Figure 1.

A) Sensor array layout placed over the right hemisphere of an adult head. With an extent of 11 cm, good coverage of right hemisphere is obtained in children in the 6-50 month age range. Channel numbers are displayed for the waveforms shown below. B) Example single channel auditory evoked fields across 6 channels in one 9 – month old child reveal amplitude reversal (compare channels 13, 14, and 15 vs. 27, 28 and 66) representing the maxima/minima of the evoked response, consistent with a source lying midway between these groups of channels. A head surface template specific to a 9 – month old child is not available and therefore the specific sensor placement over the adult head only approximates the head position of the 9-month old child relative to the sensor array. A pediatric template MRI was used for source localization (Fig. 3) providing good approximation to the head shape. The figure demonstrates that both positive and negative maxima can be captured by the sensor array in young children when the right hemisphere is centered over the array as was done in each child.