week 8 Motivation and Emotion Flashcards
Understand the concepts of Homeostasis and Allostasis.
Homeostasis is the body maintaining certain parameters such as temperature and blood glucose within a narrow range.
Allostasis is maintaining homeostasis but under stress or anticipated stress. Examples include hibernations and utilisation of fat reserves, pre-emptively drinking more prior to anticipated exertion etc.
Understand Mechanisms of water regulation, Osmotic thirst and Hypovolemic thirst.
OSMOTIC thirst= thirst driven by increased salt intake eg eating salty foods. Eating salty foods results in increased solutes in the extracellular fluid which causes fluid to leave the cells for the extracellular fluid.Neurons within the OVLT (Organum vasculosum lamminae terminalis near the third ventricle) and the SFO (Subfornical organ also near the third ventricle) detect water leaving their cells via osmosis. The OVLT and the SFO then send signals to the hypothalamic nuclei to increase thirst.
the SFO can increase or decrease thirst whereas the OVLT can only increase. the OVLT also receives info from the gut and so can be “pre warned” that a salty meal has been ingested and start the desire for water.
Vasopresin (=Anti Diuretic Hormone) is released from the pituitary due to the Paraventricular and Supraoptic nerves. Vasopressin acts to conserve water in the kidneys.
HYPOVOLAEMIC thirst=thirst due to loss of fluids (haemorhage or sweat/dehydration/d+ Hypovolaemia causes the release of Angiotensin and Renin.). Causes desire for fluid but also desire for salty foods as need to replenish both. Baroreceptors in kidneys and blood vessels detect hypovolaemia. Again the Pituitary releases vasopressin. The kidneys also release Renin which converts Angiotensin to Angiotensin One which is converted to Angiotensin Two and this causes blood vessel constriction to increase Bp. Angiotensin 2 also increases thirst.Adrenal glands release Aldosterone which causes salt retention in the salivary glands, sweat glands and kidneys. Together Angiotensin 2 and Aldosterone alter taste to favour salty tastes (sodium specific hunger).
According to James-Lange emotions are the subjective ‘label’ we give to our own physiological responses to particular event. Explain the role of physiological arousal and motor activity according to this theory.
According to this theory, our physiological arousal and locomotary actions occur after our cognition has labelled the feeling of an emotion. Others argue that physiology occurs first, and later , cognition. Others again say they can occur together.
What is pure autonomic failure? What does its effects on emotions suggest about James-Lange’s theory?
Pure Autonomic Failure is rare. Autonomic system output fails or severely impeded. Heart and breathing etc continue but are not regulated by the autonomic nervous system , thus stress does not induce increased heartrate or sweating etc. Progressive dysfn at peripheral efferent level, usually has abnormal depositions there. Middle aged-older, more often male. Some will progress to cns abnormalities also including sometimes Parkinsons or Dementia.
Classically has orthostatic hypotension (fainting on rising) plus abnormaltites of sweat (absent/increased) and urinary/defaecation disorders (cannot pass or cannot hold). No tx. Palliative tx of blood pressure, supine position education, meds for urinary/defaecation as required.
People with PAF still describe emotions and feel them but describe them as less intense. This is consistent with James Lange Theory as he emphasised cognition more than physiology.
It is likely that generally we need both physiological feedback and cognition to experience emotions fully but that either might lead to an emotion.
Where is the limbic system? What are its components? Be able to identify these in a diagram.
The Limbic System consists of a group of structures within the interior midline of the cerebrum, surrounding the thalamus, loosely b/n cortical and subcortical.
Components (arguable which to include as typically each component involved in other systems also)include: Amygdala (always included) hippocampus (always included), thalamus (usually included) hypothalamus (usually) mammalian body, cingulate gyrus, olfactory bulbs.
Note, some other brain areas associated with emotions such as the cingulate,hypothalamus, and the midbrain.
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Note some specific cortex-emotion associations: anger and the medial frontal cortex; disgust and the insula
Some evidence for these connections but otherwise which brain area involved in experiencing an emotion is quite vague and may involve many areas, and differ with situation.
Which hemisphere of the brain is more responsive to emotional stimuli?
In very general terms (do NOT rely on this absolutely, and the hemispheres usually have a lot of cross-over of information and processing); happier emotions better detected by left hemisphere and sad or frightening emotions better detected by the right. The right is more involved with BIS and the left with BAS. On average those with more left frontal activity tend to be happier, and more outgoing, and those with increased activity in the right frontal tend to be more socially withdrawn, less satisfied and more prone to unpleasant emotions.
What is stress?
Stress is the body’s response to a fearful or uncertain situation. It may be generalised and vague. Tends to be of much longer duration than fear. Stress activates sympathetic nervous system (for flight/fight) and also the Hypothalamic-Pituitary-Adrenal cortical axis.
What is the hypothalamus-pituitary-adrenal cortex axis? (Stress increases hypothalamic activity; this stimulates the pituitary to secrete ACTH; this stimulates the adrenal cortex to secrete cortisol which increases the body’s metabolism).
HPA=Releasing Factor produced by Hypothalamus, which causes Anterior Pituitary to release ACTH, and thisacts on the Adrenal cortex and cortisol is released. Increases metabolism, raises bg, improves learnt and simple tasks but the benefits are best for brief times, otherwise effects are more deleterious, exhausts the body and decreases immune function and general wellbeing.
What is psychoneuroimmunology? In which ways can stressful experiences influence the immune system, and what effects can this have on the nervous system?
Psychoimmunology is how the nervous system (and experiences)impacts upon the immune system, and vice versa.
Brief stress; increased production of natural killer cells and cytokines. prostaglandins reach hypothalamus resulting on drowsiness, lethargy and fever.
Long term stress; symptoms similar to depression, weakened immune system, reduced t cell function, increased risk of infection and or harder to recover, damage to hippocampus (prolonged cortisol increases hippocampal cell metabolism and therefore more vulnerable to damage ).
What is posttraumatic stress disorder? Which brain region has been implicated? Which hormone has been implicated?
PTSD is a prolonged excessive continuing anxiety after a trauma. Decreased hippocampal size correlates to PTSD but unknown if this predisposing factor or resulting factor, or both. Cortisol has been implicated as a possible cause of decreased hippocampal size.
What are attack behaviours? Which brain region is implicated in generating such behaviours?
Physically aggressive behaviours. Varies with situation and individual. Corticomedial amygdala seems to have increased activity prior to an attack behaviour for many animals.
Discuss evidence in support of a genetic contribution to violent behaviour (always keeping in mind the cause-effect ambiguities that plague this type of research).
Monoamine oxidase (MAO) breaks down serotonin/dopamine and or norepinephrin after they have been re-uptaken by neurons. Levels of MOA genetically determined, and there is Low activity form and High activity form. With the high activity form, serotin (and dopamine and norepinephrin) are lower, and higher with the low MOA gene.When combined with a stressful childhood, the low MOA gene has an increased risk of displaying violent/antisocial behaviours. This is in humans and has been replicated in many studies. One theory has the low active gene form linked to greater emotional reactivity.
Discuss evidence in support of a hormonal contribution to violent behaviour (is there evidence for such a link in humans as well?)
In humans, tends to be a bit more complex than simply testosterone levels etc. Seems increased risk of aggression if increased testosterone (especially as a surge), decreased serotonin AND decreased decreased levels of cortisol. (anger decreases cortisol)
