Movement discrimination based on rat primary motor cortex responses

Intra-cortical recordings from the primary motor cortex (M1) in rat and monkey have shown to provide enough information to control a robotic arm [1;2]. However, the neural signal encoding may vary with both the functional and behavioral context of the intended motion. The objective of the present work was to investigate if different movements could be discriminated based on intra-cortical M1 recordings in freely moving, non-constrained rats performing self-paced movements. Four rats were chronically implanted with 16-channel tungsten micro-wire arrays. We first verified that the neurons encoded either forelimb movement (arm), neck and head (neck) or both (arm & neck). We recorded M1 responses while the rats performed one of two behavioral tasks (depressing a response paddle with or without restrictive bars). We compared the neural activity up to 200 ms before a paddle hit. ANOVA comparison of the pre-paddle activity showed a statistically significant neural firing difference between the two behavioral tasks. Using principle component analysis it was possible to clearly distinguish between the two behavioral tasks in neurons encoding either 'arm' or 'neck' movement. Future work will include the use of artificial neural networks to decode information about repetitive paddle events, with the aim to predict the movement intent in real-time.