Similar to beta theta power also increases with each

Similar to beta, theta power also increases with each word during sentence reading (Bastiaansen et al., 2010). However, at the point of a semantically incongruent word in the sentence, theta power is greater than when the words are semantically congruent. Similar to the N400, the amount of theta increase may be linked to how difficult it is to semantically integrate the current information with the preceding context (Davidson and Indefrey, 2007; Hald et al., 2006). However, to date, no research that we know of has studied the neural oscillations underlying the semantic aspects of sentence processing in children compared to adults. While theta and beta increase during reading of sentences, they diverge in how they respond to an error in the sentence - theta increases to a semantic error whereas beta decreases to a syntactic error (Bastiaansen et al., 2002, 2010). On the surface, it seems that theta and beta are similar to the N400 and P600 ERP responses, indexing semantic boldenone undecylenate and syntactic unification, respectively; however, further research is needed to identify the relationship between language processes and underlying neural activity. The current study uses ERP (e.g., P600, N400) and time frequency (e.g., theta, beta) analyses to investigate neural processing in children 10–12 years old and adults during a grammaticality judgment task in which they listen to sentences containing either no grammatical error or a verb agreement error (e.g., she walk). For both groups, we predicted theta and beta increases for grammatically correct sentences and a beta decrease/P600 effect following the agreement error. We examined the possibility of a theta increase/N400 because children seem to engage different strategies than adults during language processing. Further, we performed analyses to better identify the relationships between ERPs, changes in power, and behavioral measures.
Methods
Results
Discussion This paper is the first to investigate developmental changes in neural oscillations underlying auditory sentence processing. As expected, adults performed better than the 10–12 year olds on a grammaticality judgment task related to verb agreement errors. To investigate whether a developmental difference in the ability to identify errors might be associated with differences in the neural processes underlying common, day-to-day language comprehension, we analyzed the ERPs and neural oscillations underlying grammatically correct and incorrect sentences. In adult participants, grammatical violations were associated with a P600 ERP effect and beta power decrease- both of which have been related to effective syntactic processing in past literature (Hahne et al., 2004; Bastiaansen et al., 2010; Davidson and Indefrey, 2007). Children demonstrated a different pattern of engagement, specifically an apparent N400 effect, and lack of beta or theta decrease for grammatical violations compared to adults. Thus, developmental differences existed in our ERP findings, and these findings were further supported by differences in the underlying neural oscillations. We interpret the P600 effect and beta decrease to verb agreement errors in adults as indicating effective syntactic unification. Recall that studies using time frequency analysis for adults reported beta power increases related to syntactic unification and beta decreases when a violation disrupts the syntactic unification process (Bastiaansen et al., 2010; Davidson and Indefrey, 2007; Weiss et al., 2005; Weiss and Mueller, 2012). Building on past research, our findings indicate that adults effectively use syntactic information to identify a verb agreement error. The lack of an N400 effect in adults is further in line with past research, given that the N400 is commonly associated with semantic errors (Atchley et al., 2006; Friederici and Hahne, 2001; Friedrich and Friederici, 2004; Hahne and Friederici, 1999; Juottonen et al., 1996; Silva-Pereya et al., 2005). Based on previous work (Bastiaansen et al., 2002, 2010), we expected to see a theta increase as adults integrated the semantic information related to the presentation of each new word in the sentence. Indeed, there was a slight increase in theta for the grammatically correct sentences and an unexpected significant decrease in theta after the critical verb for ungrammatical sentences. Theta increases are generally related to semantic integration (Davidson and Indefrey, 2007; Hagoort et al., 2004; Hald et al., 2006; Klimesch et al., 1994; Maguire et al., 2010; Wang et al., 2012; Bastiaansen et al., 2002, 2005, 2010); therefore, we speculate that our identified theta decrease in adults’ processing of grammatical violations occurs because adults have enough syntactic information to make the appropriate grammaticality judgment and no longer need to integrate semantic information.