Highly read on www.cell.com/neuron in February

Socially isolated adolescent rats acquire amphetamine- and alcohol-associated memories faster — and in the case of amphetamine are slower to extinguish, or 'unlearn', them — than rats kept in groups.

Hitoshi Morikawa and his colleagues at the University of Texas at Austin found that isolated rats formed a preference for drug-associated stimuli after only one exposure, whereas rats housed in groups required repeated exposures. The researchers also showed that social isolation boosted signalling by certain neurons in a part of the brain that links behaviours with rewards. This boost was not reversed by returning the rats to a social environment.

Such effects may help to explain how pre-adult experiences can increase vulnerability to addiction, the authors suggest.

Neuron 77, 335–345 (2013)