Haptic Interfacing in Animal Behavioral Systems: Implications for Motor Rehabilitation

Parameters such as speed, position, movement direction, and force have been reported to independently and dependently alter neural activity in the motor cortex (M1). Many types of animal behavioral tasks have been designed to associate these desired kinematic or spatiotemporal parameters with M1 neural activity. However, to date, minimizing undesired movement variation of animals performing behavioral tasks has not been achieved. Moreover, behavioral systems to date have not been utilized on overtrained animals in order to study the effects of a learned behavior on M1 activity prior to, and following, motor cortical injury. Haptics interfacing, a platform commonly used in human motor retraining, affords adaptability to independent changes in targeted kinematic or dynamic parameters with relative ease; thereby encouraging movement repeatability. This platform was used in a novel animal behavioral-brain-machine interface (BMI) to inhibit undesired movement variation. Utilization of a haptics system as an animal behavioral-BMI in a preliminary pre-to post-stroke study has shown task performance repeatability, in addition to revealing that the threshold for neural activity baseline deviation increases in response to change in neural behavioral-influencing parameters as a result of performing a learned behavior. Additionally, neuronal excitability in the M1 following focal cortical infarction showed dependence on location relative to the site of infarction. Further studies are needed in overtrained animals prior to M1 injury to observe the neural response to a learned behavior, in order to gain a better understanding of M1 activity stability. Furthermore, future studies in overtrained animals following M1 injury are needed, and should focus on observing changes in neuronal excitability, relative to location from infarct site, in order to improve localized treatment methods for motor rehabilitation.