Brain imaging and electrophysiological markers of anaphoric reference during speech production

Pronouns create cohesive links in discourse by referring to previously mentioned elements. Here, we focus on pronominalization during speech production in three experiments employing ERP and fMRI methodologies. Participants were asked to produce two short sentences describing a man or woman using an object. In the second sentence, they were instructed to use a pronoun to refer to the same person and a noun to refer to a different person. The first ERP experiment revealed that noun conditions elicited more negative ERPs starting at 220 ms, with significant differences in early and later time windows, particularly in the left hemisphere. The second ERP experiment showed divergence at 280 ms, with significant differences between 300-400 ms at midline electrodes, again indicating more negative ERPs for nouns. The fMRI experiment identified greater activations for nouns than pronouns in regions like the superior temporal gyrus (STG) and cerebellar vermis, suggesting higher working memory load and lexical retrieval demands for nouns compared to pronouns. Moreover, pronouns elicited an enhanced centro-parietal positivity, indicating increased attentional demands. These findings suggest that while noun processing requires greater working memory and lexical retrieval, pronoun processing engages more attentional resources. This study advances our understanding of the neural mechanisms underlying pronominalization during speech production, highlighting distinct neural responses for nouns and pronouns.