Fetal sheep cerebral electrical activity: A new technique to record EEG.

BACKGROUND: Sheep models are commonly used to study fetal cortical activity, including response to hypoxia. The standard technique consists of recording electrocorticogram (ECOG) in utero using electrodes placed on the dura mater. NEW METHOD: We propose a new method for recording the electroencephalogram (EEG) of fetal sheep, using electrodes placed above the skull bone and fixed to the cranial periosteum. RESULTS: Twelve animals were instrumented with this new technique. The EEG signal recorded in utero was of sufficient quality for visual and quantitative analysis of the fetal cortical activity. COMPARISON WITH EXISTING METHOD: This new method is less invasive than the standard method commonly used to record cerebral activity in fetal sheep, because it avoids drilling the skull by hand. The EEG signal recorded in utero had visual and quantitative characteristics comparable to ECOG. CONCLUSIONS: We present a new method of EEG recording that appears to be an acceptable alternative to the standard ECOG recording method. Fetal sheep EEG can be used to better understand the physiological mechanisms involved in the cerebral response to hypoxia.