Biological Approach Flashcards
Define localisation
Specific functions have specific locations in the brain
Broca’s Area (localisation)
Left frontal hemisphere responsible for language production discovered through patients with production aphasia
Method for Broca’s Area (localisation)
A case study of a Frenchman who could only say the word “Tan” but could understand speech and follow instructions
- Studied symptoms and did autopsy to find damage in left frontal
- Studied further with 25 cases
Results for Broca’s Area (localisation)
All had damage to the same area with same condition
Conclusion for Broca’s Area (localisation)
Supports localisation since that area was responsible for speech production
Evaluation for Broca’s Area (localisation)
Small sample size limits generalisation (one case study)
Maguire study (Aim)
Investigating the brains of London taxi drivers to investigate size of posterior hippocampus
- Taxi drivers undergo intensive training programme to navigate city known as ‘The Knowledge’
Method (Maguire)
- 16 right-handed male licensed taxi drivers (2 year training, 14 years experience)
- MRI scans of control Ps compared with MRI scans of Ps
Results (Maguire)
Taxi drivers had significantly more volume in posterior hippocampus than control (28% larger)
- posterior hippocampus: used in spatial and navigational skills
Conclusion (Maguire for localisation)
supports localisation since a larger volume of that area displays that section constantly being used (has a specific function)
Greater neural density as localised plasticity processes have developed neural pathways there showing that there is greater demand for function in that area
Evaluation (Maguire for localisation)
- All right-handed so limited generalisation towards left-handed (all male too)
- Reductionist as it looks at one specific area of the brain only
Critical thinking of localisation
- Neuroplasticity argues against localisation that brain can change and adapt over time (not a fixed entity)
- Evidence of interdependence instead of dependence, brain regions must interact with each other to work with research finding damaged connections between the visual cortex and Wernicke’s area lead to losing the ability to read suggesting complex behaviours built on connections between areas
Neuroplasticity
- Define
The ability of the brain to change and adapt its structures and processes as a result of development or experiences of new learning
- neural connections can be made and changed
- each neuron is connected to many others and these new connections create neural networks
Experience dependent plasticity
The brain’s adaptation to change in response to environmental experience across the lifespan
Dendritic branching
A response to environmental demands where connections between existing neurons will become stronger due to intense demand.
- Result is much greater synaptic density (more connections)
Synaptic pruning
Neural networks where are rarely used as ‘pruned away’ allowing connections which are in more regular use to be strengthened and work more efficiently
Maguire - conclusion for neuroplasticity
Supports experience dependent plasticity and dendritic branching since learning and constant application of ‘The Knowledge’ altered structure of taxi driver’s brain (intense demand)
- increased brain matter in posterior BUT control Ps had more matter in anterior suggesting distribution of grey matter
Evaluation (Maguire for neuroplasticity)
- Quasi experiment so cause-effect cannot be assumed (could be people with larger posterior hippocampus are predisposed to that profession)
BUT positive correlation of +0.6 where longer experience = larger volume increase
Critical Thinking of neuroplasticity
- Neuroplasticity can make the brain more efficient due to stronger connections in regularly used areas and is an ongoing dynamic process
- Challenges concept of localisation and is more applicable in recovery of patients from physical and cognitive deficits
Draganski Neural pruning and neural networks (Aim)
To see whether learning a new skill (juggling) would have an effect on the brains of Ps
Method (Draganski)
neural pruning
- Ps were 24 volunteers between ages 20-24 (21 female and 3 male) – non-jugglers
- Each P had a MRI scan at the start of the study as a base rate for grey matter and brain structure
- Condition 1 (Jugglers): Ps taught a 3-ball cascade juggling routine and asked to practice and notify when mastered; then had a second MRI and told not to juggle anymore; third MRI 3 months later
