Low pre-treatment activity in the pregenual anterior cingulate cortex (pgACC) during a working memory task predicted greater antidepressant response to a single ketamine infusion in patients with major depressive disorder. Patients who showed the least pgACC engagement in response to increased working memory load experienced the greatest symptomatic improvement within four hours. Pre-treatment functional connectivity between the pgACC and the left amygdala was also negatively correlated with symptom change. These findings suggest pgACC activity during cognitive tasks may serve as a biomarker of antidepressant response.
Gamma-band synchronization in the brain is linked to conscious awareness but is not sufficient for it. Using brain-imaging, researchers observed increased gamma event-related synchronization (ERS) in prefrontal-anterior cingulate, visual, parietal, posterior cingulate, and superior temporal cortices when stimuli were consciously detected. However, gamma ERS also increased in the amygdala, visual, prefrontal, parietal, and posterior cingulate cortices for emotional versus neutral stimuli, regardless of whether participants were aware of them. This indicates that gamma-band activity is related to both conscious perception and emotional processing, but its presence does not guarantee consciousness.