Which linguistic measures distinguish transient from persistent language problems in Late Talkers from 2 to 4 years? A study on Italian speaking children.

BACKGROUND: In spite of the large literature on Late Talkers (LTs) it's still unclear which factors predict outcome in children younger than 3 years old. AIMS: To identify the early language characteristics of LTs whose outcome was either a transient delay or a Developmental Language Disorder (DLD). METHODS AND PROCEDURES: 50 LTs were assessed both by indirect and direct measures of expressive and receptive language at three time points between 2 and 4 years of age. OUTCOMES AND RESULTS: At the first evaluation, all LTs had an expressive language delay; 61% also had delayed early syntactic comprehension. Three different linguistic outcomes emerged: children who caught up with their peers ("Late Bloomers") at age 3; children with slow language recovery ("Slow Learners") at age 4 and children at risk of DLD. The linguistic measures that differentiated the groups changed with age. By 28 months, impaired syntactic comprehension differentiated children at risk of DLD at 4 years of age, from the other two groups. By 36 months, the discrepancy between vocabulary size and age was larger in children with persistent language difficulties compared to both "Late Bloomers" and "Slow Learners". Expressive grammar differentiated the groups significantly by age 3 with difficulties in this domain still persisting in children with DLD at age 4. CONCLUSIONS: An early syntactic comprehension delay was a predictive index of DLD in LTs, suggesting the importance of evaluating this language component when assessing LT toddlers. IMPLICATIONS: LTs with receptive-expressive language delay around 24-30 months could benefit from an early language intervention.

Language organisation in left perinatal stroke.

Right-hemispheric organisation of language has been observed following early left-sided brain lesions. The role of the site of damage is still controversial, as other aspects influence the pattern of speech organisation including timing of the lesion and the presence of epilepsy. We studied a group of 10 term-born children homogeneous for timing/type of lesion and clinical picture. All subjects had left perinatal arterial stroke, right hemiplegia, normal cognitive functions and no or easily controlled epileptic seizures. In half the patients, the lesion clearly involved Broca's area, in the other half it was remote from it. Language lateralization was explored by an fMRI covert rhyme generation task. Eight of 10 subjects showed a right lateralisation of language, including all five patients with a damaged left Broca and 3/5 of those without it. Group analysis in patients with right hemispheric organisation showed brain activations homotopic to those found in the left hemisphere of a matched control group. Our findings confirm that, at the end of gestation, the human brain exhibits extraordinary (re-)organisational capabilities. Language organisation in the right hemisphere is favoured by the presence of destructive lesions of the left Broca's area at birth, and occurs in brain regions homotopic to those usually involved in language processing.

Visual scanning and reading ability in normal and dyslexic children.

Very few studies have investigated the development of visual search of aligned stimuli in relation to normal reading acquisition and in developmental dyslexia. In this study we used a new computerised experimental task which requires a visuo-motor response (RT) to a target appearing unpredictably in one out of seven different spatial positions on a horizontally aligned array of 18 geometrical figures. The aims of the study were to investigate: 1) the visual scanning development in normal children from pre-school to school age; 2) whether visual scanning performance in kindergarten children could predict reading acquisition; 3) the visual scanning abilities in a group of developmental dyslexic children. The main results were: 1) a significant decrement of RTs with age and a progressive increase of the left-to-right gradient with reading experience; 2) visual scanning abilities in kindergarten proved to be a good predictor of reading acquisition; 3) dyslexics were slow scanners and did not present the left-to-right strategy typical of normal readers. The results support the hypothesis of a relationship between visual scanning and reading abilities.

Acquired focal brain lesions in childhood: effects on development and reorganization of language.

In the present paper, we address brain-behaviour relationships in children with acquired aphasia, by reviewing some recent studies on the effects of focal brain lesions on language development. Timing of the lesion, in terms of its occurrence, before or after the onset of speech and language acquisition, may be a major factor determining language outcome. However, it is still unclear which are the effects of aphasia occurring between 2 and 5 years of age, a time window which is crucial for acquiring and automatizing the basic rules of native language. A comprehensive review of the literature on acquired childhood aphasia precedes the description of long-term follow-up (20 years) of two identical twins, one of whom became aphasic at 3 years and 4 months after infarction of the left sylvian artery. Psycholinguistic analysis and fMRI data show a slow and incomplete recovery from non-fluent aphasia associated to an intra-hemispheric organization of language. These data, which support the potential but also the limits of neural plasticity during language development, are discussed in the light of the literature on the time-course and neural bases of acquired childhood aphasia.

