Temporary strengthening of connections in the brain's reward area during stopping cocaine seeking

Increased ratio of AMPA to NMDA glutamate receptor currents was observed in medium spiny neurons of the nucleus accumbens shell during drug-seeking refraining.

• Repeated exposure to drug-related cues without reward may lead to refraining from drug-seeking behavior in rodents.
• The increased AMPA to NMDA ratio in nucleus accumbens shell medium spiny neurons normalized to baseline levels by the end of a 2-hour extinction session.
• Refraining was not associated with dendrite spine head enlargement or activation of matrix metalloproteases.
• No changes were observed in paired pulse ratio, NMDA receptor current decay time, or AMPA receptor rectification index in nucleus accumbens shell medium spiny neurons.
• Preliminary data in transgenic mice suggest that transient synaptic plasticity may increase D2-MSN inputs relative to D1-MSN inputs.

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