Continuous theta burst stimulation (cTBS) over the occipital cortex, expected to impair conscious vision, instead enhanced it relative to a sham control. The stimulation decreased cortical excitability and increased regional GABA concentration, suggesting that suppression of neural noise can improve the signal-to-noise ratio for conscious vision. No significant effects on magnetoencephalography measures were observed, though weak evidence for potentiation of beta-band event-related desynchronisation appeared. The authors propose that gating-by-inhibition in the visual cortex may be a foundation of consciousness.
About 30% of people with treatment-resistant depression respond to ketamine, but reliable predictors of response have been lacking. This study examined whether the ratio of glutamate+glutamine (Glx) to GABA in the dorsal anterior cingulate cortex (dACC) could predict ketamine's effectiveness. In a double-blind randomized trial with an open-label extension involving 30 participants, a higher baseline Glx/GABA ratio in the dACC correlated with greater improvement in depression scores (measured by the HDRS-17). After ketamine treatment, a reduction in this ratio also correlated with symptom improvement. The findings suggest that an excitatory-inhibitory imbalance in the dACC may help predict which patients will benefit from ketamine therapy.