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BIOLOGICAL (THE BRAIN AND BEHAVIOUR (PHEROMONES (Problems with pheromone…

- - - - Modern technology is no extensively use in Psychology because it provides an opportunity to study not only brain structures but also the active brain while avoiding many of the ethical concerns of animal experimentation.
        
        This allows researchers to see localisation of function.
        
        Magnetic Resonance Imaging (MRI scans) give 3D pictures of the brain's structure. An MRI scanner uses a magnetic field and radio waves to map the activity of hydrogen molecules, which are present in different brain tissue to different degrees. The image an be viewed as a whole image of the brain or it can be viewed as a slice of the brain.
        
        Non-invasive, high-resolution image.
        
        Only looks at structure doesn't look at what is actually happening in the brain.
        
        HM: Milner (1966), Maguire (1999), Eugene Pauly
        
        Maguire et al (2000) - To see whether the brains of London taxi drivers would be somehow different as a result of the exceptional training they have to do. Quasi-experiment, 16 right-handed male taxi drivers. Their brains were MRI scanned and compared with the scans of 50 right handed males who were not taxi drivers (control). The drivers had to have completed their knowledge test and had their licence for 1.5 years. The researchers were looking to see if there was a relationship between the number of years of driving a taxi and the anatomy of one's brain. The posterior hippocampi of taxi drivers were significantly larger than control subjects and the anterior hippocampi were significantly smaller. The volume of the right posterior hippocampi correlated with the amount of time spent as a taxi driver. Maguire argues that this shows that the hippocampus changes in response to environmental determinants.
        
        Positron Emission Tomography (PET scans) observe metabolic processes in the brain by detecting the gamma rays emitted indirectly by a tracer. before a PET scan, the patient is given a safe does of radioactive tracer compound which is introduced into the body using a modified glucose molecule (FDG). This enters the bloodstream an travels to the brain. If an area of the brain is more active, more glucose will be needed there. When more glucose is used the radioactive tracer is detected by the PET scanner.
        
        It allows participants to perform psychological tasks while the researcher observes brain activity. It produces a multi coloured image that shows which parts of the brain are most active. The colour of each dot shows the intensity of the energy signal.
        
        It requires an injection with a small amount of radioactive material. This won't cause the patient much harm but it is still an invasive procedure so raises ethical concerns. PET scanning is quite slow and has relatively poor resolution.
        
        Functional magnetic resonance imaging (fMRI) shows actual brain activity and indicates which areas of the brain are active when engaged in behaviour or cognitive processing. fMRI measures changes in blood flow and oxygen level as a measure of neural activity in the active brain.
        
        fMRI has a higher resolution than PET scanning and they are easier to carry out. fMRIs are non-invasive and there is no radioactive isotope needed. It produces a film that demonstrates change in the brain.
        
        For both MRI and fMRI, any iron must be removed from the patient. It is not a natural environment for patients so brain behaviour may change and therefore the research will lack ecological validity. Patients may experience anxiety due to claustrophobia. The use of colours may exaggerate brain activity.
        
        Baumgartner et al (2008), Harris and Fiske (2006), Sharot et al (2007)
  - - - Several parts of the brain have to work together in order to help us create and retrieve memories. Today researchers continue to attempt to map the brain. One of the ways they are doing this is by looking at neural connections in the brain and creating a map called a connectome.
    - - Four key areas: The stem, the cerebellum, the cerebrum, and the limbic system.
        
        The stem is responsible for regulating life functions, such as breathing, heart rate and blood pressure.
        The cerebellum plays a key role in balance and motor function, including speech production.
        The cerebral cortex is the largest part of the human brain, associated with higher brain function such as thought and action. The cerebrum is divided into four sections, called lobes.
        
        Each lobe plays a key role in behaviour
        
        The frontal lobe is associated with executive functions - planning and decision making.
        The Occipital lobe is associated with visual processing
        The Parietal lobe is associated with perception of stimuli
        The Temporal lobe is associated with auditory processing and memory.
        
        The limbic system
        
        Amygdala - plays a role in the formation of emotional memory and fear responses.
        Basal ganglia - Plays a role in habit-forming and procedural memory.
        Hippocampus - Responsible for transfer of short-term memory to long-term memory.
        Hypothalamus - Involved in homeostasis, emotion, thirst, hunger, circadian rhythms and control of the automatic nervous system. In addition, it controls the pituitary gland.
        Nucleus accumbens - Plays a role in addiction and motivation.
      - Brain and plasticity
        
        Plasticity - Plasticity refers to the brain's ability to alter its own structure following changes within the body or in the external environment.
        Brain Plasticity - refers to the brain's ability to rearrange the connections between its neurons. These are the changes that occur in the structure of the brain as a result of learning oor experience.
        
