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
Give three ways that the cognitive enhancer methylphenidate affects neurotransmitters. (3)
- Increase DA in prefrontal cortex (acts on DA alpha 1 receptor)
- Increase NA in prefrontal cortex (acts on NA alpha 2 receptors)
- Small increase in DA in nucleus accumbens
Describe the shape of the dose response curve of methylphenidate and other prescription cognitive enhancers. (1)
Describe what this means. (1)
(Dose on X axis; dopamine level on Y axis)
Narrow inverted U shape
Psychostimulants at low/clinical doses but increasing doses has no/negative effect.
How do high dose prescription cognitive enhancers (such as methylphenidate) affect working memory and sustained attention? (1)
Both are decreased at high doses
Give two natural substances which are used as cognitive enhancers (not foods/herbs). (2)
Which receptors do they act on? (2)
Caffeine (adenosine receptors)
Nicotine (Nicotinic receptors)
Give three foods/herbs which are used as cognitive enhancers. (3)
Describe how each one is thought to enhance cognition. (3)
Deanol (choline precursor in salmon)
Ginseng (increases NO production and antioxidant)
Ginko (antioxidant and reduces blood viscosity for increased circulation)
Define ‘eustress’. (1)
A small amount of stress acting as a performance enhancer.
Describe the general affect of eustress/positive mindset on dopamine in the brain. (2)
People with a positive mindset have higher DHEAs during times of stress.
DHEAs increase tonic and phasic dopamine transmission in the striatum.
*DHEAs have also been associated with mental resilience
Describe the connectivity between the amygdala and prefrontal cortex during distress. (2)
Amygdala inhibits PFC
which may result in less understanding that the stress may not be that bad.
Describe the connectivity between the amygdala and prefrontal cortex during eustress. (2)
PFC regulates stress response from the amygdala
so there is less cortisol release and the response appears less intense.
Describe three effects of physical exercise on mental health. (3)
- Lower anxiety
- Decrease depression
- Improve attention and memory
Describe the effect of physical exercise on levels of growth factors in the brain and adult neurogenesis. (1)
Increased growth factors and adult neurogenesis
Give three effects of physical exercise (both cardio and weights) on dopamine in the brain. (3)
- Increased dopamine in plasma and urine
- Increased DA release in caudate nucleus
- Increased striatal D2/D3 receptor availability
Describe the expected levels of D2/D3 receptors in the striatum of people with a methamphetamine addiction. (1)
How does this change if addicts in recovery are exposed to an exercise intervention? (1)
Reduced receptor
Receptor availability increases
Describe two ways in which practicing mindfulness or mindful breathing can reduce symptoms of mental illness. (2)
Increases grey matter density (and prevents age-related decrease in grey matter)
Activate the vagus nerve (increased PNS activity)
Give five mental illnesses which may have their symptoms reduced by mindfulness. (5)
- Anxiety
- Depression
- Substance abuse
- Eating disorders
- Chronic pain
Describe the relationship between tonic dopamine release and performing meditation. (1)
Meditation increases dopamine tone
Give three general consequences of sleep loss. (3)
- Increased depressed mood
- Increased anxiety
- Increased mortality
Describe the circadian fluctuation of dopamine levels in the ventral striatum (nucleus accumbens). Relate these fluctuations to sleep. (2)
High DA levels during waking
Low DA levels in NREM sleep
True or false? (1)
As well as dopamine showing circadian fluctuations related to sleep, DAT also shows circadian fluctuations in expression and function.
True
Describe the effect on a rat’s sleep if they are deficient in DA afferents to the striatum. (1)
Spend more time awake
How does sleep deprivation affect dopamine D2 receptors in the ventral striatum? (1)
Downregulation
When investigating the relationship between dopamine and sleep in rats, give three outcomes. (3)
- More DA release when rats sleep at correct time
- More REM sleep = more dopamine
- More DA uptake during sleep
Describe the dopamine, noradrenaline, and adrenaline levels in people who are immersed in cold water for a period of time. (3)
Large DA increase
Small NA increase
No change in A
What are telomeres? (1)
DNA-protein complexes located at both ends of the chromosomes
True or false? (1)
Telomeres are found in prokaryotic and eukaryotic organisms.
