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Core Psychology (Biological (Chapter 2 Genetics and behaviour (Genetic…

- - - - Definition
        
        Modern biologists do not simply argue that a gene “causes” a behaviour; instead, they recognize what is known as the gene-environment interaction. This is part of a field of study known as epigenetics. Epigenetics argues that in order for a behaviour to occur, genes must be “expressed.” Genetic expression is a complex chemical reaction to environmental or physiological changes that allow a gene to “do its job.”
    - - Strengths
        
        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.
        
        Twin studies have been shown to be highly reliable in their results.
      - Weaknesses
        
        Firstly, genetic arguments are correlational – they do not – and cannot – establish a cause and effect relationship.
        
        Twin studies have a problem with population validity. The samples are not representative of the general population – and they tend to be small.
      - Definition
        
        Depression – officially known as Major Depressive Disorder - is considered the common cold of mental health. In the abnormal option, you may study this disorder in depth. Here, we are using it as an example of how genetic research is applied to understand human behaviour.
      - Studies
        
        Caspi et al
        
        https://www.thinkib.net/psychology/page/22430/epigenetics-and-depression
      - Arguments
        
        Genetic researchers argue that genetic predisposition can partly explain depression. We know that mood disorders tend to run in families, so one of the ways to investigate this is twin studies. Kendler el 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 MZ male twins was 31 per cent and for MZ female twins 44 per cent, while for DZ twins it was 11 and 16 per cent respectively. Overall, Kendler concluded that heritability of depression is estimated to be 38%. The fact that the concordance rate for MZ twins is far below 100 per cent indicates that depression may be the result of a genetic predisposition - also called genetic vulnerability. The fact that the concordance rate for MZ twins is below 100 % does not contradict the argument that depression is genetically inherited. It may mean that the gene is there, but both twins have not experienced the same level of stress and thus both twins have not "expressed their genes." The fact that some of the DZ twins also both had depression is also explained by the fact that they do share some of the same genes.
    - - Adoption studies
        
        Researchers investigate similarities between the adoptee and their biological and adoptive parents. Similarity with the biological parent is potentially the result of genetic inheritance, while similarity with the adoptive parent is more likely the result of environmental factors.
      - Linkage analysis
        
        Matching genetic variations (polymorphisms) with the frequency of a behaviour.
      - Family studies
        
        Researchers trace a phenotype over several generations in a family tree to determine the likelihood that a behaviour is inherited.
      - Genome-wide Association Studies
        
        An examination of a genome-wide set of genetic variants in a large sample individuals to see if any variant is associated with a trait.
      - Twin studies
        
        Researchers compare behavioural traits of monozygotic (MZ or identical) twins and dizygotic (DZ or fraternal) twins to evaluate the degree of genetic and environmental influence on a specific trait.
    - - Arguments
        
        Evolutionary theories are based on the assumption that behaviours are inherited. As we know from our study of genetics, it is difficult to know the extent to which certain behaviours are, in fact, genetically inherited.
        
        Research often involves animals as participants. It is debatable to what extent we can generalise from animals to human beings.
        
        Much of the research to test evolutionary theories is highly artificial and lacking ecological validity
        
        Evolutionary arguments often underestimate the role of cultural influences in shaping behaviour.
        
        Since it may be difficult to test empirically some evolution-based theories, researchers may be susceptible to confirmation bias—that is, they see what they expect to see.
      - Definition
        
        Evolutionary psychology is grounded in the theory that as genes mutate, those that are advantageous are passed down through a process of natural selection. Evolutionary psychologists attempt to explain how certain human behaviours are the result of the development of our species over time. It is important to remember that natural selection cannot select for a behaviour; it can only select for the genes that may produce behaviour. As you can see, there is another assumption made by evolutionary psychologists – that behaviours are genetic and may be inherited. As we know from the first part of this chapter, this assumption is still being tested.
    - - Definition
        
        Genetic arguments of behaviour are based on the principle of inheritance. Genes and their DNA are passed down from parents to their offspring, with 50% of our genes being inherited from each parent. Humans have 23 pairs of chromosomes, with approximately 20.000 – 25.000 genes. We now know this number as a result of the worldwide research initiative started in 1990 called the Human Genome Project.The goal of this project was to map and sequence the human genome,. This incredible project was completed in 2004. However, although the mapping of human genes could be an important step in understanding the complexity of human behaviour, as well as developing treatments for specific disorders, the exact role of specific genes in many behaviours remains unknown. Although you can undergo genetic testing for some medical conditions, the same is not entirely true for a disorder like depression.
    - - Ethical considerations
        
        In addition, the aims and procedure of the study must be explained in plain language and participants must sign an informed consent paper to show that they have a clear understanding of the study they are participating in, and the implications, including any potential harm.
        
