Real-time estimation and biofeedback of single-neuron firing rates using local field potentials

The long-term stability and low-frequency composition of local field potentials (LFPs) offer important advantages for robust and efficient neuroprostheses. However, cortical LFPs recorded by multi-electrode arrays are often assumed to contain only redundant information arising from the activity of large neuronal populations. Here we show that multichannel LFPs in monkey motor cortex each contain a slightly different mixture of distinctive slow potentials that accompany neuronal firing. As a result, the firing rates of individual neurons can be estimated with surprising accuracy. We implemented this method in a real-time biofeedback brain–machine interface, and found that monkeys could learn to modulate the activity of arbitrary neurons using feedback derived solely from LFPs. These findings provide a principled method for monitoring individual neurons without long-term recording of action potentials.
The use of local field potential (LFP) brain signals may allow development of more efficient and robust neural prosthetic devices. Here, Hall et al. develop a method for estimation and biofeedback control of single-neuron firing rates using signals extracted from multiple low-frequency LFPs.