Mental training is not "flaky" any more now that technology can visualize the results by spectral EEG or fMRI. Gamma synchrony appears during interesting cognitive activities (attention, working memory, gestalt perception) and it is abnormal in conditions like autism, genetic disorders, or schizophrenia. Here is a picture of Buddhist monks activating gamma with meditative techniques (see link to full PNAS article below):
These studies are laying the groundwork for more non-pharmacological interventions in disorders of attention, working memory, and gestalt perception.
Mental Training in Monks
Memory and Gamma Responses