Lecture 14: Basal Ganglia Flashcards
What are the functions of the basal ganglia?
- Release appropriate movements from premotor and motor areas
- Allows a smooth motion that is planned an purposeful without extraneous movements
- Allows appropriate movement to start and stop
What are the functions of the cerebellum?
- Modulate cortical output
- Controls the maintenance of equilibrium, posture and muscle tone
- Coordinates movements (and corrects for errors in movements)
How does the cerebellum modulate cortical output?
It gets information from the cortex, forms a plan and sends a signal back to the premotor cortex
What tracts does the cerebellum coordinate conscious movements for?
Corticospinal and Corticobulbar tracts
What is the Corticopontocerebellar pathway?
The pathway that descends from the premotor or supplementary motor cortex when we want to make a conscious movement
What is the pathway that allows motor planning information to enter the cerebeelum?
The Corticopontocerebellar pathway
Which peduncle does the Corticopontocerebellar pathway enter the cerebellum?
The middle cerebellar peduncle
What tract enters the middle cerebellar peduncle?
The corticopontocerebellar pathway
What does the Corticopontocerebellar pathway descend onto?
Granule cells
Why does the Corticopontocerebellar pathway descend onto Granule cells?
Because it is a mossy fiber
Is the Corticopontocerebellar pathway a mossy or climbing fibers?
It is a mossy fiber and descends on Granule cells
What happens after the corticopontocerebellar pathway descends on Granule cells?
It activates glutamatergic signaling to activate purkinje cells
What cells do Granule cells activate with glutamate?
Purkinje cells
Where does the cerebellum project to after receiving motor planning information?
It projects to the contralateral cortex via the thalamus
Which side of the cortex does the cerebellum send and receive motor plans?
It sends and receives motor plans to and from the contralateral cortex
Which side of the cortex does the basal ganglia project to?
The ipsilateral side of the cortex
Which nucleus in the thalamus does the cerebellum and basal ganglia project to?
The VA/VL nucleus
What does the basal ganglia allow for?
It allows for movements to be initiated and helps to plan for the best movement by tweaking movements in real time
If there is a lesion to the cerebellum, where would the effect be seen?
On the ipsilateral side because the corticospinal tract crosses over
What are the two different pathways of the basal ganglia?
- Indirect pathway
- Direct pathway
What nucleus in the the thalamus do both basal ganglia pathways act on?
The VA/VL nucleus
Where does the basal ganglia receive input from?
The premotor cortex (premotor cortex also acts on the cerebellum)
What will the direct or indirect pathway of the basal ganglia do?
They will either inhibit the thalamus and decrease movement or not inhibit the thalamus and promote movement
What can Cerebellar lesions cause?
- Cerebellar ataxia
- Forced Tremor
- Inability to coordinate smooth purposeful movement