Biological Psychology Flashcards
1/10/19 (70 cards)
1
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Biological psychology
A
- The study of behaviour
- Anything that an organism does that involves action and response to a stimulus
- Are the result of a number of internal process (e.g. learning, memory, emotion)
- Types: Biopsychology, Behavioural Biology, Psychobiology, Behavioural Neuroscience
- ‘The scientific study of the biology of behaviour e.g., what physiological, evolutionary and developmental mechanisms influence our behaviour’
- Biological psychology is an integrative subject that draws on knowledge from several sub-disciplines
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The ‘classic’ divisions of biological psychology - 1) Physiological Psychology
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Study of the neural mechanisms of behaviour usually by direct manipulation of the brains of non-human in controlled experiments
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The ‘classic’ divisions of biological psychology - 2) Psychopharmacology
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The manipulation of neural mechanisms using drugs and observing their effects on behaviours
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The ‘classic’ divisions of biological psychology - 3) Neuropsychology
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Study of the psychological effects of (non-experimental) brain damage in human subjects
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The ‘classic’ divisions of biological psychology - 4) Psychophysiology
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Study of the relationship between physiological / biological activity and psychological processes
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The ‘classic’ divisions of biological psychology - 5) Cognitive Neuroscience
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Study of the neural mechanisms involved in higher cognitive functions such as memory and perception
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The ‘classic’ divisions of biological psychology - 6) Comparative Psychology
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Study of behaviours across different species to understand the role of evolution, genetics and adaptiveness
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Integrating disciplines: Psych-neuro-endocrinology (PNE), Psycho-neuro-immunology (PNI)
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- Exploring the nervous, hormonal and immune pathways that link psychological factors (e.g., stress) to ill-health
- Endocrine system ⟷ Nervous system ⟷ Immune system ⟷ Endocrine system
9
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Approaches to Biological Psychology
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- Behaviour is caused by identifiable events within biological systems
-This demonstrates a causal approach of the form ‘if X then Y‘ For example:
∙ Does stress make you ill?
∙ Does nicotine affect cognitive performance?
∙ Does the hippocampus affect memory and learning?
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1) Somatic Intervention - The investigator can manipulate a biological system to see how it affects behaviour
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Somatic intervention: 1. Administer a stress hormone → Behaviour change: ...increase feeling of stress S.I.: 2. Block nicotine receptors in brain → B.C.: ...decrease smoking cravings S.I. 3. Lesion brain area (e.g., hippocampus) → B.C.: ...disrupt memory process
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2) Behavioural Intervention - The investigator can manipulate experiences to see if this affects biological systems
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Somatic effects: 1. ...changes in hormone levels ← Behavioural Intervention: Expose individual to a stressful situation S.E.: 2. ...changes in nicotine receptors activity ← B.I.: Implement a smoking cessation programme S.E.: 3. ...changes in hippocampal connections ← B.I.: Implement a memory training programme
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3) Correlational Approach - Observing whether biological measures covary with behavioural measures
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- The previous approaches pose ethical problems for psychologists e.g., the investigator is interfering in some way
Somatic measures: 1. Changes in hormone levels ⟷ Behavioural measures: Self-reported stress S.M.: 2. Nicotine receptor activity ⟷ B.M.: Smoking frequency S.M.: 3. Hippocampal size ⟷ B.M.: Memory performance
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Problems with correlation
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1) Correlation is NOT proof of causality
2) The same behaviours might occur for different reasons
3) Physiological systems do not work in isolation
∙ They receive input from external world and other physiological systems making simple correlation tricky
✳︎ You need to know the underlying cause to understand the behaviour
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The Comparative Approach - cross-species comparisons of biology & behaviour
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Different species have the same basic structures (qualitative) ► But they vary in size (quantitative)
15
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Why use non-human subjects?
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1) Animal & human brains similar in structure & function
2) Simpler brains make brain-behaviour interactions easier to observe
3) Knowledge of animal behaviour can aid animal welfare
4) Studying similar species (e.g., chimps) helps to understand evolution
5) Fewer ethical & legal restrictions
- BUT
1) Animal research also subject to strict ethical legislation
2) Animal research cannot answer all questions about human behaviour
- (most) Humans are more complex!
