Evidence for separate tonal and segmental tiers in the lexical specification of words: A case study of a brain-damaged Chinese speaker (original) (raw)

Neural correlates of segmental and tonal information in speech perception

Human Brain Mapping, 2003

The Chinese language provides an optimal window for investigating both segmental and suprasegmental units. The aim of this cross-linguistic fMRI study is to elucidate neural mechanisms involved in extraction of Chinese consonants, rhymes, and tones from syllable pairs that are distinguished by only one phonetic feature (minimal) vs. those that are distinguished by two or more phonetic features (non-minimal). Triplets of Chinese monosyllables were constructed for three tasks comparing consonants, rhymes, and tones. Each triplet consisted of two target syllables with an intervening distracter. Ten Chinese and English subjects were asked to selectively attend to targeted sub-syllabic components and make same-different judgments. Direct between-group comparisons in both minimal and non-minimal pairs reveal increased activation for the Chinese group in predominantly left-sided frontal, parietal, and temporal regions. Within-group comparisons of non-minimal and minimal pairs show that frontal and parietal activity varies for each sub-syllabic component. In the frontal lobe, the Chinese group shows bilateral activation of the anterior middle frontal gyrus (MFG) for rhymes and tones only. Within-group comparisons of consonants, rhymes, and tones show that rhymes induce greater activation in the left posterior MFG for the Chinese group when compared to consonants and tones in non-minimal pairs. These findings collectively support the notion of a widely distributed cortical network underlying different aspects of phonological processing. This neural network is sensitive to the phonological structure of a listener's native language.

Dissociation in the neural basis underlying Chinese tone and vowel production

NeuroImage, 2006

Neuropsychologists have debated over whether the processing of segmental and suprasegmental units involves different neural mechanisms. Focusing on the production of Chinese lexical tones (suprasegmental units) and vowels (segmental units), this study used the adaptation paradigm to investigate a possible neural dissociation for tone and vowel production. Ten native Chinese speakers were asked to name Chinese characters and pinyin (Romanized phonetic system for Chinese language) that varied in terms of tones and vowels. fMRI results showed significant differences in the right inferior frontal gyrus between tone and vowel production (more activation for tones than for vowels). Brain asymmetry analysis further showed that tone production was less left-lateralized than vowel production, although both showed left-hemisphere dominance. D

Hemispheric asymmetries in phonological processing of tones versus segmental units

NeuroReport, 2010

The aim of this functional magnetic resonance imaging study is to identify neuroanatomical substrates underlying phonological processing of segmental (consonant, rhyme) and suprasegmental (tone) units. An auditory verbal recognition paradigm was used in which native speakers of Mandarin Chinese were required to match a phonological unit that occurs in a list of three syllables to the corresponding unit of a following probe. The results show that hemispheric asymmetries arise depending on the type of phonological unit. In direct contrasts between phonological units, tones, relative to consonants and rhymes, yield increased activation in frontoparietal areas of the right hemisphere. This finding indicates that the cortical circuitry subserving lexical tones differs from that of consonants or rhymes.

Effects of syllable structure in aphasic errors: Implications for a new model of speech production

Cognitive Psychology, 2011

Current models of word production assume that words are stored as linear sequences of phonemes which are structured into syllables only at the moment of production. This is because syllable structure is always recoverable from the sequence of phonemes. In contrast, we present theoretical and empirical evidence that syllable structure is lexically represented. Storing syllable structure would have the advantage of making representations more stable and resistant to damage. On the other hand, re-syllabifications affect only a minimal part of phonological representations and occur only in some languages and depending on speech register. Evidence for these claims comes from analyses of aphasic errors which not only respect phonotactic constraints, but also avoid transformations which move the syllabic structure of the word further away from the original structure, even when equating for segmental complexity. This is true across tasks, types of errors, and, crucially, types of patients. The same syllabic effects are shown by apraxic patients and by phonological patients who have more central difficulties in retrieving phonological representations. If syllable structure was only computed after phoneme retrieval, it would have no way to influence the errors of phonological patients. Our results have implications for psycholinguistic and computational models of language as well as for clinical and educational practices.

Syllable structure and lexical frequency effects in the phonemic errors of four aphasics

Journal of Neurolinguistics, 1990

Four fluent aphasics were submitted to a repetition task including high-frequency words, lowfrequency words and non-words, varying with respect to syllable markedness. The word/nonword opposition is significant in the responses of all patients, while a frequency effect is observed in the responses of two of them. Results suggest that all stimuli are processed through a single route by these patients. It is proposed that lexicality (word vs non-word) and frequency effects are related to variations in the degree of automaticity reached in the processing of stimuli. A second experiment reveals that length, rather than syllable complexity, is the structural factor with the most significant impact on performance. A qualitative analysis demonstrates, however, that syllable is a relevant structural unit at the psycholinguistic level. Recent studies (Joannette et al. 1980; Caramazza et al. 1986; Caplan et al. 1986) have shown that aphasics as well as normal subjects perform significantly better on real words than on non-words in repetition and naming tasks. McCarthy and Warrington (1984) have demonstrated that conduction aphasics perform significantly better on high-frequency stimuli than on low-frequency stimuli in a repetition task.