The extended evolutionary synthesis and addiction: the price we pay for adaptability --The Dopamine Theory of Addiction -- Substance Use in Animals and Humans -- Psychiatric Comorbidity -- Dopamine and Impulsivity -- Human Flexibility, Adaptability, and Innovation -- Pleiotropy -- The EES and Addiction -- Discussion -- Conclusion -- Cross-talk between the epigenome and neural circuits in drug addiction -- Drug Addiction Is a Behavioral Learning Disorder -- Drug-Induced Plasticity: How Is Drug-Associated Information Stored for Long Periods of Time in the Brain? -- The Neural Circuits Controlling Motivated Behaviors and Their Dysregulation in Drug Addiction -- How Are Changes in Neural Morphology and Function Maintained? -- Epigenetic Regulation Is the Key to a Central Property of Neural Networks: Plasticity -- The Interface Between Neuronal Activation and Epigenetic Remodeling -- Bidirectional Cross-Talk Between the Epigenome and Cellular Activity -- Focusing to the Future -- Addiction: A dysregulation of satiety and inflammatory processes -- Brief Summaries of Selected Theories of Addiction -- Brain Circuitry and Areas Involved in Addiction -- Drug-Induced Alterations in Dopamine Neurotransmission -- Changes in Dopamine Signaling May Mediate Addictive Behavior -- Regulation of Satiety -- The Hypothalamus: The Intersect Between Addiction and Satiety -- Inflammation and Addiction -- Conclusion -- Corticostriatal plasticity, neuronal ensembles, and regulation of drug-seeking behavior -- Introduction: Ensembles in Addiction -- Constitutive Changes Induced by Drugs of Abuse -- Glutamate Spillover and Transient Synaptic Plasticity, Common to All Drugs of Abuse -- Could the t-SP Be Embedded in a Neuronal Network Specific to Drug Seeking? -- Paraventricular thalamus: Gateway to feeding, appetitive motivation, and drug addiction -- Anatomical Organization of the PVT Within a Motivational Framework -- PVT and Appetitive Motivation -- PVT in Drug Taking, Withdrawal, and Relapse -- Conclusions -- Functional roles of orexin/hypocretin receptors in reward circuit -- Reward and Reward Processing -- Reward Processing and Drug Abuse -- Reward Promotion -- Conclusion.