Cerebellum 33

Question 0

Relative mass of the cerebellum in the brain?

Answer 0

10%

- Latin for Little Brain

Question 1

Primary function of the cerebellum?

Answer 1

For motor learning
integrating sensory information
cognition
and modulating motor output

Question 2

Percentage of neurons of the brain that are found in the cerebellum?

Answer 2

More than 50%

• over 50 billion neurons
• some of the largest neurons found here

Question 3

Description of the cerebellum’s structure?

Answer 3

Highly folded

- stretched out flat would be ~1m long

Question 4

What areas is the cerebellum divided into? (3)

Answer 4

Vestibulocerebellum (found under)
Spinocerebellum (found middle)
Cerebrocerebellum (found at the sides)

*given image shown in notes

Question 5

Associated nuclei of the cerebellum (3)

Answer 5

Fastigial nuclei
Dentate nuclei
Interposed nuclei

Question 6

Input and output of cerebellum through?

Answer 6

Cerebellar peduncles (inferior, middle, superior)

Question 7

Output from the cerebellum through the cerebellar peduncles is by what type of cells? What affect do they have?

Answer 7

Purkinje cells: inhibitory

- reduces descending output

Question 8

Vestibulocerebellum functions? (3)

Answer 8

VOR- ability to maintain focus with our eyes via vestibular system
Balance
Posture

• will be affected when improperly functioning

Question 9

Vestibulocerebellum subdivisions? (2)

Answer 9

Flocculus and modulus

Question 10

Vestibulocerebellum input and output?

Answer 10

Vestibular input from vestibular nuclei and directly from 8th cranial nerve
Output back to vestibular nuclei (within the brainstem)

Question 11

Spinocerebellum function ? (2)

Answer 11

Sensory integration (efferent copy) 
and gain of descending output for multi-joint movements and dynamic stability

Question 12

Spinocerebellum subdivisions (and relative location)? (2)
- organization?

Answer 12

Intermediate zone and vermis

• vermis in middle and intermediate zone on on either side
• organized somatotopically: vermis controls axial (core muscles) balance

Question 13

Spinocerebellum input and output?

Answer 13

Input: somatosensory info from periphery, visual and vestibular information

Output: vestibular nuclei, M1 areas via thalamus, other nuclei within brainstem (activation of CPGs) central pattern generators

Question 14

Spinocerebellum nuclei? (2)

Answer 14

Interposed nuclei (intermediate)
And
Fastigial nuclei (vermis)

Question 15

Spinocerebellum deficits? (Legions in this region)

Answer 15

Smooth control of muscles
Gain of muscle tone
Uncertain starts and stops
Lateral deviations 
Unequal steps 
74-93 of patients have fallen at least once per year 
(Can't walk straight)

Question 16

Cerebrocerebellum functions? (3)

Answer 16

Visually guided and goal directed movements
Supraspinal control circuits
Planning of movements

Question 17

Vestibulocerebellum deficits? (Caused by lesions). (3)

Answer 17

Balance
Posture
Eye movements

Question 18

Cerebrocerebellum subdivions?

Answer 18

None

Question 19

Cerebrocerebellum input and output?

Answer 19

Input: M1 Premotor cortex, frontal and parietal lobes

Output: thalamus - circuit of motor areas

Question 20

Cerebrocerebellum nuclei?

Answer 20

Dentate nucleus

Question 21

Cerebrocerebellum deficits? (4)

Answer 21

• visually guided movements (reach and grasp)
• dysdiadochokinesia (DDK impaired ability to perform rapid, alternating movements)
• dysmetria (lack of coordination, under or overshoot intended arm leg hand etc position - multijoint movements)
• rebound phenomenon (push down on someone’s arms as they hold it flexed, release will cause their arms to quickly contract back)
• • locomotion generally intact

Question 22

Common signs of cerebellar deficits?

Answer 22

Wide base of support
Ataxic gait (imbalance medial-lateral, purpose of wide base)
Impaired multi joint coordination
Dysdiadochokinesia - alternating movements
Dysmetria -over under shoot movements
Rebound phenomenon
Overshooting reactions to perturbations (difficulty regaining balance)

Question 23

How is cerebellum involved in voluntary movements?

Answer 23

Feedback ( for slow movements)
- desired output “continuously compared” with actual output
- pro: actuate output / con: slow
Feedforward (for rapid movements)
- sensory feedback evaluated before output program is generated
- **adapts with experience
- coordinates muscle groups in trail and error fashion

Question 24

Alcohols affect on the cerebellum?

Answer 24

Can cause LTD in cerebellum
Long term effects are “atrophy” (neuron cell death in cerebellum)
Results in ataxic gait (stumbling, uncoordination)

Question 25

What happens when born without cerebellum? Why?

Answer 25

Some unable to adapt and live life in wheelchair
Others can live semi normal lives

• cerebellum is redundant, there are other systems that do same functions

Question 26

Cerebellum vs basal ganglia, similarities?

Answer 26

Both revives massive ‘cortical input’
- only cerebellum receives real time sensory feedback (from thalamus and cortex)
Both send output to thalamus, which relays back to motor and Premotor cortex to influence cortical control of voluntary movement

Question 27

Cerebellum vs basal ganglia, differences?

Answer 27

Basal ganglia: involved in planning and gain of complex movements
Cerebellum: concerned with coordinated execution of ongoing movements

• only cerebellum receives ‘real time sensory feedback’

Question 28

Basal ganglia pathway

Answer 28

Cortex
Claudette and putamen (also receives modulatory inputs)
Relay nuclei (Globus Pallidus and Substantia nigra)
Thalamus
-back to cortex

Question 29

Cerebellum pathway

Answer 29

Cortex
Cerebellum cortex (also receives modulatory inputs)
Relay nuclei (Fastigial and interposed Dentate)
Thalamus
-back to cortex

Question 30

Cerebellum vs basal ganglia during complex task (signing your name)
- purpose of each structure?

Answer 30

Basal ganglia plays critical role in “preparatory phase”
- selection of a motor program
- motivation and context
Cerebellum governs coordination of ongoing movements
- sequencing, coordination of timing
- status info from sensory systems