Anti depressants such as MAOI’s which increase the available amount of nor adrenaline in the brain, were found to be effective for elevating the symptoms of depression. So when noradrenalin is increased in the brain, symptoms of depression get better, suggests that it is chemicals that are the root cause of depression. This idea is also found in the results of taking reserpine, a drug used to treat high blood pressure. Depression is a unwanted side effect of this drug, as this drug acts by lowering levels of nor adrenaline. So again strongly suggests that low activity noradrenaline, is a factor contributing to the cause of depression.
This drugs effects are similar to but more rapid than those of amphetamines. Additionally the effects of cocaine are short-lived, which may help explain why this drug is especially addictive both psychologically and physiologically. Dopamine transporters are responsible for removing dopamine molecules from the synaptic cleft after they have done their job. Cocaine blocks thee transporters, leaving dopamine trapped in the synaptic cleft. As a result, dopamine binds again and again to the receptors overstimulation the cell.
This suggest that depression must be passed on through genes if there is a high concordance rate between twins which share the same genetic makeup both having depression. However, biological factors such as the amine hypothesis states that if amines such as serotonin and noradrenalin become unbalanced, they can lead to depression. PET scans support this idea as they show that low levels of serotonin are present in people that are depressed. Other supporting evidence is that drugs such as MAOI’s, which work by increasing the available amount of noradrenalin in the brain, were found to be effective in alleviating the symptoms of depression. A problem with this is that it doesn’t state whether it is cause or effect.
For example, Piggott et al. (1990) used drugs that increased the amount of serotonin in the brain such as the selective serotonin reuptake inhibitor (SSRI) Anafranil, which has been shown to reduce the symptoms of OCD. PET scans show lower serotonin levels in OCD patients than control patients. After treatment with SRRIs, the PET scan of an OCD patient looks more like the scan of a normal
Normal aggressive behaviour involves an interaction of a system of structures, as opposed to being dependent on separate brain structures. One part of this system is the Amygdala. This is a structure inside the temporal lobe which, plays an important role in the mediation of affective activities and on the expression of mood; mainly fear, rage and aggression. The amygdala is connected to many structures in the brain including the hippocampus, thalamus and pre frontal cortex. It is fundamental for self-preservation as it enables the identification of danger; therefore exhibiting clear links to aggression.
Discuss the role of neural and hormonal mechanisms in aggression (24) Aggression is deliberate anti-social behaviour that is often intended to cause harm, usually observed through verbal or physical acts. There are two mechanisms said to be involved in aggression, neural and hormonal. Neural mechanisms such as the amydgala and the prefrontal cortex are thought to be involved in aggressive behaviour. The amygdala is a group of nuclei in the frontal lobe of the brain which is associated with primitive aggressive responses of instinct fear and aggression. The prefrontal cortex is in charge of thought analysis and regulated behaviour.
When stressed our immune system’s ability to fight off viral infections is reduced due to a decrease of white blood cells. This is known as immunosuppression, this occurs when the stress hormone corticosteroid is present from a stress response and lowers the number of lymphocytes such as B-cells and T-cells . Stress can have two types of effects, a direct effect or an indirect effect. The direct effect is when stress affects our health directly, for example, when stressed our digestive system is inhibited, after stress is gone, the digestive activity increases, this can lead to the occurrence of Ulcers in the stomach. Stress also increases the heart rate and can lead to the increase of blood pressure, thus Hypertension and can lead to Coronary Heart Disease (CHD).
When the nicotine in a cigarette is inhaled this activates nicotinic receptors in the brain which leads to a release of dopamine in the NA. This creates a sense of pleasure however this sensation of the nicotine is rapidly broken done by enzymes in the liver and removed from the bloodstream so within hours this pleasure sensation is replaces by low moods and reduced concentration. According to the biological model people with certain genes may find it harder to stop behaviour once it has started. There is no single gene responsible for this, however a number of genes have been linked to playing a role. This has been shown in research done by Noble et Al in which a gene DRD2 responsible for the D2 dopamine receptor, to severe alcoholism.
The inelasticity of drugs creates a steep negative slope. This means that the price can experience great changes and the quantity demanded will change at a much smaller rate. This is further seen in the article in reference to Portugal’s decriminalization of drugs dating back to 2001. A study by the British Journal of Criminology found that the increase in users has increased only marginally if at all. The deregulation of government involvement has decreased the price of drugs but the demand has not greatly increased in response.
Research by Geen & O’Neal (1969) suggests that noise may be more of a trigger to pre-existing aggression than actually causing it. They exposed participants to either an aggressive or non-aggressive film then gave them the opportunity to administer electric shocks to others. It was found that, when noise levels were elevated, the frequency of shocks increased. However, this was only in the group who’d watched the aggressive film. Donnerstein & Wilson (1976) conducted a similar experiment and found, if participants were given control over the noise, levels of aggression decreased.