxiety result from increased norepinephrine activity and decreased GABA activity
6.6. Amygdala and anxiety
(1). Amygdala activity (using PET Scans) was greatest when people feel fear
(2). People with amygdalectomy did not develop learned fear
(3). People with amygdala atrophy experience very low level of fear and anxiety
(4). People with amygdala atrophy have trouble recognizing facial expression of fears in other people