- Condition 2: Control group
Results (Draganski)
neural pruning
- Researchers used voxel-based morphometry (VBM) to determine if there were significant differences in neural density (grey matter) between Ps and control
- Second MRI: jugglers had significantly larger amount of grey matter in mid-temporal area (visual memory are) ; neural networks strengthened
- Third MRI: amount of grey matter in these parts had decreased so evidence of neural pruning
Conclusion (Draganski)
neural pruning
supports neural pruning since when pathways required for juggling were no longer being used they were pruned
- Neurological pathways were also stimulated to create stronger pathways (neural networks strengthened)
Neurotransmitters and their effects on behaviour
- Describe neurotransmission
- Electrical signal (action potential) travels down axon of presynaptic neuron
- Action potential arrives at terminal button of neuron (end of axon and contains vesicles filled with neurotransmitters) and causes versicles to rupture, releasing neurotransmitters into synapse (electrical signal converted to chemical one)
- Neurotransmitters move across synapse and bind to receptors on the dendrites of post-synaptic neuron (specialised to recognise chemical)
- Chemical message converted to electrical AP and transmission begins again in same neuron
- Unused neurotransmitters are absorbed back (aka reuptake)
Excitatory neurotransmitters
More likely that the neuron will fire, excitatory synapse
e.g Adrenaline
Inhibitory neurotransmitters
Less likely that neuron will fire, inhibitory synapse
e.g Serotonin
Agonist
A substance which binds to receptors in the brain to increase activity (activates receptor)
- Endogenous: in body
- Exogenous: outside body, mimicking action of endogenous agonist
Antagonist
A substance which blocks receptors in the brain and reduces the effects of neurotransmitters
Martinez and Kesner (Excitatory, Agonist, Antagonist)
- Aim
- Role of Acetylcholine
To investigate the role of the neurotransmitter acetylcholine (ACh) on memory
- ACh is an excitatory neurotransmitter which causes neurons to fire and allow the transfer of information from short-term memory to long-term memory in mice (many ACh receptors found in hippocampus, area responsible for memory)
Method (Martinez and Kesner)
excitatory, agonist, antagonist
- Mice were placed in a maze that had food hidden in one end. Having completed the maze, they were given one of 3 treatments and placed back in the maze and timed to see when they would find the food.
- Condition 1: Injected with scopolamine (Antagonist) which blocks ACh and decreases its availability
- Condition 2: Injected with physostigmine (Agonist) which inhibits enzyme that destroys ACh in the synapse, increasing ACh availability
- Condition 3: control (placebo)
Results (Martinez and Kesner)
excitatory, agonist, antagonist
Condition 1: slowest times for completion of maze
Condition 2: fastest time
Order: 1 > control > 2
Conclusion (Martinez and Kesner)
excitatory, agonist, antagonist
Supports the idea that he more acetylcholine is available, the more productive memory formation is. This can be concluded because condition 3 rats were in-between the other two conditions in terms of maze-completion time.
Evaluation (Martinez and Kesner)
excitatory, agonist, antagonist
- Very high levels of control (lab experiment)
- Application to humans as the same chemicals are present in humans with low levels of ACh found in Alzheimer patients
- Ethics to do with animal testing with not full applicability to humans
Crockett (Serotonin as an inhibitory neurotransmitter)
- Aim
- Role of serotonin
Aim: Effect of serotonin on pro-social behaviour
- Serotonin: chemical to promote ‘happy’ moods
Method (Crockett)
inhibitory
- Condition 1: Ps given a SSRI (boosts serotonin concentration and prolongs its effects)
- Condition 2: Ps given a placebo
Ps were then given a series of moral dilemmas such as the trolley problem where they had to choose between saving 5 people by pushing a man off the bridge to block the train from hitting the 5 people further down the track .
Results (Crockett)
inhibitory
After receiving SSRI, Ps were less likely to push a man off a bridge to save 5 lives than Ps in a placebo condition.
Conclusion (Crockett)
inhibitory
Opposition to pushing a man becomes even stronger when serotonin levels are increased showing serotonin modulates reaction to certain stimuli inhibiting the acceptability of inflicting harm which promotes social behaviour.
