Cerebellum Flashcards
What are the 3 functions of the cerebellum
What are the 2 inputs
What are the 2 outputs
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
Describe the feedforward mechanism
What symptoms may you get if the cerebellum is damaged
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
What are some causes of cerebellar lesions
-6 causes
What is the presentation of any cerebellar lesion
Developmental Stroke Injury Tumor Surgery (surgery to repair medulloblastomas) Alcohol
Unilateral injury => ipsilateral deficit
What are the functions of the cerebellar zones
- cerebrocerebellum (lateral)
- spinocerebellum (medial)
- vestibulocerebllum (flocculonodular)
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
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
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
What connections are found in each cerebellar peduncle?
- superior
- medial
- inferior
Superior
- Crossed spinocerebellar input
- Output to thalamic, red nuclei
Medial
-Pons input
Inferior
- Spinocerebellar
- Vestibular connections
Describe the
- organisation of Purkinje cells, mossy fibres, granule cells, climbing fibres and deep nuclei
- interaction between the cortex and the medulla
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)
What is the function of Long Term Depression
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