Abstract : Human behavior is remarkably diverse, ranging from simple reflexes to extremely elaborated patterns of social interactions such as cooperation. Understanding the neural basis of complex behaviors is one of the most challenging tasks in neuroscience. Recent technical advances, namely optogenetics approaches, have enabled the manipulation of neuronal activity with an unprecedented precision providing novel and exciting insights into the brain networks involved in such behaviors. However, how behavior is controlled at the molecular level remains largely unknown. Here, we will illustrate how deviant behaviors observed in certain pathological conditions could be exploited as a powerful tool to address this issue. Behavioral variant is the most common clinical form of frontotemporal dementia (FTD) and is characterized by strong changes in behavior and personality. Using cellular and mouse models of FTD as well as human samples, we were able to identify a number of molecular changes associated to precise behavioral deficits. Moreover, our data support the notion that a functional loop involving microRNA-124 and AMPA receptors is critical to maintain adequate levels of sociability.