Evaluation (Crockett)
inhibitory
- Hypothetical situation so may not truly reflect their actions in real world
- Social desirability bias: changing decision to seem more favourable
- Low ecological validity: may not happen in the real world (artificial)
Critical Thinking of neurotransmitters and their effects on behaviour
- Theory is reductionist to assume ‘single substance’ neurochemical explanation as recent research suggests a number of specific factors (availability of serotonin, receptor sensitivity, genes) might produce specific behaviours
- Single substance allows creation of medication targeted at specific imbalances to help reduce symptoms in patients (may not give causal explanations but offers relief from symptoms)
- Neurotransmitter levels are difficult to measure, found in cerebrospinal fluid (painful process) so most studies use indirect ways of measuring neurotransmitter levels
Hormone and behaviour
- Function of hormones
- Hormones travel with blood, regulate long-term ongoing processes (growth, metabolism) and allow for lesser voluntary control
(nervous and endocrine system are independent) - Hormone are released by endocrine glands, generally in response to situations or experiences by physiological and behavioural altercations
- Hormones only influence cells with receptors for particular hormones (target cells) so when a hormone binds to the receptor it launches a sequence of changes (gene activation or suppression)
- Hormones do not influence behaviour directly but change the probability of a certain behaviour in response to a stimulus
Oxytocin (role and where its produced)
- Produced in the hypothalamus and released into the blood by the pituitary gland to the amygdala (responsible for emotion)
- Known as the “love hormone” and responsible for forming and maintaining social bonds
Baumgartner (aim)
hormones
Role of oxytocin on trust
Method (Baumgartner)
hormones
- fMRI study on brain activity during game (49 Ps)
- trust game of two individual groups one with oxytocin via a nasal spray and other received placebo
- Game procedure:
- 1st P (investor) given a sum of money and had the choice of keeping it or sharing with trustee and have it tripled
- Dilemma of trusting since trustee can choose to repay trust or violate it
Results (Baumgartner)
hormones
- Placebo: when they had their trust betrayed, became less trusting in the following rounds
- Oxytocin: continued to trust despite being betrayed once
- fMRI results displayed brain activity in amygdala and caudate nucleus with placebo but minimal brain activity for those with oxytocin
Conclusion (Baumgartner)
hormones
- Oxytocin dampened or reduced activity in the brain (gene suppression) since Ps didn’t experience negative feelings strongly associated with betrayal and influenced their behaviour in the following rounds
- unable to learn since no emotion felt
Evaluation (Baumgartner)
hormones
- High level of control (cause-effect conclusion)
- Unlikely oxytocin may be the only thing that influences trust
- Use of technology gives objective evidence pointing towards the conclusion
- Deception: Ps didn’t know they were given oxytocin and experiment manipulated their feelings/emotions
Scheele (Aim)
hormones
If oxytocin modulates fidelity
Method (Scheele)
hormones
- 86 heterosexual men (some single some in stable relationships)
- Double blind independent measures design
- Ps given either placebo or oxytocin intranasally
- – Condition 1: Stop-distance paradigm where male opposite was required to slowly move towards an attractive female experimenter until it made him feel slightly uncomfortable
- – Condition 2: Approach/avoidance task where Ps were shown different images of women and decide whether they would avoid her or approach using their senses
Results (Scheele)
hormones
- Condition 1: Men with oxytocin kept a further distance away from women than placebo
- Condition 2: Men in relationships had slower reaction times (greater hesitance) than single men
Conclusion (Scheele)
hormones
Oxytocin had positively effected fidelity in relationships since it affected those in relationships
- Oxytocin selectively inhibits approach to certain stimuli such as attractive women in order to maintain their current social bonds
Evaluation (Scheele)
hormones
- Ps were all male so application to women is difficult
- Social desirability bias: may have stood further distances away to seem more favourable
- Demand characteristics: Ps exposed to both conditions
Critical Thinking of hormones and behaviour
- Nasal spray to administer doesn’t reflect natural physiological process (more oxytocin administered than naturally produced)
- Reductionist approach as studies focus only on oxytocin and not multiple hormones
