Lecture 16: Cerebellum

Question 1

What are the lobes of the cerebellum?

Answer 1

Anterior, posterior and flocculonodular

Question 2

What is contained within the inferior, superior and middle cerebellar peduncles

Answer 2

Inferior contains input and output - spinocerebellar fibres enter the cerebellum,
Middle contains pontocerebellar fibres
Superior contains mainly output.

Question 3

What are the deep cerebellar nuclei?

Answer 3

Dentate, emboliform, globose and fastigial

Question 4

What makes up the archicerebellum? What is the functional name for this area?

Answer 4

flocculonolar lobe (tonsils and nodule). This is also known as the vestibulocerebellum

Question 5

What makes up the paleocerebellum? What is the functional name for this area?

Answer 5

Culmen and inferior part of vermis. This is also known as the spinocerebellum (but also includes tonsils)

Question 6

what makes up neocerebellum? What is the functional name for this area?

Answer 6

anterior and posterior lobes also known as the cerebrocerebellum.

Question 7

What are the inputs and outputs of the dentate nucleus?

Answer 7

Lateral lobes (neocerebellum) projects to dentate nucleus. And prokects to the contralateral ventrolateral nucleus of the thalamus then up to the cortex.

Question 8

What is the visuocerebellum and audiocerebellum?

Answer 8

Parts of vermis recieving visual and auditory input

Question 9

What are the inputs and outputs of the globose, emboliform and fastigial nuclei?

Answer 9

Input from the spinocerebellum (culmen and inferior part of the vermis) projects to the globose, emboliform and fastigial nuclei and then to the contralateral red nucleus and reticular formation.

Question 10

What are the symptoms of damage to the neocerebellum?

Answer 10

(incl. paravermal regions i.e. parts of spinocerebellum): loss ofmuscle tone and fatigue, asynergia, dysmetria (hypermetria, pastpointing), intention tremor, dysdiadochokinesia (inability to perform rapid successive movements), nystagmus, speech disturbances (slurred speech, separating of syllables).

Question 11

Where does cerebellar output originate?

Answer 11

With one exception, cerebellar output originates from cell bodies in the deep nuclei. The exception is a relatively small portion of cerebellar cortex—the flocculonodular lobe—whose cells project to the lateral and medial vestibular nuclei in the brain stem.

Question 12

How many layers of the cerebellar cortex are there? What are their names?

Describe the cells in each layer.

Answer 12

The 1st layer (closest to the surface) is the molecular cell layer, then the purkinje cell layer then the granule cell layer.

Mossy fibres project to granule cells in granule cell layer providing input to the cerebellum. Granule cells produce excitatory parallel fibres which contact purkinje cells and basket cells. Each parallel fibre excites the purkinje cells in its path, and inihibits the purkinje cell in the path of the parallel fibre next to it. Parallel fibres also contact golgi cells, which send inihibitory feedback to the rosette of mossy fibre to cut off signal.

Question 13

What cell groups provide input and output to the cerebellum

Answer 13

Most input to the cerebellum will be by mossy fibres, whereas output will be via purkinje cells.

Question 14

Describe the structure of mossy fibres

Answer 14

All mossy fibres are excitatory. They form ‘rosettes’ which are surrounded by ~ 20 granule cells and astrocytes.

Question 15

What type of cells are contained in the deep cerebellar nuclei?

Answer 15

The deep cerebellar nuclei (dentate, emboliform, globose and fastigial) all consist of purkinje cells as they provide the output of the cerebellum

Question 16

Name the cells found in the cerebellar cortex

Answer 16

Mossy fibres, granule cells, purkinje cells, basket cells, golgi cells and climbing fibres

Question 17

What are climbing fibres?

Answer 17

Climbing fibres are cells that project from the contralateral inferior olivary complex. They are excitatory and contact 2-10 purkinje cells. Each purkinje cell only receives one climbing fibre. Repeated firing of climbing fibres slow down the activity of the purkinje cell resulting in long term depression. Climbing fibres are though to have a role in cerebellar learning.

Question 18

What are the possible functions of the cerebellum?

Answer 18

vestibulocerebellum:
maintaining posture and balance while standing and moving

spinocerebellum:
monitoring movement as it is executed

cerebrocerebellum:
coordinating synergy of muscle activity in groups of muscles to generate complex movements

integrating sensory input to help plan and execute complex and precise movement - essential in activities such as sports or playing musical instruments. (spinocerebellum, audiocerebellum, visuocerebellum and probably cerebrocerebellum.

Question 19

What are the possible functions of the cerebellum?

Answer 19

vestibulocerebellum:
maintaining posture and balance while standing and moving

spinocerebellum:
monitoring movement as it is executed

cerebrocerebellum:
coordinating synergy of muscle activity in groups of muscles to generate complex movements

integrating sensory input to help plan and execute complex and precise movement - essential in activities such as sports or playing musical instruments. (spinocerebellum, audiocerebellum, visuocerebellum and probably cerebrocerebellum.)