Decompositional Representation of Morphological Complexity: Multivariate fMRI Evidence from Italian

Abstract

Derivational morphology is a cross-linguistically dominant mechanism for word formation, combining existing words with derivational affixes to create new word forms. However, the neurocognitive mechanisms underlying the representation and processing of such forms remain unclear. Recent cross-linguistic neuroimaging research suggests that derived words are stored and accessed as whole forms, without engaging the left-hemisphere perisylvian network associated with combinatorial processing of syntactically and inflectionally complex forms. Using fMRI with a "simple listening" no-task procedure, we reexamine these suggestions in the context of the root-based combinatorially rich Italian lexicon to clarify the role of semantic transparency (between the derived form and its stem) and affix productivity in determining whether derived forms are decompositionally represented and which neural systems are involved. Combined univariate and multivariate analyses reveal a key role for semantic transparency, modulated by affix productivity. Opaque forms show strong cohort competition effects, especially for words with nonproductive suffixes (ventura, "destiny"). The bilateral frontotemporal activity associated with these effects indicates that opaque derived words are processed as whole forms in the bihemispheric language system. Semantically transparent words with productive affixes (libreria, "bookshop") showed no effects of lexical competition, suggesting morphologically structured co-representation of these derived forms and their stems, whereas transparent forms with nonproductive affixes (pineta, pine forest) show intermediate effects. Further multivariate analyses of the transparent derived forms revealed affix productivity effects selectively involving left inferior frontal regions, suggesting that the combinatorial and decompositional processes triggered by such forms can vary significantly across languages.

Morpho-syntactic complexity modulates brain activation in Persian-English bilinguals: An fMRI study

“…This interpretation of our brain imaging results are aligned with the predictions of the dualsystems framework described in the introduction (Marslen-Wilson et al, 2014;Tyler & Marslen-Wilson, 2008), where it's expected that inflectional morphology will rely on brain regions including the left IFG. Other studies, including ones that have been designed to probe this framework, have also observed more extensive activation of left BA44 with increasing combinatorial load where inflectional morphology was involved (Bozic et al, 2007(Bozic et al, , 2015Carota et al, 2016;Klimovich-Gray et al, 2017;Schell et al, 2017). The specificity of our findings to the anterior-ventral Cluster 3 of BA44 is consistent with recent brain imaging findings on variations in combinatorial load within one language (Schell et al, 2017).…”

“…Inflectional morphology, which is computationally more complex, is expected to induce activation in the left hemisphere fronto-temporal regions (i.e., dorsal BA44 and pSTG), while derivational morphology is expected to engage bilateral temporal regions (i.e., STG and MTG; Klimovich-Gray, Bozic, & Marslen-Wilson, 2017). These predictions are borne out in studies having examined specific languages having different degrees of morpho-syntactic complexity, such as English, Arabic, Polish, Russian, and Italian (Boudelaa, Pulvermuller, Hauk, Shtyrov, & Marslen-Wilson, 2010;Bozic, Fonteneau, Su, & Marslen-Wilson, 2015;Bozic, Marslen-Wilson, Stamatakis, Davis, & Tyler, 2007;Carota, Bozic, & Marslen-Wilson, 2016;Klimovich-Gray et al, 2017).…”

Syntactic Complexity and Frequency in the Neurocognitive Language System

“…Although the simple nouns used in this experiment were words without inflectional affixes, they were typically multisyllabic words with onset-embedded pseudostems (e.g., cutlet, turnip), which are likely to generate cohort competition during spoken language comprehension. Our results are consistent with studies showing that bilateral temporal areas are implicated in the accessing of semantic representations of words (Binder, Desai, Graves, & Conant, 2009;Jung-Beeman, 2005) as well as studies showing that bilateral IFG and temporal areas are engaged in processing perceptually complex words (e.g., Carota, Bozic, & Marslen-Wilson, 2016;Zhuang, Tyler, Randall, Stamatakis, & Marslen-Wilson, 2014;Bozic et al, 2010).…”

How the brain composes morphemes into meaning

“…not bound to the visual or auditory sensory modalities) that can be accessed and therefore primed during comprehension; (ii) the representation is somewhat stable in order to generalize across lexical contexts. Furthermore, findings from fMRI link the processing of derived forms with activity in the left inferior frontal gyrus (LIFG) [57]-i.e. Broca's areawhich is traditionally associated with syntactic processing, broadly construed.…”