Emotional behaviors Flashcards
What is an emotion?
- Psychologists define emotion in terms of these components
- Cognition (e.g. thinking, memory, judgement, thinking “this is dangerous”)
- Action (physical response to stimuli, e.g. run away)
- Feeling (emotional state/reaction, “I feel scared”)
- Physiological changes (e.g. breathing, rapid heartbeat)
Emotions and autonomic arousal
- Emotional situations arouse the autonomic nervous system
- ANS divided into sympathetic (fight flight, increase heart rate)) and parasympathetic (rest and digest system,
- Most situations (incl emotional situations) evoke a combination of sympathetic and parasympathetic arousal
- Fear can not only elicit sympathetic activity, but also parasympathetic (e.g. FREEZE response when threat is at distance rather than closer)
The James-Lange Theory of Emotion
the autonomic arousal and skeletal actions come before the emotion.
An emotion includes cognitions, actions, and
feelings. The cognitive aspect comes first. You quickly appraise
something as good, bad, frightening, or whatever. Your
appraisal of the situation leads to an appropriate action, such
as running away, attacking, or sitting motionless with your
heart racing. When James said that arousal and actions lead
to emotions, he meant they lead to the feeling aspect of an
emotion
- James-Lange theory leads to two predictions:
- People with a weak autonomic or skeletal response should feel less emotion
- Increasing one’s response should enhance an emotion
(These are to some degree supported, but it seems there are also other components involved in emotion)
James-Lange theory leads to two predictions:
Do they hold?
- People with a weak autonomic or skeletal response should feel less emotion
- Increasing one’s response should enhance an emotion
• Do the james lange predictions hold?
• Research findings
• Paralyzed people report feeling emotion to the same degree as prior to their injury
• They have skeletal damage (they have physiological response, but action can’t happen) = emotions don’t require feedback from whole body movements
• Pure autonomic failure
• Output from autonomic nervous system to body fails – we would expect such people to report no emotions.
• People with this condition have no autonomic response to stress – they report feeling same emotions, but less intensely = decrease in emotional feeling IS consistent with james lange theory
Taken together = there are other factors involved in perception and emotion (I guess beyond the physical response as emphasized by james lange)
people with damage to the right somatosensory
cortex have normal autonomic responses to emotional music but report little subjective experience. People with damage to part of the prefrontal cortex have weak autonomic responses but normal subjective responses. These results suggest that autonomic responses and subjective experience are not always connected to each other.
BOTOX – how does it affect Autonomic and Emotional Responses?
- Botox can fix wrinkles + handle migraines
- BOTOX blocks transmissions at synapses and nerve-muscle junctions
- People with BOTOX injections report:
- Weaker than usual emotional responses after watching short videos
- Implies feeling a body change is important part of feeling an emotion
Physiological Arousal and Emotions - is it necessary/sufficient?
- According to the James-Lange theory, emotional feelings result from the body’s actions
- But is physiological arousal sufficient for emotion to occur? (probably no, e.g. we don’t feel an emotion after tough exercise = physical arousal – but panic attacks is another case!
- Although physiological responses are seldom sufficient to produce emotional feelings, they increase the feelings (e.g. in cold room = shiver = rate horror movie as scarier).
- Cannon-Bard theory: disagrees with james lange theory - feedback from the viscera is neither necessary nor sufficient for emotion – no consensus.
- Panic attacks are marked by intense sympathetic nervous system arousal ((sometimes brought on by) rapid heartbeat, fast breathing, etc.)
- Only if perceived as occurring spontaneously
- Creating certain body actions may also slightly influence emotion
- Smiling slightly increases happiness
- Inducing a frown leads to the rating of stimuli as slightly less pleasant
- Indicates that perception of the body’s actions do contribute to emotional feeling
The Limbic System - role and evidence in emotion
• Emotional experiences arouse many areas of the brain
• The limbic system includes the forebrain areas surrounding the thalamus (and brainstem)
• Includes amygdala important for fear
From google: The primary structures within the limbic system include the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus.
• Traditionally regarded as critical for emotion
• PET and fMRI studies suggest particular cortical areas are activated during an emotional experience – when we review brain imaging studies, what emerges is NO evidence for localization of emotion/single area critical to emotion in general without being behavioral aspects. – many emotions elicit activity in many different areas.
