Mental Workload Assessment During Upper Limb Prosthetic Training and Task Performance

Abstract

Mental workload, defined as the recruitment and allocation of cortical resources in response to task demands, is an integral underlying mechanism of cognitive-motor learning and performance. Although widely examined in individuals without motor impairment, the study of mental workload in a clinical context of motor rehabilitation is limited. In particular, it is not well understood how the cortical processes underlying mental workload adapt over time as individuals learn to operate upper-limb prosthetic devices. In this work, mental workload assessment using electroencephalography (EEG) along with other ancillary measurement tools were employed to examine the recruitment of cognitive-motor processes as individuals learned to operate either a body-powered (BP) or myoelectric (MYO) bypass prosthesis during a ten session upper limb prosthetic training program. The first two studies examined changes in mental workload and cognitive-motor performance as prosthesis users executed tasks requiring transport of objects with the same or different shape/size during a prosthetic training program. Then, these newly trained prosthesis users engaged in activities which manipulated contextual demands to examine how real-world scenarios affect mental workload and cognitive-motor performance. Finally, a preliminary validation of a novel mental workload self-report measure aimed to address the paucity of mental workload measurement tools in upper-limb rehabilitation was implemented. Although these four studies offer a rich and complex pattern of results, the main findings suggested that i) while both prosthetic groups experienced similar levels of cognitive-motor performance by the end of training, the BP group exhibited more refined cortical dynamics and better cognitive-motor efficiency when compared to the MYO group, thus indicating a more advanced progression of learning; ii) contextual demands degrade mental workload and cognitive-motor performance similarly in both prosthetic groups and; iv) the preliminary assessment of reliability and validity of the novel mental workload self-report measure shows promise for capturing changes in mental workload during cognitive-motor performance in a rehabilitation context. Although more research is warranted to confirm and extend the findings of this work to clinical upper-limb prosthesis users, this work has the potential to inform the cognitive-motor processes in this population and inform prescriptive decisions for patient device selection, prosthetic device design and rehabilitation program development.