Methods in Neuroscience Flashcards
Give some examples of model organisms used for neuroscience methods and why they are suitable/not
- Humans
- Primates (unethical)
- Cats and rodents (rodents have short lifespan)
- Zebrafish (transparent so can visualise)
- Drosophila (key mechanisms conserved but holistically v different)
Explain the Marilyn Einstein illusion
- Far away the picture looks like Marilyn Monroe due to low spatial resolution
- Closer looks like Einstein due to high spatial resolution
What experiments can be used to study where the behaviour of interest is initiated in the brain?
- Brain lesions (removal or dysfunction)
- Whole brain imaging techniques
3, Multi-electrode recordings in different brain areas
What are the two ways we can study brain lesions?
- Through direction (brain lesions for the purpose of the experiment in animals)
- Patients who already have lesions due to neurodegenerative diseases
How is patient LM an example of a brain lesion in studying behaviour related to brain localisation?
- Stroke patient
- Good with colour, face and object recognition
- But people tended to just appear, she didn’t see motion
How does fMRI work?
- Highlights parts of the brain that are metabolically active by looking at blood flow
- Glucose is carried in the blood, neurons need glucose for ATP and synaptic transmission
Can be used with visual system, getting a person to look at stimuli and observe which brain parts are active
What is the problem with fMRI?
Very low resolution, shows areas but not individual neurons or synapses
Once you have found the brain area what techniques do you use next?
- Describe morphology of individual neurons to split into different classes
- Map connections
- Describe activity (methods that tell you how and when the neuron is active during behaviour)
- Theoretical study
How did Cajal and Golgi investigate morphological studies of neurons/cells?
- Staining techniques, dye to label neurons
- Sparsely labelled so its not just one big blob, you can see the start and end of neuron
- Cajal labelled retinal neurons and looked at their spatial organisation
What is an enhancer trap and some of its drawbacks?
Enhancer = contain binding sites for specific transcription factors which when bind upregulate expression of gene
Enhancer trap= fluorescent reporter gene to see expression patterns of regulatory genes of transcription
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- But cannot stain individual neurons
- Cannot combine electrophysiological and morphology assessment for the same cell
What are sharp electrode recordings?
- Sharp tip injects current into the cell so you can image the membrane potential of the neuron
- On the x axis you have time and on the y is membrane potential
- You can then depolarise the neuron or activate a neighbouring neuron etc and see what happens
Give an example of where sharp electrodes have been used
- Juusola lab = sharp electrodes being used in drosophila
- Show that fly photoreceptor cells show high depolarisation when exposed to light
What are the disadvantages of sharp electrodes?
- No solution change inside or outside the cell
- Limited possibility for controlling the membrane potential
- Cannot measure single channels
How do patch clamp methods work?
-Tip is not as small as a sharp electrode - Contact with membrane and applies suction rather than puncture
- Can measure currents which go through that part of the membrane
What are the types of patch clamp methods?
Inside-Out Patch clamp= exposes the intracellular face of the membrane to the extracellular solution, direct manipulation of intracellular signaling pathways and ion channels
Outside- Out patch clamp= excising a patch of membrane from the cell such that the extracellular face of the membrane is exposed to the intracellular solution of the pipette
Whole cell = Suction applied to rupture membrane patch and establish electrical contact between the pipette solution and contents of cell