        Genetic research can reveal unexpected information that may result in undue stress or harm to the research participants. Examples include evidence of misattributed paternity or unrevealed adoptions within a family. Another example occurs when a person discovers from the study that he or she carries the gene for a particular genetic disorder. This may cause undue stress as the participant then fears the potential onset of the disorder.
        
        Confidentiality and privacy can be protected by coding information or by fully anonymizing the sample. Anonymization protects confidentiality from insurance companies, employers, police, and others, but it also can limit the scientific value of the study by preventing follow up and further investigation.
      - Studies
        
        Wilhelm et al
        
        https://www.thinkib.net/psychology/page/22432/ethical-considerations-genetics
      - Definition
        
        In any study, participants should always know how their privacy and confidentiality will be protected, and what will happen to any genetic material or information obtained as part of the study.
  - - - Types of research methods used
      - studies
      - Definition
    - - Ethical considerations
      - Laws
      - Definition
      - Studies
    - - Arguments for
      - Arguments against
      - Key terms
      - Studies
      - Definition
    - - Key terms
      - Studies
      - Definition
  - - - Definition
        
        Plasticity refers to the brain’s ability to alter its own structure following changes within the body or in the external environment.
      - Studies involving Plasticity
        
        Rosenzweig
        
        https://www.thinkib.net/psychology/page/9279/rosenzweig-bennet-diamond-1972
        
        Maguire
        
        https://www.thinkib.net/psychology/page/22420/localization-plasticity
      - Information on brain plasticity
        
        Brain plasticity refers to the brain’s ability to rearrange the connections between its neurons - that is, the changes that occur in the structure of the brain as a result of learning or experience. High levels of stimulation and numerous learning opportunities lead to an increase in the density of neural connections. This means that the brain of an expert musician should have a thicker area in the cortex related to mastery of music, when compared to the brain of a non-musician. The same can be said about students who spend a lot of time studying, compared to students who do not. 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.
    - - Studies involving neurotransmitters
        
        Rogers & Kesner
        
        https://www.thinkib.net/psychology/page/22421/neurotransmission-
      - Definition
        
        Nerve cells, called neurons, are one of the building blocks of behaviour. It is estimated that there are between 10 and 100 billion neurons in the nervous system and that neurons make 13 trillion connections with each other. The neurons send electrochemical messages to the brain so that people can respond to stimuli—either from the environment or from internal changes in the body.
      - Neurons and Neurotransmitters
        
        Types of neurotransmitters
        
        Norepinephrine
        
        Arousal and alertness.
        
        Serotonin
        
        Sleep, arousal levels and emotion.
        
        Dopamine
        
        Helps control the brains' reward and pleasure centres. Plays a key role in motivation; low levels are linked to addictive behaviour.
        
        Acetylcholine
        
        Plays a role in the consolidation of memory in the hippocampus.
        
        Structure of a neuron
        
        Explanation of diagram
        
        The process by which these messages are sent is called neurotransmission. The electrical impulse that travels along the body of the neuron is called an action potential. When an action potential travels down the body, or axon, of the neuron, it releases neurotransmitters that are stored in the neuron’s terminal buttons. The neurotransmitters are then released into the gap between the neurons – called the synapse. The synaptic gap is an incredible one-millionth of a centimetre! 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, like a key in a lock. Once the message is passed on, the neurotransmitters are either broken down by an enzyme or reabsorbed by the terminal buttons, in a process called reuptake.
    - - Parts and systems of the brain
        
        Limbic system
        
        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 autonomic nervous system. In addition, it controls the pituitary gland.
        
        Basal ganglia
        
        Plays a role in habit-forming and procedural memory.
        
        Nucleus accumbens
        
        Plays a role in addiction and motivation.
        
        Amygdala
        
        Plays a role in the formation of emotional memory and fear responses.
        
        Areas of brain
        
        The Parietal Lobe is associated with perception of stimuli
        
        The Temporal Lobe is associated with auditory processing and memory.
        
        The Occipital Lobe is associated with visual processing.
        
        The Frontal Lobe: is associated with executive functions – that is, planning, decision making and speech.
      - Definition
        
        Localization of function is the theory that specific parts of the brain are responsible for specific behaviours or cognitive processes. The hippocampus is responsible for transferring short-term memory to long-term memory. Although we know that some parts of the brain do play specific roles in behaviour, rarely does a part of the brain work in complete isolation. For example, in memory research, we argue that the cognitive process is the result of distributive processing rather than localization of function – in other words, several parts of the brain have to work together in order to help us create and retrieve memories.
      - Studies involving Localisation
        
        Study on HM
        
        https://www.thinkib.net/psychology/page/22419/methodology-biological-approach
    - - Types of hormones
        
        Testosterone
        
        Produced by the testes; plays a facilitative role in aggressive behaviour - that is, it doesn't cause aggression, but higher levels of testosterone result in higher levels of aggression.
        