Brain representation of phonological processing in Italian: individual variability and behavioural correlates.

Neuroimaging literature on phonological processing during reading lacks of studies taking into account orthographic differences across languages and behavioural variability across subjects. The present study aimed at investigating brain representation of phonological processing in reading Italian, a language with regular orthography, with particular regard to inter-individual variability and brain-behavioural correlates. Ten Italian adults performed a rhyme generation and a rhyme judgment task during fMRI acquisition and were tested with behavioural measures of phonological processing. Results for both tasks showed activations of the left Inferior Frontal Gyrus and Dorsolateral Prefrontal Cortex, likely underlying output sublexical strategies, for all or most of the subjects, while a minority of subjects activated the Superior Temporal Sulcus and the Temporo-Parietal-Occipital Junction. These results suggest that phonological processing of written Italian is based on the prevalent use of frontal structures. However, it is of interest that the activation of the Superior Temporal Sulcus, involved in phonological input, was associated to better behavioural performances in tasks of phonological processing. Our findings may contribute to understand neural correlates of phonological processing of languages with regular orthography.

Italian neuropsychological instruments to assess memory, attention and frontal functions for developmental age.

In this study, a series of tests exploring long-term verbal memory (the Short Story Test), attention (a modified version of Attentional Matrices and the Trail Making Test) and frontal functions (a modified version of the Frontal Assessment Battery) have been standardised on an Italian population of 283 children aged 5-14. Raw scores for each test have been adjusted for a series of variables (child's age, years of parents' education, handedness, gender) and transformed in equivalent scores enabling direct comparison across measures. This study was promoted by LICE (the Italian League Against Epilepsy) in order to provide Italian instruments standardised on the developmental age population and to study some of the most frequently impaired cognitive functions in epilepsy.

Atypical language lateralization and early linguistic development in children with focal brain lesions.

The effects of congenital, unilateral, focal brain lesions on early linguistic development and hemispheric lateralization for language were investigated longitudinally in 24 preschool children with hemiplegia (14 males, 10 females), 12 with left hemisphere damage (LHD) and 12 with right hemisphere damage (RHD). A comprehensive linguistic assessment was performed at 2 and 3 years of life; cerebral lateralization for language was measured by the Fused Dichotic Words Listening Test. An early left-side specificity for language was indicated by the presence of lexical and grammatical delay in most children with LHD. In the dichotic listening test all 12 children with LHD showed a shift of language lateralization from the left to the right hemisphere. Atypical lateralization coefficients (lambda), i.e. values falling more than two standard deviations from the mean of a normative sample, were associated with a delay in lexical and grammatical development, especially after LHD. In addition, cortical-subcortical-periventricular lesions rather than solely periventricular damage, and larger lesions rather than small, were associated with the most atypical lateralization coefficients, irrespective of lesion side. Results of this study suggest that language and lateralization data are closely related and that reallocation of language functions in alternative regions of the brain has a cost in terms of a slow rate of language acquisition.

del (9p) syndrome: proposed behavior phenotype.