Pheromones and behaviour
- Animals vs Humans
- Vomeronasal Organ (VNO)
- Role of pheromones on behaviour
- Animals: more primitive and unable to communicate so need for pheromones to communicate
- Humans: verbal and non-verbal communication so we have evolved beyond the need and don’t need VNO to detect it
- VNO: where pheromones are processed (accessory olfactory bulb)
- Pheromones have the ability to affect our behaviour through their influence on endocrine functions
Wedekind
- assumptions (pheromones)
- Based on the idea that evolutionary, combination of genetically different immune systems would produce offspring with a strong immune response
Aim (Wedekind)
pheromones
Whether women would rate a sweaty T-shirt as more attractive if worn by a man with a different immune system from her (evolution and sexual selection)
Method (Wedekind)
pheromones
- 49 females and 44 males tested for immune system type
- Males wore plain T-shirt for two days and females were asked to smell and rate T-shirt for pleasantness and sexiness
Results (Wedekind)
pheromones
Women rated T-shirt more pleasant and sexier if from a man with a different set of MHC genes (involved in immune system)
Conclusion (Wedekind)
pheromones
- We are motivated/pre-programmed (as a result of evolution) to find a mate with different immune system genes
- Encoded and communicated by body odour which influence our endocrine functions to affect behaviour
Evaluation (Wedekind)
pheromones
- Standardised procedure (easy to replicate)
- Double blind procedure reduced experimenter bias and demand characteristics
- However, Wedekind replicated findings but since then findings have been mixed and inconclusive
- Human sweat does not have the scent of MHC and scent is also influenced by bacteria and lifestyle
McClintock (Aim)
pheromones
To test whether pheromones released by females may cause synchronisation of the menstrual cycle. It was presumed to have adaptive benefits as it has childcare benefits and less likelihood for dominant male to impregnate all members of a group
Method (McClintock)
pheromones
- 20 females with regular ovulation cycle and 9 donor females produced underarm swabs during pre-ovulation and during ovulation
- Cotton swabs were worn under the arms for 8 hours a day and were administered to PS through a daily swab under the nose
- A control group were administered with an alcohol swab
- Luteinising hormone (triggers ovulation) and length of menstrual cycle were measured daily with urine samples
Results (McClintock)
pheromones
- Exposure to pre-ovulation (follicular swab): surge in LH which advanced ovulation
- Exposure to ovulatory swab: delayed LH which delayed ovulation
Conclusion (McClintock)
pheromones
A pheromone exists, produced by females, which can alter the function of the endocrine system in other females. Supports since there was evolutionary benefit.
Evaluation (McClintock)
pheromones
- 32% of women showed no change in cycle suggesting individual differences might be an issue in human pheromonal mechanisms
- Well-controlled study
Critical thinking of pheromones
- Complexity of human attraction: This makes it very difficult to isolate and measure the effect of just one factor - such as human pheromones - on attraction.
- Complexity of human scent. Your “odourprint” - the unique smell you give off is dependent on genes, bacteria and lifestyle. It is very difficult to test how just one chemical - such as a pheromone that makes a significant difference in attraction.
- Difficulty in replicating findings. In many cases, research studies on pheromones have not been successfully replicated.
Genes and their effect on behaviour
- Definition
- Nature vs Nurture
- To what extent is our behaviour shaped by our inherited genes
- Nature: behaviour influenced by inheritance (deterministics)
- Nurture: behaviour influenced by our environment (freewill)
Diathesis-stress Approach
- Argument that biology is not sufficient to determine a behaviour (on its own) but is necessary. It needs a trigger from environmental stimulus in order to cause behaviour.
- Predisposition: Behaviour only shows when both biology and correct environment are present.
Caspi (Aim)
genetics
Determine whether there is evidence for an environment for gene mutation of serotonin transporter gene -5HTT
(serotonin transporter involved in reuptake of serotonin in brain synapses)
Method (Caspi)
genetics
- 847 New Zealand 26 year olds
- divided into 3 groups based on their -5HTT alleles (mutation of alleles are short)
1: two short
2: one short one long
3: two long - Ps were then asked to fill in a “stressful life events” questionnaire asking about frequency of events and were tested for depression.
