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1. Lesson 1: Aim: To describe the role of the CNS andneurotransmitters in human behaviourThe CNSThe nervous system has two main parts: the central nervous system and the…
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  • 1. Lesson 1: Aim: To describe the role of the CNS andneurotransmitters in human behaviourThe CNSThe nervous system has two main parts: the central nervous system and the peripheralnervous system: The central nervous system is the brain and the spinal cord The peripheral nervous system is all of the nerve cells outside the brain and spinal cord: it links the CNS to the limbs and organs of the bodyIn the developing embryo, a cylindrical structure called the neural tube separates into thebrain and the spinal cord, and there are then further subdivisionsThese are some of the most important brain (and therefore CNS) structures. Fill out thetable of functions using the textbook p.264 and internet):Brain part Functions (what it does)Striatum Important role in controlling thinking and actionHippocampusCorpus callosumAmygdala Feinstein et al (2010): case study of SM, who had focal bilateral amygdala lesions. They were unable to induce more than mild fear in her, and she reported never having really felt fear, but her other basic emotions were intactHypothalamusNeurotransmittersA Neuron is a specialized nerve cell that receives, processes, and transmits information toother cells in the body. We have a roughly fixed number of neurons as they do notregenerate (on the whole). About 10,000 neurons die everyday, but since we start out withbetween ten and 100 billion (Hooper & Teresi, 1987), we only lose about 2% over ourlifetime.Information comes into the neuron through the Dendrites from other neurons. It thencontinues to the Cell Body (soma) which is the main part of the neuron, which contains the
  • 2. nucleus and maintains the life sustaining functions of the neuron. The soma processesinformation and then passes it along the Axon. At the end of the axon are bulb-likestructures called Terminal Buttons that pass the information on to glands, muscles, orother neurons.Information is carried by biochemical substances called neurotransmitters. The terminalbuttons and the dendrites of other neurons do not touch, but instead pass the informationcontaining neurotransmitters through a Synapse. Once the neurotransmitter leaves theaxon, and passes through the synapse, it is caught on the dendrite by what are termedReceptors.The neurotransmitter, once received, will either excite or inhibit the postsynaptic neuron.That is, they will either encourage it to fire or discourage it from doing soSee powerpoint for how neurotransmission works. Print slides.BBC Video of chemical effects of alcoholCharlie MacDonald video on YouTubeActivity: find behavioural effects of different neurotransmitters (one each if not much time)Neurotransmitter Functions/relations/effectsAcetylcholine (ACh) Involved in stimulation of muscles
  • 3. Noradrenaline/nore Increases heart rate and blood pressurepinephrine (NA)Dopamine (DA) Related to reward mechanisms (tells us when things are good)GABA Low levels related to anxietyGlutamate Important in memorySerotonin (5-HT) Low levels might be related to depression
  • 4. Acetylcholine It is responsible for much of the stimulation of muscles, including the muscles of thegastro-intestinal system. It is also found in sensory neurons and in the autonomic nervoussystem, and has a part in scheduling REM (dream) sleep. There is something on the order of a 90% loss of acetylcholine in the brains of peoplesuffering from Alzheimers, which is a major cause of senility.NorepinephrineNorepinephrine is strongly associated with bringing our nervous systems into "high alert."It is prevalent in the sympathetic nervous system, and it increases our heart rate and ourblood pressureIt is also important for forming memories.Stress tends to deplete our store of adrenalin, while exercise tends to increase it.Amphetamines ("speed") work by causing the release of norepinephrine, as well as otherneurotransmitters called dopamine and seratonin..Dopamine It is an inhibitory neurotransmitter, meaning that when it finds its way to its receptor sites,it blocks the tendency of that neuron to fire.Dopamine is strongly associated with reward mechanisms in the brain. Drugs likecocaine, opium, heroin, and alcohol increase the levels of dopamine, as does nicotine. If itfeels good, dopamine neurons are probably involved!The severe mental illness schizophrenia has been shown to involve excessive amounts ofdopamine in the frontal lobes, and drugs that block dopamine are used to helpschizophrenics.On the other hand, too little dopamine in the motor areas of the brain are responsible forParkinsons disease, which involves uncontrollable muscle tremors.GABAUsually an inhibitory neurotransmitter.People with too little GABA tend to suffer from anxiety disorders, and drugs like Valiumwork by enhancing the effects of GABAIf GABA is lacking in certain parts of the brain, epilepsy results.GlutamateGlutamate is an excitatory relative of GABA. It is the most common neurotransmitter in thecentral nervous system - as much as half of all neurons in the brain - and is especiallyimportant in regards to memory.ALS, more commonly known as Lou Gehrigs disease, results from excessive glutamateproduction.SerotoninSerotonin is an inhibitory neurotransmitter that has been found to be intimately involved inemotion and mood.
