Hypothetical interactions between two tasks

What do these observations say about the pathway of vllrH23D if simultaneous actions of the left hand influence the reaction time of vllrH23D. The two pathways must interact anywhere on their route, for example in the prefrontal cortex. The sensorimotor structure of the 2 finger tapping looks like  

This set system may work as a motor generator but it must influence the pathway of vllrH23D. The PFC contains two sensorimotor sets (SMS). These two SMS interact with each other in an unknown way. At the present time, only hypotheses can be made how the two task sets are coordinated with each other  

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