The cerebellum Flashcards

1
Q

Cerebellum - Prominence

A

Accounts for 10% of total brain volume but more than HALF of the brain’s neurons

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2
Q

Cerebellar cortex - Key things

A

1) Consists of large number of virtually identical functional units suggesting that it performs similar functional operations on different inputs
2) It receives massive input from sensory systems and from systems involved in planning and execution of movement
3) Forms loops with premotor and motor systems of cerebral cortex and brainstem that are involved in controlling movement. It also has reciprocal connections with association cortex, especially in the frontal lobes
4) Synaptic transmission in the cerebellum is subject to modification (long term depression) which is thought to be important for motor learning

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3
Q

Damage to cerebellum causes…

A

Ataxia
Intention tremors
Decomposition of movements

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4
Q

Ataxia

A

Abnormalities in execution of voluntary movements. Lack of coordination

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5
Q

Intention tremors

A

Tremors DURING movements (diff from Parkinson’s) Most noticeable at the end of a movement

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6
Q

Decomposition of movement

A

Fragmentation of complex movements that are normally carried out in a smooth coordinated fashion

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7
Q

Folia

A

Folds in cerebellum
Increase the surface area of the cerebellar cortex

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8
Q

Flocculonodular region

A

Old structure
Balance and eye movements
Flattened under cerebellum

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9
Q

Spinocerebellum

A

Intermediate hemisphere - Vermis - Intermediate hemisphere
Gets most its inputs from spinal cord
Outputs go to brainstem and down spinal cord
Coordination of limbs

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10
Q

Vermis

A

Worm
Posture control

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11
Q

Intermediate hemispheres

A

Control limbs

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12
Q

Lateral hemisphere

A

Cerebrocerebellum
Communicates with cortex
Much bigger in humans
Some cognitive functions

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13
Q

Cerebellar peduncles

A

Connect the cerebellum to the brainstem
Superior peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle

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14
Q

Inferior cerebellar peduncle

A

Inputs from spinal cord (directly and through brainsten) and vestibular nuceli

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15
Q

Middle cerebellar peduncle

A

Huge ones
Inputs from cerebral cortex by way of PONTINE (pons) nucleus

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16
Q

Superior cerebellar peduncle

A

The output of cerebellum to brainstem and thalamus

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17
Q

Deep nuclei

A

Inputs to the cerebellum project to both the cortex and the deep nuclei
Outputs from the cortex project to the deep nuclei, which, in turn, form the outputs of the cerebellum

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18
Q

Fastigial

A

Outputs from Vermis, most medial pathways, balance and posture

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19
Q

Interposed

A

Inputs from intermediate hemispheres
Outputs go for cortex and rubrospinal tract limb control

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20
Q

Dentate nucleus

A

Go back up to thalamus and then to cerebral cortex

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21
Q

What is between molecular layer and granule cell layer in the cerebellar cortex?

A

Purkinje cell layer!!

22
Q

How many layers in cerebellar cortex?

23
Q

Half the neurons in your brain are…

A

Cerebellar granule cells

24
Q

Purkinje cell dendrites are in…

A

the molecular layer

25
5 types of neurons found in cerebellar cortex
- Purkinje cells - Granule cell Three inhibitory interneurons: - golgi cells - stellate cells - basket cells
26
1 mossy fiber makes connections with a few granule cells
Granule cell axon goes up to molecular layer and then head in opposite directions Extend through dendrites of purkinje cells: these are called parallel fibers, extend half a centimeter and extend through hundreds of purkinje cells and makes excitatory synapses on all of these purkinje dendtrites
27
Where do mossy fibers make excitatory connections?
Granule cells Deep cerebellar nuclei
28
Bundles of parallel fibers that excite the dendrites of Purkinje cells and basket cells?
Beams
29
Basket cell effect on Purkinje cells
Inhibit Purkinje cells on the parallel beam
30
Simple spikes
In Purkinje cells. Modulated by sensory stimuli and voluntary movements
31
Inferior olive
Source of climbing fibers
32
Climbing fiber
Makes direct synapse on...Purkinje cells Results in very powerful excitation When climbing fiber fires AP purkinje cell fires AP
33
Climbing fibers generate...
Complex spikes Large prolonged depolarization caused by voltage-gated calcium channels and smaller sodium spikes
34
Golgi cells
Granule layer Axons extend into molecular layer and are excited by purkinje cells Golgi cells inhibit granule cells
35
Stellate cells
In molceular layers Inhibit purkinje cells
36
Basket cells
molecular layer activated by parallel fibers
37
Flocullonodular lobe
Input from vestibular system and visual system balance
38
Spinocerebllum
Vermis Balance and posture
39
Where does vermis project?
Fastigial nucleus Involved in what? Posture
40
Ventral lateral nuclei of thalamus
relays cerebellar info
41
After the vermis projects to the fastigial nucleus, where does the fastigial nucleus project to and what tract? Mainly involved in what?
Vestibular nuclei: Vestibulospinal tract Reticular formation: Reticulospinal tract Mainly involved in posture
42
Intermediate hemispheres project to where before they go to M1?
Interposed nuclei Magnocellular red nucleus
43
Magnocellular red nucleus
Rubrospinal tract Control of limb movements
44
Lateral hemispheres of cerebellum form...
cerebrocerebellum
45
Feedback control
AFTER error has been made
46
Feedforward control
Anticipating that error will come, contracting
47
Intention tremor and cause
Have feedback control but not feedforward control INACTIVATED DEEP NUCLEI
48
Efference copy comes down to cerebellum
Cerebellum gets the motor command of what you were trying to do and what you did
49
Long term depression - synapses that get weaker
Get weaker if active during complex spike
50
The hypothesis of Improvement in movement
Complex spikes, through long-term depression eliminate simple spikes that create movement errors, creating an accurate model Complex spike spikes when incorrect and then that simple spike is eliminated