Daniela Brizzolara

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.

Rapid naming, not cancellation speed or articulation rate, predicts reading in an orthographically regular language (Italian)

This study examined the influence of rapid automatization naming (RAN) measures on various parameters of reading performance in children who were native speakers of a language with a shallow orthography (Italian). Participants included 281 children enrolled in first-to-sixth grade. They were given a Naming test, in which they had to name rapidly matrices of colors, objects, or digits, a Cancellation test, using the same stimulus materials, and an oral Articulation test. Performance on all tests improved steadily across ages tested. Performance on the Naming test, but not on the Cancellation and Articulation tests, predicted speed and accuracy in reading; none of these measures reliably predicted the reading comprehension measure. Data on a Blending test were also available for a subsample of first- and third-graders. Both RAN and phonological ability contributed independently to the prediction of reading ability (accuracy and speed) in these participants. The results extend observations on RAN to an orthographically shallow language (Italian) and suggest an element of continuity between languages with opaque and transparent orthographies.

Do phonologic and rapid automatized naming deficits differentially affect dyslexic children with and without a history of language delay? A study of Italian dyslexic children.

ObjectiveThe study aims to verify whether phonologic and rapid automatized naming (RAN) deficits are present and associated in Italian dyslexic children and whether they differentially affect dyslexics with and without a history of previous language delay (LD). BackgroundAccording to the phonologic core deficit hypothesis, dyslexia may stem from impairment of the representation and manipulation of phonemes and may be closely associated with oral language deficits. However, deficits in tasks not requiring fine-grained phonologic representations, such as RAN, have also been described in dyslexic children. MethodsThirty-seven children were selected on the basis of a reading deficit and were assigned to 2 groups according to whether or not they had a history of early LD as determined retrospectively by parental report. A battery of reading and writing, verbal working memory, metaphonologic, RAN, and visual search tests were administered. ResultsRAN deficits were shared by most dyslexics (with and without a history of LD), whereas phonologic deficits were mainly associated with a previous LD. This last condition did not result in a more profound impairment of reading and writing decoding skills. ConclusionIn a shallow orthography such as Italian, RAN, not phonologic deficits, may represent the main cognitive marker of developmental dyslexia.

Spatial and motion integration in children with autism.

Neuropsychological and psychophysical studies report controversial results regarding local-global visual processing and motion perception in autism. Here, we investigate contour integration and motion perception in an accurately diagnosed sample of autistic children, using low-level psychophysical tasks. We measured detection thresholds for a closed chain of Gabor patches, for different values of inter-element distance and we measured coherency thresholds of optic flow motion stimuli. Both experiments show comparable performances between autistics and normal subjects, demonstrating no evidence of early perceptual integration deficits. Some improvement in performance with age is detected in both groups.

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.

Abnormal Phonologic Processing in Familial Lateral Temporal Lobe Epilepsy Due to a New LGI1 Mutation

Summary:  Purpose: Autosomal dominant lateral temporal lobe epilepsy (ADLTLE) is a rare familial epilepsy with onset in adolescence or early adulthood, associated with mutations of LGI1 in most families. We describe the clinical, neuropsychological, and molecular genetic study of a new ADLTLE Italian family.

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 Brocas 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 Brocas area at birth, and occurs in brain regions homotopic to those usually involved in language processing.

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.

Naming speed and visual search deficits in readers with disabilities: evidence from an orthographically regular language (Italian).

The study examined rapid automatized naming (RAN) in 42 children with reading disabilities and 101 control children—all native speakers of Italian, a language with shallow orthography. Third-, 5th- and 6th-grade children were given a RAN test that required rapid naming of color, object, or digit matrices. A visual search test using the same stimulus material (but not requiring a verbal response) and an oral articulation test were also given. Readers with disabilities performed worse than controls on the RAN test. This effect was larger in higher grades than in lower ones. Readers with disabilities were also slower than controls in performing the visual search test. The pattern of results for the RAN test held constant when the visual search performance was partialed out by covariance analysis, indicating the independence of the 2 deficits. The 2 groups did not differ for articulation rate. Finally, analysis of the pattern of intercorrelations indicated that reading speed was most clearly related to RAN, particularly in the group with reading disabilities. The results extend observations of RAN effects on reading deficits to Italian, an orthographically shallow language.

A case of amnesia at an early age

A dissociation between short- and long-term memory (LTM) and between the episodic and the semantic component of LTM is reported in a young girl who became amnesic at the age of 6 after an episode of acute encephalopathy resulting in bilateral frontal, insular, thalamic, ponto-mesencephalic, hippocampal and temporal lesions, as documented by MRI. The girl became amnesic a few months after starting school. A follow-up investigation showed that she was able to learn to read, write and acquire number facts and procedures and to improve her semantic knowledge. Our results show that the features of adult amnesia can also be found in children and that new semantic knowledge can be acquired in spite of an anterograde memory deficit. This dissociation does not agree with theories viewing long-term declarative memory as a unitary process mediated by the hippocampal system, but supports recent hypotheses that the acquisition of semantic knowledge is independent from episodic memory processes, and takes place through spared cortical regions subjacent to the hippocampi (Vargha-Khadem et al., 1997).