Lecture 14-Cerebellum

Question 1

What are the gyri of the cerebellum called? What does the cerebellar cortex surround? What is found deeply in the cerebellum?

Answer 1

Gyri of cerebellum = folia
Surrounds arbor vitae (tree of life) white matter tracts
Deep cerebellar nuclei found in central white matter

Question 2

What is the role of the deep cerebellar nuclei?

Answer 2

The deep cerebellar nuclei process and relay information between the cerebellar cortex and other brain regions via the cerebral peduncles.

Question 3

Anatomy of Cerebellum:

Answer 3

1) 2 hemispheres divided by vermis
2) 3 lobes -anterior, posterior, flocculonodular
3) The cerebellar cortex is on the outside, covering the white matter located on the inside.

Question 4

Three Functional Subdivisions of the Cerebellum

Answer 4

1) Cerebrocerebellum
(lateral hemisphere) -posterior lobe -Neocerebellum -newest

2) Spinocerebellum (vermis and intermediate) -anterior lobe-Paleocerebellum-middle

3) Vestibulocerebellum
(flocculonodular lobe) -Archicerebellum (oldest)

Question 5

How many cell types does the cerebellum have? Name them. Which of these cell types have the biggest somas? The smallest somas?

Answer 5

1. Outer stellate
2. Basket
3. Purkinje (biggest somas)
4. Granule (smallest somas)
5. Golgi
6. Unipolar brush

Question 6

What are the three layers of the cerebellar cortex? Name the cells that are present in each layer.

Answer 6

1. Granular layer (inner): granule, Golgi, & unipolar brush cells
2. Purkinje layer (middle): Purkinje cells
3. Molecular layer (outer): basket & outer stellate cells

Question 7

What layer are granule cells found in the cerebellum? Are they excitatory or inhibitory? Where are the dendrites of the granule cells found? Where does its axons rise up to? What do these axons eventually become?

Answer 7

Granular layer → excitatory
Dendrites found within the glomeruli w/inputs from Golgi cells & mossy fibres
Axons rise to molecular layer, turn 90 degrees, & become parallel fibres to run perpendicular to folia axis

Question 8

What layer are Golgi (inner stellate) cells found in the cerebellum? Are they excitatory or inhibitory?

Answer 8

Granular layer → inhibitory

Question 9

Where are the dendrites of the Golgi cells found? Where do the dendrites receive their inputs from? Where are its somas found?

Answer 9

Dendrites in all three layers
Dendrites receive input from granule cells, mossy & climbing fibres
Somas found in glomeruli

Question 10

Where are the arborizing dendrites found for the Purkinje cells in the Purkinje layer? Where do they project to?

Answer 10

• Dendrites in molecular layer, perpendicular to folia axis
• Project to deep cerebellar nuclei & some vestibular nuclei in the brainstem, making them the only extracerebellar projection from the cerebellar cortex.

Question 11

What layer are the basket & outer stellate cells found in the cerebellum? Where do they project their inhibitory synapses to? What are they excited by?

Answer 11

Molecular layer
Inhibitory synapses onto Purkinje cells
Excited by parallel fibres of granule cells

Question 12

What are the four deep cerebellar nuclei? Which of these nuclei make up the interposed nuclei?

Answer 12

1. Dentate
2. Emboliform
3. Globose
4. Fastigal
   Emboliform & globose make up interposed nuclei

Question 13

What are the three main zones of the cerebellar cortex? Where does each project to?

Answer 13

1. Vermal zone projects to fastigial nucleus
2. Paravermal zone projects to interposed nuclei
3. Hemispheric zone projects to dentate nuclei

Question 14

Where does the flocculonodular lobe (vestibulocerebellum) get direct projections from as its input?

Answer 14

Projections from vestibulocochlear nerve (CN VIII) & 2nd-order projections from vestibular nuclei →via the inferior cerebellar peduncle (vestibulocerebellar fibres)

Question 15

Where does the flocculonodular lobe (vestibulocerebellum) project its output to? What structure does it go through?

Answer 15

Projects to vestibular nuclei → goes through superior cerebellar peduncle (fastigiovestibular tract)

Question 16

What does the flocculonodular lobe (vestibulocerebellum) influence? How does it do this?

Answer 16

Influences vestibulospinal tract (posture, balance, head movement) →vestibular projections to MLF involved in coordinating head & eye movements

Question 17

Where does the anterior lobe (spinocerebellum) get projections from as its input? From what structure?

