Alternatively, beta reduction may result from inhibition of local PFC somatostatin interneurons by ketamine (Chen, Zhang et al. 2017, Ali et al. 2020), and reflect deficits in somatostatin interneurons in people with MDD (Fee et al. 2017), as a result of direct inhibition of cortical pyramid cells (Miller et al. 2016), or finally, as a knock-on effect of theta disruption, as discussed earlier. Here, SST is linked to major depressive disorder.