Cerebellum

Question 1

What are the 3 functions of the cerebellum

What are the 2 inputs
What are the 2 outputs

Answer 1

Precision, timing of motor control
Motor learning
Cognitive function

Input

• from cortex via pons about motor commands
• from spinal proprioceptors about body position

Output (spontaneously active and excitatory)

• to cortex via thalamus, modulate primary motor
• to midbrain and SC via descending motor systems

Question 2

Describe the feedforward mechanism

What symptoms may you get if the cerebellum is damaged

Answer 2

Anticipate error, makes motor adjustments to avoid error

If cerebellum damaged => cannot coordinate and adjust movements

• ataxia
• intention tremor
• decomposition of movements
• disdiachokinesia
• hypotonia + pendulous reflex
• dysarthria
• abasia

Question 3

What are some causes of cerebellar lesions
-6 causes
What is the presentation of any cerebellar lesion

Answer 3

Developmental
Stroke
Injury
Tumor
Surgery (surgery to repair medulloblastomas)
Alcohol

Unilateral injury => ipsilateral deficit

Question 4

What are the functions of the cerebellar zones

• cerebrocerebellum (lateral)
• spinocerebellum (medial)
• vestibulocerebllum (flocculonodular)

Answer 4

Cerebrocerellum

• plan, execute
• coordinate mv (if this damaged => decomposition)
• cognitive function

Spinocerebellum

• coordinate body and limb mv (fractured somatotrophy)
• vermis => central body
• intermediate => distal limbs
• maintain posture (if this damaged => hypotonia)

Vestibulocerebellum

• balance
• ocular mv and gaze stability

Question 5

Where are the deep nuclei found

• what are they inhibited by
• what are they stimulated by
• what is their function

Why is the dentate nuclei important?
Where is it

Answer 5

PROVIDE EXCITATORY OUTPUT VIA LONG CONNECTIONS TO THE BRAIN

Inhibited by Purkinje cells (release GABA) in cerebellar cortex

Stimulated by mossy and climbing fibres (release Glut)

Dentate nuclei is the largest nuclei
-found under cerebrocerebellum

Question 6

What connections are found in each cerebellar peduncle?

• superior
• medial
• inferior

Answer 6

Superior

• Crossed spinocerebellar input
• Output to thalamic, red nuclei

Medial
-Pons input

Inferior

• Spinocerebellar
• Vestibular connections

Question 7

Describe the

• organisation of Purkinje cells, mossy fibres, granule cells, climbing fibres and deep nuclei
• interaction between the cortex and the medulla

Answer 7

Mossy fibres stimulate granule cell
Excitatory signal sent to PC via granule cell parallel fibre
Distance between each PC is the same => regular rate of stimulation by Glucose
Normally, this stimulates GABA release from PC => inhibit deep nuclei function

However, if PC stimulation coincides with climbing fibre impulse => long term depression of PC (AP generated)

Question 8

What is the function of Long Term Depression

Answer 8

Important in motor learning

• Pattern of PC inactivation that lasts minutes-hours
• AP due to Ca influx => reduced synaptic efficiency of parallel fibre input

Memory trace lost from cerebellum but consolidated in other areas