Higher Level Biological Extension Flashcards
Value of Animal Models
Animal Models
Use of a non-human animal to study a psychological process that is similar to a human condition.
Tests a causal hypothesis about certain human behaviour.
Value of Animal Models
Value of animal models
Manipulating biological variables in humans would result in long-lasting and irreversible physical/physiological damage.
- Reason why we use animal models.
- Unethical for humans.
Animals and humans have massive amounts of biological similarity.
- Mice/human brains share 99% of DNA responsible for brain construction.
Animals have shorter lifespans and therefore less time.
- E.g. mice have 2 year lifespan and whole life can be in highly controlled environment (high internal validity).
Multiple generations of a specific ‘breed’ of mice can be bred quickly.
Mice are cheap to source and maintain in labs.
Value of Animal Models
Purpose of APA guidelines
Ethical commitee in US.
There is an obligation to respect animals.
- Responsibility for use of animals scientifically is ethically acceptible.
Research must have scientific or educational merit (beneficance).
- Must benefit humans.
- Conducted with integrity (adoption of the 3 principles).
Ethical considerations of Animal Models
The three principles
Proposed by Russel and Rex.
Replacement
Use of methods that replace/avoid use of animals in research and teaching.
Opportunities to replace use of animals must be kept under review during lifetime of a project.
Reduction
Methods for obtaining comparable levels of information from the use of fewer animals in scientific procedures or for obtaining more information from the same number of animals.
Number of animals used must be minimum necessity to achieve proposed aim(s).
May be reduced by appropriate reuse of animals.
Refinement
Methods that alleviate or minimise potential pain and distress and enhance animal wellbeing.
Duration must be no longer than required to meet the aim(s) of project.
General
Serotonin
Serotonin (5-HT) is a neurotransmitter which modulates mood, sleep and appetite.
Correlated with numerous behaviours including impulsive aggression, antisocial behaviour, and violence.
Made from amino acid: tryptophan. Tryptophan Hydroxylase-2 (TPH-2) gene plays role in converting tryptophan into serotonin.
- If ablated, affects this conversion, thus less serotonin.
Study - Brain and Behaviour, Genetics and Behaviour
Mosienko et al
Animal True experiment
Aim
Investigates genetically modified mice with a control group (serotonin and aggression).
Method
Number of tests used to study effects of the removal of the TPH-2 gene.
- One is the resident-intruder paradigm (a third group of mice were intruders).
Ablated TPH-2 gene within mice to create “TPH-2 knockout mice”.
Same group of rats that have been exposed to an earlier DV
- Reduction
Results
Knockout mice attacked 6 times faster than control group.
Total # of attacks and total time attacked was 7 times more than control group.
Test lasted 10min but 100% of knockout mice attacked within 5 minutes compared to 22% of control group.
Knocking out TPH-2 caused significant increase in agressive behaviour.
Ethics
Application of 3 principles:
Reduction
Reduced mice sample and reuse through RIP.
Refinement
Lab animals are to be probvided humane care conditions during stay.
- Maintained in ventilated cages with circadian cycle.
- Access to food and water whenever needed.
Animals in state of severe distress/chronic pain that cannot be alleviated should be euthanised immediately in humane manner.
- Mice are euthanised with medication if too much harm is involved.
Postroperative monitoring and care should be provided.
- Mice are relieved with medication when harmed and operated.
RIP
- Studies show that engaging in aggressive behaviours and winning a fight are highly rewarding; no suffering when attacking.
- Submission is a natural response to domiance; Subjugation triggers adaptive behavioural response (adopting a subordinate oposition in social group). Leads to well-adoption, therefore does not suffer.
- Only repeated exposure to dominance and social isolation after defeat may lead to conditions beyond adaptive capabilities.
- Biologically functional aggression may change to a violent form of out-of-control aggression (serious wounds, e.g. belly, throat, paws). To be clinically relevant, development poses central ethical dilemma of this type of aggression research (harm and injury).
Beneficial to human population.
- Aggression and social stress are serious problems in human society.
- Gives causal insight.
Brain and Behaviour
Neurotransmitters + Behaviour Argument
Low levels of serotonin results in higher levels of aggression.