  • 5. Too little serotonin has been shown to lead to depression, problems with anger control,obsessive-compulsive disorder, and suicide.Too little also leads to an increased appetite for carbohydrates (starchy foods) and troublesleeping, which are also associated with depression and other emotional disorders.It has also been tied to migraines, irritable bowel syndrome, and fibromyalgia.Prozac and other recent drugs help people with depression by preventing the neuronsfrom "vacuuming" up excess serotonin, so that there is more left floating around in thesynapses. It is interesting that a little warm milk before bedtime also increases the levelsof serotonin. Serotonin is a derivative of tryptophan, which is found in milk. The "warm"part is just for comfort!On the other hand, serotonin also plays a role in perception. Hallucinogens such as LSD,mescaline, psilocybin, and ecstasy work by attaching to serotonin receptor sites andthereby blocking transmissions in perceptual pathways.Homework:Finish chartsLGB definitions of: Central nervous system Neuron Dendrite Axon Soma Terminal button Action potential Synapse Neurotransmitter Receptor
  • 6. Lesson 2: Aim: To describe the role of genes in behaviour anddescribe the method of twin and adoption studiesTest on vocab from homeworkRevise five key stages in neurotransmissionClass feedback on neurotransmitter functionsList traits (both physical and psychological) that you have in common with various familymembers. Discuss genes/environmentsVideo: what are genes? role of genes in behaviourGenes do not affect behaviour directly. They are recipes for the creation of proteins, whichthen (along with the environment) dictate how an organism will developIn this process there are many ways in which the environment can affect the developmentof traits, especially psychological onesPsychological traits are always caused by multiple genes interacting in combination withthe environmentThe nature-nurture “debate” concerns the extent to which different people view traits asdetermined by genes or environment. Genetic determinism in psychology is the view thatour psychological traits are completely accounted for by genesUsing p.266 of the textbook, define the following terms: Gene Genotype Phenotype DNA Genome Dominant genes Recessive genesMethodology: Twin and adoption studiesVideo of twins reunited: and molecular genetics: Behavioural genetics tries to calculate to what extent a given psychological trait is inherited and to what extent it is affected by the environment. Molecular genetics involves trying to work out which specific genes code for the psychological traits that behavioural genetics has told us are inherited. These
  • 7. studies are immensely complicated and often inconclusive. For example, despite the fairly frequent newspaper headlines claiming that genes for schizophrenia or autism have been discovered, conditions like these are so complex that many different genes are actually involved – there are many genes of small effect. However, molecular genetics have thrown up some important results, such as those that demonstrate that only people with certain genes seem to be at risk of developing schizophrenia as a result of cannabis smoking in adolescence (Caspi et al, 2005)Diagrams on board for research methodsTwins reared apart studies: These look at twins (usually MZ) who have been rearedapart to see whether they still have similar traits despite growing up in differentenvironmentsAdoption studies: these look at children who have been brought up by adoptive parentsto see if they share psychological traits with their biological parents.Twin studies: these studies compare monozygotic (MZ) and dizygotic (DZ) twins andlook for concordance rates. This is the probability that one twin will have a particular trait given that the other twin has it, and is measured from 0 (impossible that the second twin also has the trait) to 1 (certain that the other twin has the trait). Higher concordance for MZ twins suggests greater genetic influenceAn example of research using twin study methodology: Recent twin studies suggest that environmental differences, such as parenting, largely explain the differences in the attachment relationships children develop with their parents. These studies compare identical and fraternal twins’ attachment relationships. Because these studies find that fraternal twins, who only share 50% of their genes, are more similar in the types of attachment relationships they develop with their parents and the caregiving they receive from their parents than identical twins, who share 100% of their genes, the development of attachment relationships is suggested to largely be due environmental factors, such as parenting (Bokhorst et al., 2003; Fearon et al., 2006; Roisman & Fraley, 2008). Genetic influences Environmental influencesMZ twinsrearedtogetherMZ twinsrearedapart