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Brain, Mind & Behaviour
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- Most animal behaviours can be easily understood in terms of: genes, neural activity, hormones etc
- ‘Hardcore’ biological psychologists apply the same concept to humans
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Deterministic
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‘We can identify physical causes for ALL observed behaviours’
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The extreme form of determinism is
Reductionism
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‘All behaviours can be reduced to physical activity’
- Problems: What about complex human behaviour? e.g. consciousness, love, religious experience, morality…
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The Mind/Body problem - 2 different schools of thought - 1) DUALISM
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- e.g., René Descartes (1596 – 1650)
- ‘Mind (soul) & body are separate but communicate in the Pineal Gland’
- Dualism makes ‘intuitive sense’
∙ Many people consider their ‘mind’ separate to their ‘brain’
∙ Many believe that the soul will continue beyond existence of the body - BUT: How can ‘something’ with no physical properties, location or mass produce physical changes in the brain and then body
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The Mind/Body problem - 2 different schools of thought - 2) MONISM
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- Modern (Western) view of singularity of ‘Mind’ & ‘Body’
- Human thoughts, feelings, experiences, etc are simply the product of complex
neurological / neurochemical / neuroelectrical / neurohormonal activity - Many human behaviours can be explained by ‘Monism’
- BUT: Other, more complex behaviours cannot be explained in terms of simple physiological actions
✳︎ The Whole is greater than the sum of the parts (it cannot easily be reduced)
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GENETICS AND BEHAVIOUR: Early thoughts of genetics
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- Acquired characteristics can be inherited..BUT, how are they passed on? Darwin - Pangenesis: the body produces ‘Gemmules’ which travel to sex organs and pass on characteristics to the next generation
- BUT - Children are not an exact copy of their parents…some features are identifiable as coming from one parent and others appear to be blends of both parents
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GENETICS AND BEHAVIOUR: The Daddy of Genetics: Gregor Mendel (1822 – 1884)
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✳︎ Augustinian monk
✳︎ Series of experiments (1856-1863)
✳︎ But only really acknowledged in 1900s
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GENETICS AND BEHAVIOUR: Dichotomous Traits
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Traits that occur in one form or another NOT BOTH
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GENETICS AND BEHAVIOUR: True-Breeding Lines
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Pure Inter-breeding always produces same trait
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GENETICS AND BEHAVIOUR: Genotype
genetic information
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GENETICS AND BEHAVIOUR: Phenotype
physical traits that result from the genotype
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GENETICS AND BEHAVIOUR: Homozygous
2 identical trait genes
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GENETICS AND BEHAVIOUR: Heterozygous
2 different trait genes
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GENETICS AND BEHAVIOUR: Genes
factors that are passed on
✳︎ There are 2 Genes for each dichotomous factor
✳︎ Organisms randomly inherit one gene from the mother & one gene from the father and the combination determines the genotype & phenotype for the trait - one of these genes can be dominant
- What are these genes? DNA aka the ladder of life
- Where are these genes?
→ Genes are located on chromosomes
→ The 34,000 genes found in each cell nucleus of the human body are housed in 46 chromosomes (23 pairs)
- Why are the chromosomes arranged in pairs? Because we inherit one from mum and one from dad
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GENETICS AND BEHAVIOUR: DNA
✳︎ The Base-Pair Rule
✳︎ The rungs work in sequences of 3 – a codon
✳︎ Amino acids to proteins
✳︎ The code for a single protein = (approx) 10,000 pairs
✳︎ The complete code is called a gene
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GENETICS AND BEHAVIOUR: Sex Chromosomes: the 23rd pair
- 22 (out of 23) pairs of chromosomes are autosomal
- They determine all traits apart from SEX
- The 23rd pair determines the sex of the child
- The sex of a child is determined by which chromosome (X or Y) they inherit from the father
- Eggs fertilized by sperm with an X chromosome develop into females
- Eggs fertilized by sperm with a Y chromosome become males
- The X chromosome carries a lot of information (genes)
- The Y chromosome only carries genes relating to ‘being male’
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GENETICS AND BEHAVIOUR: Sex-Linked Genes
- Because females receive two X chromosomes they get two doses of sex- linked genes, but males only receive one dose, which always comes from the mother
- This asymmetry leaves males susceptible to a number of genetic defects that do not affect females – Sex-linked Diseases
- This is because if a female has a harmful recessive gene on one chromosome, she usually has a dominant 'normal' gene on the other chromosome to counteract it, so the recessive gene is not expressed...not so in males...
