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Background: Lemniscus (Latin lēmniscus, ribbon) is a strap of second order nerve fibres which twist as they ascend to the brainstem.


Why do these these nerve fibres rotate? What could be the functional significance of such rotation?

I think that rotation is somewhat less beneficial because firstly it causes increase in length thereby increasing the conduction time , secondly it may decrease structural integrity of such a bundle of axons.

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  • $\begingroup$ Why downvote???? $\endgroup$ – JM97 May 9 '17 at 15:30
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    $\begingroup$ I didn't downvote, but I think you are overestimating the amount of twisting that occurs, it isn't going to affect length substantially. If you mean the quarter-turn twist that makes caudal inputs turn lateral and rostral inputs turn medial then indeed this is a very minor twist. Not everything in biology is significant in terms of function, often things are significant for development; a slight twist might help to coalesce the fibers. I'd also say that the structural integrity argument makes no sense, think about how a rope is constructed via twisting smaller fiber strands for strength. $\endgroup$ – Bryan Krause May 9 '17 at 15:45
  • $\begingroup$ Okay. Does this make any functional significance just like decussation? $\endgroup$ – JM97 May 9 '17 at 15:54
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    $\begingroup$ It is probably relevant for the orientation of the homunculus in, for example, the VPL of the thalamus, but I think it's more an issue of it being important that there is a spatial organization of the fibers, rather than any particular orientation being important. $\endgroup$ – Bryan Krause May 9 '17 at 16:10

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