  • 8. DZ twinsrearedtogetherDZ twinsrearedapartSiblingsrearedtogetherSiblingsrearedapart
  • 9. Lesson 3: Aim: To describe and evaluate Gottesman & Shields(1966) (SID) and to evaluate twin and adoption studiesGottesman & Shields (1966)Aim:To investigate the relative i m p o r t a n c e o f g e n e t i c a n d environmental influences onschizophrenia by comparing MZ and DZ twins.Procedure.Records of twins from the Maudsley and Bethlem Royal Joint Hospital provided a sampleof 392 patients with twins of the same sex, born between 1893 and 1945 who had survivedto age 15 (from a total of about 45,000 psychiatric patients).Sample: 57 twin pairs MZ Same sex DZ TotalFemale 11 16 27Male 13 17 30Total 24 33 57In addition to the hospital diagnosis, the following information was obtained: •case histories based on a self-report questionnaire and interview with the twins and their parents •a personality test •a test used to measure disordered thinking conducted on twins and parents.Findings:Analysis of the data looked for similarities between each client and their twin.Concordance was assessed in three different ways: Grade 1: both client and co-twin have been hospitalised and diagnosed with schizophrenia. Grade 2: both client and co-twin have had psychiatric hospitalisation but the co-twin has a different diagnosis. Grade 3: The co-twin has some psychiatric abnormality (e.g. out-patient care, GP care, neurotic or psychotic personality profile or being abnormal on interview)Concordance rate for schizophrenia in twins of schizophrenics (bearing in mind that theprevalence rate in the general population is ~1%):
  • 10. Grade MZ(%) DZ(%) 1 42 9 2 12 9 3 25 27 Normal 21 55ConclusionsGenes appear to play an important role in schizophrenia because the concordance rate ishigher in MZ twins than DZ twins. However environmental factors must also be important.Gottesman (1991) went on to investigate the influence of genes on schizophrenia bycombining the results of 40 investigations spanning over 60 years. Concordance rate for schizophrenia (%)MZ 48DZ 17These results cannot be interpreted as meaning that “schizophrenia is 48% genetic”. Thisis because MZ twins are also brought up in largely the same environment. It is thedifference between MZ twins and DZ twins, and the comparison of this with the baselinerate in the population (~1%) that demonstrates how heavily the condition is influenced bygenetic factorsEvaluationStrengths WeaknessesResults are reliable: other studies have The study does not tell us anything aboutfound similar patterns in concordance rates. the causes about scz other than that there isE.g. with respect to differences in some genetic link. E.g. it does not look atconcordance rates when schizophrenia was environmental influences on thesevere or mild, Inouye (1961) in Japan development of the disorderfound: Is this a fair criticism? 74% concordance rate in progressive, chronic scz 39% concordance rate in mild, transient sczPrevious studies in this area had beencriticised on a number of grounds, whichGottesman & Shields addressed:
  • 11. Their sampling was careful: it was clear why participants were chosen Different data sources were used to provide convergent validity for measures of psychopathologyThe study also inherits the strengths and weaknesses of twin study methodology ingeneral...Evaluating twin and adoption studiesTwin studies:Strengths WeaknessesTwins provide a perfect way of controlling Twins brought up together do notfor genetic inheritance as MZs always share necessarily experience exactly the same100% and DZ share 50%, a naturally environmental influences:occurring manipulation of an independent oMZ twins can experience differencesvariable, yet both have the sameenvironmental experience (control of in environment even in the wombconfounding variables) meaning that the oMZ twins are typically closer thaneffect of nature over nurture can be studied DZ twins, their parents are moreeffectively. likely to dress them similarly and they are always the same sex; all these factors mean that people will treat them more similarly and therefore MZ environments may be more similar than DZs oEven though genetically identical, MZ twins are not exactly the same. One twin is typically larger and more robust than the other; this difference is first observable during pre-natal development.With increasing numbers of multiple births, Genes turn on and off at different point in lifeit is possible to replicate the findings of twin and in interaction with differingstudies with large samples in many different environmental experiences (epigeneticworld cultures, increasing the reliability and modification); therefore MZ twins may bothgeneralisability of the findings; records of share a gene or cluster of genes whichmultiple births means that researchers can predispose them to e.g. schizophreniaeasily find large sample with which to test however, only one twin may be exposed totheir hypotheses the environmental circumstances which trigger that gene to start affecting the person’s thinking and behaviour In studies of separated twins, whereby