• Much of the cerebral cortex also reacts to emotional situations
• Some part of amygdala maybe specialized for PERCEIVING emotion in someone’s expression
• with the possible exception of happiness, no brain area appears to be specific for experiencing any particular emotion
Do People Have a Limited Number of Basic Emotions?
Do People Have a Limited Number of Basic Emotions?
• Main support for the idea of basic emotions
• Facial expressions exist for happiness, sadness, fear, anger, disgust, surprise, and perhaps other emotions
• if shown a set of faceial expressions, and a list of emotion terms, most people in cultures throughout the world pair them up with greater-than-chance accuracy.
• We rarely interpret emotion based solely on facial expressions, because…
• Two or more emotions can be present in a single facial expression
• Context and gestures important
• Both of these contribute to what the emotion really is.
• (We are better at recognizing expressions of people from our own culture)
Contributions of Left and Right Hemispheres - (2) dimensional approach to emotions
- An alternative view to this basic emotions thing
- Emotional feelings vary along two (or more) continuous dimensions (support from physiology)
- Example: weak to strong, pleasant to unpleasant, approach versus avoid
- Behavioral Activation System (BAS) - activation of the left hemisphere, especially frontal and temporal lobes
- Marked by low to moderate arousal and tendency to approach
- Can characterize happiness or anger
- Behavioral Inhibition System (BIS) - increased activity of the frontal and temporal lobe of the right hemisphere
- Increases attention and arousal
- Inhibits action
- Stimulates emotions such as fear and disgust
- (seems to be more responsive to emotional stimuli)
The difference between the hemispheres relates to personality:
On the average, people with greater activity in the
frontal cortex of the left hemisphere tend to be happier, more
outgoing, and more fun-loving. People with greater right hemisphere
activity tend to be socially withdrawn, less satisfied
with life, and prone to unpleasant emotions
• Behavioral Activation System (BAS)
activation of the left hemisphere, especially frontal and temporal lobes
• Marked by low to moderate arousal and tendency to approach
• Can characterize happiness or anger
People were quicker and more accurate at identifying happy faces when the information went to the left hemisphere
- Emotional feelings vary along two (or more) continuous dimensions (support from physiology)
- Example: weak to strong, pleasant to unpleasant, approach versus avoid
• Behavioral Inhibition System (BIS)
increased activity of the frontal and temporal lobe of the right hemisphere
• Increases attention and arousal
• Inhibits action
• Stimulates emotions such as fear and disgust
• (seems to be more responsive to emotional stimuli)
They had an advantage in
processing sad or frightened information when the information
went to the right hemisphere
- Emotional feelings vary along two (or more) continuous dimensions (support from physiology)
- Example: weak to strong, pleasant to unpleasant, approach versus avoid
The Functions of Emotion? what are they good for?
- Emotion has adaptive value (e.g. fear alerts us of danger)
- Examples: fear leads to escape, and anger leads to attack
- Adaptive value of other emotions is less obvious
- Emotions help communicate needs to others
- And understand others’ needs
- Aid in quick decision making (from gut feeling)
Emotions and Moral Decisions
- Emotions important Making important moral decisions
- We pay much attention to how the outcome will make us feel
- Contemplating moral decisions activates the prefrontal cortex and cingulate gyrus (areas responsive to emotions)
- Moral decisions are seldom made rationally
- One decision or the other just “feels” right
- We rationalize after decision has been made
Decision-Making after Brain Damage - role of PFC damage in decisions and emotions
- Damage to parts of the prefrontal cortex blunts emotions
- Impairs decision-making (If confronted with trolley dilemma, more likely to choose utilitarian option, saving 5 people)
- Leads to impulsive decision-making without pausing to consider consequences
- Those with damage to the ventromedial prefrontal cortex show (Phineas gage):
- Inconsistent preferences
- Decreased guilt (would say yes to murder someone they hate) and trust (in dictator and trust game, they show very little concern for others (keeping more to themselves)
- Damasio investigated man with frontal cortical damage, expressed basically no emotionality = does not equal rational decision making, he had bad decision making, costing him job, marriage and savings.
