Cerebellum Flashcards

1
Q

What are the 3 functions of the cerebellum

What are the 2 inputs
What are the 2 outputs

A

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
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2
Q

Describe the feedforward mechanism

What symptoms may you get if the cerebellum is damaged

A

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
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3
Q

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

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

Unilateral injury => ipsilateral deficit

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4
Q

What are the functions of the cerebellar zones

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

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
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5
Q

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

A

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

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6
Q

What connections are found in each cerebellar peduncle?

  • superior
  • medial
  • inferior
A

Superior

  • Crossed spinocerebellar input
  • Output to thalamic, red nuclei

Medial
-Pons input

Inferior

  • Spinocerebellar
  • Vestibular connections
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7
Q

Describe the

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

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)

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8
Q

What is the function of Long Term Depression

A

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

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