Neural Correlates of Visual Confrontation Naming in Persian-Speaking Individuals: An fMRI Study

Abstract

Background: Neural correlates of visual confrontation naming (VCN) have received considerable attention in previous literature. Recently, there have been a few studies that have reported the activation of the hippocampus during VCN tasks. Whether or not the hippocampus is directly involved in picture naming has clinical importance for patients with refractory mesial temporal lobe epilepsy (MTLE) who should undergo anterior temporal lobe resection (ATLR). Objectives: In this study, we investigated the neural network of VCN and the role of the hippocampus in Persian-speaking individuals by functional magnetic resonance imaging (fMRI) VCN paradigm. Subjects and Methods: Twenty right-handed, healthy, Persian-speaking adults underwent fMRI while performing VCN task. Pictures were selected from a Snodgrass and Vanderwart dataset that was normed for Persian speakers. VCN performance was assessed and entered as a covariate in whole-brain analysis. Region of interest (ROI)-based analysis was also used to obtain more accurate results. Results: Activation in the left hippocampus was significantly correlated with VCN performance. Participants with higher scores showed greater fMRI activation in their left hippocampus. Activation in left occipitotemporal regions, such as the left occipital fusiform gyrus, left temporal occipital fusiform gyrus, left temporal pole, left middle temporal gyrus, and left superior temporal gyrus also showed significant correlation with VCN performance. The main effects of VCN were also found in frontal and occipital regions, such as the left inferior frontal gyrus, right inferior frontal gyrus, right orbital frontal gyrus, right lateral occipital gyrus, right occipital fusiform gyrus, and right occipital pole. Activation in the inferior frontal gyrus was significantly left lateralized among all of the subjects. Conclusion: These findings suggest that good naming ability depends on fMRI activation in the speech-dominant hippocampus. We also found that a left-dominant network of occipitotemporal regions plays a dominant role in VCN performance in healthy Persian-speaking individuals.