- Ventromedial parts – damage result in loss of guilt.
- Damage to amygdala or PFC = slow at processing emotional information.
Attack and Escape Behaviors
Anger and fear are closely related both behaviorally and physiologically.
• Attack and escape behaviors and corresponding emotions (anger and fear)
• Closely related physiologically and behaviorally
• Role of the amygdala important (in cortex, near medial temporal lobe, almond shaped) – important in fear and escape behaviors. - no coincidence that we describe the sympathetic nervous system
as the fight-or-flight system.
if we have “attacked” once, a shot after intruder will increase our likelihood of attack. activity builds up in the corticomedial area of the amygdala and as it does so, it increases the hamster’s probability of attacking
the role of Heredity and Environment in Violence
- Individual differences in aggressive, violent, or antisocial behavior depend on both heredity and environment
- Environment
- If person was witness or victim of violence in childhood
- Living in a violent neighborhood
- Abused children are more likely to express violent behavior
- Exposure to lead (bly på dansk) harms developing brains
- Heredity
- Twin studies indicate significant amount of heritability although there is some debate about experimental design (e.g. measuring aggression)
- Furthermore, heritability for antisocial behavior is fairly high in middle-class neighborhoods, but much lower in the most impoverished neighborhoods (The interpretation is that extremely bad environment can elicit antisocial behavior in almost anyone. The same behavior is less common in wealthier environments and more likely to have a genetic predisposition.)
- MAOA gene—low activity form of this gene shows a link to aggression (lowactivity form of the gene increased violent behavior only in people who had a seriously troubled childhood environment. - possibly less active form is linked to greater emotional reactivity)
Take home message: interaction between genes and environment in aggression!
Effect of Hormones—Aggressive Behavior
- Testosterone is important – males are more aggressive than women generally (in animal kingdoms, when convicted, etc)
- Male aggressive behavior heavily depends on testosterone
- Young men have highest rates of aggressive behaviors and violent crimes
- Testosterone levels where highest for criminals of violent cries than less violent crimes
- On average, men engage in more aggressive and violent behaviors than women – is this due to testosterone? (injecting testosterone vs placebo is better, than looking at correlational studies, because subjects may be different in other regards than testosterone too)
- Increasing testosterone in women
- Increased the amount of time looking at angry faces (increase response in amygdala in response to angry faces)
- Results in more arguing during collaborative tasks
Serotonin Synapses and Aggressive Behavior
- Impulsiveness and aggressive behavior have been linked to low serotonin release
- (typically measured by) Serotonin turnover
- The amount of serotonin that neurons released, absorbed, and replaced
- Measured by the concentration of 5-HIAA in the cerebrospinal fluid
In mice:
methods of decreasing serotonin turnover also increase aggressive behavior
In humans:
• Low serotonin turnover found in people with history of violent behavior (and people attempting suicide by violent means)
• Arson & violent crimes
• Suicide by violent means
• People with lower serotonin turnover has higher chances of re-conviction.
• Relationship between serotonin and aggression is small
• Cannot be used to make predictions about an individual
Testosterone, Serotonin, and Cortisol - the role of NT interactions/combinations
• Aggressive behavior does not correlate strongly with any one chemical because it depends on a combination
• Testosterone, facilitates aggressive, assertive, dominant behavior
• Serotonin tends to inhibit impulsive behaviors
• Cortisol inhibits aggression
• Aggressive behavior depends on ratio of testosterone to cortisol
But even a combined measure of testosterone, cortisol, and serotonin provides only a modest relationship to aggressive behavior. Several medications for restraining anxiety are effective enough to justify their use in some cases. No pill is likely to be effective in controlling violence.
Fear and Anxiety, role of amygdala, and startle reflex
• Proneness to approach, avoidance, and anxiety varies with the situation and the individual
• Role of the amygdala
• Important for enhancing the startle reflex (startle reflex = response one makes to sudden, unexpected loud noises-auditory stimulus stimulates pons in brainstem, commands tensing of muscles in neck, info reaches brainstem in 3-8 ms – startle response occurs within 2 tenths of a second – more likely to occur of we are already tense (more common in PTSD))
• Startle reflex
• Extremely fast response to unexpected loud noises
• Can be used as a behavioral measure of anxiety
Although you don’t have to learn to fear loud noises, your current mood or situation modifies your reaction. Your startle reflex is more vigorous if you are already tense.
startle reflex
startle reflex = response one makes to sudden, unexpected loud noises-auditory stimulus stimulates pons in brainstem, commands tensing of muscles in neck, info reaches brainstem in 3-8 ms – startle response occurs within 2 tenths of a second.
