Noise Correlations in Primary Motor Cortex are Modulated by Reward during a Grip Force Task

Reinforcement-learning brain machine interfaces could reduce the number of times a neural prosthesis has to be updated daily for individual use. This can be achieved by using reward signals that are present in cortical neural activity but firing rates have been shown to be varied across trials, even if the same stimulus is being presented. This trial-to-trial variability, also known as noise correlation, is shared across a neuronal population and has been shown to be modulated by attention, learning, and behavior. To investigate this the current study performs a noise correlation analysis using data recorded from the primary motor cortex (M1) of two rhesus monkeys performing a grip force task (GFT). It is seen that the noise correlation generally increases with the presentation of a rewarding cue. The results also suggest a stimulus dependence as well as independence to changes in firing rates.