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)
