One behavioral correlate of synaptic plasticity is the manifestation of locomotor sensitization, which is defined as an enhanced locomotor response after repeated exposures to a drug compared to the activity measured during the first drug administration. Increased locomotor response to prolonged nicotine, ethanol, cocaine, amphetamine, and methamphetamine has been extensively studied in rodent animal models and is thought to have relevance to drug seeking and relapse in humans (Steketee and Kalivas, 2011).
