Interactions between prefrontal and insula circuits during normal and disrupted state representation processes in mice

PROJECT 1 - PROJECT SUMMARY The purpose of PROJECT 1 is to use mice as an experimental system to study the effects of NMDA receptor (NMDAR) disruption on interactions between medial prefrontal cortex (mPFC) and insular cortex. During the initial grant period, we found that individuals with early psychosis (EP) showed significant failures during exploration and state learning in salience network (SN) activation (of which the insular cortex is a critical hub), implicating deficits in communication from this network in engaging appropriate strategy switching. These findings highlight the potential role for activity in the insular cortex as an important influence on the mPFC, as well as the ability to learn and maintain state representations. A large body of evidence indicates that NMDAR hypofunction in frontal cortex is a pathogenic factor in psychosis spectrum illness. We will build on our substantial progress during the initial funding period, which includes establishing a molecular genetic platform to manipulate NMDAR function via CRISPR/Cas9-mediated gene editing in mice. Building on findings across PROJECTS from the first cycle, we hypothesize that neuronal synchrony in the mPFC is necessary to support state representations, and this synchrony is controlled at multiple levels: molecularly within mPFC by NMDAR ablation, and at a circuit level by insular cortex inputs driving the engagement of mPFC. Both should be necessary to engage mPFC-mediated cognitive control to support state learning and maintenance. In two Aims, we will test the relationship between neuronal activity in mPFC and insular cortex inputs, and discover how this relationship is impacted by CRISPR-mediated loss of NMDAR function across mPFC neurons. In Aim 1, we will determine the relationship between mPFC in vivo activity supporting state representation with insular cortex activity via silicon probe recordings across regions, testing the directionality of ensemble and local field potentials from insula to mPFC, and determine whether this relationship is impaired by ablation of NMDAR function in mPFC neurons. In Aim 2, we will measure and modulate synaptic input from insular cortex after NMDAR ablation in mPFC, using parallel optogenetic manipulations in vivo (behaving animals) and ex vivo (acute brain slice physiology). We will combine these approaches to test whether state representation processes and mPFC synaptic connectivity can be bidirectionally modulated by insular cortex, and whether this is prevented by NMDAR manipulations.