1. A neural interface system to receive a plurality of types of physiological activity signals from a prosthetic device user, decode a user movement intent from each of the plurality of signals types, and fuse the movement intents into a joint decision to control moveable elements of the prosthetic device, comprising: a plurality of classifier modules, each associated with a corresponding one of the signal types to determine a user movement state from signals of the signal type; a plurality of decode modules, each associated with a corresponding one of the signal types to decode a movement intent from signals of the signal type and from one or more of the user movement states; and a fusion module to fuse movement intents from a plurality of the decode modules into the joint movement decision; wherein the plurality of signal types include a combination of two or more of, a local filed potential (LFP) signal, a unit activity (spike) signal, an epidural electrocorticography grid (ECoG) signal, an electromyography (EMG) signal, an electroencephalography (EEG) signal, and an electronystagmography (ENG) signal.