Cerebellum

1
Cerebellum
John H. Martin, Ph.D. Center for Neurobiology
Behavior Columbia University
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Cerebellar Signs
Hypometria Response delays
Ataxia
Incoordination/rapid alternatingmovements(disdi
adocho-kinesia)
PNS Fig. 42-16
3
Research Points to Several Key Cerebellar
Functions

• Comparison of intent and action (ie., errors) and
  generates corrective signals
• Motor learning and adaptation
• Plays a role in automating and optimizing
  behavior
• Motor cognition and general cognition emotions
  (new evidence controversial)

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Goal Cerebellar function

• Overview of motor system hierarchy
• Cerebellar anatomy
• Principal pathways out of the cerebellum-- How
  the cerebellum impacts the motor pathways
• Experimental approaches to reveal
• Motor learning
• Mental processes underlying movement control
• Role in cognition and emotions

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Motor Hierarchy
1 Som sensory
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Cerebellar Functional Anatomy
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Cerebellar Anatomy
PNS Fig. 42-1
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Input-output Organization
Deep Cerebellar Nuclei
Fastigial
Cerebellar cortex
Interposed
Dendate
Vestibularnuclei
NTA Fig. 13-2,4
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Cerebellar divisions
IVth vent
NTA Fig. 13-1
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Cerebellar Cortex
Inputs
Climbing fibersfrom Inferior olive
Mossy fibers
Output
Purkinje neurons
Interneurons
Granule neurons
Stellate neurons
Basket neurons
Golgi neurons
Molecular
Purkinje
Granular
NTA Fig. 13-11
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With inhibitory circuits
Without inhibitory circuits
Inhibitionreduces size of active
Purkinje neurons
Lateral inhibition Output morefocused
moreprecise
Parallel fiber input to cerebellar cortex
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Cbm unfold
Functional divisions of cerebellar cortex --gt
Deep nuclei
PNS Fig. 42-2
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Functional divisions of cerebellar cortex --gt
Deep nuclei
Spinocerebellum
Vermis
Intermediate hem
CerebrocerebellumLateral hemisphere
Vestibulo-cerebellum Floculo-nodularlobe
Motor execution
PNS Fig. 42-3 NTA Fig. 13-1
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Medial lateral systems
Interposed nuclei
Fastigial
Vestibulocerebellum via vestibular nuclei
NTA Fig. 10-2
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Intermediate and Lateral Hemispheres
Vermis Vestibulocerebellum
Planning andlimb control
Thalamus and Cortical motor areas
Brain stem nuclei
Cerebellar cortex Deep nuclei
Brain stem nuclei
Axial control
PNS Fig. 42-10, 12
Bilateral
Ipsilateral
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Functions of the Cerebellum

• Motor learning/adaptation
• Non-motor functions
• Active tactile exploration
• Higher brain functions (cerebellar
  cognitive-affective syndrome)

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MotorLearning
Before
Before
Prisms
Prisms
After
After
PNS Fig. 42-15
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Non-motor Function
Passive stimulation
Discriminate roughness
Manipulate only
Manipulate discriminate
PNS Fig. 42-14
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Cerebellar Motor Functions

• Implemented via lateral and medial pathways,
  especially the corticospinal tract
• Incorporated into motor programs via frontal
  motor areas (SMA, premotor cortex)
• Becomes part of motor strategy via prefrontal
  cortex

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Cerebellar Cognitive Affective Disorder

• Lesions of the posterior cortex and vermis
• Impairment of executive functions
• Planning, verbal fluency, abstract reasoning
• Difficulties with spatial cognition
• Visuo-spatial organization, visual memory
• Personality changes
• Blunting of affect, inappropriate behaviors
• Language disorders
• Agrammatism

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Conclusions

• Cerebellar lesions produce
• Incoordination errors not weakness
• Lose ability to anticipate errors
• Lose ability to correct

• Motor learning
• Requires sensory awareness
• Implemented via the descending cortical and brain
  stem pathways

• Cognitive and emotional disturbances
• Anatomical connections to prefrontal and
  cingulate cortex (via thalamus)

• No single function
• Clearly mostly motor learning, optimizes
• Functions may apply to cognitive and emotional
  behaviors