Distinctive neural signatures for negative sentences in Hindi: an fMRI study

We examined cortical activations using functional magnetic resonance imaging (fMRI) technique in skilled native Hindi readers while they performed a 'target-probe' semantic judgment task on affirmative and negative sentences. Hindi, an Indo-Aryan language widely spoken in India, follows subject-object-verb (SOV) order canonically but allows free word order. The common cortical regions involved in affirmative and negative sentence conditions included bilateral inferior frontal gyrus (IFG), left parietal cortex (BA 7/40), left fusiform (BA 37), bilateral supplementary motor area (SMA) (BA 6), bilateral middle temporal gyrus (BA 21), and bilateral occipital area (BA 17/18). While no distinct region was activated for affirmative sentences, we observed activations in the region of bilateral anterior temporal pole for negative sentence. The behavioral results showed no significant mean difference for reaction times (RT) and accuracy measures between affirmative and negative sentences. However, the imaging results suggest the recruitment of anterior temporal pole in processing of negative sentences. Region of interest (ROI) analysis for selected regions showed higher signal intensity for negative sentences possibly indicating the associated inherent difficulty level of processing, especially when integrating information related to negations.