The role of the left medial prefrontal cortex and posterior cingulate cortex in processing positive emotion words: Evidence from a meta-analysis and an empirical study

In the present research, we examined the neural substrates supporting positive word processing by using Activation Likelihood Estimation (ALE) and Seed-based d Mapping (SDM) approaches. In study 1, taking effect sizes, peak coordinates of brain region activation, sample sizes, and experimental paradigms into consideration in ALE and SDM meta-analyses, we identified two largely overlapping brain regions with comparable peak coordinates, i.e., the left medial prefrontal cortex (mPFC) and the left posterior cingulate cortex (PCC), showing greater activities in these two regions during positive word processing than neutral word processing. In Study 2, we further examined the universality and language specificity of neural mechanisms underlying positive word processing by comparing two typologically distant languages, Chinese and English, in both native speakers and bilinguals using ROI (regions of interest) analyses. The results showed no significant difference across two native languages or between bilinguals’ two languages, highlighting the crucial roles of the two regions in positive word processing. These findings also hold implications for the models of bilingual emotion processing (e.g., the valence hypothesis and the hierarchical emotion model) and the system accommodation hypothesis.