Neuroscience Research Methods 4 Flashcards
Give a definition of ‘in vivo electrophysiology’. (2)
Measurement of neuronal physiological characteristics
in a living organism.
Give four advantages of using in vivo electrophysiology in neuroscience research. (4)
- Can study neuronal activity at a cellular level
- Can study neurones in their normal environment (and disease states)
- Can identify targets for disease treatments
- Neurones are still connected to their natural network
Give six types of information that can be obtained via in vivo electrophysiology. (6)
- Characteristics of the cell (eg. basal firing levels)
- Resting membrane potentials and reversal potentials
- Pharmacological properties
- Synaptic responses
- Neuronal connections and networks
- Response to a stimulus
Why is in vivo electrophysiology not carried out on humans? (1)
It is an invasive technique which requires surgery.
Briefly describe how in vivo electrophysiology is carried out. (4)
- Animal anaesthetised
- Vertebrae/skull segments removed via stereotaxic surgery, or peripheral nerve dissected to gain access
- Tungsten microelectrode inserted into area of interest
- Testing usually carried out while animal still anaesthetised, but can also be carried out after it wakes up
Why are in vivo electrophysiology studies investigating neurones in the spinal cord usually carried out while the animal is still anaesthetised? (1)
- The electrode needs to stay in very close proximity to the neurone
- and the spinal cord is very flexible but equipment very bulky.
True or false? (1)
During in vivo electrophysiology, the tungsten microelectrode is directly inserted into the neurone to record action potentials.
False - it is inserted into the area of interest, in very close proximity to the neurone but not actually inside the neurone
What data is collected using in vivo electrophysiology? (1)
Number of action potentials per unit time
A newer approach to in vivo electrophysiology is to use multielectrode arrays. Describe what is meant by a multielectrode array. (2)
One probe with multiple electrodes
so we can record from multiple neurones at the same time.
Describe two advantages of using multielectrode arrays when performing in vivo electrophysiology for neuroscience research. (3)
- Collect more information
- Use fewer animals (more ethical)
- Can produce a spatiotemporal map of neuronal responses
Give two ways which can be used to measure pain in humans. (2)
- Visual analogue scales
- Quantitative sensory testing (eg. testing thresholds)
Give two potential ways of measuring pain in rodents (that are not in vivo electrophysiology). (2)
- Looking at behaviour such as flinching, licking, burrowing
- Facial grimace scale
Give five disadvantages of using behaviour to measure pain in humans and rodents. (5)
- Experimenter bias
- Difficult to interpret behaviour
- Implies neuronal activity on a population level
- May have confounding effects (eg. sedation from analgesics)
- In rodents you cannot use behaviour to measure spontaneous pain
In rodents, the compound S1P increases pain.
Describe the changes you would expect to see in:
a) flinching behaviour
b) licking behaviour
in rats exposed to S1P compared to control rats. (2)
Increased number of flinches and licks
and increased time spent licking in S1P rats.
In rodents, the compound CFA causes inflammation.
Describe the effect you would expect CFA to have on the burrowing behaviour of rats. (1)
How might ibuprofen affect this? (1)
CFA rats displace less gravel (less burrowing)
but ibuprofen increases burrowing activity in rats exposed to CFA.
When using in vivo electrophysiology to measure pain, where would the microelectrode be placed? (1)
Explain your answer. (1)
Lamina V of the dorsal horn
Because this is where sensory input is integrated.
Describe and explain what in vivo electrophysiological spinal recordings of a pain stimulus would look like. (4)
Quick increase in neuronal activity
due to transmission by A fibres.
Followed by a slower increase in neuronal activity
due to transmission by C fibres.
Briefly describe how in vivo electrophysiology could be used to assess the effectiveness of an analgesic drug on reducing pain. (2)
- Record in dorsal horn before drug and after drug
- If drug is effective in reducing pain, there will be less action potentials per second after the drug has been administered
ON cells become activated in response to pain.
OFF cells become inactivated in response to pain.
These neurones are located in the brain and modulate spinal responses to pain.
Describe what you would expect to see regarding the responses of these neurones to a pain stimulus, as measured by in vivo electrophysiology. (2)
ON CELLS:
- more APs per unit time when painful stimulus is applied
OFF CELLS:
- fewer APs per unit time when painful stimulus is applied
Name a technique which is able to provide a compromise between subjective behavioural and invasive electrophysiological ways to assess pain in humans and animals. (1)
Briefly describe the principle behind this technique. (1)
Electromyography (EMG)
which measures and quantifies muscle activity in response to a stimulus.
Describe an example of using EMG to quantify a pain response in a human subject. (4)
- Apply heel lance (taking blood from heel, which is a painful stimulus)
- In control group, can apply non-noxious stimulus to heel
- Use EMG to measure withdrawal response
- Muscle activity likely to be higher with noxious stimulus as reflex withdrawal will occur
True or false? (1)
Dopamine is a monoamine neurotransmitter.
