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Flashcards in Cerebellum Deck (90):
1

What is the middle of the cerebellum called?

The vermis

2

What are the lateral masses of the cerebellum called?

The hemispheres

3

From what structures embryologically does the cerebellum develop from?

The alar plates of the neurotube

4

What type of disorders result from damage to the cerebellum?

Disruption of normal movement

5

How are lesions to the cerebellum and cerebral cortex different in terms of symptoms?

Movements are disrupted, not abolished

6

What are the 4 symptoms caused by a lesion to the cerebellum?

- Hypotonia
- Inability to walk or stand
- Ataxia
- Intension tremor and terminal tremor

7

What is loss of the ability to maintain a steady limb or body posture?

Astasia

8

What is loss of the ability to maintain an upright stance against gravity?

Abasia

9

What is ataxia?

Abnormal execution of multi-joint voluntary movements

10

What are intension tremors?

Begin to shake when beginning movements

11

What are terminal tremors?

Shaking at ends of movements

12

Does the cerebellum connect to lower motor neurons?

No, it synapses on centers that control LMN such as cortex, vestibular nuclei, reticular formation, etc...

13

What does the cerebellum regulate?

The force and timing of motor activities

14

What type of learning is the cerebellum involved in?

Motor learning

15

What level of consciousness does the cerebellum function at?

Subconcious

16

How does the cerebellum help muscle interplay?

Smooths interaction between agonists and antagonists

17

What type of posture does the cerebellum help to maintain? What system does it work in conjunction with in maintaining this type of posture?

- Upright posture
- Vestibular system

18

How does the cerebellum regulate movements and posture?

Adjusts output of major descending systems of the brain

19

Describe how the cerebellum adjusts movements in a feedforward manner?

- Compares movement intention with performance
- Integrates current state of motor system with the internally generated commands to PREDICT future state

20

How can the cerebellum be changed?

- Experience
- Practice makes perfect

21

What are the 3 functional divisions of the cerebellum?

- Archicerebellum/ vestibulocerebellum
- Paleocerebellum/ Spinocerebellum
- Corticocerebellum/ Pontocerebellum/ Neocerebellum

22

What is the function of the vestibulocerebellum?

- Coordinates head and eye movement
- Coordinates equilibrium of the body/ maintains balance

23

What are the 5 afferents of the vestibulocerebellum?

- Vestibular system
- Vestibular apparatus
- Superior colliculus
- Lateral geniculate
- Striate cortex

24

What are the 2 efferents of the vestibulocerebellum?

- Vestibular nuclei
- Reticular formation

25

What is the oldest functional division of the cerebellum phylogenetically?

- Vestibulocerebellum

26

What type of animals did the vestibulocerebellum originally develop in? What is the implication for its function?

- Water dwelling animals
- All that was required was an upright posture

27

What structures make up the paleocerebellum/ spinocerebellum?

- Vermis
- Intermediate areas of hemispheres

28

What are the 2 functions of the paleo/spinocerebellum?

- Execution of ongoing limb movements
- Regulation of muscle tone

29

What portions of the descending motor system are controlled by the paleo/ spinocerebellum?

- Medial and lateral components

30

How is the cerebellum somatotopically arranged?

Vermis (proximal and axial musculature)
Hemispheres (spinocerebellar and reticulocerebellar tracts)

31

What afferent information is processed in the vermis of the paleo/ spinocerebellum?

- Visual
- Hearing
- Vestibular

32

What afferent tracts are processed in the hemispheres of the paleo/ spinocerebellum?

- Spinocerebellar
- Reticulocerebellar

33

What are the efferent fibers of the paleo/ spinocerebellum?

- Brain stem motor nucleus such as red nucleus or reticular formation

34

What are the 3 functions of the cortico/ponto/neocerebellum?

- Planning/ PREPARATION and initiation of movements
- Learning and storage
- Precision in control of rapid movements and fine dexterity

35

What is the afferent tract of the cortico/ ponto/ neocerebellum?

Pontocerebellar tract

36

What is the efferent tract of the cortico/ ponto/ neocerebellum?

- Dentothalamic fibers (cerebellothalamocortical fibers)

37

What is the function of the motor loop through the lateral cerebellum?

- Execution of planned, voluntary, multijoint movements

38

What tract makes up the projection from the pons to the cerebellum that is involved in the motor loop through the lateral cerebellum?

Corticopontocerebellar

39

How many times larger is the corticopontocerebellar tract than the pyradmidal tract?

20 times

40

What two cerebellar nuclei are involved in motor execution?

- Fastigial nucleus
- Interposed nucleus

41

In what structure are the fastigial and interposed nuclei found?

The vermis of the cerebellum

42

What cerebellar nucleus is involved in motor planning?

Dentate nucleus

43

Which cerebellar nucleus is related to motor execution of the medial descending musculature?

Fastigial nucleus

44

Which cerebellar nucleus is related to motor execution of the lateral descending musculature?

Interposed nucleus.

45

What nuclei are responsible for coordination of balance and eye movements?

Vestibular nuclei

46

Which portion of the cerebellum receives input from the vestibular system?

The vestibulocerebellum, and the vermis

47

Which portion of the cerebellum receives input from spinal and trigeminal inputs?

- Spinocerebellum (medial portion/ intermediate hemisphere)

48

Which portion of the cerebellum receives input from the visual and auditory systems?

Middle of vermis

49

Which portion of the cerebellum receives input from the corticopontine systems?

- Lateral hemispheres

50

What is the lobe on the inferior aspect of the cerebellum?

- Flocculonodular lobe

51

What descending musculature does the vestibulocerebellar cerebellum innervate?

