Functional connectivity of inferior parietal mirror neurons during self-face processing

Abstract

Objectives: The inferior parietal lobule (IPL) represents an integral part of mirror neuron system (MNS) implicated in self-related behaviours such as imitation, empathy, and self-others distinction. In this study we examined the functional connectivity of IPL during processing of one’s own face relative to faces of loved ones to understand the specific contribution of the MNS to self-face processing. 

 

Methods: We measured BOLD responses in 10 healthy young women while they viewed self faces, personally familiar faces (another close female friend) and faces of age- and gender-matched two strangers during three task conditions; passive viewing,  emotional and self relevance evaluation. Preliminary subtraction analysis showed increased activation of left IPL during self-face processing compared to personally familiar and strangers face processing across all tasks.  We therefore selected this region as a seed for correlational analysis, to investigate the differential functional connectivity of IPL with other brain regions during processing of self-face versus other face conditions.

 

Results: During self-face processing, IPL showed selective positive correlation with other regions of the MNS (right inferior frontal, right inferior parietal, bilateral superior temporal), and emotional system (insula, putamen, and thalamus). The functional connectivity of IPL with cortical midline structures (CMS) (cuneus/ precuneus,   cingulate and medial prefrontal regions) overlapped during processing of both self and personally familiar faces although there was also evidence for non-overlapping voxels in these regions. 

 

Discussion: The results suggest differential IPL functional connectivity with MNS and CMS during self-face versus personally familiar face processing. The functional connectivity of IPL with MNS (embodied self) may be crucial for processing self-other distinction whereas IPL connectivity with CMS may involve processing self-other relatedness.