1. Touch and pain Chapter 8 (cont.)

2. Somatosensation includes a variety of submodalities Fine touch pain temperature kinesthesis joint position muscle stretch interoception

3. Somatosensation involves a variety of receptors

4. Transduction usually involves stretch

5. Input from different receptors is carried by different fibres

6. Receptor specificity is carried into spinal cord

7. Input from different parts of the body is segregated into dermatomes

8. Somatosensory input ascends to cortex Ventral posterolateral nucleus of the thalamus

9. Submodality processing in cortex

10. Columnar organization in cortex

11. Barrel fields in rat cortex

12. Somatosensory agnosias Astereognosia – can’t recognize objects with hands Anosognosia – deny neurological symptoms Asomatognosia- deny ownership of body parts Neglect – neglect of left half of body and external world in grooming, drawing, etc.

13. The man who mistook his wife for a hat: The opera?

14. Pain is multifaceted

15. Pain transduction is chemosensory

16. Central pain pathways

17. Central pain pathways II

18. Descending control of pain

19. Endogenous opiates and pain control

20. More complicated pain phenomena Phantom limb pain –Suggests that one can experience pain without a transduction event Chronic pain syndromes –Sometimes pain persists in the absence of any evidence of trauma

21. Phantom limb pain Feelings of pain, pressure, burning in missing limb Walls’ theory does not account for facts very well Melzack hypothesizes that there is a complex ‘neurosignature’ that composes the perception of self

22. Merzenich and neural plasticity Following amputation, considerable re- arrangement of neocortex takes place

23. Merzenich (cont)

24. Vilayanur Ramachandran rearrangement of sensory cortex is responsible for phantom limb pain

25. Functional imaging of somatosensory cortex in a right limb amputee (From Ramachandran, 2000)

26. Possible treatment for phantom limb pain? Mirror imaging of limbs