Medial/ proximal/ axial

52

What is the overall pathway from afferent to efferent output through the spinocerebellar pathway?

- Spinal cord afferents to spinocerebellum
- Vestigial nucleus to controlling areas
- Ventral medial system activated for proximal and axial musculature (????) (slide 13)

53

Describe the corticocerebellar pathway from the cerebral hemispheres back to the motor cortex.

- Corticopontine tracts project to the internal capsule
- Cortico pontine continue through the inferior the inferior colliculus to pontine nuclei in the mid pons
- Pontine nuclei in the mid pons project to the cerebellum through the middle cerebellar peduncle/ pontocerebellar projection
- Pontocerebellar projections synapse on the posterior lobe complex of the lateral the contralateral cerebellum
- Cerebellar nuclei project through superior cerebellar peduncle
- Cross at decussation of superior cerebellar peduncle
- Project to the ventral lateral nucleus of the thalamus (???)
- Project to the motor cortex

(This is all guesswork from the picture)

54

What are the 2 excitatory fibers to the purkinje cells in the cerebellar cortex?

- Mossy fibers
- Climbing fibers

55

From what do the mossy fibers originate from?

- Spinal cord
- Pontine nuclei
- Vestibular ganglia and nuclei
- Reticular formation nuclei

56

What cell do mossy fibers synapse on?

Granule cells and directly on deep cerebellar nuclei

57

What is the name of the fiber of the granule cell that rulls along the moelcular layer of the cortex?

Parallel fiber

58

What do parallel fibers of granule cells synapse on?

- Purkinje cells
- Basket cells
- Stellate cells
- Golgi cells

59

What type of neurotransmitter is released by basket, stellate, and golgi cells? What is its effect?

- GABA
- Inhibitory effect

60

What are Purkinje cells?

Output cells from the cerebellar cortex

61

From where do climbing fibers originate?

Exclusively the inferior olivary nucleus

62

What do climbing fibers synapse on?

- Dendrites of purkinje cells
- Collateral to deep cerebellar nuclei

63

What neurotransmitter is released by climbing fibers? What is the effect?

- Glutamate or aspartate
- Excitatory response

64

What neurotransmitter is released by Purkinje cells? What structures does this affect?

- GABA
Inhibits deep cerebellar nuclei

65

What structures do efferent fibers of the deep cerebellar nuclei project to?

- Inferior olive
- Reticular formation
- Vestibular nuclei
- Red nucleus
- Thalamus

66

What does the recurrent collateral from the deep cerebellar nuclei project to?

Granule cells in granular layer.

67

What is the ratio of climbing fibers to purkinje cells?

1:1

68

What portion of the cerebellum processes forward models of motor command?

Neocerebellum

69

Describe the forward model of motor command.

- Cerebellum receives copy of efferent motor commands from the cortex through the corticopontocerebellar tract (mossy fibers) to granule cells, which send collateral to cerebellar nuclei, which generate predictions
- The cerebellar nuclei send signals to the inferior olive to generate an error signal to update plastic microcircuits
- Excitatory connections send expected outcome information to the primary motor cortex

70

What is the function of the forward model of motor command?

- Increases time and accuracy of simple motor tasks
- Contributes to proper execution of complex motor tasks (comprehension and awareness of sequences over time)

71

See slide 17 for homunculus

See slide 17 for homunculus

72

What 2 structures process information from the sensory association cortex to plan and program movement for the premotor cortex?

- Basal ganglia
- Cerebro-cerebellum
(There are also direct connections from the sensory association cortex)

73

What structures have an influence on the output of the motor cortex?

- Spino-cerebellum
- Pre-motor cortex

74

Describe the interplay between the motor cortex and spino-cerebellum.

- Motor cortex sends collaterals to spinocerebellum, which is also receiving feedback from the body
- The spinocerebellum sends back efferents to the motor cortex

75

Which part of the cerebellum is the most commonly injured?

- The vestibulo cerebellum

76

What are symptoms of a vestibulo cerebellum lesion?

- Ataxia of gait and/ or upright posture
- Wide base of support
- Pathological nystagmus

77

What type of environment causes some of the effects of a vestibulo cerebellum lesion to be lessened?

Gravity eliminated environment

78

What are symptoms of a spinocerebellum lesion?

- Hypotonia throughout th ebody
- Titubation (staggering when trying to walk)

79

What causes the hypotonia associated with a spinocerebellar lesion?

- Decrease in gamma motor neuron drive

80

What causes the titubation associated with a spinocerebellar lesion?

- Ataxia of axial and proximal muscles

81

What portions of the cerebellum are typically damaged when titubation is present?

Vermis and intermediate zones

82

How does gravity affect titubation?

It doesn't

83

Is titubation usually worse in upper or lower extremities?

LE

84

What is the overall effect of lesions to the corticocerebellum?

- Delays in initiation and termination of movements
- Disordered temporal and spatial coordination of multiple joints

85

What type of tremor may occur in a corticocerebellar lesion?

Intention tremor

86

What is dysdiadochokinesia? (caused by corticocerebellar lesion)

- Inability to perform quick alternating movements

87

What is decomposition of movement? (caused by corticocerebellar lesion)

- Not bracing proximal joints

88

How is speech affected by corticocerebellar lesions?

- Rhythm and flow of movement causes slurred speech and broken syllables
- Dysarthria due to vermis control of facial muscle loss

89

What is dysmetria? (caused by corticocerebellar lesion)

- Errors in range and force of movements
- Overshooting and undershooting

90

What is dyssynergia? (caused by corticocerebellar lesion)

- Break down of symmetry across multiple joints during movement