Neurological Welfare Indicators Flashcards
The earliest knowledge about brains was gathered by looking at patients with what?
Brain pathologies like stories and brain cancer
The earliest knowledge about brains was gathered by looking at patients with brain pathologies and seeing how the brain pathologies affected their behaviour and abilities
In welfare what effects of brain pathologies do we look at?
Behaviour and affect on affective states
In welfare we aren’t just interested in how brain pathologies affected behaviour or behavioural abilities but also how they affect affective states
Since the late 19th century what has given us a new perspective on how the brain works?
Brain imaging of human brains
Since the late 19th century brain imaging of human has given us a new perspective on how the brain works
How does brain imaging work?
Blood capillaries dilate to deliver more oxygenated blood to areas that are low in oxygen
The areas with low oxygen in the brain are areas with very active neurones that need oxygen to help generate energy
Due to this if we measure capillary dilation we can indirectly measure the energy usage of different brain regions
Why is most brain imaging data from humans?
Most brain imaging data is from humans since you usually need to anaesthetise other animals for them to be put through a brain imaging device
Give examples of brain imaging devices
Magnetic Resonance Imagery (MRI)
Positron Emission Tomography (PET)
How does Magnetic Resonance Imagery (MRI) work?
MRI detects the iron compounds in the red blood cells haemoglobin to detect blood flow
MRI can detect the concentration of iron levels to be able to let us know if vasodilation has occurred in an area
How does Positron Emission Tomography (PET) work?
PET is used by injecting a radioactively labelled compound into the bloodstream and tracking it as it moves around the brain
The compound will move with the blood flow and so the speed and area which the compound is in will be effected by vasodilation and vasoconstriction
Since the 19th century animal experimentation on non-human animals has led to a better understanding of brain function
In recent years what kinds of experiments have been done?
We can now detect specific neurones firing even if we only want to look at 1 specific neurone
We can manipulate the stimulation to a particular area of the brain
In both methods to measure brain activity there will be devices implanted in the animals brain to record neural activity or stimulate a specific response
Give examples of what MRI’s have been used to detect in non-human animals
Age-dependent neuroanatomical deterioration
Brain cancer
Brain herniation
Brain herniation = when something inside the skull produces pressure that moves brain tissue
Brain imaging devices allow us to see what?
Brain imaging techniques allow us to see potential neurological issues in animals
In terms of welfare what neurological effects/changes do we measure?
In terms of welfare we mainly focus on:
- What stress does to the brain
- How can we measure the brain changes caused by stress
Effects of stress on the brain are different according to what?
Effects of stress on the brain are different according to the individuals stage in their life span
What does pre-natal exposure to glucocorticoid hormones alters what?
Pre-natal exposure to glucocorticoid hormones alters:
- the Hypothalamic-Pituitary-Adrenal axis reponsivity of the foetus - the individuals neurological development
Give examples of effects of pre-natal stress on foetal development
Decrease the number of neurones
Reduce the volume of certain areas of the brain
Impair the formation of important receptors in the brain
How can post-natal stress in the offspring be induced by maternal separation?
Maternal separation can induce stress in both the mother and the offspring, leading to the activation of the HPA axis
The prolonged activation of the HPA axis in the offspring leads to:
- reduced glucocorticoid binding in the pituitary gland
- reduction of glucocorticoid receptors in the hypothalamus and pituitary gland
This can lead to the offspring having compromised reactions to stress when they become adults
This is because if there are not enough glucocorticoid receptors in the HPA axis then the excess glucocorticoids will bind to hormone receptors on other organs leading to damage
This causes deleterious effects
How does post-natal stress affect the mother?
If the mother is stressed they show poor maternal behaviour
Stress causes the mother’s Nr3c1 gene to get methylated which leads to a reduction in glucocorticoid receptor expression
The reduction in glucocorticoid receptor expression leads to:
- high glucocorticoid levels
- high anxiety
- low licking and grooming of offspring
Stress in early life can lead to the underdevelopment of which certain brain regions?
Basal ganglia
Hippocampus
The areas of the brain that are more plastic/changeable are more likely to be changed by stress
How does stress in later life effect the brain?
Small acute increases in glucocorticoids can be adaptive and increase learning and memory
Large chronic increases in glucocorticoid levels can impair the hypothalamic function via:
- dendritic atrophy
- inhibition of neurogenesis
Give examples of neurological indicators
Electroencephalography (EEG)
Evoked potentials
Neuroimaging:
PET
fMRI
Near-infrared spectroscopy
Immunohistochemistry (IHC)What do electroencephalography (EEG) measure?
EEG’s measure spontaneous activity in the brain
EEG’s measure electrical oscillations, or brain wave voltages, from ionic currents within the brain
Changes in the EEG readings represent near real time changes in brain functional activity
What have EEG’s been to research?
Pain physiology Traumatic brain injury Epilepsy Anaesthesia Sleep Neurological disorders Time to insensibility during slaughter
How invasive are electroencephalography EEG?
The degree of invasiveness of EEG usage varies due to the fact that electrodes do need to be attached to the individual to get a brain reading
What are the 2 advantages to EEG usage?
EEG offers good temporal resolution
EEG offers real time data
EEG offers a direct measure of the brains electrical activity
What are the 4 disadvantages of EEG’s?
