Mismatch negativity (grand average, infrequent-frequent difference waveform) reflects the development of language specific memory traces (left-hemisphere C3 in the figure). Frequent phoneme was/e/, infrequent phoneme was non-native, Estonian/õ/. The MMN amplitude in response to non-native phoneme contrast diminished from the age of 6 months (on the left) to the age of 12 months (on the right) in the full-term controls, while in the prematurely born children this kind of reduction was not observed.
Jansson-Verkasalo et al. BMC Neuroscience 2010 11:88 doi:10.1186/1471-2202-11-88