  • 12. similarity in developmental outcomes must be due to genes and not to similar environments are problematic as often the environments that they are placed in are actually more similar than the researches have creditedAdoption studies:Strengths WeaknessesHomework:With reference to one or more studies, evaluate twin studies as a research method. (20mins writing)Twin studies are a widely used method for investigating the relative influences of geneticand environmental factors on psychological traits. Twin studies take advantage of the factthat MZ twins share 100% of their genes whilst DZ twins share only 50% of their genes – anatural manipulation of an independent variable – whilst pairs of MZ and DZ twins arelikely to share the same levels of environmental influence – a natural control of anextraneous variable.
  • 13. Gottesman & Shields (1966) used a twin study to work out the extent to whichschizophrenia can be accounted for by genetic factors. The key statistic that twin studiesgenerate is a concordance rate estimate. A concordance rate is the probability that if onetwin has the trait of interest, the co-twin will also have it. If MZ twins have a higherconcordance rate for the trait than DZ twins then this suggests a strong genetic influence,because it is only the difference in genetic relatedness (100% v 50%) that can account forthe difference in concordance. G&S uncovered concordance rates of 42% for MZ twinsand 9% for DZ twins, suggesting a large genetic influence in schizophrenia.A strength of using twin studies to investigate the extent of genetic influence overpsychological traits is, as mentioned above, that they provide a natural manipulation of anindependent variable (genetic relatedness) that could not be manipulated artificially, forboth practical and ethical reasons. Furthermore, twin studies can easily be replicated inany country, thus allowing for conclusions to be tested for reliability and generalisability. Ina review of twin studies of schizophrenia, Gottesman (1991) found that his earlier resultswere reliable: overall concordance rates of 48% for MZ twins and 17% for DZ twins werefound.A weakness of twin studies is the assumption that pairs of MZ twins and DZ twins sharethe same level of environmental similarity. In fact, because MZ twins are identical and arealways of the same sex they are likely to be treated more similarly than DZ twins, and thusmay be exposed to more similar environments. A further weakness of twin studies is theassumption that genetic and environmental influences can be neatly distinguished. In fact,the environments that people are exposed to can affect which of their genes areexpressed – an effect known as epigenetic modification – which means that even thoughMZ twins technically share 100% of their genes, they might not experience the effects ofthe same genes due to differing environmental influences.Overall, twin studies are an invaluable methodology in the unweaving of genetic andenvironmental influences on psychological traits. However, some of the assumptionsembedded in the methodology can be questioned and so conclusions drawn from twinstudies must be treated with some caution.
  • 14. Lesson 4: Aim: To describe PET and MRI scanning techniquesShow my brain pictureThere are two types of brain scan that can be done: structural and functional: Structural: cross-sectional photographs are taken of the brain Functional: images are created which show activity in the brain at different timesPET (positron emission tomography) is a functional scanning technique. The decay of a radioactive ligand, most often Oxygen 15, involves the emission of positrons, which collide with electrons in annihilation reactions which release two gamma-ray photons at 180 degrees to each other Coincidence detectors allow the localisation of these emissionsMRI (magnetic resonance imaging) is a structural imaging technique MRI uses a powerful magnetic field to align the magnetisation of some atoms in the body, then uses radio frequency fields to systematically alter the alignment of this magnetization. This causes the nuclei to produce a rotating magnetic field detectable by the scanner—and this information is recorded to construct an image of the scanned area of the bodyVideo of cannister in fMRI scannerActivity: write an information sheet for participants in psychology experiments explaininghow PET and MRI work (and putting them at their ease!)E
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