        High levels of stimulation and numerous learning opportunities lead to an increase in the density of neural connections. Every time we learn something new, the neurons connect to create a new trace in the brain. This is called dendritic branching because the dendrites of the neurons grow in numbers and connect with other neurons.
        
        Rosenzweig, Bennett and Diamond (1972) - The researchers conducted experiments where they placed rats into one of two environments to measure the effect of either enrichment or deprivation on the development of neurons in the cerebral cortex. In the enriched environment, rats were placed in cages with up to 11 other rats. There were stimulus objects for the rats to play with, as well as maze training. In the deprived environment, the rat was alone with no stimulation. The rat spent 30 or 60 days in their respective environments and then were killed in order to measure the effect of the environment on their brain structures. mortem studies of their brains showed that those that had been in the stimulating environment had an increased thickness in the cortex as a result of increased dendritic branching compared to the rats in the deprived environment
  - - - The process by which these messages are sent is called neurotransmission.
        
        The electrical impulse that travels along the body of the neuron is called the action potential. When an action potential travels down the body, or axon, it releases neurotransmitters into the gaps between neurons (synapses). Neurotransmitters are the body's natural chemical messengers that transmit information from one neuron to another. After crossing the synapse, the neurotransmitters fit into receptor sites on the post-synaptic membrane. Once the message is passed on, the neurotransmitters are either broken down by an enzyme or reabsorbed - reuptake.
        
        Neurotransmission and behaviour
        
        Acetylcholine - Plays a role in the consolidation of memory in the hippocampus.
        
        Dopamine - Helps control the brain's rewards and pleasure centres.
        
        Rogers & Kesner (2003) - to determine the role of acetylcholine in memory formation. There is a significant number of acetylcholine receptors in the hippocampus. They first had mice run a simple maze to find food. After running the maze, but before memory could be consolidated, the researchers injected the mice with one of two chemicals. One group was injected with scopolamine, which blocks the acetylcholine receptor sites so inhibits any response. The control group was given a placebo, to avoid the injection alone having an effect. The mice were placed in the maze again to see how long it would take them to find the food. The scopolamine group took longer and made more mistakes than the control group who learned faster. It appears that acetylcholine may play an important role in memory consolidation.
  - - - Adrenaline - Secreted by the adrenal glands, responsible for arousal and the flight or fight response. Plays a role in emotional memory formation.
      - Cortisol - Secreted by the adrenal gland; helps to control blood sugar levels, regulate metabolism, reduce inflammation and assist memory formation.
      - Melatonin - Secreted by the pineal gland; signals the relaxation and lower body temperature that help with a restful sleep.
      - Neuropeptide Y - Produced by the hypothalamus; acts as a neurotransmitter in the brain. Stimulates food intake, reduces anxiety and stress, reduces pain perception.
      - Oxytocin - Produced by the hypothalamus and secreted by the pituitary gland. When it affects the brain it acts as a neurotransmitter.
      - Testosterone - Produced by the testes, plays a facilitative role in aggressive behaviour.
    - - It is a hormone cascade (hormones triggering hormones). When a stimulus threatens us - the hypothalamus responds by activating the pituitary gland. The pituitary gland then releases a hormone that activates the adrenal gland. As a result, both cortisol and adrenaline are released into the bloodstream
      - Cortisol is responsible for dumping glucose into your bloodstream in order to provide energy, and adrenaline increases the heart rate, blood pressure and respiration.
      - This reaction has evolved to help humans survive in the face of danger so that they can quickly escape an immediate threat.
    - - Cahill and McGaugh (1995): The aim of the study was to investigate the role of adrenaline and the amygdala on emotional memory. There were 2 groups which both saw 12 slides except with a different story. The first group heard a boring story about a woman and her son who went to the hospital to see the father where they witnessed the staff in a drill of an accident victim. The second group heard a story where the boy was involved in a car accident where is feet were severed. At the hospital they re-attached his feet. Two weeks after this slideshow the participants were asked to come back and their memory of specific details was tested. The test consisted of multiple-choice questions about the slides. The researchers did a follow-up study which was the same except the participants in the "traumatic story" condition were injected with a beta blocker. In the original study, they found that participants from the traumatic story demonstrated better recall of specific details of the story. In the follow-up study they found that adrenaline and activation of the amygdala play a significant role in the creation of memories linked to emotional arousal.
        
