The Cerebellum Flashcards
What is the function of the cerebellum?
Motor learning
Coordination of movements (timing, force)
Maintenance of balance and posture
Cognitive functions
What are the entryways and exits to the cerebellum?
Inferior peduncle - afferents from medulla
Middle peduncle - afferents from pons
Superior peduncle - efferents to midbrain
What are the 3 different nuclei of the cerebellum? Medial to lateral
Fatigial nucleus
Interposed nucleus
Dentate nucleus
Briefly, What are the outputs from the fatigial nucleus/
Output to vestibular nuclei and medial descending tracts for posture and movement execution
Briefly, what is the output of the interposed nucleus/
To lateral descending tracts
Briefly, what is the output of dentate nucleus?
Output to the thalamus (VA+VL) to cerebral cortex
What are the lobes of the cerebellum?
What separates them?
anterior
Posterior
Flocculonodular (most primitivel
Anterior - posterior = primary tissue
Posterior - flocculonodular = posteriorlateral fissue
What are the threes functional zones of the cerebellum?
Vesitubulocerebellum
Spinocerebellum
Cerebrocerebellum
Breifly, what is the function of the different functional zones
Vestibulocerebellum = balance Spinocerebellum = error correction Cerebrocerebellum = movement planning
What lobes form the spinocerebellum?
Anterior lobe, Vermal region and medial posterior lobe
What deep nuclei are associated with outputs of the spinocerebellum?
Interposed
Fastigial
Where does the interposed N. project to? How do they act ipsilaterally?
Goes via the superior peduncle to the contralateral red nucleus (decussate). Inputs to the rubrospinal tract which decussates again (lateral descending tract). Thus interposed outputs at ipsilaterally
Interms of outputs from the spinocerebellum to the fastigial N, where do these project to?
Project to the reticular formation and form the medial descending tracts
What inputs into the spinocerebellum?
The spinocerebellum tracts, reticular formation and vestibular nuclei via the inferior peduncle
What nuclei is associated with outputs from the cerebrocerebellum?
The dentate nucleus
What lobes form the functional zone the cerebrocerebellum
The lateral parts of the posterior lobe
Where is the vestibulocerebellum located?
In the flocculonodular lobe
What inputs into the cerebrocerebellum?
Inputs from the motor cortex areas via the pontine nuclei (enter cerebellum via middle peduncle). This contains information regarding the motor plan
What is unique about the inputs and outputs of the cerebellum?
They are all ipsilateral
Where do outputs from the cerebrocerebellum go?
To dentate nucleus (synapse here)
Onto the thalamus (synapse)
To motor cortex. M1, SMA and PMC receive inputs from dentate gyrus
Where do inputs from mossy fibres project from?
The spinal cord
Reticular nuclei
Pontine nuclei
Depending on what functional zone they are in they contain information regarding proprioception, muscle load, desired muscle movements)
The inferior olive sends error signals to the PC’s via climbing fibres. But what inputs into the inferior olive?
CF fire when unexpected event in movements occur
Receive inputs from spinal cord (cutaneous afferents, joint afferents, muscle spindles)
And cerebral cortex
What occurs in the cerebrocerebellum?
Planning, organisation + co ordinating aspects of movements
What projects into the vestibulocerebellum?
Inputs from the vestibular nuclei
Where does the outputs of the vestibulocerebellum project to?
The vestibular nuclei and the vestibular spinal tracts (controls balance and eye movements)
What is the role of basket/stellar cells?
PF will stimulate basket cells and stellate cells. These will then cause lateral inhibition of neighbouring PC to cause a clear contrast between excitatory and inhibitory signalling
The role of the spinocerebellum is to function as an error corrector. How does it do this?
Acts as a smiths predictor
Will predict where limb is in space in the time taken for error signal to be processed and will correct for predictive error (i.e. Correct for the error of where the limb currently is) instead of the error which initiated the error signalling. If it did not error for the predictive error the error correction would not be appropaote as the limb will have moved
When does the dentate nucleus fire?
Before movement
What occurs on cooling the dentate nucleus?
Increases time taken for motor cortex output compared to controls and causes movement decomposition and loss of predictive movements
When do the interposed nuclei fire?
After movement onset and is related to velocity error correction
When does the fastigial nuclei fire?
After movement onset and is related to force error correction
Name some signs of cerebellar lesions
Dysdiadochokinesia Ataxia of gait Nystagmus intention tremor Spacing/slurred speech Hypotonia Writers cramp Decomposition of movement Dysmetria Loss of motor memory
What is dysdiadochokinesia?
Inability to perform rapidly alternating movements
What is an ataxic gait?
Wide based staggering gait
Cannot walk toe to toe
(Vestibulocerebellum lesion)
What is an intention tremor?
More pronounced tremor towards the end of target directed movements
What is meant by the decomposition of movement?
Movement will be split up into individual parts rather tan coordinated
What is dysmetria?
Overcompensation in speed (interposed N) and force (fatigial n) leading to overcorrection
What is writers cramp?
When writing the co ordinated activation of the agonist and antagonist muscle is important for writing. If cerebellar lesion lack of coordination means they will be active together = writers cramp
