The functional neuroanatomy of morphology in language production

The present study investigated the neural correlates of morphological priming in overt Dutch language production using a long-lag priming paradigm. Compound words were read out loud as primes that were morphologically related to picture names (e.g. the word jaszak, 'coat pocket' was used for a picture of a coat; Dutch jas), or primes were form-related, but not morphologically related monomorphemic words (e.g. jasmijn, 'jasmine'). The morphologically related compounds could be semantically transparent (e.g. eksternest, 'magpie nest') or opaque (e.g. eksteroog, lit. 'magpie eye,' 'corn,' for a picture of a magpie, Dutch ekster). These four priming conditions were complemented by two matched, unrelated conditions. The production of morphologically related, complex words but not the production of form-related words facilitated subsequent picture naming. Also, morphologically related but not form-related words led to a neural priming effect in the left inferior frontal gyrus (LIFG). The effects did not differ for transparent and opaque relations. The results point to a functional role of LIFG in morphological information processing during language production contrary to previous meta-analytic findings. Specifically, morphological priming effects in language production seem to be independent from semantic overlap. However, further research should confirm the independence of morphological and phonological factors. It is suggested that LIFG subserves word form encoding in language production.

Research Highlights► Morphological priming in overt language production is supported by left inferior frontal gyrus. ► Such priming is associated with increased neural activity and leads to faster vocal responses. ► These priming effects cannot be explained by semantic or phonological factors. ► Morphological information seems to be processed independently at the neural level.