Results (Caspi)
genetics
- Those with at least one short allele showed more symptoms of depression in response to stressful life events (gene’s interaction with events increased likelihood of depression)
- However, effect was strongest for those with 3 or more stressful life events
Conclusion (Caspi)
genetics
- Inheriting gene was not enough to lead to depression, showed that both are necessary to trigger behaviour
- Environment triggered genes so supports diathesis-stress theory
Evaluation (Caspi)
genetics
- Correlational and assumes serotonin mutation causes depression
- Salience of stressful life events plays a role (self-report so it could vary)
- Problem of generalisation
Lemons
- Theory
- Aim
(genetics)
Based on the theory that a stimulating atmosphere can mediate in cases of genetic vulnerability to decrease its effects
- Aim: whether adapting a particular phonological awareness programme would increase children’s phonological awareness and learning of letter sounds and words
Method (Lemons)
genetics
- 5 children (4F and 1M) with Down Syndrome - associated with intellectual disability
- Repeated measures design experiment
- Students participated in between 24-45 sessions of specially adapted test delivered across 15 weeks where they learnt phonological awareness (matching word cards with 1st letter) and learning target words
Results (Lemons)
genetics
- 4 girls showed significant improvement
- Boy showed slight improvement
Conclusion (Lemons)
genetics
- A functional relationship between adaptation of test and learning
- Modifying teaching and assessment procedures and materials for children with Down Syndrome provided environment mediation of their genetic disorder
- Situation changed how genes were expressed
Evaluation (Lemons)
genetics
- Strong inter-observer agreement
- Longitudinal study gives high reliability
- Very small sample size
- Little change in boy gives ambiguity in gender (anomaly)
- Ambiguity in changes made to test which decreases internal validity and replicability
- Children are very young (may be different for older people)
Critical thinking for genes on behaviour
- Not reductionist but more holistic approach to determining behaviour (makes use of both nature and nurture)
- Good applicability as there is evidence for sessions being effective for certain disabilities (can be adapted to other disorders)
Genetic Similarity
- Definition
Genetic similarities refer to relatedness. The greater the genetic similarities between two individuals or a group of individuals, the higher the degree of relatedness.
Family studies
- Compare rates of disorder in families where it has been diagnosed with families where there is no diagnosis. They also look at heritability rates based on genetic relatedness with family members (study on genetics and disorder)
- To support a genetic hypothesis, longitudinally, you would expect more members of the family in which the disorder has been diagnosed to have it compared to family where it has not been diagnosed.
Twin studies
- Compare concordance rates (expressed as % or decimal and is the number of cases where if 1 twin has it the other does)
- Comparison between MZ and DZ pairs:
Monozygotic pairs: shares 100% of genetic material
Dizygotic pairs: share 50% of genetic material - Supporting a genetic hypothesis: expect to see higher concordance rates in MZ than DZ
Family study: Sullivan
- Aim
Identify the risk of depression in first degree relatives of a proband with this disorder
Method (Sullivan)
family
- Meta-analysis of 5 family studies where the concordance rates of probands with depression and their first degree relatives (share at least 50% of genes)
- Compared with risk of depression in first degree relatives of control Ps
Results (Sullivan)
family
- First degree relatives of a proband with depression were significantly more likely to have the disorder themselves than the first degree relatives of the controls
(2. 84 times more likely)
Conclusion (Sullivan)
family
Strong support for genetics having strong element of inheritance involved
Evaluation (Sullivan)
family
- High internal validity as assessors were blind to proband or control when diagnosed
- Meta-analysis results in discrepancies between method of obtaining results which decreases reliability (replication)
Critical Thinking of Family Studies
- Often focused first degree relatives and thus may not be true for many relatives
- Deterministic and reductionist
Twin study: Kendler
- Aim
Test gender differences in heritability of depression in MZ and DZ twins
Method (Kendler)
twin
- Retrospective study with 15,500 twins identified by Swedish Twins Registry and were screened for lifetime incidence of unipolar depression
Results (Kendler)
twin
Increased concordance rates in MZ relative to DZ but women was 42% and men was 29%
- M-F DZ twins were significantly lower than F or M DZ twins
