Pacemaker, ArtificialBiological ClocksSinoatrial NodeBrain ChemistrySick Sinus SyndromeBrain InjuriesHeart BlockBrain NeoplasmsEquipment FailureAtrioventricular BlockBrain MappingBradycardiaHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsBrainCircadian RhythmBrain StemElectrodes, ImplantedBrain EdemaNeuronsInterstitial Cells of CajalSuprachiasmatic NucleusBrain IschemiaDevice RemovalMagnetic Resonance ImagingArrhythmias, CardiacEquipment SafetyHeart Conduction SystemPeriodicityElectrocardiographyElectrophysiologyCyclic Nucleotide-Gated Cation ChannelsTime FactorsBrain AbscessAction PotentialsAtrioventricular NodeFlufenamic AcidDefibrillators, ImplantableMembrane PotentialsArrhythmia, SinusPeriod Circadian ProteinsEquipment DesignCerebral CortexHypoxia, BrainSyncopeBlood-Brain BarrierHeart RateHeart AtriaAtrial FunctionAtrial FibrillationTachycardiaRats, Sprague-DawleyForeign-Body MigrationNerve NetIon ChannelsProsthesis ImplantationBrain Damage, ChronicTreatment OutcomePotassium ChannelsRespiratory CenterBrain InfarctionNeural PathwaysAnimals, NewbornElectric Power SuppliesNerve Tissue ProteinsElectromagnetic PhenomenaElectromagnetic FieldsImage Processing, Computer-AssistedSinoatrial BlockDeep Brain StimulationElectric StimulationCalciumHippocampusBehavior, AnimalFollow-Up StudiesHeartImmunohistochemistryDogsMice, Inbred C57BLTissue DistributionDisease Models, AnimalRats, WistarPatch-Clamp TechniquesRabbitsTelemetrySubclavian VeinNeuropeptidesPurkinje FibersHeart InjuriesModels, NeurologicalGastrointestinal MotilityTetrodotoxinPhotoperiodPotassiumRNA, MessengerCells, CulturedProspective StudiesElectroencephalographyCesiumElectrocardiography, AmbulatoryAnalysis of Variance