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Cerebellum

Little brain Midline vermis

Paravermis 2 hemispheres

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Cerebellum

TonsilsPart of the posterior

lobe

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Cerebellum - Structure

Graymatter

Whitematter

Tree of life

Folia orleaves

Gyri

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Deep Cerebellar Nuclei

Dentate Emboliform

Globose Fastigial

Dont Eat GreasyFood

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Cerebellar Lobes

2 fissures: anterior & posterolateral 3 lobes: anterior, posterior,

flocculonodular

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Cerebellar Lobes

2 fissuresAnterior

Posterolateral

3 lobes

Anterior

Posterior

Flocculonodular

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Longitudinal Divisions

VermisFastigial nucleus

Paravermis

Emboliform

Globose

Hemisphere

Dentate

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Functional Divisions Vestibulocerebellum

Flocculonodular lobe Vestibular and reticular nuclei Body equilibrium and eye movements

Spinocerebellum Anterior lobe

Spinal cord Axial and limb movements: walking, swimming

Cerebrocerebellum Posterior lobe

Cerebral cortex

Planning and initiation of movements Regulate discrete limb movements

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Microscopic Structure Cerebellar Cortex

3 layers Outer molecular

Basket cells

Stellate cells

Middle Purkinje cell layer

Purkinje cells

Projection neurons.

Innermost granule cell layer

Granule cells

Golgi cells

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Cerebellar Cortex Neuronal Types

Purkinje cell Large dendritic tree

1 axon

Deep cerebellar nuclei Lateral vestibular nucleus

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Cerebellar Cortex Neuronal Types

Basket cell next to Purkinje cells. Synapses: dendrites, soma, axons of Purkinje

Stellate Synapses: dendrites of Purkinje

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Cerebellar Cortex Neuronal Types

Golgi (Type II) Cell

Axon forms part of the glomerulus

Axonal arborization

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Cerebellar Glomerulus

Mossy Fiber Incoming cerebellar

input

Dendrites ofgranule cells

Axons of Golgi cells Dendrites of Golgi

cells

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Cerebellar Input

3 major inputs

Spinal cord

Vestibular system

Cortex Over half the neurons

in the brain are in the

cerebellum So theyre also smaller

than cortical neurons

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Spinal Input

Spinocerebellartract

Dorsal and ventral

Position & conditionof muscles,

tendons, and joints

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Vestibular Input

Vestibular nerve Vestibular nuclei

Body equilibrium

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Cortical Input

Cortex toPons

Inferior Olive

Then to Cerebellum

Planning & initiation

of movement

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Climbing Fiber System

Olivocerebellar tract Synapse on dendrites of Purkinje cells and

intrinsic cells (Golgi, basket, stellate)

Climbs dendrites of 1 Purkinje cell Powerful excitatory effect on *one*

Purkinje cell Less powerful on intrinsic neurons

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Mossy Fiber System

Branch out into terminal rosettesCenter of each glomerulus

Contacts 20 different granule cells

Diffuse and complex

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Climbing vs Mossy Input

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Intrinsic Cerebellar Circuitry

Output: deepcerebellar nuclei

Combination of

Excitatory mossy &climbing fiber input

Collateralprojections

Inhibitory input

from Purkinje cells

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Deep Cerebellar Nuclei OutputMajor output

Vestibular & reticular nuclei Nucleus fastigius

Red nucleus & inferior olive Interposed nuclei

Thalamus Dentate

Interposed nuclei Hypothalamus

all

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Dentate Nucleus

InputsLateral cerebellar

Purkinje cells

Climbing fibers

Mossy fibers

OutputsVentrolateral

nucleus of the

thalamus

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Fastigial Nucleus

InputsVermal Purkinje

cells

Climbing fibers

Mossy fibers

OutputsVestibular nuclei

Reticular nuclei

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Output by Peduncle

SuperiorThalamus

Red nucleus

Inferior Olive

Inferior

Vestibular nucleiReticular nuclei

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Cerebellar Functions Motor functions

Control and integration of motor activity

Motor learning & memory

Signs Asthenia gets tired easily

Ataxia trouble walking

Atonia poor muscle tone/coordination Problems in speed, range, force, or timing of

movement

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Motor signs (cont). Asynergia lack of coordination

Dysarthria slow, slurred speech Adiadochokinesis delay in initiating each movement

of a sequence

Dysmetria delay in termination of movement Hypermetria overshooting target

Hypometria undershooting target

Gait ataxia - staggering gait Unsteady standing

Nystagmus

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Cerebellar vs Basal Ganglia

Motor Functions

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Cerebellar Non-motor Functions

VisceralCardiovascular, endocrine, altered respiration,

intestinal motility, bladder tone

AffectiveReduced aggressiveness, mood changes

Through connections to reticular formation