Description: Segment 1 Wall begins by referring to a 300-year-old diagram from Descartes depicting the classical pain mechanisms. This shows three stages: injury, nerves detecting the injury and then conduction this information to the central nervous system. However, Wall explains that this does not explain unusual occurrances such as injury without pain and pain with only minor or unseen injury. Secondly, the early diagram also doesn't fit with more recent knowledge about anatomy, physiology and pharmacology. Thirdly, the diagram doesn't leave many opportunities for dealing with or treating pain. Time start: 00:00:00:00 Time end: 00:04:02:00 Length: 00:04:02:00 Segment 2 Wall elaborates on the second problem with Descartes' pain model. He refers to a diagram showing the most basic possible model of a pain pathway, then photographs and diagrams showing more complex alternatives from a cellular basis. He uses these to isolate and label many types of cell from the spinal cord which respond to injury. Time start: 00:04:02:00 Time end: 00:10:26:00 Length: 00:06:24:00 Segment 3 Wall refers back to his original most simple diagram of pain and adds to it. He discusses the 'referred pain', pain that results from an injury in a different location to where it is perceived as emanating from. He shows a diagram illustrating the pattern of referred pain. Time start: 00:10:26:00 Time end: 00:15:05:00 Length: 00:04:39:00 Segment 4 Wall adds more information to his earlier diagram of a basic pain model. This time he adds to it with factors which might work to inhibit the perception of pain. Wall describes how, when we feel pain, we might scratch or rub the area and how this might distribute the sensation into a larger area, thus dulling the intensity of the pain. Time start: 00:15:05:00 Time end: 00:21:12:00 Length: 00:05:21:00 Segment 6 Wall summarises the lecture by going back over each detail that was added to his basic pain model diagram, recapping each point made along the way. Time start: 00:26:30:00 Time end: 00:30:05:07 Length: 00:03:35:07