week 2 - behavioral studies with animals Flashcards
Are humans more genetically similar to rodents or cats and dogs?
Humans are more similar to rodents than cats and dogs
What is an endophenotype
An endophenotype is a measurable, heritable biological or behavioural trait that is intermediate between a genetic cause and a clinical disorder. It is more specific and quantifiable than the broad symptoms of a condition.
Key features:
Associated with a specific disorder (e.g. schizophrenia, depression).
Found in both affected individuals and their unaffected relatives.
Heritable and linked to genetic risk.
More stable and easier to study than complex behavioural symptoms.
Example: In schizophrenia, working memory deficits or abnormal eye-tracking might be considered endophenotypes. Studying them helps bridge the gap between genes and behaviour, improving the development of animal models and targeted treatments.
What is advantages of the endophenotype approach
Improves specificity: Focuses on precise, measurable traits rather than broad, variable symptoms.
Bridges genes and behaviour: Helps link genetic risk factors to underlying neural mechanisms.
Enhances animal modelling: Traits like working memory or synaptic plasticity can be reliably modelled in animals, improving translational research.
Increases statistical power: Endophenotypes are often less variable than clinical diagnoses, making them easier to study in genetic or neuroimaging research.
Identifies at-risk individuals: Can be present in unaffected relatives, aiding early detection and prevention strategies.
Facilitates biomarker discovery: May lead to objective markers for diagnosis or treatment response.
pros and cons of zebrafish
Pros:
Transparent embryos for easy brain imaging
Fast development and high offspring numbers
Genetically tractable and cost-effective
Useful for high-throughput drug and behaviour screening
Cons:
– Simpler brain than mammals
– Limited complex behaviours
– Some genetic and physiological differences from humans
Why are rodents developmentally useful as a model?
They have a quick developmental timescale. They get through childhood, puberty and reach adulthood within 8-10 weeks
What is the immemorial association hypothesis?
Hypothesis of why were genetically and behaviorally similar to rodents
Rodents have been associated with us for a very long time
They are commensal organisms because they benefit from living with us - we share the same food
This means they were with us since we transitioned from nomadic hunters into farmers
This means that over hundreds of years we have likely had the same environmental influences on man and mouse
what are some environmental influences that we don’t share with rodents
The social environment
They don’t live in a society so this is something we can never properly translate
Psychosocial disorders are hard to model with rodents
Advantages and disadvantages of rats
Rat advantages:
* physiology
* anatomy
* behaviour
Rat disadvantages:
* limited genetic diversity
* difficult to manipulate genome
Behavior definition
Observed animal activity
Activity refers to voluntary or involuntary movements made by conscious, unrestrained animals
Brief history of studying behavior
19th Century - Darwin ‘origin of species’ theory of evolution
20th century - Behaviorism, Skinner and pavlov everything can be explained by conditioning
20th century - ethology, looking at innate behaviors of animals in their natural environment
What is anthropomorphism?
Anthropomorphism - projecting human qualities onto animals or inanimate objects
How can you measure exploration in rodents?
You can measure the innate attraction of rodents to novel objects
Tasks:
-novel object exploration
-holeboard (they stick heads in holes)
- Puzzle box (give them little puzzles to solve to get into their cosy dark enclosed area that they prefer)
What types of cognition can you measure in rodents?
What tasks would you use?
- Spatial and non spatial learning
- Working memory
- Reference and recognition memory
-Attention
Tasks:
- Morris water maze (time taken to find hidden platform)
- 8 arm radial maze
- Social recognition task
- Novel object discrimination
- Two-retractable lever operant chamber (skinner box)
- 5-choice serial reaction time task
What social behaviors can you measure in rodents?
What tasks would you use:
Social play behaviour
Social approach
Social hierachy
Aggression
tasks:
- social dominance test
- Social interaction test (males you have to be careful they don’t fight)
- Three chamber social approach task
What communication can you measure in rodents
Olfactory communication
Ultrasonic vocalisation
Sonograms
describe fear vs. anxiety in rodents:
Fear = response to actual threat
Anxiety = response to a potential threat
In fear, rodents may move away from threat
For anxiety, rodents may approach a threat, to investigate it
How can you measure anxiety in rodents:
- Open field area (measure how much they avoid being in the open area)
- Light/dark box (measure how much they spend in the light
- Conditioning tasks - condition them to associate a stimulus with fear. See how quickly they become conditioned to this response, and how much they learn
How can you measure depression in rodents?
Focussed on helplesness/behavioural despair (giving up on struggling):
Porsolt swim test - Measure how long it takes before the mouse stops swimming#
Tail suspension test - Measure how long the animal keeps wriggling when suspended from tail
These tests are very sensitive to anti-depressants
How would you measure sensorimotor gating in rodents:
A loud startling stimulus (called the “pulse”) normally triggers a startle reflex (e.g. a muscle twitch).
If a weaker stimulus (called the “pre-pulse”) is presented just before the pulse — usually 30–500 ms earlier — the startle reflex is reduced.
This reduction is the PPI effect.
Rodents jump off a pressure sensitive grid when startled
Why would you look at olfactory behavior in rodents and how would you do it?
Olfactory behavior is an important confound for animal behavior in rodents
This is because rodents smell each other to communicate
What types of validity do good rodent tasks have:
Construct validity - how well the tasks reflects theoretical assumptions
Predictive validity - How well a manipulation predicts performance in the condition being measured
Face validity -Degree of similarity between the responses observed in the task and the disorder it stimulates in humans
What are common confounds of rodent tasks
Health and physical ability
Sensory ability
Anxiety/stress
Motivation/drive
Locomotor activity
Order of testing
Housing environment
Test environment
Experimental effect
how would you measure social behaviour in rodents?
The social dominance test measures hierarchy by observing which animal consistently wins access to a resource (e.g., food or territory) over another.
The social interaction test measures sociability by recording how much time an animal spends engaging with another animal compared to being alone.