Over recent years interest in the study of behavior phenotypes has gained increasing momentum. We present three white female patients, age respectively 9 years 9 months, 14 years 6 months and 18 years at the time of the last observation, seen because of developmental delay/mental retardation, seizures and learning disabilities. Cytogenetic analysis showed a de novo deletion of the short arm of chromosome 9 in all three, with the breakpoint being located at band 9p22. Although several studies have described the somatic phenotype, analytical evaluation of verbal and non-verbal cognitive functions are lacking. Our patients received a detailed neuropsychological and linguistic evaluation that showed a particular behavior profile, in the context of mental retardation of variable degree. On selective tests there was a marked deficit in visuo-praxic and visuo-spatial skills associated with memory disturbance. Visuo-motor integration abilities [VMI; Beery, 1997] and visuo-perceptual and visuo-spatial abilities [Benton line orientation test, 1992] seemed particularly impaired, both in relation to verbal mental age (vocabulary and grammatical production/comprehension) and to some non-verbal competencies [Benton face recognition test, 1992]. The profile shows advanced performances in face recognition. In addition, there is also a dissociation between verbal and visuo-spatial short term memory. This behavior phenotype is similar to that of Williams syndrome (WS) individuals. Our patients also showed some unusual within-domain dissociations regarding linguistic abilities. To better demonstrate similarities and differences between the behavior phenotypes of the del (9p22) syndrome and WS, we studied three IQ-gender-matched WS subjects. The comparison between the cognitive phenotypes of the two syndromes shows similarities in neuropsychological pattern. We hypothesize that there is a gene within the 9p22 region responsible for the neuropsychological profile described here.

"Developmental dysmnesia": a case report.

We report a 9-year-old girl who presented from an early age a severe and specific verbal memory disorder, in the absence of a definite etiology. The results of an extensive neuropsychological assessment showed a dissociation between normal visuo-spatial memory abilities and a marked short-term and long-term verbal memory impairment. We argue that our case is affected by "developmental dysmnesia", a condition so far described in two cases only (De Renzi and Lucchelli, 1990, and Temple, 1997). The disorder affected episodic as well as semantic verbal memory. The long term effects on learning and cognition of a memory deficit occurring early in childhood are discussed.

Visual information processing in infants with focal brain lesions.

Visual information processing for faces were tested by means of the Fagan test of infant intelligence (FTII) in six infants of approximately 12 months of age affected by congenital unilateral brain lesions. Magnetic resonance imaging (MRI) was used to determine the side and size of the lesions. In addition to the FTII, all infants were submitted to a psychometric evaluation using the Griffiths scales. Visual acuity, visual field, and ocular motility were also assessed. Three infants showed damage in the left hemisphere and three in the right. The severity of the lesions, as revealed by MRI scan, was similar in the two groups. All infants except one had normal or borderline cognitive scores on the Griffiths scales. Conversely, four infants showed abnormal results on the FTII, which were not associated with the severity of the lesions, psychometric scores, or the presence of visual deficits. A preference for stimuli presented on the left side of the screen was found, independent of the side of the lesions. This effect was stronger for novel stimuli. The results of this study confirm the importance of early assessment of neuropsychological functions in infants with focal brain lesions.

Memory abilities in children with Williams syndrome.

Williams syndrome (WS) is a rare genetic condition characterised by intellectual disability, typical facial dysmorphology and several medical anomalies. A specific neuropsychological profile with a dissociation between language (relatively preserved) and visuo-spatial abilities (more seriously impaired) has been hypothesised in these children. Memory abilities of these patients have not been adequately investigated, although they may substantially contribute to better understanding their neuropsychological profile. The present study aimed at investigating verbal and spatial memory in patients with WS (N = 16). Their performance was compared with that of normally developing children on tasks of verbal and spatial span and immediate and delayed recall of verbal and visuo-perceptual materials. Memory abilities of WS children appear to be characterised by defective visuo-spatial memory, both in the short-term and long-term domain, and a dissociation between normal short- but deficient long-term verbal learning. Results are interpreted by supporting the thesis that intellectual disability reflects the defective functioning of a complex system in which some cognitive competencies may be disrupted more than others (Detterman, 1987; Vicari, Albertini and Caltagirone, 1992).

Short-term memory in children with Williams syndrome: a reduced contribution of lexical--semantic knowledge to word span.

Williams syndrome (WS) is a genetic syndrome of abnormal neurodevelopment, characterised by a specific linguistic pattern. Comparing performances of WS subjects with those of normal children in a word span task, we found that WS subjects revealed normal phonological similarity and length effects but a reduced frequency effect. Our results suggest comparable phonological encoding mechanisms in WS and normal controls and, at the same time, it provides evidence for an impaired access to lexical-semantic knowledge in WS subjects. This dissociation fits well with the particular pattern of linguistic abilities of these subjects.

