An implantable system for efficiently treating targeted pain in a patient by selectively delivering electrical stimulation to a target dorsal root ganglion, wherein the target DRG is connected between adjacent distal sensory nerve fibers and adjacent proximal sensory nerve fibers, the adjacent distal sensory nerve fibers propagating an electrical signal from a periphery of the patient toward the target DRG, and the adjacent proximal sensory nerve fibers propagating an electrical signal away from the target DRG toward a central nervous system of the patient, the system comprising: one or more implantable leads each having one or more electrodes; a pulse generator configured to generate electrical stimulation pulses that can be delivered to the target DRG via one or more electrodes of the one or more leads; sensing circuitry configured to obtain one or more signals; and a controller; characterized in that; the sensing circuitry, in order to obtain the one or more signals, is configured to use at least one of the one or more electrodes of the one or more leads to obtain at least one of (a.1) an input signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent distal sensory nerve fibers toward the target DRG; (a.2) an output signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent proximal sensory nerve fibers away from the target DRG; or (a.3) a DRG signal indicative of an electrical field produced by cell bodies of primary sensory neurons within the target DRG and resulting from an electrical signal propagated by sensory nerve fibers within the target DRG; and the controller is configured to analyze at least one of the one or more obtained signals, and in response thereto, at least one of (b.1) selectively turn on and off delivery of the electrical stimulation to the target DRG; or (b.2) adjust at least one of a pulse amplitude, a pulse width or a pulse repetition rate of electrical pulses that are used for delivering electrical stimulation to the target DRG. one or more implantable leads each having one or more electrodes; a pulse generator configured to generate electrical stimulation pulses that can be delivered to the target DRG via one or more electrodes of the one or more leads; sensing circuitry configured to obtain one or more signals; and a controller; characterized in that; the sensing circuitry, in order to obtain the one or more signals, is configured to use at least one of the one or more electrodes of the one or more leads to obtain at least one of (a.1) an input signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent distal sensory nerve fibers toward the target DRG; (a.2) an output signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent proximal sensory nerve fibers away from the target DRG; or (a.3) a DRG signal indicative of an electrical field produced by cell bodies of primary sensory neurons within the target DRG and resulting from an electrical signal propagated by sensory nerve fibers within the target DRG; and characterized in that; the sensing circuitry, in order to obtain the one or more signals, is configured to use at least one of the one or more electrodes of the one or more leads to obtain at least one of (a.1) an input signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent distal sensory nerve fibers toward the target DRG; (a.2) an output signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent proximal sensory nerve fibers away from the target DRG; or (a.3) a DRG signal indicative of an electrical field produced by cell bodies of primary sensory neurons within the target DRG and resulting from an electrical signal propagated by sensory nerve fibers within the target DRG; and (a.1) an input signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent distal sensory nerve fibers toward the target DRG; (a.2) an output signal indicative of an electrical field resulting from an electrical signal propagated by the adjacent proximal sensory nerve fibers away from the target DRG; or (a.3) a DRG signal indicative of an electrical field produced by cell bodies of primary sensory neurons within the target DRG and resulting from an electrical signal propagated by sensory nerve fibers within the target DRG; and the controller is configured to analyze at least one of the one or more obtained signals, and in response thereto, at least one of (b.1) selectively turn on and off delivery of the electrical stimulation to the target DRG; or (b.2) adjust at least one of a pulse amplitude, a pulse width or a pulse repetition rate of electrical pulses that are used for delivering electrical stimulation to the target DRG. (b.1) selectively turn on and off delivery of the electrical stimulation to the target DRG; or (b.2) adjust at least one of a pulse amplitude, a pulse width or a pulse repetition rate of electrical pulses that are used for delivering electrical stimulation to the target DRG.