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Abstract: Neuroimaging studies of English suggest that speech comprehension engages two interdependent systems: a bilateral fronto-temporal network responsible for general perceptual and cognitive processing, and a specialised left-lateralised network supporting specifically linguistic processing. Using fMRI we test this hypothesis in Polish, a Slavic language with rich and diverse morphology. We manipulated general perceptual complexity (presence or absence of an onset-embedded stem, e.g. kotlet ‘cutlet’ vs. kot ‘cat’) and specifically linguistic complexity (presence of an inflectional affix, e.g. dom ‘house, Nom’ vs. dom-u ‘house, Gen’). Non-linguistic complexity activated a bilateral network, as in English, but we found no differences between inflected and uninflected nouns. Instead, all types of words activated left inferior frontal areas, suggesting that all Polish words can be considered linguistically ‘complex’ in processing terms. The results support a dual network hypothesis, but highlight differences between languages like English and Polish, and underline the importance of cross-linguistic comparisons. [Copyright &y& Elsevier]

Abstract: By employing visual lexical decision and functional MRI, we studied the neural correlates of morphological decomposition in a highly inflected language (Finnish) where most inflected noun forms elicit a consistent processing cost during word recognition. This behavioral effect could reflect suffix stripping at the visual word form level and/or subsequent meaning integration at the semantic-syntactic level. The first alternative predicts increased activation for inflected vs. monomorphemic words in the left occipitotemporal cortex while the second alternative predicts left inferior frontal gyrus and/or left posterior temporal activation increases. The results show significant activation effects in the latter areas. This provides support for the second alternative, i.e., that the morphological processing cost stems from the semantic-syntactic level. [Copyright &y& Elsevier]

Abstract: This study presents results from a nonce-word elicited production task and a reading experiment using event-related brain potentials (ERPs) investigating finite forms of Spanish verbs which consist of marked stems and regular person and number agreement suffixes. The first experiment showed that unmarked stems are productively extended to nonce words, whereas marked stems generalize more restrictively to nonce words, based on lexical similarity to existing stem forms. The second experiment yielded a lexical ERP signature for stem violations and an ERP pattern signaling morpho-syntactic (rule-based) processing for suffix violations. We argue that stem allomorphy is lexically represented in the Spanish mental lexicon, with marked stems forming subnodes of structured lexical entries. [Copyright &y& Elsevier]

Dissociations in the recognition of specific classes of words have been documented in brain-injured populations. These include deficits in the recognition and production of morphologically complex words as well as impairments specific to particular syntactic classes such as verbs. However, functional imaging evidence for distinctions among the neural systems underlying these dissociations has been inconclusive. We explored the neural systems involved in processing different word classes in a functional Magnetic Resonance Imaging study, contrasting four groups of words co-varying morphological complexity (simple, monomorphemic words vs complex derived or inflected words) and syntactic class (verbs vs nouns/adjectives). Subtraction of word from letter string processing showed activation in left frontal and temporal lobe regions consistent with prior studies of visual word processing. No differences were observed for morphologically complex and simple words, despite adequate power to detect stimulus specific effects. A region of posterior left middle temporal gyrus showed significantly increased activation for verbs. Post hoc analyses showed that this elevated activation could also be related to semantic properties of the stimulus items (verbs have stronger action associations than nouns, and action association is correlated with activation). Results suggest that semantic as well as syntactic factors should be considered when assessing the neural systems involved in single word comprehension. [Copyright &y& Elsevier]

Verb inflection errors, often seen in agrammatic aphasic speech, have been attributed to either impaired encoding of diacritical features that specify tense and aspect, or to impaired affixation during phonological encoding. In this study we examined the effect of semantic markedness, word form frequency and affix frequency, as well as accuracy and error patterns, in an attempt to evaluate whether diacritical or affixation operations are impaired. Verb inflections (V+ing, V+ed, V+s, and V stem in present progressive, past, present 3rd person singular, and future tense contexts, respectively) were elicited in eight mild-moderate agrammatic aphasic individuals in a sentence context using a picture description task. Results revealed that the majority of verbs produced were affixed (75%) although accuracy was low (36%). Word form frequency was found to be a significant predictor of the accuracy with which verb inflections were produced; while affix frequency and semantic markedness were not found to influence accuracy. These results suggest that a diacritical deficit is more likely to undermine the production of verb inflections than a affixation deficit, and indicate that when diacritical processes are compromised, word form frequency is likely to influence production of verb inflections in agrammatic aphasia. [Copyright &y& Elsevier]

This paper investigates sensitivity to gender, person, and tense inflection in individuals with Alzheimer’s disease (AD) in on-line and off-line tasks. Fourteen persons with AD and 14 matched controls participated in two studies: sensitivity to gender incongruity was tested in an on-line reading task and sensitivity to violation of tense and person was tested with an off-line grammaticality judgement test. Group performance was comparable on both tasks. It is argued that patients’ preserved sensitivity to these features is primarily a function of the simplicity of the required operations. The notion of simplicity in this context is discussed and various parameters are offered for future investigation. [Copyright &y& Elsevier]

A series of four visual–visual priming experiments investigates the role of bound stem allomorphs in the representation and processing of Finnish case inflected nouns. Niemi et al. (1994) and Laine et al. (1994) argue that Finnish nouns are parsed into stem and affix in reception and that the bound stem allomorphs have separate (visual) lexical representations. Recently Ja¨rvikivi and Niemi (in press) have provided converging evidence for their claim based on a series of lexical decision experiments with Finnish stem allomorphs. The results from the present series of four follow-up experiments reported here showed that (isolated) bound stem allomorphs primed the recognition of the corresponding monomorphemic nouns significantly compared both to phonologically unrelated pseudowords and to phonologically minimally different pseudowords. Furthermore, not only did both phonologically transparent and opaque case inflected nouns prime the corresponding nominative singulars, but also there was no difference in priming between the two. The results are well in accordance and corroborate the hypotheses drawn from the earlier investigations. Moreover, they further indicate that bound stem allomorphs have representations on a purely formal level only, i.e., they serve as indices of and entering points to morphological/morphosyntactic information. [Copyright &y& Elsevier]

This study investigates the differences in the input representations of verbs and nouns in the Italian mental lexicon. One visual lexical decision experiment in which the stem homograph effect (Laudanna, Badecker, & Caramazza, 1989) was evaluated on noun and verb targets is reported. Strong inhibitory effects on verb targets preceded by stem homographs relative to nonhomographic word pairs were found. The effects on verb targets were also much more reliable than the effects on noun targets. The pattern of results provides support for the hypothesis that noun and verbs are differently represented in the orthographic input lexicon. [Copyright &y& Elsevier]

Previous studies have found that priming a target like cerr-o (“hill”) with an unmasked stem-homograph (e.g., cerr-ar, “to close”) or with an unmasked allomorph of a stem-homograph (e.g., cierr-a, “he/she/it closes”) has an inhibitory effect on target recognition. We report evidence from stem-homograph priming studies that implicate both morphological parsing and lexical selection processes at the lemma level. We argue that stem-homograph inhibition is the product of lexical selection mechanisms that are engaged just when a fully ambiguous stimulus (here, an inflectional stem) must be assigned one of its viable interpretations in order to afford conscious perception of lexical identity. [Copyright &y& Elsevier]