Neuroligin-2 and the tightrope of excitation/inhibition balance in the prefrontal cortex

Excitation/inhibition imbalance is implicated in symptoms of neuropsychiatric disorders. We discuss a study by Liang et al. (Mol Psychiatry 20: 850-859, 2015) demonstrating that the conditional knockout of neuroligin-2, a postsynaptic adhesion protein, in the prefrontal cortex of adult mice results in alterations in inhibitory synaptic properties. However, behavioral impairments emerged prior to the development of detectable changes in excitation/inhibition ratio. This suggests there may be network-specific excitation/inhibition ratios, some of which are more vulnerable to disruption than others.