Cerebellar Microarchitecture Flashcards
Where is the cerebellum located?
At the base of the brain (looks like a small brain - cerebellum means little brain)
Where is the cerebellum most easily seen?
From a ventral view
The cerebellar cortex has ____ layers
Three
Mossy fibre input
Part of the white matter underlying the cortex
Come from many different regions of the brain and spinal cord
Synapse onto granule cells in bottom (granular) layer
Granule cells
Most numerous cells in the brain
Send their axons to top (molecular) layer, where they split into two to produce parallel fibres
These form synapses with Purkinje cells
Purkinje cells
Cell bodies in middle (Purkinje cell) layer
Sole output cells of the cerebellar cortex
Each Purkinje cell receives about 150000 parallel fibre synapses
What are the largest cells in the cerebellar cortex?
Purkinje cells
What is distinctive about the dendritic field of a Purkinje cell?
Flattened out like a fan
Climbing fibre
Each Purkinje cell also receives input from a single climbing fibre
Axons of cells in the inferior olive at base of the brainstem
Climbing fibre wraps itself around the Purkinje cell dendritic tree, forming at least 1000 synapses (all with same input signal)
Purkinje cells fire ____
Spontaneously
Firing rate of Purkinje cells
50 spikes/second
Parallel fibre input can increase this to 200 spikes/second
Complex spikes
Produced by climbing fibre input
Very reliable, whenever climbing fibre fires, PC also fires
Low frequency of firing compared with simple spikes, little effect on output
Does cerebellar damage cause paralysis?
No
It makes movements typically slow, inaccurate and uncoordinated
What is the role of the cerebellum?
To ensure that movements are carried out accurately
In order to make accurate movements…
You must have information about what you did wrong - an error signal