        The research has been applied to the treatment of accident victims with the goal of preventing PTSD.
        
        Pitman et al (2002) carried out an experimental study where patients coming into emergency rooms after a traumatic injury were given either beta-blockers (propanolol) or a placebo. One month after the traumatic event, people who had received the beta-blocker showed fewer symptoms of PTSD than those that had received no beta blockers or a placebo.
  - - - It is believed that pheromones may affect the menstrual cycle in groups of women.
        
        McClintock (1971) - McClintock had the aim of studying the effect of pheromones on menstrual synchronicity. She studied females in a college dormitory. She used questionnaires to determine the onset date of menstruation among roommates and close friends. The data showed a significant increase in synchronisation of onset dates over time. McClintock argued that this could be a pheromonal response, or it could be the result of some other process. She did not take physiological data that would have indicated whether the results were due to pheromones.
      - In animals, primer pheromones cause slow long-term physiological changes such as hormonal effects. Signalling pheromones produce rapid behavioural effects, such as mating
    - - Doucet et al (2009) This study had the aim of studying the role of secretion of the areolar gland in suckling behaviour of 3-day-old infants. The researchers administered the different secretions to the infants nasally and then measured their behaviour and breathing rate. The researchers compared the infant's reaction to seven different stimuli - including, secretions of the areolar glands, human milk, cow milk, formula milk and vanilla. They found that the infants began suckling only when exposed to the secretions of the areolar glands. There was also a significant increase in their breathing rate. The researchers argue that this stimulus of the areolar odour may initiate a chain of behavioural and psychological events that lead to the progressive establishment of attachment between the mother and the infant.
    - - The human sense of smell is very complex. Two scientists found that we have 400 different kinds of odour receptors. This makes it very difficult to see how pheromones would work in humans
      - Many body odours are actually not caused by secretions, but by bacteria that mix with our secretions e.g. in the armpits.
      - Culture plays a key role in our sense of smell - we learn what smells bad and what smells good. This could potentially be a confounding variable when trying to determine the role of pheromones on behaviour.
- - - - Researchers study twins because they share common genetic material
      - The concordance rate is the probability that the same trait will be present in both members of a pair of twins.
        
        If the concordance rate for MZ twins is significantly higher than for DZ twins or siblings, it is likely that there is a genetic component to the behaviour.
      - Monozygotic twins (MZ): Are genetically identical because they are formed from one fertilised egg split into two. These twins are of the same sex and look very much alike.
        Dizygotic twins (DZ): Dizygotic means from two eggs. DZ twins will not be any closer genetically than brothers and sisters. They will have about 50% the same genes and will not necessarily be the same sex.
        
        Limitations: - Twins are very rarely raised apart so they tend to experience a very similar environment while growing up. So, it is difficult to isolate environmental influence as a variable. Assuming that twins grow up in the same environment is often called equal environment fallacy. Also twins are not highly representative of the general population.
        
        Psychologists use different degrees of genetic relationships as a basis for their hypotheses about the contribution of genetic and environmental factors to behaviours. It should be the case that the higher the genetic relationship, the more similar individuals will be if the particular characteristic being investigated is inherited.
    - - More representative of the general population than twin studies
      - A child inherits half of its genes from its mother and half from its father. Brothers and sisters with share 50% of their genes with each other. Grandparents will share 25% of their genes with their grandchildren. In family studies, these different degrees of genetic relatedness are compared with respect to specific traits or behaviours.
        
        The notion is that concordance rates will increase if heritability is high
      - Weissman et al (2005): The study looked at three generations over a 20 year period to determine the level of inheritance of depression and anxiety disorders. The findings showed that depression in grandparents was a greater predictor of depression in grandchildren than depression in parents.
    - - When a behaviour is suspected of being genetic within a family, psychologists will use prospective studies, that is, the sample is selected and observed before certain behaviours are observed. The researchers watch for outcomes, such as the development of a disorder.
        
        For example, in individuals who are considered "genetically vulnerable" for schizophrenia can be followed over many years to see if they actually develop the disorder.
      - There are ethical concerns that such research may cause undue stress in someone who is "vulnerable".
    - - These allow the most direct comparison of genetic and environmental factors.
      - Adopted children generally share none of their genes with their adoptive parents, but they share 50% of their genes with their biological parents.
        
