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Modulation of Movement by the Cerebellum - Coggle Diagram
Modulation of Movement by the Cerebellum
The cerebellum doesn't project directly to spinal cord motoneurons.
It regulates upper motoneurons in the motor cortex >> involved in motor learning + if cerebellar deficit = impaired ML
Comprises cerebellar cortex and deep cerebellar nuclei.
Primary function: detect and correct motor errors, involving sensory-motor integration.
INPUTS:
Mossy fibers (from cortex and brainstem >> excitatory to Purkinje)
Climbing Fibers: from inferior olive >> exc. synapses onto Purkinje
PURKINJE CELLS = only output cells
Cerebrocerebellum:
Indirect input from various cerebral cortex areas.
Regulates highly skilled movements, e.g., planning and executing complex sequences like speech.
Spinocerebellum:
Direct input from the spinal cord.
Lateral part controls distal muscle movement, central part (vermis) regulates proximal muscles and some eye movements.
Vestibulocerebellum:
Oldest part.
Receives input from vestibular nuclei in the brainstem.
Involved in maintaining posture, balance, and the vestibulo-ocular reflex.
Cerebellar Communication:
Communicates through three cerebellar peduncles:
Superior Cerebellar Peduncle: Efferent pathway, projecting to upper motor neurons in motor cortex and superior colliculus.
Middle Cerebellar Peduncle: Afferent pathway with over 20 million axons from contralateral pontine nuclei.
Inferior Cerebellar Peduncle: Contains multiple afferent and efferent pathways.
Functional Organization of Inputs:
Cerebral cortex provides the largest input, reaching the cerebrocerebellum indirectly via ipsilateral pontine nuclei.
Vestibular and somatosensory inputs come through inferior cerebellar peduncle to vestibulocerebellum and spinocerebellum, respectively.
Functional Organization of Outputs:
Mediolateral organization: fastigial nuclei (medial) mediate axial and proximal muscles, interposed nuclei mediate limbs.
Somatotopic Rep
Somatosensory input is organized in topographic maps in the spinocerebellum.
Fractured maps represent each body area multiple times by spatially separated cell groups.
Projections from the Cerebellum
Most cerebellar cortex projections go to deep cerebellar nuclei before reaching the target.
Thalamus serves as a major relay target to the motor cortex.
Four major deep nuclei: dentate, interpositus (2), and fastigial.
Damage to the cerebellum:
Causes persistent errors in movement on the same side as the deficit.
Alcohol abuse can lead to anterior cerebellar damage and ataxia (difficulty coordinating movement).