• Startle reflex
• Extremely fast response to unexpected loud noises
• Can be used as a behavioral measure of anxiety
Although you don’t have to learn to fear loud noises, your current mood or situation modifies your reaction. Your startle reflex is more vigorous if you are already tense.
Neuroanatomy of Fear and Anxiety (amygdala)
- The amygdala is important for knowing what to fear.
- If a person is attacked or has a fearful experience, he/she becomes fearful in a wide variety of circumstances (long term generalized emotional arousal is associated with bed nucleus)
- Bed nucleus of the stria terminalis (stria terminalis itself if the projection/axons connecting bed nucleus to amygdala)
- Brain area that controls long-term, generalized emotional arousal
Much input from sensory
systems including vision and hearing goes to the lateral and
basolateral areas of the amygdala, which relay the information
to the central amygdala, which combines it with pain and
stress information that it received from the thalamus
Learning a fear strengthens synapses at several of the connections along this route
stronger connections between the lateral and central amygdala is characterized by heightened anxiety in many cases (in mice)
By stimulating or damaging parts of laboratory animals’
amygdala, researchers have found that one path through the
amygdala is responsible for fear of pain, another path for fear
of predators, and yet another for fear of aggressive members of
your own species (Gross & Canteras, 2012). Also, one part of
the amygdala controls changes in breathing, another controls
avoidance of potentially unsafe places, and another controls
learning which particular places are safest (Kim et al., 2013).
= what we call fear is a conglomerate of separate aspects, not a single indivisible state
Klüver-Bucy Syndrome
- Damage to the amygdala
- Monkeys with this syndrome are tame/placid
- Display less than normal fear of snakes and larger, more dominant monkeys
- Have impaired social behaviors (largely because they don’t seem to learn which monkeys to approach with caution.)
- monkeys with such damage are impaired at learning what to fear
Human Amygdala (fMRI) Studies
- fMRI studies show the amygdala responds strongly to photos that arouse fear or photos of faces showing fear or anger (also to a less degree to faces showing happiness or sadness)
- Response is stronger when the meaning (in facial expression) is unclear and likely does so because it requires some processing to make sense of.
- Responds more strongly to a frightened face directed toward the viewer and angry faces directed elsewhere
amygdala’s response to a frightened face emerges in the remarkably fast time of just 74 milliseconds (ms) after presentation (faster than fysiform gyrus)
Individual Differences in Amygdala Response and Anxiety
Part of the variance in anxiety relates to genes and part relates to epigenetic changes caused by experiences,
especially experiences early in life
Individual differences in anxiety correlate strongly with amygdala activity.
However, anxiety depends on more than just the amygdala. It also depends on cortical areas that help people cope with threatening information. An effective way to cope is reappraisal— reinterpreting a situation as less threatening. Reappraisal and similar methods of suppressing anxiety depend on top-down influences from the prefrontal cortex to inhibit activity in the amygdala. People with stronger connections between the prefrontal cortex and the amygdala tend to make more use of reappraisal and tend to feel less anxiety.
Anxiety reactivity affects much of life, even political attitudes. (more support for military = more startle reflex)
Damage to the Human Amygdala
- In humans, amygdala damage does not result in the loss of emotion
- Effects of damage
- Individuals can classify emotional pictures without difficulty
- Individuals experience little arousal from viewing unpleasant photos
- –> cognitive aspect works, but the “feeling” aspect is impaired.
- Impaired at creating drawings of fearful expression, at least for Urbach-Wiethe (patient SM drew baby when asked to draw fear – said she couldn’t imagine what fearful face would look like)
- Urbach-Wiethe Disease: rare genetic condition that causes calcium to accumulate in the amygdala until it wastes away - they are impaired at processing emotional information and learning what to fear
- SM always looked at nose instead of eyes – when she looks at eyes, she could recognize fear.
