Long-term meditators blink less frequently and show a different eyeblink pattern than meditation-naive participants, with high consistency over three time points. This pattern may reflect differences in striatal dopamine activity, as spontaneous eyeblink rate is a peripheral correlate of such activity. An 8-week mindfulness-based stress reduction course did not alter eyeblink rates compared to active or waitlist controls, and a full day of two different meditation types also had no effect. These results suggest either that individual differences in dopaminergic neurotransmission predispose people to meditation, or that long-term, but not short-term, practice induces stable changes in baseline striatal dopaminergic functioning.
Recent EEG studies on the early postmortem interval suggest the persistence of electrophysiological coherence and connectivity in the brain of animals and humans, reinforcing the need for further investigation of brain activity during the dying process. Under the direction of the Center for Healthy Minds at the University of Wisconsin-Madison, research was conducted in India on a postmortem meditative state (tukdam) cultivated by some Tibetan Buddhist practitioners, in which decomposition is putatively delayed. For healthy baseline and postmortem subjects, resting state EEG, mismatch negativity, and auditory brainstem response data were collected. Living subjects displayed well-defined MMN and ABR responses, but no recognizable EEG waveforms were discernable in any of the tukdam cases.
Long-term meditators showed increased low- and fast-frequency brain oscillations during wakefulness after two 8-hour sessions of mindfulness or compassion-and-loving-kindness meditation, peaking at 8 and 15 Hz over prefrontal and left centro-parietal electrodes. These waking changes correlated with previously observed meditation-related increases in low-frequency NREM sleep EEG activity (4-12 Hz), particularly in the theta-alpha range. The findings suggest that sleep homeostatic response alone cannot explain the post-meditation sleep changes; instead, a reverberation of meditation-related processes during subsequent sleep may be involved. No differences emerged between meditation styles or in meditation-naïve participants.