→ X-Linked Genetic Disorders - So, women often carry the gene (part of genotype) If men have the gene it shows in phenotype
→ Sex-Limited Genes - Genes present in both sexes but (normally) have effects in one sex (usually activated by specific patterns of sex hormones in later life)
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GENETICS AND BEHAVIOUR: From Genes to Behaviour
- Badcock (2000) argued
‘....it is wrong to think of genes as forming a 'blueprint' for the body and mind, as genes do not specify every detail of an individual....’
- Genes initiate a particular developmental pattern that is then left free to run in the face of many possible environmental and physiological changes
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GENETICS AND BEHAVIOUR: Heredity and Behavioural Genetics - Do the observed differences among individuals depend more on differences in heredity or on differences in environment?
∙ The degree to which differences in a characteristic are due to genetic differences is called heritability
∙ This always takes a value between 0 and 1 - e.g., Eye colour has a heritability of 1 (environment plays no role)
∙ The scientific study of heritability (the effects of genes on behaviour) is called behavioural genetics
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GENETICS AND BEHAVIOUR: METHODS IN BEHAVIOURAL GENETICS: 1) Artificial Selection
- E.g. Tryon (1940) trained rats to find their way through a maze. He selectively bred the 'fastest' and the 'slowest'.
Over many generations two clear groups emerged: Dulls (made more errors over generations) and Brights (made less errors over generations)
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GENETICS AND BEHAVIOUR: METHODS IN BEHAVIOURAL GENETICS: 2) Family Studies
∙ We can take a specific family member and compare their behaviours with people of differing genetic relatedness
∙ If a characteristic is more common in closely related individuals then we may conclude that it has a genetic component
∙ Some studies have compared identical (monozygotic or MZ) twins with non- identical (dizygotic or DZ) twins
∙ Because MZ twins are genetically identical they should show greater similarities (concordance) in their behaviours than non-identical twins
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GENETICS AND BEHAVIOUR: METHODS IN BEHAVIOURAL GENETICS: Concordance Studies
- Studies have shown that MZ twins show high concordance for many physical and behavioural characteristics than fraternal twins
✳︎ But how much is heredity?
∙ Twins are reared in the same environments, and are often dressed in the same way, parents expect them to behave in the same way
∙ Such expectations can influence how they behave
∙ If genes play a role in certain behaviours then identical twins raised apart should still be more similar than non-identical twins raised apart
- Minnesota Twin Studies - IQ: Bouchard et al, 1990 (8000+ twins) - identical twins reared together = highest BUT no behaviour has heritability of 1 = so genes & environment interact to form behaviours
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NEURONS AND NEURAL COMMUNICATION: Neurons (nerve cells)
- Specialised cells that receive and transmit information throughout the central nervous system
- Neurons vary in size but all have the same basic structure:
1. Soma
2. Dendrites
3. Axon
4. Pre-synaptic terminals
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1. Soma aka cell body
- The soma contains the cell nucleus (which houses the chromosomes & DNA)
- The bulk of the cell is made of cytoplasm (a jelly-like substance) which houses a variety of structures
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Plasma membrane
Separates the inside of the cell from the outside
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(some) structures in the cytoplasm
- Endoplasmic Reticulum: stores & transports chemicals -
∙ Rough: involved in protein synthesis
∙ Smooth: produces lipids (fats)
- Golgi Apparatus: a type of endoplasmic reticulum. Produce small packages used to transport chemicals
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2. Dendrites
✳︎ large ones = dendrites
✳︎ small ones = dendritic spines
- All information is received by dendrites
- This information is received from other neurons across a tiny gap called a synapse
- Synapses line the surface of the dendrites
- Outgrowths called dendritic spines increase the surface area available for synaptic communication
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3. Axon
- All information is sent along the axon
- Information is sent as electrical impulse called an Action Potential
- Axon is covered with a layer of insulating material called Myelin Sheath (vertebrates only)
- In vertebrates there are breaks in the myelin called Nodes of Ranvier
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The information flow
- Information (the action potential) passes from the cell body along the axon to Pre-synaptic terminals (buttons)
- Axons that send information OUT (Exit) from nervous systems are Efferent e.g., motor neurons
- Axons that send information IN to nervous system are Afferent e.g., sensory neurons
