Basal Ganglia Flashcards
What makes up the basal ganglia?
Substantia nigra
Striatum
Globus pallidus
Subthalamic nucleus
Where is the substantia nigra?
In the midbrain
What is the role of the substantia nigra?
Produces dopamine
What makes up the striatum?
Caudate nucleus
Putamen
Where is the putamen found?
Centre of the caudate nucleus
Where is the caudate nucleus found?
Under the 4th ventricle
What connects the caudate nucleus and the putamen?
Thin strands of grey matter
What are the parts of the globus pallidus?
Internal (GPi)
External (GPe)
What is the lentiform nucleus?
Putamen + globus pallidus
What is the role of the basal ganglia?
Finds most appropriate movement for goal
Which side of the body does the basal ganglia affect?
Contralateral side
How do the motor cortex and basal ganglia interact?
Motor cortex prepares movement and sends to basal ganglia
What is the effect of the BG if the movement in appropriate?
Reinforces it via direct pathway
What is the effect of the BG if the movement is inappropriate?
Inhibits it via indirect pathway
What is the effect of dopamine in the BG?
Excites the direct pathway
Inhibits the indirect pathway
What receptors does dopamine act at in the direct pathway?
D1
What receptors does dopamine act at in the indirect pathway?
D2
What is the effect of dopamine in the motor cortex?
Increases activity via BG
What conditions affect the basal ganglia?
Parkinson’s disease
Huntington’s disease
Hemiballismus
What is Parkinson’s disease?
Loss of dopamine production in the pars compacta of the substantia nigra
What are the clinical features of Parkinson’s?
Tremor (pill rolling)
Rigidity
Bradykinesia
Psychiatric features
What are the signs of bradykinesia?
Hypophonia
- soft speech
- slowness of pharyngeal muscles
Micrographia
- small handwriting
‘Mask-like’ facies
- slow muscles of facial expression
What are the psychiatric features of Parkinson’s?
Depression
Dementia
What causes the psychiatric features of Parkinson’s?
Reduced dopamine
