Sources of dual-task interference in visuomotor tracking assessed with behavioral and fMRI analyses

Compensatory tracking was studied alone and simultaneous with a speeded go-no-go task using behavioral and neuroimaging with BOLD fMRI. In the dual-task condition, subjects used their right hand to track while making button presses with their left hand to respond to the secondary task. The study was replicated in two experiments. Replication was tested both behaviorally and with neuroimaging analyses using multivariate linear modeling. Tracking error and joystick velocity were binned into 640 ms and 100 ms intervals centered at secondary task stimulus onset and response in separate analyses to locate the time points at which the tracking behavior showed an interference effect due to the secondary task. Neuroimaging analyses located brain regions associated with compensatory tracking and with dual-task coordination. The binned time-series analyses revealed interference effect in joystick velocity about 200 ms before secondary task response. This finding combined with decreased activation in the left motor cortex during left hand response to a secondary task demonstrated that dual-task interference occurred in the motor preparation stage.