Lecture 5: Cerebellum, Corticospinal tract and Motor Systems

Question 1

What are the 4 functions of the Cerebellum relating to motor control

Answer 1

1. Receives and modulates inputs that relate to balance (vestibulo-spinal inputs)
2. Receives and modulates inputs relating to the reticular formation which controls neuronal excitability and gravity opposing muscles
3. Engages motor planning and monitoring to ensure the motor movement goes to plan.
4. Controls highly repetitive and swift movements

Question 2

What are the 3 major regions of the cerebellum: Anatomical and matching functional systems (primal purposes to more refined, close to pons vs further away)

Answer 2

1. Archicerebellum = Flocculonodular lobe + Vermis = Part of the Vestibulocerebellum involved in balance and eye movements, orientation of head
2. Palaeocerebellum = Spinocerebellum involved in balance and posture using info of body in space
3. Neocerebellum = Cerebrocerebellum involved in coordination of movement.

Question 3

What is the tissue structure of the Cerebellum

Answer 3

Folia: Lots of very small gyri with thin sulci in between them many granular neurons, not many large neurons to have 80% of brains neurons in there

Question 4

What are the inputs to the archicerebellum, the peduncle travelled through and what information

Answer 4

1. Vestibular nerve from vestibular organ in ear brings info about the body in space to –>
2. Vestibular nucleus in Medulla
3. Travels through Inferior Peduncle
4. Goes into the grey matter cortex of the cerebellum to synapse with granule cell which forms a lattice structure.

Question 5

What are the inputs to the paleocerebellum, the peduncle travelled through, and what information

Answer 5

Dorsal SpinoCerebellar tract

1. Spinal nerve from the Dorsal nucleus of Clark carries information about where the body is in space based on golgi tendon organs and muscle spindle fibres
2. Goes into the inferior peduncle
3. Enters the grey matter cortex of cerebellum and forms synapses with granule cells there that form lattices

Question 6

Where does the Ventral spinocerebellar tract operate at and which peduncle

Answer 6

Upper limb areas, it goes into the superior peduncle but it has little bearing on posture

Question 7

What are the inputs to the Neocerebellum, the peduncle travelled through, and what information

Answer 7

1. Fibres coming down from the pre motor cortex, motor cortex, basal ganglia, frontal cortex + other parts of cortex and either synapse with cells in pons or enter directly into the cerebellum
2. Goes through the middle peduncle
3. Synapses with granule cells in the grey matter of cerebellar cortex

Question 8

What is the job of the Inferior Olivary nucleus/complex in the medulla and what is its input and path of input

Answer 8

Regulator and integrator of other inputs to the cerebellum.

It produces climbing fibres which enter the cerebellum through the inferior peduncle.

These interact with purkinje fibres in cortex and can stop them from firing, therefore if the plan needs to be changed it can stop output until a new plan is made - stop movement at the right time

Question 9

What happens after the input nerves have synapsed with granule cells in grey matter cortex of cerebellum

Answer 9

1. granule cells are mossy fibres and they run parallel to the synapse to form a dense lattice in the upper layer of the cerebellar cortex
2. Some processing happens then Purkinje cell fibres carry the info to the Deep Cerebellar Nuclei which gives rise to the output neurons of the cerebellum.

Question 10

Where does the neocerebellar output go to (from the deep cerebellar nuclei)

Answer 10

1. Exits through the superior peduncle to the
2. thalamus and then to the
3. Motor cortex

Question 11

Where does the paleocerebellar and archicerebellar output go to (from the deep cerebellar nuclei)

Answer 11

1. Exits through superior peduncle then travels back down through pons etc to the spinal cord.
2. Give feedback to neurons of the spinal cord to change the postural balance or Give feedback to neurons of the head and neck for vestibular balance

Question 12

What are the deep cerebellar nuclei associated with the Archicerebellum, and what tracts do they take to the Lower motor neuron pool

Answer 12

1. Fastigial nucleus which goes to the
   a) . Lat Vestibular nucleus (also has input from flocculonodular lobe).-> Vestibulospinal neurons
   b) . Reticular formation -> Reticulospinal neurons
2. LMNP (vestibular is head balance, reticular is postural muscle excitability)

Question 13

What are the deep cerebellar nuclei associated with the Paleocerebellum, and what tracts do they take to the Lower motor neuron pool

Answer 13

1. Interpositus Nucleus goes to the
2. Red nucleus (also receives input from dentate nucleus) -> Rubrospinal neurons to
3. LMNP (Automated pattern generated movement which is still planned despite being autonomic)

Question 14

What are the deep cerebellar nuclei associated with the Neocerebellum, and what tracts do they take to the Lower motor neuron pool

Answer 14

1. Dentate nucleus goes to the
2. Ventral anterior Ventral lateral of the thalamus
3. Planning part of cortex
4. Upper motor neuron
5. LMNP: affects a planned motor movement; fine movement control

Question 15

What are the 3 layers of the cerebellum from outer to inner

Answer 15

1. Molecular layer :
2. Purkinje cell layer: smaller # of large cells
3. Granule layer: many little granule cells
4. Synapse with mossy cells