Authors:

TAYLOR, J.S.H., Rastle, K., & DAVIS, M.H.

Reference:

Year of publication:

2011

CBU number:

7260

Abstract:

Dehaene and colleagues propose that the left fusiform gyrus (LFG) contains a specialised visual word form area (VWFA) representing abstract orthographic units. Conversely, Price and others argue that the LFG processes visual objects as well as words, attributing word-specific responses to task-related top-down modulation. Differences between these two tasks should be greatest during learning: words must be decoded using systematic spelling-sound mappings whereas objects must be arbitrarily associated with their names. We combine an artificial language paradigm with fMRI, providing a unique opportunity to explore ventral-temporal specialisation whilst learning novel words and objects. Twenty healthy adults learned new names for 24 novel objects and to read 24 new words written in novel symbols, whilst in an MRI scanner. Learning consisted of interleaved phases of training (paired visual and spoken forms) and testing (read words/name objects). Participants learned the trained items (words-69% correct, objects-68% correct) and generalized their orthographic knowledge to untrained words (62% correct). Relative to unimodal listening or viewing, cross-modal associative learning of spoken words paired with objects and novel written words activated bilateral superior parietal cortices, fusiform gyri and left hippocampus (p<.01 whole-brain corrected). The LFG (overlapping with VWFA) was more active when learning object-name associations than when learning to read words. The reverse contrast revealed activation in bilateral superior parietal cortices. The fact that the LFG was less involved in learning a new orthography than in learning new object-label associations challenges the idea that this region is specialised for word reading.