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Theories of pain.
Wall, Patrick D
Encoded moving images
Professor PD Wall presents a fascinating account of how the human body responds to pain. He begins his lecture by pointing out the most simple and obvious understanding of pain, exemplified by a diagram from Descartes, 300 years ago. Then, utilising a very simple model of this diagram, Wall starts from the basic assumption of a simplified pain system and gradually adds features which show the multi-layered complexity of a theory of pain.
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 5 Wall adds more features still to his original diagram of a basic pain model. This time he adds in messages that travel from the head to the sites of pain. These descending pathways can provide natural analgesic relief from pain and, if understood properly, might lead to a new class of narcotics being developed. Time start: 00:21:12:00 Time end: 00:26:30:00 Length: 00:05:18:00 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
Presented by Professor PD Wall, Department of Anatomy and Embryology, University College London. Produced by David Sharp. made for British Postgraduate Medical Federation. Made by University of London Audio-Visual Centre.
This video is one of around 310 titles, originally broadcast on Channel 7 of the ILEA closed-circuit television network, given to Wellcome Trust from the University of London Audio-Visual Centre shortly after it closed in the late 1980s. Although some of these programmes might now seem rather out-dated, they probably represent the largest and most diversified body of medical video produced in any British university at this time, and give a comprehensive and fascinating view of the state of medical and surgical research and practice in the 1970s and 1980s, thus constituting a contemporary medical-historical archive of great interest. The lectures mostly take place in a small and intimate studio setting and are often face-to-face. The lecturers use a wide variety of resources to illustrate their points, including film clips, slides, graphs, animated diagrams, charts and tables as well as 3-dimensional models and display boards with movable pieces. Some of the lecturers are telegenic while some are clearly less comfortable about being recorded; all are experts in their field and show great enthusiasm to share both the latest research and the historical context of their specialist areas.
The Scientific Basis of Medicine