Detection of single-trial neonatal auditory evoked responses via spatial filtering

Several groups, including ours, have attempted to use MEG to record the fetal auditory evoked response. Because the recordings are so difficult to make, it is helpful to study the same signals in neonates. Neonatal auditory evoked responses (nAERs) are relatively easy to record because they have much larger amplitude; however, typically the recordings are quite variable due to changes in state and movement artifact. In such circumstances, averaging the evoked responses may give poor results. We have found, however, that it is often possible to detect the nAER with little or no averaging. In this work we investigate the use of a signal processing method known as linearly constrained minimum variance (LCMV) spatial filtering for improving the signal-to-noise ratio of single trial nAERs.