Is interhemispheric transfer time related to age? A developmental study.

In simple visuomotor reaction time tasks, the difference between reaction time (RT) in the uncrossed hand/hemifield condition from RT in the crossed hand/hemifield, known as CUD (crossed-uncrossed difference), has been interpreted as reflecting interhemispheric transmission time (IHTT). Several studies in normal adults have found a CUD of a few milliseconds (3-4), while an abnormally long CUD has been reported in patients who underwent a surgical section of the corpus callosum or in congenital acallosal subjects. The corpus callosum, which is the most important structure for interhemispheric transfer of information, completes its myelination approximately by age ten. It has been hypothesized that the functional maturity of the corpus callosum coincides with the termination of the myelination cycle. No developmental study has focused on the development of IHTT, in relation to callosal maturation. The purpose of our study has been to investigate the development of interhemispheric transfer of visuomotor information in children aged seven to eleven, using a simple RT task with lateralized visual stimuli. The results indicate an age-related decrease of CUD, which we interpret as reflecting the maturation of the corpus callosum during childhood years.

Neuropsychological assessment in schoolchildren from an area of moderate iodine deficiency.

Neuropsychological assessment was carried out in schoolchildren from a montane area of Eastern Tuscany (Tiberina Valley). This area was found to be moderately iodine deficient (mean urinary iodine excretion: 39 micrograms/g creatinine), with a cumulative goiter prevalence of 51.9% in schoolchildren aged 6-14 yr (goiter prevalence in the control iodine-sufficient area: 5.6%). No significant differences in serum TT4, TT3, FT4I, TSH levels between the endemic and control areas were found, whereas serum thyroglobulin values were significantly higher in the iodine-deficient area (61 +/- 8 vs 17 +/- 1 ng/ml, p less than 0.01). No differences were found as to the height, body weight and pubertal development in the two areas. Neuropsychological assessment, performed in a representative sample of 50 schoolchildren from the endemic area and 50 schoolchildren from the control area, matched for age, sex and socioeconomical conditions, failed to show major differences between the two groups in the global neuropsychological performance and cognitive levels. However, minor but significant differences were noted in the information vocabulary and coding subtests, at least in children aged 8. Although familial cultural influences might play a role, it would appear that some marginal impairment, with particular regard to motor-perceptual functions, be present in areas of moderate iodine deficiency.

Neuropsychological assessment of a case of early right hemiplegia: qualitative and quantitative analysis.

Evidence for normal development of linguistic but poor visuo-perceptual skills has been obtained with the neuropsychological assessment of a case of early left-brain injury. Data suggest the transfer of linguistic functions from the left to the right hemisphere at the expense of visuo-perceptual capacities for which the right hemisphere is potentially specialized.

Functional cerebral lateralisation; dichotomy or plurality?

Cartoon faces were presented tachistoscopically in the right and left visual fields, and required to be matched to a previously memorised target face. The three different stimuli differed from the target either on only one, or on all three features (eyes, nose, mouth). Reaction times varied considerably across the individual different responses in both conditions. In the first condition field differences consistently favoured the right field; in the second, two favoured the left and the third the right. In both conditions same responses were faster than at least one different response class. Several interpretations in terms of the distinction between "analytic" and "holistic" processes were entertained. Such processes themselves remain somewhat obscure, but there is nothing in the data to suggest that the two cerebral hemispheres might not be essentially ambivalent in their predilections for the two kinds of processing. In which case future research might profitably focus on the emerging plurality of experimental factors governing this cognitive ambivalence, rather than on the simple physical dichotomy.

Tactile discrimination of direction of lines in relation to hemispheric specialization.

The role of the right hemisphere in a task of haptic discrimination of line orientation was studied in 16 children aged 7.6 and 16 adults aged 25 yr. The exploratory movements were limited to hand and wrist, since it has been shown that distal movements are mediated by the contralateral hemisphere. A comparison of the performance of the two hands shows a clear superiority of the left hand and inferred right hemisphere in both children and adults. An special emphasis in the discussion is given to the role of the experimental procedure in enhancing the effect of the hemispheric functional asymmetries.