1. A system, comprising: a wireless wrist-mounted user interface device configured to enable a user to control a function of a target component by finger and hand motions, the wireless wrist-mounted user interface device comprising: at least one pair of electrodes configured to be positioned adjacent to particular detection locations on the skin on top of a wrist of the user, each of the at least one pair of electrodes being configured to detect raw electrical potential that includes characteristics of electrical activity of (a) nerve tissue in the vicinity of the at least one pair of electrodes and (b) muscle tissue in the vicinity of the at least one pair of electrodes; signal processing electronics comprising: at least one filter configured to reduce amplitudes indicative of frequency components of the raw electrical potentials that are characteristic of the electrical activity of the muscle tissue in the vicinity of the at least one pair of electrodes and of noise so as to improve a signal-to-noise ratio of each of the raw electrical potentials; a threshold processor configured to process each of the filtered raw electrical potentials and configured to provide an output signal only when an amplitude of each of the filtered raw electrical potentials exceeds a threshold, and an analytical component configured to detect a differential signal between the output signals from the threshold processor and to use the differential signal to determine a direction of propagation of the electrical activity of the nerve tissue in the vicinity of the at least one pair of electrodes; a data processor comprising: storage containing historical information representative of known relationships between (a) features of data values generated from electrical potentials of nerve tissue previously detected by electrodes on wrists of users and (b) actions of particular muscles, gestures, or intent corresponding to the features of the stored data values, a generator configured to generate data values based upon the differential signal representing the activity of the nerve tissue, a feature extractor configured to extract features from the data generated by the generator, and a component inferring actions of particular muscles, gestures or intent of the user based on (a) the stored historical information representative of the known relationships and (b) the extracted features from the data values; and a controller configured to control the function of the target component based on the inferred actions of particular muscles, gestures, or intent.