False - not found in bacteria as their chromosomes are rings (plasmids)
Describe the DNA sequence that makes up telomeres in humans. (1)
Tandem repeats of TTACGGG
Describe the role of telomeres in cells. (1)
Protect cells from genome instability (eg. fusion between chromosomes or chromosomal instability)
How do telomeres play a role in ageing? (1)
Extremely short telomeres induce cellular apoptosis or activate senescence (inflammation).
Give two things that decrease telomere length. (2)
- Cumulative exposure to inflammation and oxidative stress (in both dividing and non-dividing cells)
- Mitosis
Name something that can increase telomere length. (1)
Telomerase
Describe how telomerase increases telomere length. (3)
Telomerase is a reverse transcriptase
which makes DNA from RNA
and adds telomeric DNA to telomeres.
Name the 2 components which make up the telomerase complex. (2)
TERT
TERC
TERT is a component which forms part of the telomerase complex.
What is TERT? (1)
Protein component that serves as a catalytic subunit
TERC is a component which forms part of the telomerase complex.
What is TERC? (1)
Essential telomerase RNA component which serves as a template for telomere elongation.
Describe telomerase TERT expression in brain cells. (4)
- High in neural stem/progenitor cells
- Low in mature neurones, but detected in mature hippocampal neurones
- Present in activated microglia
- Absent from astrocytes
Describe a subset of cells in which telomerase may be especially high. (1)
Tumour cells
Give four physiological cellular functions which are influenced by telomerase activity. (4)
- Proliferation
- Differentiation
- Survival
- Apoptosis
Describe how telomerase (TERT) expression is altered in ALS. (2)
How could telomerase (TERT) be involved in treating ALS? (1)
ALS patients have reduced TERT expression in spinal cord
Post-mortem ALS brain has longer telomeres in microglia (suggesting microglia are activated)
- In animal models transient TERT expression in brain delays ALS onset and progression
How does ischaemic injury alter TERT expression? (1)
What is the benefit of this? (1)
Increase in TERT after ischaemic injury.
Protects against NMDA excitotoxicity and decreases neuronal cell death.
Describe the correlation between basal (saliva) cortisol levels and telomere size. (1)
No correlation
Describe the correlation between transient cortisol levels (reaction to acute stress) and telomere size. (1)
Bigger cortisol stress response = shorter telomeres
Describe how childhood psychological stress affects telomere size. (1)
Shorter telomeres in middle age - stress has long term effect on telomeres
Describe how depression affects telomeres. (1)
Depression shortens telomeres
How is growth mindset/grit linked to telomere length? (1)
No evidence
Describe the correlation between physical activity and telomere length. (1)
Being physically active correlates with longer telomere length.
Describe a confounding factor that should be taken into account when assessing the correlation between physical exercise and telomere length. (1)
Younger people are more likely to be physically active and also more likely to have longer telomeres.
Describe how physical exercise and stress may interact to affect telomere length. (1)
Physical activity may diminish negative effect of stress on telomere length.
How is amount of time spent sleeping related to telomere length? (1)
Less sleep = shorter telomeres
for each hour less sleep, 0.015kb shorter chromosomes
How is sleep quality associated with telomere length and perceived stress? (2)
Poor sleep quality:
- Shorter telomeres
- Higher perceived stress
Describe the overall relationship between mindfulness and telomeres. (1)
Mindfulness increases telomere length.
What is neuroimmunology? (1)
The interaction between the immune and nervous systems during development, homeostasis, and response to injuries.
In the past, why were the nervous system and immune system thought of as separate? (1)
The brain is protected by the BBB
True or false (1)
Molecules associated with the immune system are not found in the brain because they cannot cross the BBB.
False - many molecules associated with the immune system are widely expressed and functional in the nervous system (and vice versa)
*Although these molecules CANNOT cross the BBB I don’t think
Give three cell types in the brain which crosstalk with each other to maintain immune homeostasis. (3)
- Microglia
- Neurones
- Oligodendrocytes
Describe the neuro-immune interaction in multiple sclerosis. (1)
Immune system attacks the CNS
Describe the neuro-immune interaction in rheumatoid arthritis. (1)
16.8% of RA patients have major depressive disorder (higher than general population)
Describe the neuro-immune interaction in inflammatory bowel disease. (1)
More than 20% IBD patients have depressive symptoms, and more than that have sleep difficulties and fatigue
Describe the neuro-immune interaction in stress. (1)
Stress in early life leads to activation of the SNS, which promotes pro-inflammatory changes.
