Resting state functional connectivity and neural correlates of face-name encoding in patients with ischemic vascular lesions with and without the involvement of the left inferior frontal gyrus

Face-name association is a relevant ability for social interactions and involves the ventral and dorsolateral prefrontal cortices, particularly in the left hemisphere, bilateral hippocampal, fusiform gyrus and occipital regions. Previous studies demonstrated the primary role of the hippocampus for this ability in healthy subjects. However, no study has examined the participation of the left inferior frontal area, specially the left inferior frontal gyrus (LIFG) in patients with ischemic vascular lesions. In the present study we addressed this issue and investigated the neural correlates and resting state functional connectivity of face-name memory encoding in ischemic patients with LIFG or without lesions in the left IFG (nLIFG) and healthy controls (HC) using fMRI. The main results showed that the nLIFG group demonstrated efficient compensation related to encoding and performance on face-name learning and recognition memory task, in addition to similar brain areas activated during task performance compared to healthy controls. Some of these areas were more activated in nLIFG group, indicating a compensation mechanism. In contrast, the LIFG group showed worse behavior performance, and no signs of an efficient compensation mechanism. Functional connectivity analysis suggested that the left IFG region seems to be important for maintaining the connectivity of the right fusiform gyrus or, perhaps, lesion in this area is associated to maladaptive reorganization. Our findings highlight the relevant role of the left IFG in face-name learning and encoding, possibly as a primary region in addition to the bilateral hippocampal formation and fusiform gyrus.