CEREBELLAR FUNCTION

1. CEREBELLAR FUNCTION NBIO 401 Robinson

2. Objectives: • There are 6 signs of cerebellar damage. For each sign accurately describe: • what part of the cerebellum is damaged to cause that sign • the characteristics of that sign • for the motor learning deficit, the last sign we describe, the proposed mechanism by which the cerebellum learns new sensory-motor associations.

3. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

4. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

5. 1) postural instability Static (while standing) instability is evident when a patient cannot maintain a stable posture in some or several parts of her body (e.g., limbs, trunk, head, or eyes) while trying to stand still. When you ask such a patient to stand with her eyes closed and her arms raised, her body will sway and she will wave her arms. This is called the Romberg sign. vestibulocerebellum

6. 1) postural instability Dynamic (moving) instability occurs when the patient has trouble holding a stable posture while walking. Such a patient will exhibit cerebellar ataxia, i.e., a staggering gait with feet placed widely apart, and a difficulty walking in a straight line. Cerebellar ataxia will make a patient's gait look like she is drunk. vestibulocerebellum

7. Ataxic Gait - Simulated

8. Ataxic Gait - Real

9. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

10. 2) delayed movement start/stop Patients with this problem will be slow to start and stop movements. For example, when you ask such a patient to walk across the room, she will be slow to start and will have trouble stopping. In extreme cases someone else will need to stop her. neocerebellum

11. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

12. 3) deficit in performing continuous, repetitive movements Patients with this problem, called dysdiadochokinesis, have a hard time doing rapidly alternating movements. For example, in a commonly used diagnostic test, you can ask a patient to tap one hand on the other while rapidly alternating which surface of the target hand, palmar or dorsal, the patient taps. A patient with lateral cerebellar damage cannot do this task rapidly. She will not rotate the target hand completely and will not coordinate these rotations very well with the taps of the other hand. neocerebellum

13. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

14. 4) movement dysmetria Dysmetria (wrong movement size) can occur in different movements after damage to any region of the cerebellum. Movements that are usually fast and accurate, such as rapid reaching or a rapid eye movement to a target, overshoot or undershoot their targets. A patient with cerebellar dysmetria may reach for something, overshoot, reach back, overshoot that movement and so on, so that her hand oscillates around the target. Paleo- or neocerebellum

15. Signs of Cerebellar Damage in Limb Movements NORMAL CEREBELLAR DAMAGE (which side?)

16. Signs of Cerebellar Damage in Limb Movements NORMAL CEREBELLAR DAMAGE (which side?)

17. Signs of Cerebellar Damage in Limb Movements NORMAL CEREBELLAR DAMAGE (which side?)

18. Signs of Cerebellar Damage in Limb Movements NORMAL CEREBELLAR DAMAGE (which side?)

19. Ataxic Arm Movement (On which side is the damage?)

20. Signs of Cerebellar Damage in Eye Movements normal bilateral cerebellar damage

21. Signs of Cerebellar Damage in Eye Movements normal bilateral cerebellar damage

22. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

23. 5) movement decomposition A patient with a large cerebellar lesion cannot smoothly execute movements that require several simultaneous joint rotations. Such a patient will rotate one joint at a time in sequence. Paleo- or neocerebellum

24. Six signs of cerebellar damage • postural instability (static & dynamic) • delayed movement start/stop • deficit in performing continuous, repetitive movements • movement dysmetria • movement decomposition • motor learning deficit

25. 6) motor learning deficit This apparent function of the cerebellum has attracted a great deal of attention from scientists because it represents a variety of learning, a phenomenon that everyone wants to understand in any form. We will discuss three examples in animals. Paleo- or neocerebellum

26. The Network of Neurons in the Cerebellar Cortex

29. (complex spikes) (simple spikes)

30. Proposed Mechanism for VOR Adaptation

31. Surgical Method for Causing Adaptation of Saccade Size

32. Causing Adaptation of Saccade Size by Manipulating Target Movement

33. Saccade eye position record

34. Example of Saccade Adaptation Caused by Target Movement

35. the end