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4. Pre-synaptic terminals/buttons
- When an action potential reaches the terminal buttons they secrete a transmitter substance (Neurotransmitter) which travels across the synapse to the next neuron in the chain
- The neurotransmitter either excites or inhibits the postsynaptic receptors on dendrites of another neuron
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Support cells in the nervous system
- Glia /glial cells/microglia cells
provide support to development & activity of neurons
- Astrocytes:
∙ Wrap around related neurons helping to synchronise activity
∙ Prevent blood-borne toxins entering neurons (e.g., blood-brain-barrier)
- Schwann Cells:
∙ Build myelin sheaths in peripheral nervous system
∙ Help neuron re-growth & guide to appropriate targets
- Oligodendrocytes:
∙ Build myelin sheaths in brain & spinal cord (Central Nervous System)
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Electrical activity in the neuron
- The inside of an inactive axon is more negatively charged than outside
- This is called the Resting Potential (-70mV)
- We know this from probing a squid; microelectrodes are placed inside and outside the axon. Both are connected to a voltmeter & voltage inside & out recorded
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What causes the resting potential?
- Resting potential caused by concentrations of ions inside & outside cell
- More Sodium (Na+) outside the cell...causing a negative charge (-70mV) inside the cell
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Movement of ions in and out of the cell
- Axon membrane is selectively permeable to Potassium & Sodium
- At Rest...Potassium & Sodium diffuse slowly through ion channels in axon membrane
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Maintaining the resting potential
✳︎ BUT - Sodium tries to sneak into cell to balance concentration and charge
- The balance is maintained by ion pumps:
►3 sodium (Na+) OUT
►2 potassium (K+) IN
- The neuron is Polarised during Resting Potential
- A difference in electrical charge between inside & outside
Polarisation is Essential: ensures neuron is ready to fire when it receives impulse
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Passing information - the action potential; All or Nothing Rule
- Neurons have different thresholds of excitation (the strength of the trigger required to respond)
- BUT once threshold is reached an action potential is triggered
1. A positive charge applied to the inside of the axon makes it more positive (Depolarisation)
2. Membrane potential rapidly reversed, inside becomes strongly positive (up to +40mV) 3. The membrane potential quickly returns to normal (Repolarisation),
but first it briefly overshoots (Hyperpolarisation)
✳︎ This entire process takes about 2 milliseconds
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Action potential - electrical changes; ion exchange
→ 0 Rest: More sodium outside axon than inside So, inside is more negative (-70mV) Inside & outside = Polarised Maintained by ion pumps
→ 1 Depolarisation: When stimulated past threshold sodium channels (red) open and sodium rushes into axon causing a region of positive charge
→ 2 Repolarisation: Sodium channels (red) close, potassium channels (blue) open and potassium exits the axon
→ 3 Hyperpolarisation: Potassium continues to exit after repolarisation causing brief undershoot in charge (too negative)
So, ion pumps restore resting balance
Sodium out, Potassium in
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After the action potential
- The axon cannot cope with repeated excitation as the sodium-potassium pump cannot keep up
- Absolute Refractory Period: After action potential sodium channels remain closed for about 1 ms During this time no stimulus can excite the neuron (no matter how strong)
- Relative Refractory Period: Sodium channels open but potassium channels remain closed for 2-4 ms Only an extremely strong stimulus can excite the neuron
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Movement of the action potential
- Unmyelinated Axons (invertebrates & small neurons)
- Each point along the axon membrane generates the action potential. The next area of membrane is depolarised, reaches its threshold and generates another action potential. So the action potential passes down the axon like a wave
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Myelinated axons (only in vertebrates)
- Saltatory Conduction: ions cannot enter or leave the axon in myelinated (insulated) areas. The action potential jumps between unmyelinated areas (Nodes of Ranvier)
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Advantages of saltatory conduction
- Energy saving: sodium-potassium pumps are only required at specific points along the axon
- Speed
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Synaptic transmission: Discovery of the synapse
- Cajal (1800s):
✳︎ Neurons do not physically touch each other
✳︎ Separated by tiny gaps - Synapses
✳︎ Synapses allow neurons to communicate
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What message is sent across the synapse?
