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Slides Introduction Psychology And Its Methods
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Slides Introduction to Psychology and its Methods 2019-2020Lecture 1: Genes and Evolution
Overview
• The genetic basis
• Evolution by natural selection
• Genes and behaviour
The genetic basis
• Is it correct to claim that “a violent person has violent genes?
- In the seventies: no! Environment → (violent) behaviour
- In the nineties: yes! Genes → (violent) behaviour
- Today: Genes ↔ environment ↔ (violent) behaviour
• Genes
- Meaningful sections of the DNA molecule
- Govern the cell’s functioning by providing instructions for making proteins
▪ Where
▪ When
▪ How much
• Gene expression: whether a gene is turned “on” or “off”; the extent to which a gene is
transcribed into a sequence of amino acids (protein)
- In each cell, some genes are expressed at any point in time and others are not. This
is controlled by the biochemical environment inside the cell.
▪ The biochemical environment inside the cell is influenced by e.g., the
environment outside the cell, timing in development, the overall environment,
experience, behaviour.
• Genotype = an organism’s specific set of genes •
• Phenotype = the overt traits and behaviours of an organism
- Phenotype is determined by genotype x environment (experience, past and present).
• Each gene is paired with another gene
- The pairs are located at corresponding positions on pairs of chromosomes.
- Allele is one specific variant of a gene.
▪ Dominant
▪ Recessive
• Homozygote: alleles on locus are the same
• Heterozygote: alleles on locus are different
• A specific trait or behaviour is determined by the interaction between the environment (past
and present) and
- One gene pair
- Multiple gene pairs: polygenetic inheritance.
• Where do our parent’s sets of genes come from?
- From their parents
• and theirs?
• from their parent
• and theirs?
• from their parents etc.
• The genome is shaped by evolution over the years → Darwin’s evolution theory
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,Slides Introduction to Psychology and its Methods 2019-2020
Evolution by natural selection
• Charles Darwin hypothesized that all modern organisms
- are descended from a small set of shared ancestors.
- have merged over time through the process of evolution.
• The key mechanism of evolution is natural selection.
- Three conditions
▪ There is variation among individuals of a populations
▪ Individuals with a certain trait survive and reproduce at higher rates than
others
▪ The trait associated with this advantage is passed from parents to offspring
- This specific trait will be better represented in the next generation.
• Organisms differ in genotype and variations in genotype are passed from generation to
generation.
• What matters is the survival of genes, not the survival of individuals.
• The evidence for modern evolutionary theory comes from many sources
- The fossil record
- The resemblance between genomes of various organisms
- Pseudogenes
- Distribution of species across the world
▪ Continental islands versus oceanic islands
• Despite overwhelming evidence, many people remain skeptical about the theory of evolution.
- Results of a survey (2005): “human beings, as we know them, developed from earlier
species of animals.”
• It does not follow that evolution
- Somehow improves organisms
- Can only lead to rigid behavioural patterns
Genes and behaviour
• Nature versus Nurture
- The nature (genes) nurture (environment) debate has become increasingly irrelevant.
- Instead, there is a continuous interaction between genes and environment!
• Who we are is determined by how our genes are expressed in distinct environments
• Behavioural genetics = the study of how genes and environment interact to influence
psychological activity.
- Methods:
▪ Twin studies
▪ Adoption studies
• Heritability (H)
• Epigenetics = the study of how environment affects genetic expression
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,Slides Introduction to Psychology and its Methods 2019-2020
Lecture 2: The Brain and the nervous system
Overview
• Introduction
• Building blocks of the nervous system
• Communicating among neurons
• Studying the brain
• The brain
Introduction
• Genes X environment = phenotype
• The nervous system consists of
- Glia
- Neurons
Building blocks of the nervous system
• Different types of neurons
- Sensory receptors
- Sensory (afferent) neurons
- Interneurons
- Motor (efferent) neurons
Communicating among neurons
• Neurons either fire or do not fire
- All-or-none law
▪ Intensity variations by
- Variations in the number of neurons firing
- Variations in firing rate
• Neurons interact
- Via synapses
- Trough chemical substances
• Synapse = the place where a signal passes from one nerve cell to another
• Neurotransmitters = chemical substances that transmit signals from one neuron to another.
- Lock-and-key Model
- Effect is terminated by
▪ Auto-receptors
▪ Synaptic reuptake
▪ Enzymes
- The binding of a neurotransmitter with a receptor produces an excitatory or inhibitory
signal.
• Drugs
- Agonists
▪ Increase of precursor
▪ Counteracting the cleanup enzymes
▪ Blocking the re-uptake
▪ Mimicking the transmitter’s action
- Antagonists
▪ Decrease precursor (or neurotransmitter)
▪ Increase effectiveness clean up enzymes
▪ Enhance the reuptake
▪ Blocking of receptors
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, Slides Introduction to Psychology and its Methods 2019-2020
Communication of the brain with the body
The sympathetic division of the nervous system prepares the body for action.
The parasympathetic system systems returns the body to a resting state.
Endocrine system
• Makes hormones that control your moods, growth, development, metabolism, organs and
reproduction.
• Controls how your hormones are released
• Sends those hormones into your bloodstream, so they can travel to other body parts
19th Century → Phrenology
• Bumps on the skull were interpreted in terms of personality traits
Studying the brain
Methods for studying the brain
• Clinical observation of patient with brain damage
• Experimental techniques
▪ Invasive: animal studies
▪ TMS (Transcranial Magnetic Stimulation)
• Other techniques
▪ Electrophysiology
▪ EEG (ERP)
▪ Brain imaging
▪ (f) MRI scan
▪ PET scan
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