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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