Functional changes of the brainstem triggering vertex sharp wave with spindle.

A vertex sharp wave followed by spindle (VS-spindle) is one of the hallmarks of human stage 2 sleep. We recorded sleep electroencephalograms (EEG) simultaneously with brainstem auditory evoked potentials (BAEP) from nine healthy male subjects. To investigate the generating mechanism of the VS-spindle, sequentially changing BAEP were analyzed around the VS-spindle. The results revealed the preceding changes of wave-V amplitude to the onset of the VS-spindle. When the generator site of wave-V in the brainstem was considered, the results suggest that the functional changes in the dorsal area of the midbrain-pontine junction participate in the organization of the VS-spindle.