Entrainment of stage 2 sleep spindles by weak, transcerebral magnetic stimulation in an "epileptic" woman.

The proportions of Stage 2 spindles present per second over the prefrontal and temporal lobes of a patient who had been experiencing complex partial epileptic-like experiences and disturbances in sleep patterns for four years following a closed head injury were measured while a weak (1 microT) burst-firing magnetic field was applied transcerebrally through the temporoparietal regions. In several successive segments during the exposure the onsets of the spindles were significantly correlated (rhos between 0.30 and 0.40) with the onset of the field that was presented once every 3 s for about 0.7 s. Lag/lead analyses indicated only the contemporary occurrence of the fields and the spindles were significantly correlated over time. These results suggest that some states of consciousness, particularly those associated with the "epilepsy spectrum disorder" may be more sensitive to entrainment or "synchronization" by weak complex magnetic fields whose temporal structures are designed to simulate natural brain activity.