Vibroacoustic stimulation in fetal sheep: effect on cerebral glucose utilization and behavioral state.

Behavioral state and cerebral glucose utilization were measured in six fetal sheep subjected to high intrauterine sound pressures created with a vibroacoustic stimulator pressed against the maternal abdomen. The signal consisted of a complex waveform that varied over time with a 50% duty cycle. An implanted hydrophone showed highest spectral levels between 3,000-16,000 Hz. The pulsed sound resulted in a significant loss of fetal rapid eye movement and non-rapid eye movement sleep. The stimulus also resulted in a disruption in the normally close relationship between these sleep states and cerebral glucose utilization rates in the brain as a whole and in its component parts.