Authors:

BOZIC, M., Tyler, L.K., & MARSLEN-WILSON, W.D.

Reference:

Year of publication:

2009

CBU number:

7011

Abstract:

Lexical complexity plays a prominent role in modulating the activity of fronto-temporal language networks. Studies with regularly inflected words (jumped, smiled) show that the presence of morpho-phonological complexity (stem + inflectional affix) activates left-lateralised areas, while lexical-semantic complexity (presence of competing alternatives due to embedded stems, e.g., claim(clay), ramp(ram), etc) engages bilateral inferior frontal regions. The current efMRI experiment asked whether similar left-lateralised decomposition and bilateral competition processes hold for derivationally complex words (darkness, warmth), where the stem-affix relationship is strongly lexicalised and less semantically predictable. In a set of single spoken words we manipulated the presence of embedded stems and derivational suffixes with varying degrees of productivity, forming a gradient in the extent that the stimuli are predicted to trigger competition and decomposition processes. Words were contrasted with a complex auditory baseline that does not trigger a speech percept (‘musical rain’, Uppenkamp et al, 2006). We found that the presence of competing embedded stems engages bilateral fronto-temporal language regions, comparable to the results observed previously. In contrast, derivational affixes do not seem to selectively activate a left-lateralised subsystem. This is arguably because derivational affixes do not trigger decompositional processes in the same way as inflectional affixes. We suggest a neuro-cognitive account of the representation and processing of derivationally complex forms in English.