Reach-to-grasp tasks have become popular paradigms for exploring the neural origin of hand and arm movement. This is typically investigated by correlating limb kinematic with electrophysiological signals from intracortical recordings. However, it has never been investigated whether reach and grasp movements could be well expressed in the muscle domain and whether this could bring improvements with respect to current joint domain-based task representations. In this study, we trained two macaque monkeys to grasp 50 different objects, which resulted in a high variability of hand configurations. A generic musculoskeletal model of the human upper extremity was scaled and morphed to match the specific anatomy of each individual animal. The primate-specific model was used to perform 3-D reach-to-grasp simulations driven by experimental upper limb kinematics derived from electromagnetic sensors. Simulations enabled extracting joint angles from 27 degrees of freedom and the instantaneous length of 50 musculotendon units. Results demonstrated both a more compact representation and a higher decoding capacity of grasping tasks when movements were expressed in the muscle kinematics domain more than in the joint kinematics domain. Accessing musculoskeletal variables might improve our understanding of cortical hand-grasping areas coding, with implications in the development of prosthetics hands.
This project provides OpenSim models for characterizing the musculoskeletal kinematics in the primate hand.
The project aims to investigate and characterize the complex function of the primate hand at the musculoskeletal level. The OpenSim models used in this project enabled extracting joint angles from 27 degrees of freedom as well as length of 50 musculotendon units in the hand and upper extremity. Results demonstrated both a more compact representation and a higher decoding capacity of grasping tasks when movements were expressed in the muscle kinematics domain than when expressed in the joint kinematics domain. The OpenSim models in the project were adapted from the upper extremity model by Holzbaur et al., Ann.Biomed. Eng., 2005.
The project provides two primate-specific OpenSim models. These characterize all degrees of freedom in the hand and can be used for reconstructing accurate musculoskeletal hand kinematics. The OpenSim models are adapted from the upper extremity model by Holzbaur et al., Ann.Biomed. Eng., 2005.See all Downloads