- Female MZ – 0.44
- Female DZ – 0.16
- Male MZ – 0.31
- Male DZ – 0.11
- M-F DZ – 0.11
Conclusion (Kendler)
twin
Supports genetic involvement increased in MZ than DZ
Evaluation (Kendler)
twin
- Large sample size
- Compares concordance rates of all possible pairings of twins
Critical Thinking of Twin Studies
- Twins have shared environment so ambiguous whether genes or environment affect similarity
- Deterministic
Evolutionary explanation for behaviour
- Theory
- Survival of the fittest
- Natural selection
- Sexual selection
Suggest that present day behaviours came about because they were adaptive and beneficial for survival
2 Evolutionary processes:
- Survival of the fittest – adaptive behaviour/characteristics that have a higher likelihood of survival giving opportunity to reproduce
- Natural selection – offspring inherit the adaptive characteristics
- — Sexual selection: particular traits which are adaptive are found to be attractive to opposite sex (pre-programmed through evolution)
Attractive traits by females
Essential for child’s survival since she can reproduce a finite number of children thus looks for a man with financial support and resources
Attractive traits by males
Can have many children in a lifetime but want to produce as many healthy babies as possible so look for young attractive females
Buss (aim)
evolution
Test the predictions of sexual selection for male and female choice in humans
Method (Buss)
evolution
- Very large questionnaire study of 37 cultural groups in 33 different countries
- Ps were asked to expressed preferences for a variety of qualities (target characteristics)
- Results collected as number of samples where effect matched predictions of theory
Results (Buss)
evolution
- Females have greater preference for financial prospects, ambition and older partners
- Males have greater preference for good looks and young partners
Male
- Good looks: 34/37
- Young: 37/37
Female
- Ambition: 29/37
- Financial: 36/37
Conclusion (Buss)
evolution
Supports evolutionary approach of sexual selection since adaptive traits for survival were perceived as attractive to opposite sex
Evaluation (Buss)
evolution
- Sample size is large so easy to generalise
- High external validity
- Cross-cultural
- Risk of social desirability bias
- Ethical issues = study is socially sensitive and reinforces a double standard.
Waynforth and Dunbar (aim)
evolution
Test idea that mate choice reflects predictions of sexual selection theory
Method (Waynforth and Dunbar)
evolution
- Natural experiment
- ‘Lonely Hearts’ adverts collected from 2 national and 2 local publications
- 479 adverts from men seeking women; 402 adverts of women seeking men
- Adverts sorted on age and frequency of key terms mentioned (attractiveness, wealth, family commitment and fidelity)
Results (Waynforth and Dunbar)
evolution
- Men significantly more likely to offer resources, women more likely to request it
- Women significantly more likely to offer attractiveness, men more likely to request it
Conclusion (Waynforth and Dunbar)
evolution
Supports evolutionary explanation since:
- Men with resources are more financially stable and able to support child better
- Women with good looks are young and can produce young babies
Evaluation (Waynforth and Dunbar)
evolution
- May be different depending on the culture of place (one country studied only despite large sample size)
- Vulnerable to social desirability bias
- Cant extrapolate- volunteer sample
Critical Thinking for evolutionary explanations
- Reductionist to assume that the prospect of survival for offspring is what people find attractive as traits in a partner
- Deterministic since it is assumed that is what is found attractive (social standards)
- Doesn’t include married couples without children or single mothers
Evaluation (Draganski)
- Unable to generalise (small sample size and gender imbalance)
- Confounding variables (unable to control P’s activity outside of the lab)
- Objective data collected (technology, MRI)
- Low ecological validity (conducted in lab, activity does not reflect common social activities)
Techniques used to study the brain
- Outline how fMRI is conducted
- Records blood flow around the brain and detects areas which have more oxygen rich blood (Blood-oxygen-level-dependent/BOLD signals)
- Areas receiving the highest volume of oxygenated blood are presumed to be the most active
- Strong signals are coloured to be seen visually in comparing brain activity
Outline how MRI is conducted
- Utilises the fact that different types of tissue in the body contain different concentrations of hydrogen atoms (most in water).
- A MRI scanner uses very powerful magnets to make hydrogen atoms ‘reverberate’ and then detects the volume of ‘resonance’ found inside the body to create an image of the brain
- Used to compare brain structures not activity
