L10 motor disorder Flashcards
What is the striatum made of?
Caudate nucleus and putamen
Where does the cerebellum get input from?
Motor and sensory cortex (via pons), spinal cord and vestibular system (sense of balance)
How does the cerebellum send output back to motor cortex?
Via deep cerebellar nuclei and thalamus
Name a deep cerebellar nuclei.
Dentate nucleus
What are peduncles?
Major fibre tracts
Motor cortex neurons project to ____, and then to cerebellum then project directly to ____
pontine nuclei; spinal cord
Input from the pons forms ____, onto _____ in cerebellar cortex
mossy fibre input; granule cells
Granule cells form parallel fibres which synapses onto ______
Purkinje cells
How does Purkinje cells learn associations between parallel fibre inputs?
Climbing fibre inputs from the inferior olive as teaching input
What does the basal ganglia compose of? (5pts)
Putamen and caudate globus pallidus (external &internal) substantia nigra (pars compacta& .. reticulata) ventral tegmental area subthalamic nucleus
Name the motor loop process.
Cortex -> putamen -> GPi (directly, indirectly) -> GPe -> optionally STN
GPi -> thalamus -> cortex
Basal ganglia loops projections all occur in a _____
somatotopic (homunculus) framework
Even numbers of inhibition is what kind of pathway?
Direct pathway
Odd numbers of inhibition is what kind of pathway?
Indirect pathway
What does indirect pathway do to the cortex?
More inhibition, less activity in cortex
What pathways are inhibitory?
From putamen, from GPi, from GPe
Dopaminergic inputs from substantia nigra pars compacta play what kind of role in basal ganglia?
Regulating and shaping the pathways
What does tonic dopamine release from substantia nigra pars compacta do to D1 and D2 dopamine receptors?
D1: makes their neurons more active
D2: less active
What is the relationship between dopamine release, direct pathway activity and motor output?
Positively related
What is the cause of Parkinson’s disease?
Degeneration of dopaminergic neurons in the substantia nigra pars compacta
What are the prominent symptoms of Parkinson’s disease?
Slowness of movement (bradykinesia), difficulty in initiating movements and tremor
What is L-DOPA the precursor of…?
Melanin and dopamine
Why substantia nigra neurons black?
Common biochemical pathway for melanin and dopamine
How can L-DOPA treat Parkinson’s?
Make the remaining SNc cells produce more dopamine
Under what condition will L-DOPA works well to treat Parkinson’s?
When the degeneration is partial
What is the common side-effect of L-DOPA therapy?
Dyskinesia
Cause of dyskinesia.
Too much dopamine produced
What will too much dopamine produced cause on thoughts?
Bad spontaneous ‘motor ideas’ are executed unfiltered
What is stem cell therapy for Parkinson’s disease?
Make new dopaminergic neurons from stem cells to inject into basal ganglia
Undifferentiated stem cells are rare in ___ but common in ____
adults; embryos
What is MPPP?
A synthetic heroin substitute
What is MPTP?
A contaminant that can arise from MPPP synthesis
What does MPTP do?
Kills dopaminergic neurons and makes people (and animals) instantly have severe Parkinson’s
How to treat MPTP poisoned addicts?
Embryonic tissue grafts
Where does deep brain stimulus target?
Subthalamic nucleus
What causes Huntington’s disease?
Genetic mutation of the HTT gene on chromosome 4, causes premature neural cell death in homozygous carriers
Which part is firstly affected for Huntington’s disease?
Spiny stellate neurons projecting from putamen to the GPe
Where does the Huntington’s disease damage? and what will this cause?
The indirect pathway; not enough inhibitory control on spontaneous movement
Which loop is under dopaminergic control?
Limbic parts of the brain, forms loops through the basal ganglia (cognitive and limbic loops)
- motor loop
- executive loop
- limbic loop
Describe motor loop.
Motor cortex -> putamen -> lateral globus pallidus, internal segment -> ventral lateral nucleus -> motor cortex
Describe executive loop.
Dorsolateral prefrontal cortex -> dorsolateral caudate -> medial globus pallidus, internal segment -> medial dorsal and ventral anterior nuclei -> cortex
Describe limbic loop.
Anterior cingulate cortex -> ventral striatum -> ventral pallidum -> medial dorsal nucleus -> cortex
What is used to treat psychiatric diseases, e.g., OCD, tourette’s , anxiety, psychotic states?
Dopamine antagonists
Name the dopamine antagonists.
Dopamine, chlorpromazine
What is the common side effects of dopamine antagonists?
Parkinson’s disease