True - however some consider it a neuromodulator
Why can dopamine be considered a neuromodulator? (1)
It affects how other neurotransmitters work.
What type of receptor does dopamine act on? (1)
a) inotropic
b) metabotropic
c) a mixture of both
b) metabotropic GPCRs
Describe the relative speed of the brain reacting to dopaminergic transmission, and the longevity of the effect. (2)
Slow reaction
but long lasting effect.
Give four roles of dopamine in the brain. (4)
- Motor control
- Motivation
- Reward/craving
- Modulation of emotional states
Name two families of dopamine receptors in the brain. (2)
For each of the dopamine receptors (D1, D2, D3, D4, D5), state which family they belong in. (5)
D1-like family (D1, D5)
D2-like family (D2, D3, D4)
Are D1-like dopamine receptors in the brain mainly located pre- or post- synaptically? (1)
Post-synaptic
Are D2-like dopamine receptors in the brain mainly located pre- or post- synaptically? (1)
Located pre- and post- synaptically
Describe the effect of activating D1-like dopamine receptors on LTD. (1)
Activation enhances LTD
Describe the effect of activating D2-like dopamine receptors on LTD. (1)
Activation inhibits LTD
Name the molecule which removes dopamine from the synaptic cleft. (1)
dopamine transporter (DAT)
Name three dopamine pathways in the brain. (3)
- Nigrostriatal
- Mesolimbic
- Mesocortical
Describe the anatomy and function of the nigrostriatal dopamine pathway. (2)
Substantia nigra to basal ganglia
Involved in movement
Describe the anatomy and function of the mesolimbic dopamine pathway. (2)
VTA to nucleus accumbens, amygdala, and hippocampus
Involved in motivation, reward, and craving
Describe the anatomy and function of the mesocortical dopamine pathway. (2)
VTA to prefrontal cortex
Involved in cognition
Which dopamine pathway in the brain is involved with addiction? (1)
Mesolimbic
Name two patterns of dopamine signalling in the brain. (2)
Synaptic transmission
Volumetric transmission
Describe synaptic transmission of dopamine in the brain. (2)
Describe the resulting profile of dopamine levels in the brain. (1)
Dopamine is released within the synapse
for precise signalling between two cells.
- Burst firing of neurones leads to phasic spiking with dips/pauses
Describe volumetric transmission of dopamine in the brain. (2)
Describe the resulting profile of dopamine levels in the brain. (1)
DA released outside the synapse
and has a slow effect on many cells.
- Background tonic DA levels
How is dopamine signalling involved in Parkinson’s Disease? (1)
How is dopamine signalling involved in treating Parkinson’s disease? (1)
Death of DA producing cells in substantia nigra.
L-DOPA (DA precursor) improves PD symptoms.
How is dopamine signalling involved in schizophrenia? (1)
How is dopamine signalling involved in treating schizophrenia? (1)
- Striatal DAT availability inversely correlated with hallucinations
- Most antipsychotic drugs block DA receptors
How is dopamine signalling involved in ADHD? (1)
How is dopamine signalling involved in treating ADHD? (1)
- Mutations associated with ADHD decrease NA and DA activity in synapses
- ADHD medication inhibits NA and DA reuptake
How is addiction (especially addictive drugs) related to dopamine levels in the brain? (1)
Most addictive drugs elevate extracellular DA
Define motivation. (1)
Willingness to exert physical or mental effort in pursuit of a goal or outcome.
Describe how motivation/effort are altered in:
a) depression
b) addiction
(2)
Less motivation in depression
More motivation in addiction
Complete the sentence regarding the role of dopamine in motivation and reward. (2)
…………….. neurones which project to the …………………. control the motivation circuit.
VTA
nucleus accumbens
Describe how dopamine and the mesolimbic pathway is involved in ‘reward prediction error’. (4)
When a reward is expected, GABAergic VTA neurones inhibit DA neurones
Therefore if a reward is as expected, dopamine does not rise as much.
If a reward is better than expected, dopamine rises more (as less initial inhibition).
If a reward is not as good as expected, dopamine is decreased.
Briefly describe how the reward prediction error and dopamine signalling play a role in learning from experience. (2)
If reward/result is same as predicted, there is very little dopamine signalling.
If the dopamine response is strong (either positive or negative) then the prediction changes to suit previous experiences.
What type/pattern of dopamine signalling is involved in:
a) learning
b) motivation
(2)
a) phasic DA signalling
b) tonic DA signalling
Describe the role of dopamine signalling in pleasure adaptation. (3)
ie. when something good stops being so good after a long period of time
How can we overcome pleasure adaptation? (1)
- Prolonged phasic signal from reward increases tonic DA
- So baseline dopamine increases
- and DA bursts still reach same level, but appear smaller in comparison to baseline.
This can be overcome by leaving an interval between rewards to allow the baseline dopamine to decrease.
Name a prescription drug which is currently abused as a cognitive enhancer. (1)
What is this drug normally prescribed for? (1)
Methylphenidate
Normally prescribed for ADHD