• primary motor cortex
• grasping
• monkeys
• neuroengineering
• motor control
• hand

The investigation of the role of the primary motor cortex (M1) in grasping movements is crucial for the development of advanced prosthetic devices and for enhancing our understanding of the neural basis of motor control. I addressed two primary research questions in this study. The first research question aimed to determine the type of information encoded by M1 during grasping movements. Specifically, whether M1 encodes information about the position, velocity, or muscle activity. The second research question focused on whether M1 encodes this information using single actuators or synergies. Synergies are coordinated patterns of joint motion or muscle activity that may simplify motor control by reducing the degrees of freedom that need to be controlled in grasping actions. To address these questions, experiments were conducted with a monkey performing a variety of grasping movements to obtain a broad range of movements. Encoding models considering different inputs were used and their performances were compared. Clustering techniques were also used to investigate whether synergies are a mechanism used by the central nervous system.
The study's results revealed that during grasping actions M1 encodes both EMG and position information but not velocity information. This conclusion it is in contrast with the neural response during reaching movements, which preferentially track velocity kinematics. Additionally, I found that single actuators are better encoded than synergies. This suggests that during grasping movements synergies do not appear to be the primary strategy adopted by M1 to simplify the motor control problem.