new words continually and many of the words that are currently contained in our vocabulary were initially perceived as PW. The words used in the present study had very low frequency (4.3 ± 2.4 occurrences per million), which can explain the imperfect accuracy on SW (90.9 ± 7.2%). The low frequency of SW made the lexical decision task more difficult as some PW were categorized as real words (PW accuracy was 92.9 ± 12.9%). However, only the trials with correct responses were included in the aMEG analysis, assuring that erroneous processing did not confound the observed activity. Consequently, theta power to SW was associated with successful lexical-semantic access and retrieval. Even though both SW and PW are processed for orthographic and phonological dimensions, they differ in the actual access to semantic representations since only SW are associated with meaning. Therefore, significantly larger theta to SW than to PW uniquely demonstrates that theta is sensitive to semantic retrieval and may be used as an index of that process, further confirming the fundamental association between language and memory functions (Kutas and Federmeier, 2000; Hanslmayr et al., 2011). Future studies could explore the nature of PW processing and its similarity to SW processing
