Behavioural Methods Flashcards
Why do some investigations require behavioural models?
- Some investigations require behavioural models because they might involve certain variables that can’t be directly physiologically measured.
- E.g. shaking in Parkinson’s disease, or pain responses induced by a pain stimulus can’t be measured physiologically because they are behavioural responses.
- ‘Behavioural model’ and ‘animal model’ are interchangeable terms in the context of this lecture because behavioural models are done using animals (at least before human trials).
List 3 ways of validating a behavioural model.
What do these models mean?
1 - Face validity.
- Involves applying a superficial and subjective assessment of whether or not a behavioural model measures what it is supposed to measure. I.e. a form of observational validity / taking it on face value.
E.g. if a behavioural model for Parkinson’s that measures the severity of hand tremor assesses a patient as ‘severe’ for Parkinson’s disease, and it appears to the researcher by observation alone that the patient does indeed have a severe case of Parkinson’s disease, that is a form of face validity.
2 - Construct validity.
- Involves assessing whether the results of a behavioural model are consistent with the theory that underpins the model.
- E.g. if the same behavioural model as above assesses a patient as ‘severe’ for Parkinson’s disease, and the patient is also found to have many degenerated dopaminergic neurones in the substantia nigra, that is a form of construct validity.
3 - Predictive validity.
- Involves assessing the model’s ability to create accurate predictions about other individuals’ results based on the results from the model.
- This relies on pharmacological isomorphism, which is the phenomenon in which the same set of ligands / receptors are present in the individual / species being tested compared to another (e.g. in rodents compared to humans).
- E.g. in an animal model, good predictive validity is being able to say ‘if, according to the behavioural model, drug X works on a rodent, it will also work in humans’.
List 4 issues with using animals for behavioural models.
1 - Ethics.
2 - Differences in species-specific behaviours.
- This can lead to ‘behavioural anthropomorphism’: the attribution of human characteristics or behaviour to the animal being used in the model. By attributing these characteristics, you are assuming that the animal behaves in the same way that a human would in response to a particular stimulus, which might not necessarily be true.
3 - Behaviours interact / superimpose to result in one overarching behaviour, but this might not be interpreted as such. E.g. a stimulus might cause both pain and movement, but if the pain prevents an animal from moving, this could be interpreted as the stimulus not causing the animal to move in the first place. Interacting behaviours are more difficult to identify in animal models.
4 - Sex differences. Because of this, nowadays it is required to test both males and females in both animal and human trials.
What is neuroethology?
Why is this important for using animals for behavioural models?
- Neuroethology is the study of how the nervous system influences behaviour.
- A good neuroethological understanding of a behaviour in a particular species can help avoid behavioural anthropomorphism.
What is endophenotyping?
- Endophenotyping is identifying a measurable component that links one facet of a multifaceted behaviour to a particular gene or biological process.
- E.g. in the case of schizophrenia, the overt symptom could be a psychosis, but the underlying phenotypes are, for example, a lack of sensory gating and a decline in working memory. Both of these traits have a clear genetic component and can thus be called endophenotypes.
List 3 advantages of using animals for behavioural models.
1 - Using animals gives the researchers control over population heterogeneity that wouldn’t be possible with human models. This allows the researchers to control more variables.
2 - Measurement can be more easily automated, e.g. tracing an animals movement using software.
3 - Ethics prevents some behavioural models from being done on humans.
List 5 behavioural indicators of pain in rats.
1 - Orbital tightening.
2 - Nose bulge.
3 - Cheek bulge.
4 - Ear position.
5 - Whisker change.
List 3 untrained behaviours that might be observed in a behavioural model in animals.
1 - Feeding behaviours.
2 - Facial expressions.
3 - Exploratory patterns (often used as an index of anxiety).
Give an example of a method used to assess exploratory patterns in behavioural models.
Why is this useful?
- The elevated plus maze is a method used to assess exploratory patterns in behavioural models.
- It involves placing a rodent on an elevated plus-shaped platform with walls surrounding only one line of the plus.
- The rodent is naturally expected to move to the walled area of the platform (or when it is anxious).
- This is useful for assessing the effects of anxiolytic drugs.
Give an example of a method used to assess learning / memory in behavioural models.
Why is this useful?
- The Morris water maze can be used to assess learning / memory.
- The rodent is placed in a bath of opaque water with a floating platform (to obstruct the rodent’s vision and ensure it cannot see the platform).
- The bath of water is placed in a room with various visual landmarks laid out to give the animal a reference for its position.
- The rodent must swim around until the platform is found.
- The movement of the rodent can be tracked and the test can be repeated.
- Over time, the rodent should learn the position of the platform and move more directly to it from the its starting point.
- This is useful for assessing the effects of particular drugs or brain lesions on memory.
What is passive avoidance?
Give an example of a method used to assess passive avoidance in behavioural models.
- Passive avoidance is a behaviour in which animals avoid an aversive stimulus by inhibiting a previously punished response that was part of their normal, untrained behaviour.
- Two cardboard boxes are connected, with a port between them through which a rodent can pass.
- One cardboard box is lit, the other is dark.
- It is expected that the rodent will naturally pass into the dark box.
- If a small current is passed into the dark box, stimulating the rodent, the rodent is expected to leave the dark box when it begins to associate the dark box with the uncomfort of the current.
- If the rodent is placed back into the light box, it will not pass into the dark box as it did before (this is passive avoidance because it is avoiding the environment that it would normally prefer when untrained).
What is the difference between classical and operant conditioning?
- Classical conditioning involves associating an involuntary /reflexive response with a stimulus (e.g. Pavlov’s dog - salivating and ringing the bell).
- Operant conditioning is involves associating a voluntary behaviour and with a punishment or reward (e.g. teaching a dog to sit by rewarding it with food).
How might operant conditioning be used to investigate the properties of drugs in behavioural models?
- Operant conditioning can provide information on the degree of motivation an animal can have to carry out a voluntary behaviour in order achieve a reward or avoid a punishment (once it has associated that voluntary behaviour with the reward / punishment through operant conditioning).
- The degree of motivation provides insight into the severity of the reward / punishment (e.g. from a drug).
- This can be used to investigate the abuse potential of a drug. ‘How hard will the animal work to obtain the drug?’.
