Experimental Techniques Flashcards
Explain the concept of the elevated plus maze task.
The elevated plus maze is a square with four chambers, two open and two closed. Rats are naturally ‘anxious’ animals and prefer the closed areas. Anxiety drugs can be tested by comparing the amount of time spent in open and closed spaces.
This ignores individual differences.
Explain the Rotarod task.
The rodent is placed on a rotating drum with the speed gradually increasing. The effects of drugs and brain injury can be investigating by comparing the highest speed at which the rodent does not fall off the drum.
Why are rodents used in behavioural experiments?
Rodents are used to simplify a complex phenotype to a single behaviour, e.g. anxiety, memory.
This does involves many assumptions.
Explain the Morris water maze task.
The Morris water maze is used to study spacial learning and memory. Rat is placed into pool of water which contains hidden platform. Visual cues around the room provide navigation cues
Rat eventually finds platform,
and on subsequent trials will
swim directly to platform as it learns where it is. Many assumptions including that rats don’t like water and that the rat actually stood on the platform.
How can lesions be used to study the functions of structures of the brain?
The loss of a function following trauma can be attributed to the damaged brain area. E.g. Phineas Cage.
How does function magnetic resonance imaging (fMRI) allow studying of functions of brain areas?
Oxygenated blood supply increases with neuron activity. Iron in haemoglobin is detected by the fMRI.
- Non-invasive
- Cannot be used if patient has metals in the body.
Explain two-alternative forced choice testing.
An animal is given two alternatives and its forced to choose between them. Characteristics of animals perceptual abilities of animals.
- Less assumptions
Do computed axial tomography (CAT) scans provide functional information?
No
Explain intracellular recordings in terms of studying the activity of single neurons.
The activity of only one neuron is recorded as an electrode is placed inside or on the membrane.
What are the advantages and disadvantages of intracellular recordings?
Advantages: - precise information - detects very small electrical events - introduce new drugs without administering it to the entire animal. Disadvantages: - possible to damage cell - expensive - difficult to perform of whole animal, brain slices are normally used but these cannot be kept alive for long.
What does a raster diagram depict in terms of extracellular recordings?
Records whether an action potential occurred or not in response to presentation of each stimulus.
Not indication of whether IPSP or EPSP.
What does a peristimulus time histogram (PSTH) depict?
Rate of action potentials at each point in time.
What are the advantages and disadvantages of extracellular recordings?
Advantages:
- although invasive, they do not damage neurons
- relatively easy to maintain prolonged stabe recordings.
Disadvantages:
- cannot always tell whether activity of one or multiple neurons is recorded.
- cannot tell is EPSP or IPSP.
The stronger the stimulus, the higher/lower the depolarisation, the higher/lower the rate of action potential?
The stronger the stimulus, the higher the depolarisation, the higher the rate of action potential?