- The amygdala automatically directs attention toward emotionally significant stimuli, even without your awareness – people with amygdala damage lack this tendency. SM willing to look at eyes, but they didn’t attract attention.
- These observations suggest an alternative interpretation of the function of the amygdala. Instead of being responsible for feeling fear or other emotions, evidently it is responsible for detecting emotional information and directing attention to it.
• Urbach-Wiethe Disease:
: rare genetic condition that causes calcium to accumulate in the amygdala until it wastes away - they are impaired at processing emotional information and learning what to fear
• Case study of SM (only experiences excitement from scary movement – held at gunpoint, only felt angry, not scared, etc. – man stepping close to her, noses to could, did not feel discomfort (other people prefer 0.7 meter distance))
• The only event known to trigger her fear is breathing 35 percent carbon dioxide, which leaves a person gasping for breath – The difference from other fear stimuli is that carbon dioxide affects the body directly, rather than by visual or auditory signals that the amygdala would have to interpret. However, she agreed to go through it again later – Apparently the amygdala is important for imagining the fear or thinking about the danger.
• SM always looked at nose instead of eyes – when she looks at eyes, she could recognize fear.
• The amygdala automatically directs attention toward emotionally significant stimuli, even without your awareness – people with amygdala damage lack this tendency. SM willing to look at eyes, but they didn’t attract attention.
• These observations suggest an alternative interpretation of the function of the amygdala. Instead of being responsible for feeling fear or other emotions, evidently it is responsible for detecting emotional information and directing attention to it.
Eye Expressions for Fear and Happiness
- Amygdala damage affects the ability to recognize facial expressions of fear or disgust
- When recognized, rated as less intense than other people
- Lack of eye contact (people with amygdala damage avoid eye contact) – this seems important in fear recognition (and recognizing other emotions)
- Amygdala may direct other brain areas to pay attention
People in scanner when looking at eye shape, amygdala is more responsive for eye shape for fearful expressions.
Research say amygdala not so much responsible for FEELING fear, but more for detecting emotional info, and directing other brain areas towards paying attention to it in proper way.
Anxiety Disorders incl. Panic disorder
Panic disorders, GAD, phobias
= major symptom is increased anxiety
• Panic disorder
• Frequent periods of anxiety and occasional attacks of rapid breathing, increased heart rate, sweating, and trembling – extreme arousal of the sympathetic nervous system
• More common in women than men, and in adolescents and young adults than in older adulthood
• Possible genetic component (twin studies, but no single gene identified) + early life experiences.
• 15 percent of people with joint laxity (double jointed) have PD
• Linked to hypothalamus abnormalities
• Decreased GABA, increased orexin (Here she talked about “our sleep and wakefulness lectures” – did I miss something?)
Post-Traumatic Stress Disorder (PTSD)
- PTSD is psychiatric disorder in response to trauma.
- Frequent distressing recollections and nightmares about traumatic event
- Vigorous reactions to noises and other stimuli
- Not all people who endure trauma get PTSD
- Smaller hippocampus may predispose people to PTSD – is it cause or effect of PTSD? Probably both.
- Lower than normal cortisol levels in PTSD
- “pretraumatic stress disorder” – originally was comedy, but Some soldiers develop mild symptoms similar to post-traumatic stress disorder during preparation for deployment, and these soldiers are more likely than average to develop serious symptoms after actual war experiences
the amygdala, which is so important for
emotional processing, might be essential for the extreme emotional impact that produces PTSD.
Anxiety Medications
People have many ways to cope with anxiety—social support,
reappraisal of the situation, exercise, distraction, gaining a
sense of control over the situation, and so forth – also medication
- GABA main inhibitory NT in amygdala. Reducing GABA can induce panic. Medications often allow for more GABA in system (e.g. benzodiazepine, e.g. diazepam)
- The most used anti-anxiety drugs (anxiolytic) are the benzodiazepines (BEN-zo-die-AZ-uh-peens), including diazepam (Valium), alprazolam (Xanax)
- Bind to the GABAA receptor, and facilitate the effects of GABA (they cause the receptor to change shape, allowing GABA to attach more easily and tightly)
- Exert their effects in the amygdala, hypothalamus, midbrain, and other areas
- Some people self-medicate with alcohol which also effects GABA receptors
- Can cause side effects, including addiction.
