A Selective Role for Lmo4 in Cue-Reward Learning.

The ability to use environmental cues to predict rewarding events is essential to survival. The basolateral amygdala (BLA) plays a central role in such forms of associative learning. Aberrant cue-reward learning is thought to underlie many psychopathologies, including addiction, so understanding the underlying molecular mechanisms can inform strategies for intervention. The transcriptional regulator LIM-only 4 (LMO4) is highly expressed in pyramidal neurons of the BLA, where it plays an important role in fear learning. Because the BLA also contributes to cue-reward learning, we investigated the role of BLA LMO4 in this process using Lmo4-deficient mice and RNA interference. Lmo4-deficient mice showed a selective deficit in conditioned reinforcement. Knockdown of LMO4 in the BLA, but not in the nucleus accumbens, recapitulated this deficit in wild-type mice. Molecular and electrophysiological studies identified a deficit in dopamine D2 receptor signaling in the BLA of Lmo4-deficient mice. These results reveal a novel, LMO4-dependent transcriptional program within the BLA that is essential to cue-reward learning.