        Cortisol
        
        Secreted by the adrenal glands; helps control blood sugar levels, regulate metabolism, reduce inflammation and assist with memory formation.
        
        Adrenaline
        
        Secreted by the adrenal glands; responsible for arousal and the "fight or flight" response. Plays a role in emotional memory formation.
      - Studies involving hormones
        
        Cahill & McGaugh
        
        https://www.thinkib.net/psychology/page/22422/hormones
      - Definition
        
        Hormones are another class of chemicals that affect behaviour. Unlike neurotransmitters, hormones are not released by the terminal buttons of a neuron; instead, they are secreted by glands in the endocrine system. So epinephrine (adrenaline) is released by the adrenal gland into the bloodstream as a hormone whereas norepinephrine (noradrenaline) is released by neurons in the brain as a neurotransmitter. Hormones are released directly into the bloodstream; as a result, they take longer to produce changes in behaviour than neurotransmitters. However, they also produce effects that last a lot longer than an action potential.
    - - MRI
        
        Disadvantages
        
        Really Expensive to do
        
        Images do not move
        
        Patients must remain still the whole time in a tight space
        
        Claustrophobia
        
        Studies using MRI
        
        Eugene Pauley
        
        https://www.thinkib.net/psychology/page/20484/the-case-of-eugene-pauly
        
        Maguire
        
        https://www.thinkib.net/psychology/page/20668/maguire-1999
        
        Milner
        
        https://www.thinkib.net/psychology/page/20699/hm-milner-1966
        
        Advantages
        
        MRI scanning is a non-invasive and painless procedure.
        
        Detailed Images
        
        Does not involve Radiation
        
        Definition
        
        MRI uses a strong magnetic field and radio waves to create detailed images of the organs and tissues within the body
      - FMRI
        
        Disadvantages
        
        Cannot see Neurotransmission
        
        Blood flow is only an indirect correlate of brain activity
        
        Tight spaces and load noises can make patients feel claustrophobic
        
        Have to remain completely still
        
        Takes a long time
        
        Really expensive
        
        Studies using FMRI
        
        Maguire
        
        https://www.thinkib.net/psychology/page/20668/maguire-1999
        
        Sharot
        
        https://prezi.com/ogn7mto83o7x/sharot-et-al-2007/
        
        Advantages
        
        Can see activation as well as high resolution brain structure
        
        Scanners can be fitted with present stimuli
        
        Moving image
        
        Does not involve radiation, so less risk of damage
        
        Definition
        
        Functional magnetic resonance imaging (fMRI) measures the small changes in blood flow that occur with brain activity. It may be used to examine the brain’s functional anatomy, (determine which parts of the brain are handling critical functions), evaluate the effects of stroke or other disease, or to guide brain treatment. fMRI may detect abnormalities within the brain that cannot be found with other imaging techniques.
      - Pet scans
        
        Disadvantages
        
        Requires a small injection of a radioactive material
        
        Brings up ethical issues
        
        Scan is slow and takes a long time
        
        Advantages
        
        It allows participants to perform psychological tasks while the researcher observes brain activity.
        
        Scans can detect signs of diseases before the symptoms start to show
        
        Clear high definition images are produced
        
        Can show the chemical functions of organs and tissue
        
        Definition
        
        They are used used to observe metabolic processes in the brain by detecting the gamma rays emitted indirectly by a tracer. PET neuroimaging is based on the assumption that areas of high radioactivity are associated with brain activity. Before a PET scan begins, a patient is given a safe dose of a radioactive tracer compound introduced into the body by a modified glucose molecule The injected FDG enters the bloodstream, where it can travel to the brain. If a particular 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. The scan, which usually takes between 30 minutes and two hours, produces a multi-coloured image that shows which parts of the brain were the most active. The colour of each dot shows the intensity of the energy signal.
      - Key Terms
        
        A longitudinal study is correlational research that involves repeated observations of the same variables over long periods of time.
        
        Triangulation involves using multiple data sources, multiple researchers or multiple research methods in an investigation to reach a richer understanding of a behaviour or cognitive process.
        
        Artefacts are something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the investigative procedure.
    - - Definition
        
        A pheromone is a chemical substance produced and released into the environment by an animal affecting the behaviour or physiology of others of its own species. Although pheromones are known to play a significant role in signaling between members of the same species among animals to affect various behaviours, it is not clear that this is also true in humans.
      - Studies involving pheromones
        
        https://www.thinkib.net/psychology/page/7146/wedekind-1995
      - Pheromones in animals
        
        In animals, we see two types of pheromones. Primer pheromones that cause slow, long-term physiological changes, such as hormonal effects; and signaling pheromones that produce rapid behavioral effects, such as mating. In humans, there is some evidence of primer pheromones. However, for all the published research that shows these effects, there is an equal number of studies showing that there are no effects. At this stage in the study of psychology, no human pheromone has yet been found