Stress and Health
Stress is not an emotion, but a RESULT of emotion. = how emotion can negatively affect health.
• Behavioral medicine Emphasizes the effects on health of diet, smoking, exercise, stressful experiences, and other behaviors
• Emotions and other experiences influence people’s illness and recovery patterns
• Hans Selye (1979) defined stress as the non-specific response of the body to any demand made upon it (McEwen definition: events interpreted as threatening, and eliciting some kind of physiological and behavioral response) – the idea remains that many kinds of events can be stressful, and the body reacts to all kinds of stress in similar ways.
• General adaptation syndrome: threats to the body activate a general response to stress
Stages in the General Adaptation Syndrome
- Alarm stage: increased sympathetic nervous system activity
the adrenal glands release the hormone epinephrine, thereby
stimulating the sympathetic nervous system to ready the body
for brief emergency activity. The adrenal glands also release
the hormone cortisol, which increases blood glucose, providing
the body with extra energy, and the hormone aldosterone,
important for maintaining blood salt and blood volume. To
maintain energy for emergency activity, the body temporarily
suppresses less urgent activities, such as sexual arousal.
2. Resistance stage: sympathetic response declines; adrenal cortex continues releasing cortisol and other hormones to prolong alertness (and heal wounds)
the sympathetic response
declines, but the adrenal glands continue secreting
cortisol and other hormones that enable the body to maintain
prolonged alertness. The body adapts to the prolonged situation
in whatever way it can, such as by decreasing activity to
save energy. The body also has ways of adapting to prolonged
cold or heat, low oxygen, and so forth
- Exhaustion stage: occurs after prolonged stress; individual no longer has energy to sustain responses (the heightened response to stress), and is tired, inactive, and vulnerable
In modern society, many stressors are prolonged rather than transient. Stress-related illnesses and psychiatric problems are widespread in industrial societies. - Prolonged activation of the general adaptation syndrome can lead to exhaustion.
General adaption syndrom
threats to the body activate a general response to stress
Selye found patients with a wide variety of illnesses had much in common:
They develop a fever, they lose their appetite, they become inactive, they are sleepy most of the day, their sex drive declines, and their immune systems become more active. Later, when doing laboratory research, he found that rats exposed to an injection of anything, as well as heat, cold, pain, confinement,
or the sight of a cat responded with increased heart
rate, breathing rate, and adrenal secretions. Selye inferred that any threat to the body, in addition to its specific effects, activated a generalized response to stress, which he called the general adaptation syndrome, due mainly to activity of the adrenal glands.
Hypothalamus-Pituitary-Adrenal Cortex Axis and stress
• Stress activates two systems in the body:
1. The sympathetic nervous system in the autonomic system): “fight or flight” response that prepares the body for brief emergency responses
2. The HPA axis: the hypothalamus, pituitary gland, and adrenal cortex
• The HPA axis becomes the dominant response to prolonged stressors / Prolonged stressor increasingly activates HPA axis
• Activation of the hypothalamus induces the pituitary gland to secrete adrenocorticotropic hormone (ACTH)
• Hormone Stimulates the adrenal cortex to secrete cortisol
• Cortisol helps to mobilize energies (by raising blood sugar and enhances metabolism and increase alertness) to fight a difficult situation
Compared to the autonomic nervous system, the HPA axis reacts more slowly, but it dominates the response to prolonged stressors such as living with an abusive parent or spouse.
• Brief/moderate stress improves performance on simple task and habitual skills + attention and memory formation + IMPAIRS performance requiring complex, flexible thinking + enhances activity of immune system – but prolonged stress impairs immune activity and memory.
How does the immune system work?
• Stress increases activity of immune system – how?
