In patients with bipolar disorder and treatment-resistant depression, a subanesthetic dose of ketamine alters brain activity patterns measured by EEG. Ketamine reduced low-frequency power and increased gamma oscillatory power, flattened the slope of power spectra, and increased brain signal entropy, especially in high-frequency bands. Patients who responded later to treatment showed greater EEG changes than early responders, suggesting underlying differences in treatment sensitivity. These neurophysiological effects may help explain ketamine's therapeutic mechanisms and could guide personalized treatment for mood disorders.
An 8-week mindfulness-based stress reduction (MBSR) training program alters functional and effective connectivity in the dorsal striatum, particularly the putamen, in healthy individuals. After training, local connectivity decreased in the right anterior putamen and insula during spontaneous mind-wandering and in the right cerebellum during meditation. Effective connectivity analysis showed reduced modulation by the anterior cingulate cortex over the anterior putamen and a change in excitatory and inhibitory interactions between the posterior putamen and cerebellum. These connectivity rearrangements may help explain mindfulness-related behavioral effects, especially in pain perception.