Cerebellum

Front 1

Cerebellum

Back 1

- movement modulation: rate, range, F, direction

- influence exerted ipsilaterally / bilaterally

- also potentially involved in learning & memory

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Back 2

Front 3

Cerebellar peduncles

Back 3

Superior (brachium conjuctivum):

-> midbrain (-> Red nu. & VL/VA, Thalamus, contralateral)

Middle (brachium pontis):

<- pons (<- CC)

Inferior (restiform body):

<-> medulla & SC

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Front 6

Functional subdivisions of cerebellum

Back 6

Flocculonodular l. = Vestibulo/archicerebellum

<- vestibular fxn: balance, eye stabilization during head movement

Vermis + Intermediate zone = Spinocerebellum

<- SC: m. tone & movement adjustement

Cerebro/ponto/neocerebellum

<- pons <- contralateral CC: planning, initiation, learning of new movements; cognitive fxns

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Back 8

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Back 9

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Front 12

Cerebellar cortical cells

Back 12

- all cells use GABA (exc. granule cells: Glu)

- Purkinje cell axons = the only cortical output

-> deep cerebellar / vestibular nucleus

- granule cells (most abundant in brain) -> PC

- Mossy fiber = cerebellar input -> granule cells

- Climbing fiber = direct PC input <-inferior olive

- Golgi, basket & stellate cells: inhibitory IN's

Front 13

Cerebellar circuits

= inhibitory sculpting

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Front 14

Synaptic plasticity

Back 14

- parallel fibers -> PC's ~ plastic

- short-term & long-term plasticity & synapses

- effect on PC's: climbing fiber >>> parallel fibers

- parallel+climbing(error)=>synaptic depression

-

Front 15

Synaptic depression

Back 15

- parallel fibers ~ Glu -> AMPA & mGluR on PC

- climbing fibers = error message: Asp

-> PC excitation & Ca channels open -> ↑ Ca

-> PKC --| AMPA: (Pi) & ↓#

=> if parallel fiber active simultaneously

-> weakened

[example: VOR, vestibulo-ocular reflex gain Δ]

Front 16

Vestibulocerebellum

Back 16

<- inferior peduncle <- vestibular apparatus & nu (ipsilateral)

- regulates balance & eye reflex movements

PC's -> inferior peduncles (directly)

-> vestibular nuclei -> vestibulospinal tracts

=> cerebellar regulation of postular movements, VOR

Front 17

VOR (Vestibulo-ocular reflex)

Back 17

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Front 19

Spinocerebellum: input & processing

Back 19

<- inferior peduncle <- SC (spinocerebellar pwy's)

- adjusts ongoing movements & controls m. tone (proprioceptive/visual/auditory, ipsilateral)

- somatotopic organization: vermis ~ trunk mm., intermiediate zones ~ limb mm.

Front 20

Spinocerebellum: output from vermis

Back 20

vermis -> fastigial nucleus

-> inferior c. peduncle -> brain stem (bilateral): vestibular nuclei, reticular formation

=> modulates descending pwy's -> axial mm. (vestibulospinal/reticulospinal tracts; head/eye)

-> superior c. peduncle -> thalamus -> motor C

=> corticospinal/corticobulbar tracts; axial, face

Front 21

Spinocerebellum: output from intermediate zone

Back 21

intermediate zone -> interposed nuclei

-> superior c. peduncle (decussation)

--> red nuclei

--> VL, thalamus -> motor C

=> modulates limb mm. control (rubrospinal/lateral corticospinal tracts)

[tracts decussate => ipsilateral control]

Front 22

Cerebrocerebellum: input & processing

Back 22

<- middle cerebellar peduncle

<- pons (transverse pontine fibers, decussate)

<- CC (sensory/motor/association C

[corticopotine tract]

- planning & initiation of skilled movements, learning (voluntary)

Front 23

Cerebrocerebellum: output

Back 23

cerebrocerebellum -> dentate nucleus

-> superior c. peduncle (decussate)

--> VL, thalamus -> motor/premotor C (dentothalamic fibers)

=> affects corticospinal/corticobulbar tracts -> modulates complex movements

--> red nucleus -> inferior olive (dentatorubral fibers) -> inferior c. peduncle (=> learning fb)