Study - Brain and Behaviour
Mehlman et al
Observational study
Aim
Investigates the relationship between aggressive behaviour and serotonin using non-human primate model of aggression/impulse control.
Method
26 adolescent male rhesus macaques were selected where physiological data were obtained from 22-23 of subjects.
Had their blood and cerebral spinal fluid (CSF) samples obtained.
Fitted with ratio transmitter collar for rapid location.
Released into social groups and quantitative behavioural observations were made over 3 month period.
Aggression measured by observing ratio of chases/physical assaults to all aggressive acts.]
- Specifically leaps that traversed longest distances at dangerous height (impulse control).
Results
Serotonin concentrations were inversely correlated with ‘escalated’ aggression.
Low serotonin concentrations correlated with greater risk-taking (negative correlation).
Study - Brain and Behaviour
Passamonti et al
Corroborating Human True experiment
Aim
Investigate effects of serotonin depletion in the brain.
Method
Healthy volunteer samples serotonin levels were manipulated through diet manipulation.
One day, given diet that lacked tryptophan.
Control conditions were given placebo diet (same mixture but normal amounts of tryptophan).
Participants put in fMRIs and brain activity was measured while seeing happy/angry/neutral faces images.
Results
Reduced activity in frontal lobe during low serotonin conditions when viewing angry face.
Communication between amygdala and frontal lobe was weaker in this condition.
Less emotional importance and therefore more impulsive.
Genetics and Behaviour
Genetics + Behaviour Argument
One way to studying influence of genes is use genetically modified animals.
Alteration of genes may affect levels of aggression.
Study - Genetics and Behaviour
Gardner et al
Spiral from Mosienko - How environment can change due to genetic expression and link to aggression.
- Why there is a causation from Mosienko?
Aim
Investigates the effects of prolonged early life stress on the expression of the TPH-2 gene in rats.
Method
Replicate traumatic destablising conditions.
- Creating stress in unfamiliar environment (Rats were separated from their mothers and handled by the researchers for 15 minutes a day for the first two weeks of their life)
- Imitates frequent high levels of stress early in life.
- At early adulthood, they are euthanised (refinement).
Results
When traumatised rats became adults they had a 55% reduction in the expression of their TPH-2 gene compared to control group.
- Explains why children who experience chronic long-term stress in childhood group up to be antisocial adults and react violently/impulsively when treatened.
- Early life trauma causes trauma, correlates with later aggression/lack of impulse control later in life.
Deeper understanding into epigenetics processes.
Ethics
Reduction
Min time that rats need to experience trauma thought for research validity, instead live with trauma as highly anxious adults they are euthanised at 10 weeks.
Still need to be kept in healthy conditions.
- What is scientific justification? (Beneficance)
Genetics and Behaviour
Genes
A unit of heredity, a region of DNA that encodes a specific trait or function.
Building blocks to complex behaviours.
Genetics and Behaviour
MAOA Gene
Monoamine oxidase A gene - Warrior Gene
An enzyme that breaks down neurotransmitters in the synapse.
Job of MAOA-gene is to send signals from the cell to produce the MAOA enzyme.
Some humans have low expression variant of this gene (MAOA-L).
If they have low expression variant, less MAOA produced.
- Affects neurotransmitter levels and therefore brain activity.
Both protective (H) and harmful (L)
Study - Genetics and Behaviour
Caspi et al
Corroborating Human Case study
Shows gene-environment interaction.
Aim
To investigate the MAOA gene.
Method
Over 1000 children in Dunedin had their genes, blood pressure and private lives monitored and measured every few years.
Results
MAOA-L gene moderated effects of experiencing child abuse on adult aggression.
- 85% with gene and were abused as children were more likely to be antisocial/aggressive adults compared with those with just the gene.
Critical Thinking
Strengths
Credibility - Multiple data sources.
Longitudinal.
Limitations
Absence of free will
- Young people do not have free will (parents control their environment).
- Genes cannot be controlled.
Cannot be replicated.
Hormones and Behaviour
Hormones
Chemical messengers that are transported through the blood due to activation of different glands in endocrine system.
Regulates long-term ongoing processes (e.g. growth, metabolism, reproduction).
One is testosterone.
