Cerebellum Flashcards
(90 cards)
1
Q
What is the middle of the cerebellum called?
A
The vermis
2
Q
What are the lateral masses of the cerebellum called?
A
The hemispheres
3
Q
From what structures embryologically does the cerebellum develop from?
A
The alar plates of the neurotube
4
Q
What type of disorders result from damage to the cerebellum?
A
Disruption of normal movement
5
Q
How are lesions to the cerebellum and cerebral cortex different in terms of symptoms?
A
Movements are disrupted, not abolished
6
Q
What are the 4 symptoms caused by a lesion to the cerebellum?
A
- Hypotonia
- Inability to walk or stand
- Ataxia
- Intension tremor and terminal tremor
7
Q
What is loss of the ability to maintain a steady limb or body posture?
A
Astasia
8
Q
What is loss of the ability to maintain an upright stance against gravity?
A
Abasia
9
Q
What is ataxia?
A
Abnormal execution of multi-joint voluntary movements
10
Q
What are intension tremors?
A
Begin to shake when beginning movements
11
Q
What are terminal tremors?
A
Shaking at ends of movements
12
Q
Does the cerebellum connect to lower motor neurons?
A
No, it synapses on centers that control LMN such as cortex, vestibular nuclei, reticular formation, etc…
13
Q
What does the cerebellum regulate?
A
The force and timing of motor activities
14
Q
What type of learning is the cerebellum involved in?
A
Motor learning
15
Q
What level of consciousness does the cerebellum function at?
A
Subconcious
16
Q
How does the cerebellum help muscle interplay?
A
Smooths interaction between agonists and antagonists
17
Q
What type of posture does the cerebellum help to maintain? What system does it work in conjunction with in maintaining this type of posture?
A
- Upright posture
- Vestibular system
18
Q
How does the cerebellum regulate movements and posture?
A
Adjusts output of major descending systems of the brain
19
Q
Describe how the cerebellum adjusts movements in a feedforward manner?
A
- Compares movement intention with performance
- Integrates current state of motor system with the internally generated commands to PREDICT future state
20
Q
How can the cerebellum be changed?
A
- Experience
- Practice makes perfect
21
Q
What are the 3 functional divisions of the cerebellum?
A
- Archicerebellum/ vestibulocerebellum
- Paleocerebellum/ Spinocerebellum
- Corticocerebellum/ Pontocerebellum/ Neocerebellum
22
Q
What is the function of the vestibulocerebellum?
A
- Coordinates head and eye movement
- Coordinates equilibrium of the body/ maintains balance
23
Q
What are the 5 afferents of the vestibulocerebellum?
A
- Vestibular system
- Vestibular apparatus
- Superior colliculus
- Lateral geniculate
- Striate cortex
24
Q
What are the 2 efferents of the vestibulocerebellum?
A
- 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
