PainElectric StimulationPain ManagementChronic PainPain ThresholdPain, PostoperativeLow Back PainBack PainPain MeasurementElectric Stimulation TherapyPain, IntractableAbdominal PainNeck PainPain PerceptionStimulation, ChemicalPelvic PainFacial PainDeep Brain StimulationPhysical StimulationAcute PainPain, ReferredTranscranial Magnetic StimulationShoulder PainMusculoskeletal PainTime FactorsTranscutaneous Electric Nerve StimulationCells, CulturedAnalgesicsRats, Sprague-DawleyNeuralgiaNociceptive PainSignal TransductionCalciumAnalgesics, OpioidCatsHyperalgesiaDose-Response Relationship, DrugChronic DiseaseElectrodes, ImplantedNociceptorsMuscle ContractionAction PotentialsPhotic StimulationCell LineMyofascial Pain SyndromesPhosphorylationSpinal CordTreatment OutcomeVagus NerveEnzyme ActivationAcoustic StimulationComplex Regional Pain SyndromesAfferent PathwaysNeuronsEvoked PotentialsAnalgesiaVisceral PainKineticsRats, WistarElectromyographyRNA, MessengerEvoked Potentials, MotorLymphocyte ActivationArthralgiaReflexNeurons, AfferentSynaptic TransmissionMice, Inbred C57BLIsoproterenolCyclic AMPNorepinephrineMotor CortexElectrophysiologyAnalysis of VarianceAtropineMuscle, SkeletalSympathetic Nervous SystemEvoked Potentials, SomatosensoryLabor PainNeural InhibitionSubthalamic NucleusAnesthetics, LocalSpinal Cord StimulationGene Expression RegulationSelf StimulationGuinea PigsDogsEnzyme InhibitorsReaction TimeElectrodesRabbitsMorphineTouchRats, Inbred StrainsProtein Kinase CSpinal NervesMotor NeuronsProspective StudiesFunctional LateralitySomatosensory Cortex