EEG’s offer poor spatial resolution
We can’t get direct readings of brain activities from brain regions that are deeply buried inside the brain
EEG readings are susceptible to electrical noise
You need the subject and equipment within a Faraday cage
EEG’s only measure activity of neurones from the outer most layers of the brain cortex
EEG’s can be very invasive
What are evoked potentials and how does evoked potentials work as a welfare indicator?
An evoked is a response generated as an electrical potential that’s recorded from the individuals nervous system upon presentation of a stimulus
So a stimulus is presented to an individual causing them to generate an electrical potential in response which is measured from the individuals nervous system
We’d measure the electrical response to a stimulus making the electrical response data more specific in context
What can evoked potentials be used to classify?
Evoked potentials can be used to classify affective states if an invasive intracranial electrode is used to look at the action potentials
Give some examples of evoked potentials
Somatosensory Evoked Potentials (SEP)
Visual Evoked Potentials (VEP)
Auditory Evoked Potentials (AEP)
What can evoked potentials be used to study?
Pain physiology
Anaesthesia
Time to insensibility after a procedure
Give some examples of neural imaging
MRI
Normal MRI looks at how different brain structures respond to different scenarios
fMRI
Functional MRI looks more at metabolic changes in response to different scenarios
Which 4 areas of the brain are most commonly associated with pain?
1) Primary and Secondary Somatosensory Cortex
2) Insular
3) Anterior cingulate cortex
4) Prefrontal cortices and thalamus
What is the main problem of neuroimaging scans?
The main problem with using neuroimaging in non-human animals is that they usually need to be anaesthetised
This is because, even for humans, MRI scans are stressful experiences due to:
The MRI machine being so loud
The individual needs to be perfectly still to get a good scan
It can take a long time
With lots of training we can now do MRI’s on dogs, which is a massive step forward for what 3 things?
Diagnosis
Research
MRI prep time
What have dog MRI scans shown us?
Dog MRI scans have shown that dog brains reward centres light up in MRI scans nearly identical to human brains
What do you need to do to get meaningful biological relevant information from the neuroimaging device?
You need to know what affects your variable and which statistical analysis to use in order to gain any meaningful biological relevant information from the measure
What are the 3 advantages of neuroimaging?
1) Good spatial resolution
2) PET fMRI can be used to represent neurological processes at a metabolic level
PET and fMRI can be used to represent neurological processes at a metabolic level
3) They can be non-invasive
What are the 5 disadvantages of neuroimaging?
1) Indirect marker of brain electrical activity
2) Animals usually have to be secured and anaesthetised
3) Poor temporal resolution
4) Welfare of the individual may be bad short-term
5) Data generated can be misinterpreted
What are immunohistochemistry (IHC) used for?
Immunohistochemistry (IHC) neurological indicators are techniques used to determine protein expression
Give examples of how immunohistochemistry (IHC) determining protein production is useful
We can measure neurogenesis by staining a sample for Brain Derived Neurotropic Factor (BDNF)
BDNF is a protein that promotes neurogenesis so if it’s present in high concentrations then lots of neurogenesis is present in that area
We can measure neural activity by staining a sample for COx (Cytochrome oxidase)
COx is a mitochondrial energy generating enzyme used in brain studies as a marker of neural functional activity
The darker the staining the more active the neurones
What are the 2 advantages of immunohistochemistry (IHC)?
1) IHC allows us to target tissues of specific areas of the brain
2) IHC can also get data from specific protein expression factors
This means that IHC is a very targeted technique with very precise results
What is immunohistochemistry (IHC) disadvantages?
To get the brain tissue samples to undergo IHC techniques the animal needs to be dead
What 2 things can immunohistochemistry (IHC) methods be used to gather data for?
1) Validate other welfare indicators which may correlate with the data
2) Give us a causal basis for why we see some other changes in animals behaviour
How can we use neurotransmitters?
We can use neurotransmitters in non-human animals that are similar to human ones that can be used to detect differences in the non-human animals brain
Some of these neurotransmitters are relevant to welfare
Give examples of neurotransmitters that can be used for welfare
Oxytocin and vasopressin are key neurotransmitters in social affiliation and social bonding
What has research shown about oxytocin in animals?
If oxytocin receptors are blocked in female prairie voles they are no longer monogamous
In humans we know that a does of oxytocin taken nasally can make you feel more loving and trusting in general
What has research shown about vasopressin?
If vasopressin receptors are blocked in male prairie voles they are no longer monogamous
How can oxytocin be used as a welfare indicator?
High oxytocin concentrations are a sign of positive welfare
Oxytocin is a proposed marker of prosocial behaviour as it plays roles in social communication and cognition
What is the disadvantage of using oxytocin?
The oxytocin needs to be removed from the brain
What is a disadvantage of neurotransmitters?
They’re still quite invasive
What are the 3 disadvantages of neurological indicators?
1) Electrophysiological indices are indirect measures and the methodologies can limit, change or eliminate the expression of normal behaviour
This is because neurological disorders can only be used if the animal is dead or anaesthetised
2) Neurological indicators are very invasive in general
3) With neurobiologists in general they may get so focused on neurological processes that they may forget that any neurological changed have other functional and biological implications for the individual
Due to this it is always important to use biological and physiological indicators alongside neurological indicators to gain a wider picture of their relevance to welfare
