In-silico testing of new pharmacology for restoring inhibition and human cortical function in depression

Reduced inhibition by somatostatin-expressing interneurons is associated with depression. Administration of positive allosteric modulators of 5 subunit-containing GABAA receptor (5-PAM) that selectively target this lost inhibition exhibit antidepressant and pro-cognitive effects in rodent models of chronic stress. However, the functional effects of 5-PAM on the human brain in vivo are unknown, and currently cannot be assessed experimentally. We modeled the effects of 5-PAM on tonic inhibition as measured in human neurons, and tested in silico 5-PAM effects on detailed models of human cortical microcircuits in health and depression. We found that 5-PAM effectively recovered impaired cortical processing as quantified by stimulus detection metrics, and also recovered the power spectral density profile of the microcircuit EEG signals. We performed an 5-PAM dose response and identified simulated EEG biomarker candidates. Our results serve to de-risk and facilitate 5-PAM translation and provide biomarkers in non-invasive brain signals for monitoring target engagement and drug efficacy.