The crucial role of thiamine in the development of syntax and lexical retrieval: a study of infantile thiamine deficiency

This study explored the effect of thiamine deficiency during early infancy on the development of syntax and lexical retrieval. We tested syntactic comprehension and production, lexical retrieval abilities and conceptual abilities of 59 children aged 5–7 years who had been fed during their first year of life with a thiamine-deficient milk substitute. We compared them to 35 age-matched control children who were fed with other milk sources. Experiment 1 tested the comprehension of relative clauses using a sentence–picture-matching task. Experiment 2 tested the production of relative clauses using a preference elicitation task. Experiment 3 tested the repetition of various syntactic structures with various types of syntactic movement and embedding. Experiment 4 tested picture naming and Experiment 5 tested lexical substitutions in a sentence repetition task. Experiments 6 and 7 tested the children’s conceptual abilities using a picture association task and a picture absurdity description task. The results indicated a very high rate of syntactic and lexical retrieval deficits in the group of children who were exposed to thiamine deficiency in early infancy: 57 of the 59 thiamine-deficient children examined had language impairment, compared with three of the 35 controls (9%). Importantly, unlike the impairment this group sustained in their language abilities, the conceptual abilities of most of the children were intact (only six children, 10%, were conceptually impaired). These findings indicate that thiamine deficiency in infancy causes severe and long-lasting language disorders and that nutrition may be one of the causes for language impairment.

from Brain

Effects of word frequency and phonological neighborhood characteristics on confrontation naming in children who stutter and normally fluent peers

In a prior study (Newman & Bernstein Ratner, 2007), we examined the effects of word frequency and phonological neighborhood characteristics on confrontation naming latency, accuracy and fluency in adults who stutter and typically-fluent speakers. A small difference in accuracy favoring fluent adults was noted, but no other patterns differentiated fluent speaker responses from those obtained from the adults who stutter. Because lexical organization or retrieval differences might be more easily observed in less mature language users, we replicated the experiment using 15 children who stutter (ages 4;10 16;2) and age-and gender-matched peers. Results replicated the earlier study: the two groups of participants showed strikingly similar patterns of responses based on word frequency and neighborhood characteristics. There were also no differences in naming accuracy overall between the two groups. Given our results and those of other researchers who have explored the impact of neighborhood variables on lexical retrieval in people who stutter, we suggest that differences between language production in PWS and fluent speakers are not likely to involve atypical phonological organization of lexical neighborhoods.

from Journal of Fluency Disorders

The relation between content and structure in language production: An analysis of speech errors in semantic dementia

In order to explore the impact of a degraded semantic system on the structure of language production, we analysed transcripts from autobiographical memory interviews to identify naturally-occurring speech errors by eight patients with semantic dementia (SD) and eight age-matched normal speakers. Relative to controls, patients were significantly more likely to (a) substitute and omit open class words, (b) substitute (but not omit) closed class words, (c) substitute incorrect complex morphological forms and (d) produce semantically and/or syntactically anomalous sentences. Phonological errors were scarce in both groups. The study confirms previous evidence of SD patients’ problems with open class content words which are replaced by higher frequency, less specific terms. It presents the first evidence that SD patients have problems with closed class items and make syntactic as well as semantic speech errors, although these grammatical abnormalities are mostly subtle rather than gross. The results can be explained by the semantic deficit which disrupts the representation of a pre-verbal message, lexical retrieval and the early stages of grammatical encoding.

from Brain and Language