        It would be reasonable to suppose that if the heritability of a behaviour is high and the environment has little to play, then the behaviour of adopted children should correlate more strongly with the behaviour of their biological parents
      - Adoption studies are often criticised as these children are not representative of the general population. Also, adoption agencies tend to use selective placement when finding homes, trying to place children in families that are as similar as possible to the natural parents.
        
        The effects of genetic inheritance may be difficult to separate from the influences of the environment.
    - - Linkage analysis (genetic mapping) indicates which chromosome contains the gene related to the behaviour, as well as where the gene is located on that chromosome.
        
        To create a genetic map, researchers collect blood samples from members of the family in which a behaviour is common. They examine the DNA for polymorphism - the presence of genetic variation. These polymorphisms are referred to as genetic markers.
        
        Linkage studies look to see if there is a correlation between these genetic markers and certain behaviours. More precise than twin studies but results are still correlational in nature.
      - Genome Wide Association Studies are studies that compare the DNA of two groups of participants: people with the behaviour and similar people without (controls). If a genetic marker is more frequent in people with the behaviour it is said to be associated with that behaviour.
        
        GWAS studies use very large samples therefore the effect of outliers does not lead to false conclusions.
        
        To make sense of the data, "Manhattan plots" are used. It shows the chromosomes and genes are level of significance for the association with a behaviour.
  - - - Environmental factors such as stress, diet and exercise, may result in gene expression or the lack of. An individual could have the gene for a certain behaviour but if it is never expressed the behaviour won't occur.
    - - Kendler et al (2006) carried out a twin study of over 42,000 twins from the Swedish National twin registry to determine the level of heritability of depression. They found that the average concordance rate for female MZ twins was higher than for male MZ twins. DZ twins had lower concordance rates than this but women still had a higher rate than men. Kendler concluded that the heritability of depression is estimated to be 38%. The fact that the concordance rate for MZ twins is far below 100% indicates that depression may be the result of a genetic predisposition (genetic vulnerability).
    - - Caspi et al (2003) - examines the role of the 5-HTT gene in depression. It plays a role in the serotonin pathways involved in controlling mood, emotions, aggression, sleep and anxiety. Caspi suggested that people who inherit two short versions of the 5-HTT gene are more likely to develop depression after a stressful life event. They used 847 26 year olds. They were all members of a cohort that had been assessed for mental health on a 2 year basis. There were 3 groups: group one had two short alleles. Group 2 had 1 short 1 long. Group 3 had two long. The mutation of 5-HTT was on the short allele.They were asked to fill in a stressful life events questionnaire. They were also assessed for depression. People with one or more shot versions demonstrated more symptoms of depression. The response was strongest for those with three or more stressful life events. Inheriting the gene alone was not enough to lead to depression.
    - - Twin studies have highly reliable results
      - Modern research has allowed us to locate genetic variations using very large sample sizes.
      - Modern research is not reductionist, it recognises the interaction of environmental and biological factors in depression.
    - - Genetic arguments are correlational, they do not and cannot establish a cause and effect relationship.
      - Twin studies have a problem with population validity. (how well the results can be generalised to the population.) The samples are not representative of the general population.
  - - - Natural selection explains how species acquire adaptive characteristics to survive in an ever-changing environment.
        
        The result of natural selection is that the species develop characteristics that make it more competitive in its own environment. - Adaptation
    - - Raison and Miller's theory (2012) - They argue that the genes that increase one's risk for depression also increase one's immune response to infections, the genes increase levels of inflammation. The symptoms of depression have played a key role in protecting our ancestors from infectious diseases.
        
        Raison et al (2013) - gave the drug infliximab to depressed patients. Infliximab is an anti-inflammatory drug. They found that the drug reduces depressive symptoms in participants who showed elevated levels of inflammation.
      - Through GWAS studies, so far only 2 genetic variations have been identified as being linked to depression. - Neuropeptide Y (a stress hormone).
        
        Researchers argue that the symptoms of depression also reflect this need to avoid disease.
      - Consideration points
        
        Evolutionary theories are based on the assumption that behaviours are inherited. it is difficult to know the extent to which certain behaviours are in fact, genetically inherited.
        
        Researchers may be susceptible to confirmation bias (they see what they expect to see).
        
        A lot of the research to test evolutionary theories is highly artificial and lacks ecological validity.
        
        Research often involves animals, and it is questionable whether the results can be generalised to humans.
        
        Evolutionary arguments often underestimate to role of cultural influences on shaping behaviours.