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Going back to knowledge and skills when it comes to Dementia. Neuroscience is still bewildered by the fact that some can have the knowledge of an item but not have the skill to “use” that item. They believe that that knowledge is still there about an item, a book, a thought, but the ability to carry on that knowledge through action or speak is not there. The best example I observed through my research on dementia was the watering can. In response to “Tell me all about this object.” You would expect things like: it’s metal, you put water in it and water the plants. Then in response to “demonstrate how to use it” you expect, picking it up by the handle and making a pouring motion. In some patients the description is right on, but the action is not achieved. So goes the opposite in other patients who can’t find the name but show the action. These results show two separate subsystems of learned representations: object semantics vs. action semantics. This could explain why some of us have commented about things like…he had used the remote and know how it works…now he can’t, but can tell me how to work it…. OR He knows it’s the remote but won’t use it…it’s not that he won’t he simply can’t get that functionality out of it. The knowledge of what it is and what it is used for is there but the “how to” is not or the opposite the “how to” is there but the object is not named in the mind. So in the tests that those of us deal with every doc visit, the results could vary depending on which area of the brain is affected and how the doc perceives the test scores. I know one of the usual things they do is point at an object and ask for it to be named; pen, shoe or watch. These items; if there is “object semantics” issues, may be named but using them may not be known, while the action semantic issues may not know the item, but can use that item. These findings are temporal lobe related as they deal with mechanical abilities. An alternative view is that the preservation of the “actions”, with degraded concept knowledge of the object may get a different neural response by visual or tactical triggers. In this view, there may be dorsal–visual processing issues, or the action of the brain in its guidance of actions and recognition of where those items are in space. This view also is proposed to be the cause of apraxia. We have to remember, especially with PD, that the signals are crossed. The transmitters sending signals out from the brain are “incorrect” to begin with, so it is no wonder that most PD patients deal with these issues. SO...in closing this part, in some cases of dementia, the knowledge is there, but the skill to use that knowledge may be gone. OR…the skill to use that knowledge is there, is triggered, but the knowledge itself of that action is not. |