Neural correlates of priming effects in children during spoken word processing with orthographic demands.

Priming effects were examined in 40 children (9-15 years old) using functional magnetic resonance imaging (fMRI). An orthographic judgment task required participants to determine if two sequentially presented spoken words had the same spelling for the rime. Four lexical conditions were designed: similar orthography and phonology (O(+)P(+)), similar orthography but different phonology (O(+)P(-)), similar phonology but different orthography (O(-)P(+)), and different orthography and phonology (O(-)P(-)). In left superior temporal gyrus, there was lower activation for targets in O(+)P(+) than for those in O(-)P(-) and higher accuracy was correlated with stronger activation across all lexical conditions. These results provide evidence for phonological priming in children and greater elaboration of phonological representations in higher skill children, respectively. In left fusiform gyrus, there was lower activation for targets in O(+)P(+) and O(+)P(-) than for those in O(-)P(-), suggesting that visual similarity resulted in orthographic priming even with only auditory input. In left middle temporal gyrus, there was lower activation for targets in O(+)P(+) than all other lexical conditions, suggesting that converging orthographic and phonological information resulted in a weaker influence on semantic representations. In addition, higher reading skill was correlated with weaker activation in left middle temporal gyrus across all lexical conditions, suggesting that higher skill children rely to a lesser degree on semantics as a compensatory mechanism. Finally, conflict effects but not priming effects were observed in left inferior frontal gyrus, suggesting that this region is involved in resolving conflicting orthographic and phonological information but not in perceptual priming.