Systems and methods to simulate activity that would be recorded using an interface to nerve fibers are provided. Signals, such as motor intent signals, can be converted to neural recordings, such as neural recordings by longitudinal intrafascicular electrodes (LIFEs). Spinal cord motor pools and neural interfaces can be jointly simulated. Realistic simulated neural recordings, such as from electrodes such as LIFEs, can be provided and can be used for the evaluation of decoding algorithms. Systems and methods described herein provide a framework for developing neural interface devices.