Task 3 - The Cerebellum

Question 1

3 parts of the cerbellar hemispheres

Answer 1

1. Cerebrocerebellum
2. Spinocerebellum
3. Vestibulocerebellum

Question 2

2 main gray matter structures in the cerebellum

Answer 2

The cerebellar cortex and the deep cerebellar nuclei

Question 3

Cerebrocerebellum

Answer 3

• Includes most of the lateral cerebellar hemispheres and receives input directly from many cerebral cortex areas.
• Concerned with regulation of voluntary (especially highly skilled) movements, particularly planning & execution of complex spatial & temporal sequences of movemen

Question 4

Spinocerebellum

Answer 4

• Only part receiving direct input from the spinal cord.
• The more lateral (paramedian) part of the spinocerebellum is primarily concerned with movements of distal muscles.
• The median strip of cerebellar hemisphere along the midline (vermis) is mostly concerned with movements of proximal muscles and eye movements.

Question 5

Vestibulocerebellum

Answer 5

• It receives input from the vestibular nuclei in the brainstem.
• Regulates balance, posture and eye movements

Question 6

The 3 Cerebellar peduncles

Answer 6

1. Superior cerebellar peduncle
2. Middle cerebellar peduncle
3. Inferior cerebellar peduncle

Question 7

Superior cerebellar peduncle

Answer 7

(a.k.a. brachius conjunctivum)
* An almost entirely efferent pathway.
* Begins from the deep cerebellar nuclei
* Relay in the dorsal thalamus
* Projects to the deep layers of the superior colliculus
* Ends at primary motor & premotor cortical areas.
* Very important for limb coordination.

Question 8

Middle cerebellar peduncle

Answer 8

(a.k.a. brachius pontis)
An afferent pathway to the cerebellum, mostly starting from the pontine nuclei in the contralateral pons.

Question 9

Inferior cerebellar peduncle

Answer 9

(a.k.a. restiform body)
* The smallest & most complex cerebellar peduncle, containing multiple afferent & efferent pathways.
* Afferent pathways come from the vestibular nuclei, spinal cord, and the tegmentum.
* Efferent pathways project to the vestibular nuclei & reticular formation
* Proprioceptive information

Question 10

4 major deep nuclei of the cerebellar hemispheres

Answer 10

• The dentate nucleus, 2 interposed nuclei, and the fastigial nucleus.
• Each of them receives input from a different area of the cerebellar cortex.

Question 11

Where does the Cerebrocerebellum project to?

Answer 11

1. Mainly to the dentate nucleus which then
2. projects to the premotor cortex, responsible for motor planning

Question 12

Where does the Spinocerebellum project to?

Answer 12

1. To interposed and fastigial nuclei which then project to
2. the motor cortex and brain stem, responsible for motor execution

Question 13

Where does the Vestibulocerebellum project to?

Answer 13

1. It projects to the vestibular nuclei which then project to
2. lower motor neurons in spinal cord ans brain stem (for balance etc.)

Question 14

Basic circuit within the cerebellum

4

Answer 14

1. Mossy fibers main sources of info for cerebellum, send information to granule cells (+) and directly to the DCN (+)
2. Also climbing fibers from inferior olive go directly to DNC (+) and to Purkinje cells (+)
3. Granule cells have parallel fibers which also influence Purkinje cells (+)
4. Purkinje cells send to DCN (-) which sends to motor cortex

Question 15

Cerebellar ataxia

Answer 15

Difficulty in producing smooth, well-coordinated movements, and instead producing jerky & imprecise ones, caused by cerebellar lesions or disease.

Question 16

Marr-Albus theory of motor learning

Answer 16

• Motor learning is facilitated by plasticity of the parallel fiber-Purkinje cell synapse.
• The climbing fiber carries error signals indicating a movement has failed to meet expectations.
• Corrections are made by adjusting the effectiveness of the parallel fiber inputs to the Purkinje cell

Question 17

Forward model of motor learning

Answer 17

• Learning is seen as an active process where individuals make predictions about the sensory consequences of their movements before they execute them.
• These predictions are based on internal models or representations of the motor commands and their expected outcomes.
• Motor learning involves the development and refinement of these internal models through practice and feedback