Final answer:
Enhanced glutamate transmission in the nucleus accumbens is associated with behavioral sensitization to amphetamine, causing increased glutamate release and changes in synaptic strength.
Step-by-step explanation:
The neuronal changes in the nucleus accumbens that have been found to be associated with behavioral sensitization to amphetamine are enhanced glutamate transmission. Studies have shown that repeated exposure to stimulants like amphetamines increases glutamate release in the nucleus accumbens, which is a key factor in the development of sensitization. This process is believed to result in neuroadaptive changes that enhance the excitatory synaptic strength, contributing to the enduring increases in the responsiveness to the drug. The increase in glutamate can overstimulate its receptors (such as NMDA and AMPA receptors), which might lead to increased synaptic plasticity and drug sensitization.