App - Deafferentation

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Iowa State University *

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372

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Mechanical Engineering

Date

Dec 6, 2023

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docx

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Uploaded by MegaAlbatross1904

APP 6: Chronic Deafferentation (I.W. And C. F) and Integration I’ve uploaded parts of a BBC documentary on Ian Waterman. This is the ONLY person alive who is deafferented AND can walk. He is absolutely amazing. These two segments last about 30 minutes. It is fascinating to hear him talk about how he taught himself to move, and how he worked and worked to try to make his actions look "normal." However, he does not do this in a normal manner. He must use CONTROLLED PROCESSING all the time. Watch the video, work through the questions below (these answers need not be submitted, but working through them will help you complete the last question – the last question (on the next page) will be the answer that will be assessed. and submit online by 11:30 Thursday eve. Bring a hard copy of your work on Friday to class. Background: IW and CF – both became deafferented after being infected by a virus, attacking their dorsal root ganglia. IW has sensation in neck; CF has no sensation from the neck down. IW became deafferented at age 19 – and decided not to be dependent upon his mother for the remainder of his life. Thus, he worked for two years almost exclusively to regain motor control. IW’s movement ability is similar to an Olympic athlete – he has honed and continues to constantly work at maintaining his skill level. CF became deafferented at approximately age 45. He could still carry on in his business from home at his present level of disability, and has a wife who helps to care for him. Thus, motivation, desire and age (?) may be working against a recovery similar to IW’s (and possibly lack of proprioception in his neck) During video note: CF can maintain posture on hands and knees CF can walk with the aid of a therapist CF can button (but note placement of fingers) and connect paper clips (note use of fingers) IW can walk unaided – how??? What strategies does he use? IW can connect paper clips IW can move arm/hand without the jerkiness Questions to discuss What kind of closed loop control does IW utilize? What kind of open loop control does IW utilize? What has IW mastered to accomplish his motor control? How does he manage to move the way he moves? What do IW’s accomplishments tell us about central representation? Integrate vision and vestibular function into the discussion – What is the role of optic flow? feedforward vision? visual feedback? tau? How well do you think IW could catch a ball? What are specific limitations? How do we use vision for catching? How do we use proprioception?

You only need to submit your answer to this question What has IW mastered to accomplish motor control – i.e., how does he manage to move the way he moves? Address closed-loop control, open loop control, attention, and central representation in a couple of paragraphs. No more than 1 page double-spaced. Underline any key terms from above that you use. Ian is an astounding case of deafferentation. To be able to actually appear “normal” and move his muscles and appendages with what appears to be ease is actually quite a taxing ordeal that takes more attention than one could imagine. If we think about what open and closed loop control are first, we can better understand how Ian has mastered motor control. Open loop control is ballistic and fast. It also runs in a preset way. Ian has lost this control over his body. Instead, Ian has to constantly rely on closed-loop control . His movements are slower and are feedback- dependent all the time. If he doesn’t get that visual feedback for his body, he is unable to successfully perform a simple task like going grocery shopping as shown in the video. Though I mentioned that Ian may have lost his open loop control for simple motor skills, having his eyesight unhindered could maybe allow his brain to work in a preset way with practice and time. A sort of plasticity if you will where the brain needs to activate different neurons in order to keep that focus. It appears Ian has gained control over his body because of his high attention demand. Because he has lost that open-looped control, he must rely on thinking about every movement, all the time, in order to have an appearance of proprioception. Kinesthesis is out of the picture for Ian as he has to rely on his vision in order to move. Without it, as mentioned, above, Ian is unable to perform simple motor functions. This is demonstrated towards the end of the video when he was asked to gesture without looking at his hands. The impulse was there, yet the execution was lacking. Because Ian has his vision to rely on, the focus demand is beyond what most people can imagine. In the video, they state that to be able to control every movement manually and without any automaticity takes almost an obsessiveness of focus and determination. This focus and conscious thought is an extreme use of controlled processing (“attention”) . Because of the need to perform serial movements to complete a task, One could argue that Wicken’s theory is more accurate than Kahneman’s since Wicken argues that there are multiple pools of attention. If there was one attention pool being used like Kahneman argues, then Ian would be drained easily. Though the attention demands are still incomprehensible to most people, having multiple pools of attention would allow Ian to dip his brain into those different pools at a time rather than stealing from one pot for all movements.

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