1. An apparatus comprising: an ambulatory intrinsic brain signal processor circuit, configured to be coupled to a plurality of electrodes, the signal processor circuit comprising: a digital multiplexer circuit, configured to be coupled to the electrodes, and configured to multiplex brain signal data from different electrodes together into a multiplexed data stream; an ambulatory transceiver circuit, configured to wirelessly communicate information to a remote transceiver, and configured to wirelessly receive user-programming information from the remote transceiver; and a controller circuit, configured to permit a user to control: which of the electrodes contribute data to the multiplexed data stream; a data resolution of the electrodes that contribute data to the multiplexed data stream; and whether data contributed by a particular electrode includes a user-selected one of at least one of: (1) neural action potential data, from which neural field potential data has been reduced or removed; (2) neural field potential data, from which neural action potential data has been reduced or removed; and (3) both neural action potential and neural field potential data.