CocaineSpinal CordAnesthesia, GeneralAnesthesiaAnesthesia, SpinalAnesthesia, LocalSpinal Cord InjuriesAnesthesia, EpiduralCocaine-Related DisordersAnesthesia, InhalationAnesthesia, ConductionAnesthesia, IntravenousAnesthesia, ObstetricalDopamine Uptake InhibitorsAnesthesia Recovery PeriodCrack CocaineAnesthesia, DentalSelf AdministrationInjections, SpinalAnesthetics, LocalAnesthetics, InhalationAnesthetics, IntravenousAdjuvants, AnesthesiaPropofolSpinal NervesIsofluraneSpinal Cord DiseasesMethyl EthersAnesthesiologyAnesthetics, CombinedSpinal Nerve RootsMonitoring, IntraoperativeSpinal Cord NeoplasmsSpinal CanalAnestheticsNitrous OxideSpinal DiseasesSpinal Cord CompressionLidocaineRats, Sprague-DawleySpinal NeoplasmsConditioning, OperantHalothaneBupivacaineDose-Response Relationship, DrugSpinal StenosisSpinal FusionFentanylBehavior, AnimalNucleus AccumbensAnesthesia, Closed-CircuitNerve BlockAnesthetics, GeneralKetamineTime FactorsReinforcement (Psychology)Motor ActivityAmbulatory Surgical ProceduresPreanesthetic MedicationSpinal InjuriesThiopentalBehavior, AddictiveAnesthesia, CaudalMuscular Atrophy, SpinalPentobarbitalDrug-Seeking BehaviorSpinal Cord IschemiaReinforcement ScheduleAnesthetics, DissociativeGanglia, SpinalEnfluraneXylazineIntraoperative ComplicationsPain MeasurementIntubation, IntratrachealPain, PostoperativeConscious SedationNarcoticsAnesthesia Department, HospitalAnesthesia, IntratrachealThoracic VertebraeAnalgesics, OpioidSpineMotor NeuronsCesarean SectionExtinction, PsychologicalDopamineParaplegiaHeroinLocomotionIntraoperative PeriodLaminectomyDopamine Plasma Membrane Transport ProteinsSubstance Withdrawal SyndromeTuberculosis, SpinalLumbosacral RegionPainAnalysis of VarianceDrug InteractionsProspective Studies