The Cerebellum

Question 1

What is the function of the cerebellum?

Answer 1

Motor learning
Coordination of movements (timing, force)
Maintenance of balance and posture
Cognitive functions

Question 2

What are the entryways and exits to the cerebellum?

Answer 2

Inferior peduncle - afferents from medulla
Middle peduncle - afferents from pons
Superior peduncle - efferents to midbrain

Question 3

What are the 3 different nuclei of the cerebellum? Medial to lateral

Answer 3

Fatigial nucleus
Interposed nucleus
Dentate nucleus

Question 4

Briefly, What are the outputs from the fatigial nucleus/

Answer 4

Output to vestibular nuclei and medial descending tracts for posture and movement execution

Question 5

Briefly, what is the output of the interposed nucleus/

Answer 5

To lateral descending tracts

Question 6

Briefly, what is the output of dentate nucleus?

Answer 6

Output to the thalamus (VA+VL) to cerebral cortex

Question 7

What are the lobes of the cerebellum?

What separates them?

Answer 7

anterior
Posterior
Flocculonodular (most primitivel

Anterior - posterior = primary tissue
Posterior - flocculonodular = posteriorlateral fissue

Question 8

What are the threes functional zones of the cerebellum?

Answer 8

Vesitubulocerebellum
Spinocerebellum
Cerebrocerebellum

Question 9

Breifly, what is the function of the different functional zones

Answer 9

Vestibulocerebellum = balance
Spinocerebellum = error correction
Cerebrocerebellum = movement planning

Question 10

What lobes form the spinocerebellum?

Answer 10

Anterior lobe, Vermal region and medial posterior lobe

Question 11

What deep nuclei are associated with outputs of the spinocerebellum?

Answer 11

Interposed

Fastigial

Question 12

Where does the interposed N. project to? How do they act ipsilaterally?

Answer 12

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

Question 13

Interms of outputs from the spinocerebellum to the fastigial N, where do these project to?

Answer 13

Project to the reticular formation and form the medial descending tracts

Question 14

What inputs into the spinocerebellum?

Answer 14

The spinocerebellum tracts, reticular formation and vestibular nuclei via the inferior peduncle

Question 15

What nuclei is associated with outputs from the cerebrocerebellum?

Answer 15

The dentate nucleus

Question 16

What lobes form the functional zone the cerebrocerebellum

Answer 16

The lateral parts of the posterior lobe

Question 17

Where is the vestibulocerebellum located?

Answer 17

In the flocculonodular lobe

Question 18

What inputs into the cerebrocerebellum?

Answer 18

Inputs from the motor cortex areas via the pontine nuclei (enter cerebellum via middle peduncle). This contains information regarding the motor plan

Question 19

What is unique about the inputs and outputs of the cerebellum?

Answer 19

They are all ipsilateral

Question 20

Where do outputs from the cerebrocerebellum go?

Answer 20

To dentate nucleus (synapse here)
Onto the thalamus (synapse)
To motor cortex. M1, SMA and PMC receive inputs from dentate gyrus

Question 21

Where do inputs from mossy fibres project from?

Answer 21

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)

Question 22

The inferior olive sends error signals to the PC’s via climbing fibres. But what inputs into the inferior olive?

Answer 22

CF fire when unexpected event in movements occur
Receive inputs from spinal cord (cutaneous afferents, joint afferents, muscle spindles)
And cerebral cortex

Question 23

What occurs in the cerebrocerebellum?

Answer 23

Planning, organisation + co ordinating aspects of movements

Question 24

What projects into the vestibulocerebellum?

Answer 24

Inputs from the vestibular nuclei

Question 25

Where does the outputs of the vestibulocerebellum project to?

Answer 25

The vestibular nuclei and the vestibular spinal tracts (controls balance and eye movements)

Question 26

What is the role of basket/stellar cells?

Answer 26

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

Question 27

The role of the spinocerebellum is to function as an error corrector. How does it do this?

Answer 27

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

Question 28

When does the dentate nucleus fire?

Answer 28

Before movement

Question 29

What occurs on cooling the dentate nucleus?

Answer 29

Increases time taken for motor cortex output compared to controls and causes movement decomposition and loss of predictive movements

Question 30

When do the interposed nuclei fire?

Answer 30

After movement onset and is related to velocity error correction

Question 31

When does the fastigial nuclei fire?

Answer 31

After movement onset and is related to force error correction

Question 32

Name some signs of cerebellar lesions

Answer 32

``` Dysdiadochokinesia Ataxia of gait Nystagmus intention tremor Spacing/slurred speech Hypotonia Writers cramp Decomposition of movement Dysmetria Loss of motor memory ```

Question 33

What is dysdiadochokinesia?

Answer 33

Inability to perform rapidly alternating movements

Question 34

What is an ataxic gait?

Answer 34

Wide based staggering gait Cannot walk toe to toe (Vestibulocerebellum lesion)

Question 35

What is an intention tremor?

Answer 35

More pronounced tremor towards the end of target directed movements

Question 36

What is meant by the decomposition of movement?

Answer 36

Movement will be split up into individual parts rather tan coordinated

Question 37

What is dysmetria?

Answer 37

Overcompensation in speed (interposed N) and force (fatigial n) leading to overcorrection

Question 38

What is writers cramp?

Answer 38

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