• The immune system consists of cells that protects the body against viruses and bacteria by producing (primarily) leukocytes (white blood cells) (autoimmune disease = immune system attacking the body’s own cells)
B-cells: leukocytes that mature in the bone marrow and secrete antibodies (to attack antigens (that haven’t been encountered in the past))
• Antibodies: Y-shaped proteins that attach to particular kinds of antigens
• Antigens: surface proteins (on cells) that are antibody-generator molecules – when antibody meets antigen they haven’t met before, they attack it.
• Antibodies can also attack transplanted organs in surgeons don’t take necessary steps to avoid attack.
T-cells
• Attack intruders directly (without secreting antibodies) and help other T-cells or B-cells to multiply
• 2 types: cytotoxic t cell (directly attack intruder cells) and helper t cells (stimulate other t or b cells to multiply) – they are matured in the “thymus gland”
• Natural killer cells (blood cells that attach to cells and infuse them with viruses)
• Leukocytes that attack tumor cells and cells infected with viruses
• Whereas each B or T cell attacks a particular kind of foreign antigen, natural killer cells attack all intruders.
B-cells:
leukocytes that mature in the bone marrow and secrete antibodies (to attack antigens (that haven’t been encountered in the past))
• Antibodies: Y-shaped proteins that attach to particular kinds of antigens
• Antigens: surface proteins (on cells) that are antibody-generator molecules – when antibody meets antigen they haven’t met before, they attack it.
• Antibodies can also attack transplanted organs in surgeons don’t take necessary steps to avoid attack.
T-cells
Attack intruders directly (without secreting antibodies) and help other T-cells or B-cells to multiply
• 2 types: cytotoxic t cell (directly attack intruder cells) and helper t cells (stimulate other t or b cells to multiply) – they are matured in the “thymus gland”
Natural killer cells
(blood cells that attach to cells and infuse them with viruses)
• Leukocytes that attack tumor cells and cells infected with viruses
• Whereas each B or T cell attacks a particular kind of foreign antigen, natural killer cells attack all intruders.
Cytokines
- During an infection, leukocytes and other cells produce small proteins called cytokines
- Cytokines combat infection and communicate with the brain to inform of illness
- Cytokines stimulate the release of prostaglandins (and stimulate the vagus nerve)
- Prostaglandins cross the BBB and stimulate the hypothalamus to produce fever, sleepiness, lack of energy, lack of sex drive.
- Sleep and inactivity to conserve energy to fight illness
- Decreased appetite may be helpful by decreasing the need for activity, and by reducing blood glucose, the preferred fuel for many microorganisms
- Aspirin and ibuprofen decrease fever by inhibiting prostaglandins
Effects fo stress on the immune system
- In response to a (brief) stressful experience, the nervous system activates the immune system
- Increases production of natural killer cells, leukocytes and cytokines
- The cytokines combat infections but also trigger prostaglandins (reaching the hypothalamus, triggering brain to produce same symptoms as if we were ill)
- In prosperous countries, this happens e.g. for taking exams etc.
- Studies: for those with stress longer than month = increased risk of illness (e.g. catching colds, but also mental illness) (but no effect on risk, from brief stress)
- Prolonged Stress Response
- Can produce illness symptoms
- prolonged increase of cortisol directs energy toward increasing metabolism and therefor detracts energy from synthesizing proteins, including the proteins of the immune system.
- Produces symptoms like depression
- Weakens the immune system
- Causes high cortisol levels increases metabolic activity in hippocampus impairs memory and can harm the hippocampus
- Toxins or overstimulation more likely to damage or kill neurons in the hippocampus
Controlling Stress Responses / coping with stress
- Studies in mice have revealed genes that relate to being more vulnerable or more resilient
- Resilience = Having ability to recover well after traumatic experience
- In humans: resilience correlates with stronger connections between amygdala and PFC
- Methods to control stress responses
- Breathing routines, exercise, meditation, distraction, and addressing/dealing with issues (and reappraisal)
- Social support from a loved one helps to reduce stress
- Social support reduces response to stress
- Reduces response in several brain areas, including the prefrontal cortex
resilience correlates with strong social support, an optimistic viewpoint, and reappraisal of difficult situations. Those factors in turn correlate with the ability to rapidly activate the stress response and then rapidly deactivate it
Successfully coping with moderately stressful
events prepares one to cope with later events, although a history of severely adverse events leaves one too exhausted to resist.
