Cerebellum [Guest Lecture]

Question 1

List the 6 functions of the Cerebellum

Answer 1

1. Balance
2. Feedback/forward
3. Sensory info integrated into movement
4. Timing
5. Motor learning
6. Adjustment

Question 2

List the 3 lobes and 3 vertical sections of the cerebellum

Answer 2

Lobes: anterior, posterior, flocculonodular

Vertical sections: midline vermis, paravermal (medial) hemisphere, latearl hemisphere

Question 3

Describe the 3’s of the cerebellum

Answer 3

3 layers of outer cortex (gray matter)

Deep cortex (white matter)

3 pairs of cerebellar nuclei

Also: 3 lobes, nuclei, and peduncles

Question 4

List the 3 pair of cerebellar nuclei

Answer 4

1. Fastigial
2. Interposed (globose and emboliform)
3. Dentate

Question 5

List the 3 cerebellar peduncles

Answer 5

1. Inferior (largely input, some output to vestibular/reticular)
2. Middle (input only)
3. Superior (largely output to cortex, red nucleus, reticular)

Question 6

Structure: Only output of cerebellar cortex

Answer 6

Purkinje cells

Question 7

List the 2 input cell types of the cerebellum

Answer 7

Climbing: synapse directly with purkinje cells

Mossy: do not contact purkinje cell directly

Question 8

Fiber: Carry motor plan from cerebrum to cerebellum

Answer 8

Climbing fibers

Question 9

Cell: Carry peripheral sensation to cerebellum

Answer 9

Granule cell

Question 10

Structure: Parallel fiber complex

Answer 10

Mossy fibers

Question 11

Describe the arrangment of climbing fibers

Answer 11

• Synapse direclty on purkinje cells
• Their firing causing firing of purkinje cells
• Each purkinje receives input from 1 climbing fiber
• Each climbing fiber contacts 1-10 purkinje neurons

Question 12

Describe mossy fibers

Answer 12

• Have a DIVERGENT influence on cerebellar function
• DO NOT contact purkinje fibers directly
• Synapse on: granule cells, golgi cells, stellate cells, basket cells
• INHIBITORY effect on granule and purkinje cells
• PARALLEL fibers run along top of purkinje fibers
• Pass through several hundren thousand purkinje cells

Question 13

Describe the influence of climbing and parallel (mossy) fibers on perkinje cells

Answer 13

Both are EXCITATORY

Single AP from climbing = purkinje depolarize

Weaker influence from paralle fibers,

Climbing fibers act to “teach” purkinje cells how to response to particular patterns of parallel fiber (sensory) inputs – to the point where CNS info is no longer needed to make quick adjustments ex. walking

Question 14

Corresponding area: cerebrocerebellum

Answer 14

Latearl hemisphere of cerebellum

hand, arm, foot, leg

Question 15

Corresponding area: Vermis and Paravermis hemisphere

Answer 15

Spinocerebellum

Question 16

Corresponding area: Flocculonodular lobe

Answer 16

Vestibulocerebellum

Question 17

Portion of Cerebellum:

Contorls extension and proximal mm

Important for posture control/balance

Coordinates eye and head movement (VOR)

Answer 17

Descending tracts of vestibulocerebellum – flocculonodular lobe and vermis

Question 18

Portion of Cerebellum:

Primarily influence limb movement

Compares commands from M1 to actual position/velocity of moving part and can issue correcting signals

Answer 18

Descending tracts of spinocerebellum – paravermal hemisphere

Question 19

Describe the input and output of the descending spinocerebellar tract

Answer 19

Input: from motor cortex to SC

Output: via interposed n. through VL/VA of thalamus to M1/Red nucleus

Question 20

Portion of Cerebellum:

Involved in planning and programming of voluntary, learned, skillful movement by influencing output of the motor cortex

Answer 20

Descending trat of the cereberocerebellum – lateral hemisphere

Question 21

Describe the input and ouput of the descending cerebrocerebellar tract

Answer 21

Input: from widespread areas of the cerebral cortex to the pontine n.

