Unit 5

Question 1

What does cerebellum mean and why is the name misleading?

Answer 1

„Little brain“
Has more neurones that rest of brain (50 billion vs 22 billion)

Question 2

What does the cerebellum generally do?

Answer 2

Plays important role in motor functions that require coordination of muscle contractions, aim and timing
Forms connections with every major motor structure of cerebral cortex
Functions at unconscious level
-> influences balance, posture, muscle tone and coordination of movement

Question 3

What is muscle tone?

Answer 3

Tension in a muscle at rest that helps maintain posture

Question 4

How does the cerebellum control movement?

Answer 4

Receives visual, auditory, vestibular and somatosensory information + motor commands
-> integrates information to produce smooth, coordinated movements

Question 5

What does damage to the cerebellum cause?

Answer 5

Jerky, erratic and uncoordinated movements
Difficulty tapping a rhythm, clapping hands, pointing to a moving object, speaking and writing

Question 6

Finger-to-nose test

Answer 6

Used to quickly assess cerebellar functioning
Hold arm out straight, touch nose with index finger when instructed (as quickly as possible)

Question 7

Why is this test used by the police?

Answer 7

Cerebellum one of first brain areas to be affected by alcohol
-> used to assess alcohol intoxication

Question 8

What difficulties do people with damage to cerebellum have when doing the finger to nose test?

Answer 8

Disrupts ability to do the test
Miss nose/go to far/ unable to hold finger in front of nose

Question 9

What are peduncles?

Answer 9

Bundles of axon fibres through which information enters and leaves cerebellum

Question 10

Which peduncles are there?

Answer 10

Superior peduncle: connects to midbrain
Middle peduncle: from pons to cerebellum
Inferior peduncle: connects to medulla

Question 11

What is the vermis?

Answer 11

Midline/central region of the two cerebellar hemispheres (separates them)

Question 12

What is the folia?

Answer 12

The many folds the outer surface of the cerebellum consists of

Question 13

What are the three lobes of the cerebellum?

Answer 13

Anterior, posterior and flocculonodular lobe

Question 14

primary fissure

Answer 14

separates anterior from posterior lobe

Question 15

posterolateral fissure

Answer 15

demarcates small region on the ventral side
-> flocculus
-> vermis

Question 16

grey and white matter

Answer 16

white matter internal
grey matter external

Question 17

What is the branching pattern the white matter in the cerebellum produces referred to?

Answer 17

arbor vitae (tree of life)

Question 18

What are deep cerebellar nuclei?

Answer 18

grey matter
produce messages
sent from cerebellum to other areas

Question 19

The layers of the cerebellum

Answer 19

molecular (outer)
Purkinje (middle)
granular (inner)

Question 20

granular layer

Answer 20

cell bodies of granule cells
receive information from other parts of CNS and sent it to more external layers

Question 21

parallel fibres

Answer 21

originate from granular cells
extend to molecular layer
-> branch out in parallel with each other
-> oriented in parallel with surface

Question 22

What does the Purkinje layer consist of?

Answer 22

single layer of purkinje cells
-> have dendritic arborisations extending to outer layer
-> receive excitatory input from parallel fibres

Question 23

What does the molecular layer consist of?

Answer 23

mostly of dendritic arborisations of purkinje cells
granule parallel fibres

Question 24

Purkinje cells

Answer 24

only neurones in cerebellum projecting axons from cerebellar cortex to other parts of cerebellum-> carry information to deep cerebellar nuclei

Question 25

which deep cerebellar nuclei are there?

Answer 25

consist of dentate, emboliform, globose and fastigial nuclei
-> primary source of output
-> organised into four bilateral pairs

Question 26

Which neurotransmitter do deep cerebellar nuclei use?

Answer 26

GABA

Question 27

mossy fibres

Answer 27

branch out and terminate in granular layer

Question 28

climbing fibres

Answer 28

synapse with purkinje cells
some axons branch off and project directly to deep cerbellar nuclei

Question 29

What do the signals the cerebellum receives consist of?

Answer 29

sensory, somatosensory and motor information

Question 30

How does information arrive at the cerebellum?

Answer 30

through mossy and climbing fibres entering through peduncles

Question 31

How does the cerebellum coordinate movement? (path)

Answer 31

information detected around body
-> sent to cerebellum
-> processes and integrates information
-> sends information back to body parts or brain to help it modify movement

Question 32

what does damage to the flocculonodular lobe or vermis cause?

Answer 32

disturbances in posture and balance
damage to vermis can make it impossible to stand or sit without falling over

Question 33

What does damage to the anterior lobe cause?

Answer 33

deficits in movement
e.g. limb rigidity

Question 34

Does damage to the cerbellum cause contra- or ipsilateral deficits?

Answer 34

ipsilateral
-> cerebellum projects ipsilaterally to spinal cord
.> projects contralaterally to brain

Question 35

What does damage to the neocerebellum cause?

Answer 35

disrupted timing of rapid movements
uncoordinated movement
-> unilateral damage only causes incoordination of ipsilateral arm and leg
-> damage to both sides (often through alcohol intoxication) causes slow speech and dysarthria

Question 36

What is dysarthria?

Answer 36

breaking words into individual syllables

Question 37

Nystagmus

Answer 37

involuntary to-and-fro motion of eyes
-> symptoms worse when gaze directed at same side as site of damage
-> damage to cerebellum causes impairments of coordination of eyes