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Exploring Cerebellar Functions: Anatomy, Pathways, and Impacts on Motor Control

Dive into the intricate world of cerebellar functions, including its anatomy, principal pathways, and role in motor learning, cognition, and emotions. Understand how the cerebellum influences motor pathways and cognitive processes, and explore its divisions and functions in detail.

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Exploring Cerebellar Functions: Anatomy, Pathways, and Impacts on Motor Control

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  1. Cerebellum John H. Martin, Ph.D. Center for Neurobiology & Behavior Columbia University

  2. Cerebellar Signs Hypometria & Response delays Ataxia Incoordination/rapid alternatingmovements(disdiadocho-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)

  4. 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

  5. Intent Exerts influence at all levels Actual Motor Hierarchy 1° Som sensory

  6. Cerebellar Functional Anatomy

  7. Cerebellar Cortex Deep Cerebellar Nuclei: Dentate Interposed Fastigial Cerebellar Anatomy PNS Fig. 42-1

  8. + Cortex + - Nuclei + Output Extrinsic inputs: mossy fiber climbing fiber Input-output Organization Deep Cerebellar Nuclei: Fastigial Cerebellar cortex Interposed Dendate Vestibularnuclei NTA Fig. 13-2,4

  9. Spinocerebellum: Vermis Intermediate hem. Spinocerebellum (Vermis + Intermed. Hem) Cerebrocerebellum: Lateral hem. Control of limbs and trunk Cerebrocerebellum (Lateral hemisphere) Planning of movement+ Vermis Vestibulo-cerebellum (Floculo-nodular lobe) Intermediate hem. Lateral hem. Control of eye & head movements Balance Floculo-nodular lobe Cerebellar divisions IVth vent NTA Fig. 13-1

  10. Cerebellar Cortex Inputs Climbing fibers•from Inferior olive Mossy fibers Output Purkinje neurons Interneurons Granule neurons Stellate neurons Basket neurons Golgi neurons Molecular Purkinje Granular NTA Fig. 13-11

  11. Without inhibitory circuits With inhibitory circuits Inhibitionreduces size of active Purkinje neurons = Lateral inhibition Output morefocused; moreprecise Parallel fiber input to cerebellar cortex

  12. Functional divisions of cerebellar cortex --> Deep nuclei Cbm unfold PNS Fig. 42-2

  13. Spinocerebellum Vermis Intermediatehemisphere CerebrocerebellumLateral hemisphere Inter posed Dentate Fastigial Vestibulo-cerebellum To frontalmotor areas To lateral sysetms To medial sysetms To vestibular nuclei Motor Planning +++ Eye mvt & balance Functional divisions of cerebellar cortex --> Deep nuclei Spinocerebellum Vermis Intermediate hem CerebrocerebellumLateral hemisphere Vestibulo-cerebellum Floculo-nodularlobe Motor execution PNS Fig. 42-3 NTA Fig. 13-1

  14. Medial & lateral systems Interposed nuclei Fastigial Vestibulocerebellum via vestibular nuclei NTA Fig. 10-2

  15. 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 Ipsilateral Bilateral

  16. Functions of the Cerebellum • Motor learning/adaptation • Non-motor functions: • Active tactile exploration • Higher brain functions (cerebellar cognitive-affective syndrome)

  17. MotorLearning Before Before Prisms Prisms After After PNS Fig. 42-15

  18. Non-motor Function Passive stimulation Discriminate roughness Manipulate only Manipulate + discriminate PNS Fig. 42-14

  19. 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

  20. 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

  21. 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

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