The cerebellum

Question 1

Cerebellum - Prominence

Answer 1

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

Question 2

Cerebellar cortex - Key things

Answer 2

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

Question 3

Damage to cerebellum causes…

Answer 3

Ataxia
Intention tremors
Decomposition of movements

Question 4

Ataxia

Answer 4

Abnormalities in execution of voluntary movements. Lack of coordination

Question 5

Intention tremors

Answer 5

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

Question 6

Decomposition of movement

Answer 6

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

Question 7

Folia

Answer 7

Folds in cerebellum
Increase the surface area of the cerebellar cortex

Question 8

Flocculonodular region

Answer 8

Old structure
Balance and eye movements
Flattened under cerebellum

Question 9

Spinocerebellum

Answer 9

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

Question 10

Vermis

Answer 10

Worm
Posture control

Question 11

Intermediate hemispheres

Answer 11

Control limbs

Question 12

Lateral hemisphere

Answer 12

Cerebrocerebellum
Communicates with cortex
Much bigger in humans
Some cognitive functions

Question 13

Cerebellar peduncles

Answer 13

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

Question 14

Inferior cerebellar peduncle

Answer 14

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

Question 15

Middle cerebellar peduncle

Answer 15

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

Question 16

Superior cerebellar peduncle

Answer 16

The output of cerebellum to brainstem and thalamus

Question 17

Deep nuclei

Answer 17

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

Question 18

Fastigial

Answer 18

Outputs from Vermis, most medial pathways, balance and posture

Question 19

Interposed

Answer 19

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

Question 20

Dentate nucleus

Answer 20

Go back up to thalamus and then to cerebral cortex

Question 21

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

Answer 21

Purkinje cell layer!!

Question 22

How many layers in cerebellar cortex?

Answer 22

3

Question 23

Half the neurons in your brain are…

Answer 23

Cerebellar granule cells

Question 24

Purkinje cell dendrites are in…

Answer 24

the molecular layer

Question 25

5 types of neurons found in cerebellar cortex

Answer 25

- Purkinje cells - Granule cell Three inhibitory interneurons: - golgi cells - stellate cells - basket cells

Question 26

1 mossy fiber makes connections with a few granule cells

Answer 26

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

Question 27

Where do mossy fibers make excitatory connections?

Answer 27

Granule cells Deep cerebellar nuclei

Question 28

Bundles of parallel fibers that excite the dendrites of Purkinje cells and basket cells?

Answer 28

Beams

Question 29

Basket cell effect on Purkinje cells

Answer 29

Inhibit Purkinje cells on the parallel beam

Question 30

Simple spikes

Answer 30

In Purkinje cells. Modulated by sensory stimuli and voluntary movements

Question 31

Inferior olive

Answer 31

Source of climbing fibers

Question 32

Climbing fiber

Answer 32

Makes direct synapse on...Purkinje cells Results in very powerful excitation When climbing fiber fires AP purkinje cell fires AP

Question 33

Climbing fibers generate...

Answer 33

Complex spikes Large prolonged depolarization caused by voltage-gated calcium channels and smaller sodium spikes

Question 34

Golgi cells

Answer 34

Granule layer Axons extend into molecular layer and are excited by purkinje cells Golgi cells inhibit granule cells

Question 35

Stellate cells

Answer 35

In molceular layers Inhibit purkinje cells

Question 36

Basket cells

Answer 36

molecular layer activated by parallel fibers

Question 37

Flocullonodular lobe

Answer 37

Input from vestibular system and visual system balance

Question 38

Spinocerebllum

Answer 38

Vermis Balance and posture

Question 39

Where does vermis project?

Answer 39

Fastigial nucleus Involved in what? Posture

Question 40

Ventral lateral nuclei of thalamus

Answer 40

relays cerebellar info

Question 41

After the vermis projects to the fastigial nucleus, where does the fastigial nucleus project to and what tract? Mainly involved in what?

Answer 41

Vestibular nuclei: Vestibulospinal tract Reticular formation: Reticulospinal tract Mainly involved in posture

Question 42

Intermediate hemispheres project to where before they go to M1?

Answer 42

Interposed nuclei Magnocellular red nucleus

Question 43

Magnocellular red nucleus

Answer 43

Rubrospinal tract Control of limb movements

Question 44

Lateral hemispheres of cerebellum form...

Answer 44

cerebrocerebellum

Question 45

Feedback control

Answer 45

AFTER error has been made

Question 46

Feedforward control

Answer 46

Anticipating that error will come, contracting

Question 47

Intention tremor and cause

Answer 47

Have feedback control but not feedforward control INACTIVATED DEEP NUCLEI

Question 48

Efference copy comes down to cerebellum

Answer 48

Cerebellum gets the motor command of what you were trying to do and what you did

Question 49

Long term depression - synapses that get weaker

Answer 49

Get weaker if active during complex spike

Question 50

The hypothesis of Improvement in movement

Answer 50

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