CHAPTER12: EMOTIONAL BEHAVIORS
I. What is Emotion, Anyway? And What Good Is It?
A. Absence seizure: A type of epilepsy where an person has brief periods when they stare blankly without talking or moving. During the absence seizure people have an interruption of their normal conscious state and have no emotional expressions.
B. Limbic System: Forebrain area traditionally regarded as critical for emotion which form a border around the brainstem.
C. Strong emotions may impair reasoning, but lack of emotions can also lead to poor decision making.
D. James-Lange theory: Autonomic arousal and skeletal actions occur before an emotion. An emotion is the label we give to our physiological responses.
E. Cannon-Bard theory: Emotional experience and physical arousal occur simultaneously but are independent of each other.
F. Schacter-Singer theory: Physiological changes tell how intense an emotion is but cognitive appraisal is necessary to identify which emotion it is.
G. Locked-In syndrome: Caused by damage in the ventral part of the brainstern and leaves a person unable to make any voluntary movement other than moving the eyes.
2. Stress and Health
A. Behavioral medicine: Emphasizes effects of diet, smoking, exercise, and other behaviors on health.
B. Stress: The nonspecific response of the body to any demand made upon it.
C. Psychosomatic Illness: An illness whose onset is influenced by someone's personality, emotions, or experience.
1. Ulcers: A disorder where stomach secretions attack the lining of the stomach. Psychologist have found evidence that this disorder can be cause by stressful experiences in both animals and humans.
2. Heart disease is more common in people who are frequently hostile than among people who are relaxed and easy going.
3. Individuals with strong social support (i.e., friends and family) tend to keep their heart rates and blood pressure low during stressful situations.
4. Voodoo death: Death that is apparently due to the belief that a curse has destined death; however, death may actually be the result of a massive parasympathetic response causing the heart to stop altogether.
5. Serendipity: The process of stumbling upon something interesting while looking for something less interesting. Many scientific advances, such as why people die after being cursed, have been made in this way
D. Stress activates both the autonomic nervous system and HPA axis- hypothalamus, pituitary gland, and adrenal cortex. In fact, prolonged stress increasingly activates the hypothalamus/pituitary/adrenal axis. Stress activates the hypothalamus which sends messages to the anterior pituitary gland to secrete adrenocorticotropic hormone (ACTH); this hormone stimulates the adrenal cortex to secrete cortisol, which increases blood sugar levels and enhances metabolism.
E. Immune system: Comprised of cells which protect the body against intruders such as bacteria and viruses. An autoimmune disease is the result of the immune system attacking normal cells.
1. Leukocytes: White blood cells which are produced in the bone marrow before migrating to the thymus gland, spleen, and peripheral lymph nodes. Leukocytes patrol the blood and other body fluids looking for intruders.
2. Antigens (antibody-generator molecules): Proteins located on a cell surface. When leukocytes discover cells with antigens different from the rest of the body, they attack those cells.
3. Macrophages: A cell that surrounds a bacterium or other intruder, digests it, and exposes its antigens on the macrophage's own surface.
4. B cells: Leukocytes which mature in the bone marrow and produce specific antibodies to attack an antigen.
5. Antibodies: Y-shaped proteins which circulate in the blood -and attach specifically to one kind of antigen. The body develops antibodies against antigens that it has encountered in the past.
6. T cells: Leukocytes which mature in the thymus and directly attack intruder cells or stimulate added response from other immune system cells.
7. Natural killer cells: Blood cells which attach to cells infected with viruses and certain kinds of tumor cells.
8. Cytokines: Chemicals released by the immune system which cross the blood-brain barrier and influence neuronal function.
F. Psychoneuroimmunology: Deals with the ways in which experiences, especially stressful ones, alter the immune system, and how the immune system in turn influences the central nervous system.
1. Cortisol and other hormones direct energy toward increasing blood sugar and metabolism by shifting energy away from synthesizing proteins, including immune system proteins. If stress continues for weeks or months, the immune system may weaken, leaving the individual vulnerable to many illnesses.
2. High cortisol levels increase the vulnerability of neurons in the hippocampus so that toxins or overstimulation will kill the neurons.
