J. Neurosci. 30, 304–315 (2010)

Blocking the growth of new neurons in a key region of the adult rat brain may make the animal more vulnerable to cocaine addiction and relapse.

Amelia Eisch at the University of Texas Southwestern Medical Center in Dallas and her colleagues inhibited neurogenesis in the adult hippocampus by irradiating it. The rats were then trained to give themselves cocaine.

Animals whose hippocampus had been zapped self-administered more cocaine than those who had received a sham irradiation. When brain-cell generation was blocked after the rats had learned to give themselves cocaine, they worked harder than control rats to get the drug when it was no longer available.