A Computational And Experimental Study To Determine A Temporal Issue In Voluntary Movement

Every movement takes some time,but there is not a clear answer of how does brain determine the movement duration.There are hitherto two distinct principles proposed.One is finite-horizon optimal control,in which a movement duration is predetermined and then movement is optimized during that duration.The other is infinite-horizon optimal control,in which movement duration is not predetermined and movement is optimized over infinite movement period.Although whether movement is optimized over a finite or infinite period sounds a technical problem,it has an implication to a question of whether the brain predetermines a movement duration or not.We therefore compared predictions of these models in detail and tested those predictions in a behavioral experiment.A key difference between predictions of finiteand infinite-horizon control models lies in the difference in gains of Kalman filter and feedback control.Infinite-horizon models predict time-invariant gains whereas finitehorizon models predict time-variant.Experiment result is inconsistent with infinite-horizon control.To fit the experiment data by finite-horizon control,we tuned the parameters.We made a database which contains 1000 different parameters units,even though we can fit the order of the curves,the shape is quite strange in those certain values.The optimal feedback control has so many degrees of freedom,it is impossible to go over all the possible parameters.The movement duration problem is not settled yet,further research may consider finding more appropriate way to tune the parameters.