ABSTRACT
Fetal magnetoencephalography (fMEG) is the only non-invasive method for investigating evoked brain responses and spontaneous brain activity generated by the fetus in utero. Fetal auditory as well as visual evoked fields have been successfully recorded in basic stimulus-response studies. Moreover, paradigms investigating precursors for cognitive development, such as habituation and mismatch response have been applied successfully with fMEG. These and other studies have shown that the prenatal stage of life could be an important indicator for later cognitive development. This review addresses the achievements of fMEG and constructively discusses its challenges. It concludes with proposals for future studies as well as with designated new applications. Fetal MEG is a promising, and to date it is the only non-invasive approach for the prenatal assessment of precursors for cognitive development. Future fMEG studies might even enable the diagnosis of developmental delays. Furthermore, fMEG could be critical for the implementation and evaluation of fetal intervention programs in at-risk populations.
ABSTRACT
OBJECTIVE: To investigate the response decrements of visual evoked responses (VER) in newborns and assess the applicability of this paradigm to fetuses in magnetoencephalographic (MEG) recordings. METHODS: Twelve newborns with no known risks or complications participated at chronological ages between 6 and 22days. They constituted the follow-up group to a prenatal study conducted on a sample of 25 fetuses whose gestational age (GA) varied between 29 and 37weeks at the time of recording. Trains of four light flashes with an interstimulus interval of 2s followed by 10s without stimulation were delivered to record VER. RESULTS: Nine of the 12 newborns responded to the stimulation and showed response decrements in amplitude from the first to the last light flash. Furthermore, the response latency increased significantly from the first to the last stimulus. The remaining three recordings were discontinued early. Even though the prenatal visual evoked response rate was only 29%, the fetuses exhibited a response decrement after the first stimulus. CONCLUSIONS: The amplitude of VERs can be used to elicit a response decrement in newborns and, with limitations, even in fetuses. This paradigm might be a useful tool for a direct non-invasive assessment of neonatal and prenatal brain development and CNS functioning. SIGNIFICANCE: The proposed method might be a first step towards an early detection of developmental deficits in newborns and fetuses.
