Imagine/Optical: multiphoton microscopy, intracellular uncaging (flash photolysis); Electrophysiological/Biophysical: in vitro whole-cell patch (current/voltage) clamp, in vitro cell attached recordings (omega), in vivo and in vitro extracellular recordings, focal iontophoresis, pressure applications, focal electrical stimulation; Anatomy: ballistic labeling and dynamic imaging of dendritic spines with Dil/DiO; Behavioral models of drug abuse and addiction: rat i.v. drug (cocaine and heroine) self-administration, cue/stress reinstatement, i.v. cannulations and survival surgeries, intracranial injections, neurochemical lesions, and locomotor assays; Accepted models of chronic, peripheral pain: formalin (as a model of tissue destruction), complete freund's adjuvant (CFA, as a model of inflammatory pain or rheumatoid arthritis), and spared nerve injury (SNI; model of neuropathic pain)