Describe a possible confounding factor when investigating the links between mental health and the immune system. (1)
Is there evidence to control for this confounding factor? (1)
Pain and mental illness are consequences of living with a chronic disorder.
Yes - there is evidence that inflammation may actively contribute to pain and/or psychiatric disorders
Describe the link between depression and immune system, and also antidepressants and the immune system. (2)
MDD associated with immune system activation.
Antidepressant treatment lowers immune system activation (lower levels of IL6, TNFa, IL10, CCL2).
True or false? (1)
Psychological stress has been shown to have an impact on immune system activation.
True
Describe how neuroimmunology is able to explain the link between stress and depression. (2)
Stress induces pro-inflammatory cytokines.
Cytokines correlate with depressive-like symptoms.
True or false? (1)
Anti-inflammatory drugs have been shown in studies to decrease depressive symptoms.
True
True or false? (1)
Chronic mild stress cannot produce depressive symptoms if the pro-inflammatory immune signalling pathway is impaired.
True
True or false? (1)
Molecules that induce inflammation have also been shown to produce depression-like symptoms. These symptoms can be alleviated by SSRI administration.
True
True or false? (1)
Antidepressants have been shown to decrease both cytokines and depressive symptoms in some studies.
True
Describe the links between growth mindset/grit, immune activation, and mental health. (1)
No evidence for a link
Describe the links between mindfulness, immune activation, and mental health. (1)
TaiChi/Qigong lead to significant (although small) increase in number of immune cells.
TaiChi/Qigong lead to significant (although small) increase in number of immune cells, which seems to contradict other evidence regarding mindfulness and immune system activation.
Explain the issue with these results, and why we cannot take it as solid evidence that mindfulness increases immune system activation. (1)
We do not know how these cells are behaving or whether they are activated.
Describe the links between physical exercise, immune activation, and mental health. (2)
- Moderate exercise promotes an anti-inflammatory environment
- But excessive exercise results in inflammation and immunosuppression
Physical exercise increases expression of PGC-1a by the skeletal muscles.
Describe how this may lead to a decrease in inflammatory proteins and mental illness. (4)
- PGC-1a increases skeletal muscle expression of KATs
- KAT converts KYN to KYNA
- Lower levels of KYN protects from developing stress related depressive symptoms
- And lower levels of KYN also decreases levels of inflammatory proteins
How does overexpression of PGC-1a1 alter the effects of chronic mild stress in animals? (1)
PGC-1a1 prevents depressive-like symptoms in animals exposed to chronic mild stress
Describe the effects of normal sleep on the immune system. (1)
IL-6 levels peak during sleep
and body releases sIL-6R (soluble IL-6 receptors, which enable activation by IL6 of cells which do not usually express IL6 receptors)
Describe the effect of sleep deprivation on TNF and IL-6 levels. (2)
Lower TNF secretion at night
Lower IL6 secretion at night, but oversecretion during daytime
Describe two affects of short sleep duration on susceptibility to infection. (2)
- Increased pneumonia risk
- Increased susceptibility to common cold
Describe the effects of sleep disturbance on inflammation, cytokines, and CRP levels. (3)
- Increased CRP
- Altered levels of cytokines
- Contributes to increased inflammation in the long term
Describe the associations of too much or too little sleep with cognitive ageing. (2)
- Cognitive impairments in older adults
- Increased risk of dementia
Describe the mechanism by which sleep disturbance may contribute to cognitive ageing. (4)
Sleep disturbance activates microglia
which release microglial inflammatory mediators
which lead to enhanced beta-amyloid deposition
which causes neuroinflammation and more activated microglia.
***Sleep disturbance activates microglial inflammatory response, in simple terms
Describe how sleep disturbance is linked to depression and inflammation. (2)
- Risk of depression increased if sleep disturbance and inflammation occur together
- In individuals with pre-existing inflammatory disorders, sleep disturbance can precipitate onset of depression
