Stimulus-dependent modulation of working memory for identity monitoring: A functional MRI study.

While the neural correlates of identity monitoring working memory (WM) have been well characterised in literature, the WM subsystems for different types of stimuli have not been established. The aim of our study was to examine the neural network subtending WM for identity monitoring of both verbal and visual stimuli. We used functional magnetic resonance imaging (fMRI) with words, objects, and faces as stimuli in an n-back WM task to delineate the similarities and differences in brain activation during presentation of verbal and visual stimuli. The results revealed a predominantly left lateralized core fronto-parieto-cerebellar identity WM network comprising bilateral insula, left inferior frontal gyrus, inferior parietal gyrus, and cerebellum that is common to all stimuli. In addition, our results showed stimulus-specific recruitment of brain regions, with exclusive activations in left inferior frontal gyrus and inferior temporal gyrus for identity WM for verbal stimuli, and left middle occipital gyrus and cerebellum for identity WM for visual stimuli. The present study reveals the existence of a central identity WM network for both verbal and visual information, along with activation of distinct verbal and visual representational regions that are sensitive to respective stimuli.