Title: Precision editing of neural circuits using engineered electrical synapses Pioneering approaches including optogenetics and designer receptors exclusively activated by designer drugs (DREADDs) enable the direct modulation of the activity of individual genetically defined cell types. Nevertheless, it remains a fundamental challenge to selectively regulate the hallmark feature of neural circuits: the interface between two specific brain cells. To address this challenge, we have created a new approach, Long-term integration of circuits using Connexins (LinCx), that employs a novel pair of engineered connexin hemichannels to directly modulate genetically defined neural circuits. When each member of the hemichannel pair is expressed in two different cell(s)/cell-types that compose a circuit, they engage in heterotypic docking (docking with each other) and an electrical synapse is constituted between the two cells. These pair of hemichannels is engineered 1) to prevent them from engaging in homotypic docking (forming electrical synapses with themselves), and 2) to disrupt them from docking with other connexin hemichannels endogenously expressed in the mammalian brain. Finally, 3) the hemichannel pair exhibits rectification. Together, these three properties confer LinCx with unprecedented spatial-, temporal-, and context precision, enabling the precise editing of neural circuits. We propose to deploy LinCx across model organisms. We will determine the impact of LinCx neuromodulation on neural circuit physiology and emotional behavior. We will also test whether LinCx modulation is sufficient to restore normal behavior in animal models of psychiatric disorders. Successful completion of these high-risk experiments will yield a new method for long-term circuit editing to regulate emotional states in preclinical models. In the future, LinCx can be integrated with emerging viral tools that enable systemic delivery of genetically encoded proteins to specific brain cell-types. Thus, LinCx also has an attainable path to human translation for ameliorating devastating psychiatric disorders.

We propose to create an approach for directly regulating the transfer of electrical information across neural circuits that encode emotions. After creating this new method for rewiring synapses, we will deploy it in animal models of psychiatric disorders. Thus, our high-risk research has the potential to yield a new therapeutic strategy for treating mental illnesses such as depression, anxiety, and addiction.