- Sodium ions enter causing depolarisation - EPSP (Excitatory Post-Synaptic Potential)
- Potassium ions exit causing hyperpolarisation - IPSP (Inhibitory Post-Synaptic Potential)
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How do we know about synapses?
- Sherrington (1906), Eccles (1963)
- Reflex Arc: automated (involuntary) response to stimulus e.g. muscle flexing reflex: a sensory neuron excites an interneuron which excites a motor neuron triggering the muscle to contract - e.g. if someone tickles you
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Findings from the reflex arc (1)
- Speed: Speed of conduction (stimulus to response) significantly slower in a reflex arc compared to a conduction along single axon
- Conduction is slower because of delays at junctions [synapses]
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Findings from the reflex arc (2) - When is a signal sent on?
- When a single weak stimulus is applied a reflex unlikely to occur
- BUT
- if several weak stimuli are rapidly applied their cumulative strength can be sufficient to trigger a reflex
► E.g. A single pinch may not produce a response BUT repeated pinches (in the same location) in quick succession will
= THIS IS CALLED TEMPORAL SUMMATION
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Findings from the reflex arc (3) - When is a signal sent on?
- Single or uncoordinated stimuli in one location might not produce a reflex
- BUT
- If several separate stimuli are simultaneously received at different locations their cumulative input strength can trigger a reflex
► E.g. Uncoordinated pinches may not produce a response BUT several simultaneous pinches will
= THIS IS CALLED SPATIAL SUMMATION
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Remember the 'All or Nothing Rule'
- An action potential is either produced or not produced
If stimuli is of sufficient strength (exceeds excitatory threshold) – there will be an action potential
- BUT
- The same sensory experiences & responses can be weak or intense
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Rate Law
- Strength of stimulus affects the rate of firing
- A strong stimulus produces more action potentials than a weak stimulus
- The more the axon fires the greater the response
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Post-synaptic responses
The stimuli received will alter the charge (positive or negative) of the post-synaptic membrane
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Excitation
- If received stimuli causes inside of neuron to become more positive (depolarisation)
- EPSP
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Inhibition
- If received stimuli causes inside of neuron to become more negative (hyperpolarisation)
- Remember:
∙ Refractory Periods in action potentials NO responses when axon is hyperpolarised (-ve)
- IPSPs DO NOT produce an action potential at next neuron
- IPSP
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Inhibitory or excitatory output?
- What determines the output of the Post-Synaptic Potential?
e. g., whether the message is passed on (EPSP) or not (IPSP)
- All inputs are integrated in the receiving neuron (Neural Integration)
- The NET SUMMATION of these inputs determines the response
- The more EPSPs received the greater the firing rate of receiving neuron
- If more IPSPs are received the firing rate of receiving neuron is reduced
- If only IPSPs are received (NO EPSPs) – the neuron will not fire
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So - what is this stimulus?
- Axons and synapses
- Electrical → Chemical → Electrical
- How does the electrical message (axon) produce a chemical message (synapse)
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Chemical events at the synapse
- Loewi (1920s):
∙ Stimulation of Vagus Nerve = causing slowing of the heart (Bradycardia)
∙ Extraction of fluid from heart
∙ Fluid injected into another frog