Answer 17

Input projections from spinocerebellar, cuneocerebellar, & trigeminocerebellar tracts → inputs via inferior cerebellar peduncle

Question 18

What is the main role of the anterior lobe (spinocerebellum)?

Answer 18

Proprioceptive info of stereotyped movements ( repetitive and predictable body movements)

Question 19

What parts/areas of the cerebellum are responsible for the trunk/head & the distal limbs?

Answer 19

Vermis controls trunk/head for vermis and paravermal zone controls, distal limbs

Question 20

Where does the posterior lobe (cerebrocerebellum) receive its inputs from?

Answer 20

Received pontocerebellar fibre inputs via middle cerebellar peduncle

Question 21

Where does the posterior lobe (cerebrocerebellum) project to?

Answer 21

Projects via superior colliculus back to cortex and other brainstem areas

Question 22

What is the role of the posterior lobe (cerebrocerebellum)?

Answer 22

Information about planned and ongoing voluntary non-stereotyped movements​ (e.g reaching for an object, writing, dancing)

Question 23

What are most inputs to the cerebellum coming in as? What do they release? Are they excitatory or inhibitory?

Answer 23

Most inputs to cerebellum are MOSSY FIBRES releasing GLUTAME → excitatory

Question 24

Explain the direct & indirect path of mossy fibres that leads to output.

Answer 24

Direct: synapses w/ deep cerebellar nuclei for EXCITATORY output
Indirect: synapse onto Purkinje (& other) cells in cortex, then synapses onto nuclei to INHIBIT output

Question 25

List the major input, cerebellar cortical zone(s), deep nuclei involved, & descending system(s) for the ANTERIOR LOBE (SPINOCEREBELLUM)

Answer 25

Major input: spinal cord Cerebellar cortical zones: vermis & paravermal Deep nuclei: fastigial (vermis) & interposed (paravermal) Descending systems: medial (vermis) & lateral (paravermal)

Question 26

List the major input, cerebellar cortical zone(s), deep nuclei involved, & descending system(s) for the POSTERIOR LOBE (CEREBROCEREBELLUM)

Answer 26

Major input: cerebral cortex Cerebellar cortical zone: hemispheric Deep nuclei: dentate Descending system: lateral & motor planning

Question 27

List the major input, cerebellar cortical zone(s), deep nuclei involved, & descending system(s) for the FLOCCULONODULAR LOBE (VESTIBULOCEREBELLUM)

Answer 27

Major input: vestibular receptors Cerebellar cortical zone: flocculonodular lobe Deep nuclei: vestibular nuclei Descending system: lateral( balance and posture) and medial ( control of neck muscles

Question 28

What are the two main destinations for outputs from the cerebellum?

Answer 28

1. Purkinje cells (to vestibular nuclei from flocculonodular lobe) 2. Deep cerebellar nuclei

Question 29

What are the components of the medial descending system, and what functions do they influence?

Answer 29

The medial descending system includes the reticulospinal and vestibulospinal tracts, which play a role in posture, balance, and muscle tone.

Question 30

How does the medial descending system connect to the oculomotor system?

Answer 30

The medial descending system has upward connections via the Medial Longitudinal Fasciculus (MLF) to the oculomotor system, which helps in coordinating eye movements.

Question 31

What does the lateral descending system consist of, and what functions does it primarily affect?

Answer 31

The lateral descending system includes the rubrospinal and lateral corticospinal tracts, which are involved in fine motor movements, particularly those related to distal limbs.

Question 32

Where does the primary output of the cerebellum go to? List the output projection path for it.

Answer 32

Ventrolateral nucleus of the thalamus → MI & PMC → corticospinal tract

Question 33

What layer are unipolar brush cells found in the cerebellum? Are they excitatory or inhibitory? What part of the cerebellum are they found in? What do they synapse with? What functions are they "possibly" responsible for?

Answer 33

Granular layer → excitatory Found in flocculonodular lobe & vermis → synapse w/ Golgi & granule cells Responsible for posture, eye movements, vestibuloocular reflexes

Question 34

What are the two structures that each deep cerebellar nuclei has projections to?

Answer 34

1. Inferior olivary nucleus (inferior olive) 2. Reticular formation

Question 35

Function of Anterior Lobe

Answer 35

Involved in motor planning, coordination of voluntary movements, through recieving proprioceptive information.

Question 36

Function of Flocculonodular Lobe:

Answer 36

Vestibular functions, including balance, spatial orientation, gaze stabilization, and coordination of eye movements during head motion.