Cerebellum

1. Cerebellum • More cells in cerebellum than rest of nervous system combined • Receives sensory info from somatosensory, vestibular, visual and auditory areas

2. 3 divisions of cerebellum • Vestibulocerebellum • Spinocerebellum • Neocerebellum • Different lesions produce different clinical deficits

3. Vestibulocerebellum • Input from & output to brainstem vestibular nuclei • For balance • For coordinating eye & body movements • Vestibulo-ocular reflex • Allows eyes to remain fixed on an object despite head or body movements

4. Vestibulocerebellum • Cerebellar nystagmus • Inability to fixate on object. • eyes drift away from it, with rapid return.

5. Vestibulocerebellum • Damage  decreased reflexes • Postural instability • Experience nausea

6. Spinocerebellum • Ascending sensory inputs via S.C. • Descending motor outputs • Damage  problems with smooth control of motor movements • Problems walking • Bowlegged stance

7. Spinocerebellum • Damage  rapid pointing often extends past target • Hypermetria • Damage  difficulty stopping movement • As arm approaches target, goes into oscillations

8. Neocerebellum • Control of voluntary movements

9. Neocerebellum • Damage leads to: • Clumsy movements • Hypermetria • Especially in sequences of gestures • Movements req. coordination of many body parts • Prolonged initiation of movements

10. Neocerebellum • Lesions result in deficits similar to spinocerebellum • Neocerebellum - planning movements • Spinocerebellum – regulating actual performance

11. Cerebellum • Alcohol may affect cerebellum • Sobriety tests often assess cerebellar functioning • Balance • Touching finger to nose