G. Posttraumatic Stress Disorder (PTSD): Psychiatric disorder that occurs in some people who have had a traumatic experience of being severely injured or threatened or seeing other people harmed or killed. Symptoms include frequent distressing recollections (flashbacks) and nightmares about the traumatic event, avoidance of reminders of it, and exaggerated arousal in response to noises and other stimuli.
III. Attack And Escape Behaviors
A. Affective attack: Signs of emotional arousal during an attack.
B. Attack behaviors can be primed by stimulating the corticomedial area of the amygdala in hamsters. In fact, this area shows increased activity immediately after a first attack on an intruding hamster.
C. Many studies of twins and adoptees have consistently found evidence of –genetic contributions to aggression, antisocial and criminal behavior. However, these studies do not distinguish between the effects of genetics and prenatal environment.
D. One study found that monozygotic twins were more likely to resemble each other in adult crimes and aggressive behaviors than were dizygotic twins.
E. Male aggressive behavior depends heavily on testosterone among nonhuman animals. In humans, men with higher levels of testosterone have on average slightly higher rates of violent activities and crimes than do other men.
F. Temporal lobe and Violence
I . Increased activity in the ventromedial hypothalamus improves the likelihood of an attack; testosterone exerts some effect on aggression by facilitating activity in this brain area.
2. Affective attacks can be elicited by stimulating the amygdala. Rabies is a disease caused by viral infection of the brain, especially the temporal lobes (including the amygdala).
3. Kliiver-Bucy syndrome: Tameness and placidity in monkeys following damage or removal of the amygdala.
4. Temporal lobe epilepsy can sometimes provoke violent outbursts in humans; in these cases, anti-epileptic drugs are often able to control episodic violent behaviors.
G. Serotonin synapses and aggressive behavior.
1 . Turnover: Amount of release and resynthesis of a neurotransmitter by presynaptic neurons. Serotonin turnover can be inferred from the concentration of 5hydroxyindoleacetic acid (5-111AA) a serotonin metabolite.
2. Luigi Valzelli found that social isolation induced a drop in serotonin turnover in the brains of male mice which further increased the possibility of aggressive behavior toward other males.
3. In a study of 2-year-old male monkeys, researchers found that monkeys with the lowest serotonin turnover had the highest amount of aggressive behaviors. Moreover, these monkeys died before the age of 6, while monkeys with high serotonin turnover were alive at 6.
4. Data from human studies suggest a lower-than-normal serotonin turnover in those convicted of violent crimes as well as those who committed or attempted a violent suicide.
5. Neurons synthesize serotonin from tryptophan (an amino acid found in proteins). A diet high in other amino acids but low in tryptophan impairs the brain's ability to synthesize serotonin. One study found an increase in aggressive behavior in young men a few hours after eating a diet low in tryptophan.
H. Escape behaviors
1. Fear is a temporary experience; if one escapes from danger, fear will soon subside. Anxiety is a longer-lasting, less escapable state. Many psychological disorders result in part from excess anxiety.
2. Startle reflex: Response one makes to a sudden, unexpected loud noise.
3. The amygdala enhances the startle reflex by sending axons to the hypothalamus (for controlling autonomic fear responses) and by relaying information to the central gray area in the midbrain (this area in turn sends axons to the pons, triggering the startle reflex).
4. People suffering from Urbach-Wiethe disease (a genetic disorder which causes gradual atrophy of the amygdala and nearby tissues) experience fear and related emotions very weakly. These individuals also have difficulty recognizing fear in others.
I. Anxiety-Reducing drugs
1 . CCK (cholecystokinin) one the most important excitatory neuromodulators in the amygdala. Injections of CCK-stimulating drugs into the amygdala enhance the startle reflex.
2. GABA (gamma amino butyric acid) is the main inhibitory neurotransmitter found in the amygdala. Injections of GABA blockers can induce outright panic.
3. Tranquilizers (anxiety-reducing drugs) fall into two classes:
• Barbiturates. These drugs are strongly habit forming and can be fatal by combining them with alcohol.
• Benzodiazepines have the same medicinal use as barbiturates, but are not as
habit forming. These drugs bind to a receptor site on the GABAA receptor
complex which causes the receptor to change shape, allowing GABA to attach
more easily and bind more tightly to it.
• Diazepam-binding inhibitor: Also known as endozepine, this protein
binds to the same sites as benzodiazepines but blocks their behavioral
effects.