Output : via dentate n. to VL/VA of thalamus to premotor/motor cortex

Question 22

Describe how the cerebellum is a “double cross”

Answer 22

The output from the cerebellum crosses to the contralateral thalamus/red nucleus/motor cortex. Those tracts cross to the contralateral side when they descend

Thus cerebellar lesions typically effect the ipsilatera side

The cerebellum serves the SAME SIDE of the BODY

Question 23

Function: Descending Vestibulocerebellar Tract

Answer 23

Control of extnesion and prox mm

Balance and posture control

VOR

Question 24

Function: Descending Spinocerebellar Tract

Answer 24

Compares commands from motor cortex with actual position/velocity of moving part and can issue correcting signals

Question 25

Function: Descending Cerebrocerebellar Tract

Answer 25

Involved in planning and programming voluntary, learned, skilfull movement by influencing the output of the motor cortex

Question 26

Area of Damage: Balance disorders Ataxia Full control of limbs in supine Shaking due to constant adjustment attempts

Answer 26

Vestibulocerebellum and vermis

Question 27

Area of Damage: Loss of eye control Difficulty with pursit eye movement Difficulty with accurate voluntary eye movement

Answer 27

Vestibulocerebellum

Question 28

Describe the presentation of an individual with damage to their: 1. Vestibulocerebellum and vermis 2. Vestibulocerebellum

Answer 28

1. Balance disorders, ataxia, shaking, full control of limbs in supine 2. Loss of eye control

Question 29

Describe why those with vestibulocerebellar and vermis damage still have limb control in supine

Answer 29

Because the cerebrum/lateral cerebellar hemisphere are still in tact

Question 30

Area of Damage: - Disruption of accurate execution of movement - Hypotonia (decreased corticospinal and rubrospinal tract activity) - Dysmetria - Ataxia - Intention tremor - Pendular reflex

Answer 30

Spinocerebrum and paravermis hemisphere

Question 31

Term: Disrupted accuracy of reaching b/c of increased erros in timing components of movement

Answer 31

Dysmetria

Question 32

Term: Poor coordination of joints

Answer 32

Ataxia

Question 33

Term: correction of errory

Answer 33

Intention tremor

Question 34

Term: reflex disruption

Answer 34

Pendular reflex

Question 35

Describe the presentation of an individual with spinocerebellar/paravermis damage

Answer 35

- Disrupted accuracy of movement - Hypotonia - Dysmetria - Ataxia - Intention tremor - Pendular reflex

Question 36

Area of Damage: Errors in movement timing Delays in initiating movements Increased reaction time Disrupted sequential movements

Answer 36

cerebrocerebellum and lateral cerebellar hemispheres

Question 37

Term: disrupted sequential movements

Answer 37

decomposition of movements

Question 38

Describe the presentation of an individual with cerebrocerebellar and lateral cerebellar hemisphere damage

Answer 38

- Errors in movement timing - Delays in initiating movements - Increased reaction time - Decomposition of movement

Question 39

Term: Inability to perform rapid alternating movements

Answer 39

Dysdiadochokinesia

Question 40

Term: How a behavior was accomplished and it's outcome

Answer 40

Feedback

Question 41

Term: Prediction about what is coming

Answer 41

Feedforward

Question 42

Describe the result of feedforward information

Answer 42

1. allows precisely timind movements 2. importantfor multi-joint movement - controls relative timing

Question 43

Describe the 2 cerebrocerebellar loops and their role in motor learning

Answer 43

Loop 1 = thalamus to premotor and primary motor areas Loop 2 = red nucleus to inferior olivary nucleus and back to controlateral cerebellum forming feedback loop Feedback loop pathways suports MENTAL REHEARSAL of movements and motor learning

Question 44

Describe the paravermis role in motor learning

Answer 44

Incorporates error related feedback into up coming movements during motor learning

Question 45

Describe the role of the cerebellum during learning

Answer 45

- Active early during acquisition of motor skills - Chunk information to when learning a series of movements - Allows for advanced preparation - Important for feedback and feedfoward processes

Question 46

Term: allows a series of movements to be learned and smoothed over time

Answer 46

Chunking

Question 47

Describe the role of the cerebrocerellum in cognition

Answer 47

- input to cerebrocerebellum exculsively form cerebral cortex - Interconnected with working memory regions - Dentate n. important in acquiring and processing sensory info for tasks requiring complex spatial and temporal judgments - Lateral hemisphere associated with: word learning, silent reading, pegboard puzzle solving

Question 48

Portion of Cerebellum: Functions for feeback

Answer 48

Paravermis

Question 49

Portion of Cerebellum: Functions in controlling motor tone

Answer 49

Vermis