Psychiatric and movement disorders Flashcards
main NT involved in movement control
dopamine
three dopaminergic pathways
1) Tuberohypophyseal pathway
2) mesocortical pathway
3) nigrostriatal pathway
Tuberohypophyseal pathway
Neurones which are dopaminergic , start with their cell body in the hypothalamus and spread out in the brain
Mesocortical pathway
starts in VTA (ventral tegmental area) up to the cortex
Nigrostrialtal pathway
starts in the SN (substantia nigra) and ends in Str (corpus striatum)
- Where cell death and damage occurs in Parkinsons disease
Parkinsons
A neurodegenerative disorder involving death and damage to the nigrostriatal pathway which starts in the substantial nigra and ends in the corpus striatum. All to do with dopaminergic neurones dying and muscles become rigid due to inhibition of movement
How is the brain stimulated in those with parkinsosn
high output by GABergic effects, increased inhibition of the thalamus and therefore decreased excitation of motor cortex causing BRADY KINESAI
Symptoms of Parkinsons
- bradykinesia- suppression of voluntary movement
- muscle rigidity
- cogntitive impairment variable
- tremor at rest- pill rolling
- temor lessons with voluntary movement
- shuffling gait
causes of parkinsons
- idiopathic
- cerebral ischaemia
- viral encephalitis
- drug induced
idiopathic
arises spontaneously or for which the cause is unknown.
dopamine will be found to be low in which tissue
substantia nigraand corpus striatum
In Parkinson’s there is a high output by GABAergic efferents
Increasing inhibition of thalamus
Decreased excitation of cortex (from thalamus)-bradykinesia
nigrostriatal pathway
1) Dopaminergic neurone releases dopamine into the corpus striatum (nerve terminal )
2) Inhibitory to corpus striatum
3) This inhibition to the corpus striatum excites glutamatergic and cholinergic neurones
3) GABAergic neurons are inhibited which activates motor 4) This is excitatory to glutamatergic neurones leading to the motor cortex
5) Meaning the motor cortex is activated more by glutamine
which dopaminergic pathway is linked with addiction
Mesolimbic
voluntary movement is controlled by inhibitory and excitatory neurones in
- motor cortex
- basal ganglia
- thalamus
when these neurone die or are disrupted this is when disease occurs
what is Anticipation in disease
signs and symptoms of some genetic conditions tend to become more severe and appear at earlier ages as the disorder is passed from one generation the next
- most often seen with genetic disorders of the nervous system e.g. huntingtons
wen does anticipation typically occur
with disorders caused by an unusual type of mutation called a triucleotide repeat expansion.
–> The number of repeats can change as the gene is passed from parent to child. If the number of repeats increases, it is known as a trinucleotide repeat expansion. In some cases, the trinucleotide repeat may expand until the gene stops functioning normally. This expansion causes the features of some disorders to become more severe with each successive generation.
Deep brain stimulation
is a neurosurgical procedure involving the implantation of a medical device called a neurostimulator, which send electrical impulses , through implanted electrodes to specific target int he brain for the treatment of movement and neuropsychiatric disorders.
negatives of DPS
limitations of deep brain stimulation has been that it requires brain surgery and carries an associated risk of hemorrhage, stroke, infection, and hardware failure.
DBS more detail
- uses electrical currents to target abnormal brain activity –> tigers blood flow and the release of NT (e.g. dopamine)
- connecting malfunctioning connections in the brain
- electrodes are implanted in target area of patients brain then can be turned on externally
epigenetic markers are
non-hereditary changes to the histone code or to any molecules other than the DNA itself
where does epigenetic modification normally occur
at the N terminus of histone tails