Giacomo Stella

Regional reductions of gray matter volume in familial dyslexia

An in vivo anatomic study of gray matter volume was performed in a group of familial dyslexic individuals, using an optimized method of voxel-based morphometry. Focal abnormalities in gray matter volume were observed bilaterally in the planum temporale, inferior temporal cortex, and cerebellar nuclei, suggesting that the underlying anatomic abnormalities may be responsible for defective written language acquisition in these subjects.

How Early Does Morpholexical Reading Develop in Readers of a Shallow Orthography

In this research, lexical and morpholexical reading in Italian children ages 8 to 10 years were investigated. Children and control adults were administered two tasks on words and pseudowords: visual lexical decision and naming. Word frequency effects in both lexical decision and naming were found in both children and adults. For all age groups pseudowords made up of roots and derivational suffixes were decided more frequently as possible words and were named more quickly and accurately than matched pseudowords with no morphological constituency. These results show that morpholexical reading is available and efficient in young readers of a shallow orthography, with similar patterns in children and adults.

The development of reading speed in Italians with dyslexia: a longitudinal study.

The development of reading speed in Italian children with dyslexia was estimated using individualized growth curves for a group of 38 children with dyslexia tested longitudinally from the second to the eighth grade and compared with typical readers. Their reading speed development followed a linear trend of .3 syllables per second per grade, approximately half the increment observed in typical children reading a passage and similar to typical childrens reading of nonword lists. These findings give support to the deficit hypothesis versus the lag hypothesis and to reading speed as the core deficit in dyslexia with transparent orthographies.

Neuropsychological deficits and neural dysfunction in familial dyslexia

We report the neuropsychological profile and the pattern of brain activity during reading tasks in a sample of familial dyslexics. We studied our subjects with an in-depth neuropsychological assessment and with functional neuroimaging (fMRI) during word and pseudoword reading and false font string observations (baseline condition). The neuropsychological assessment revealed that familial dyslexia, in both persistent and compensated forms, is often associated with deficits in verbal short-term memory, phonological awareness and automatization abilities. The functional results showed a lack of activation in the posterior areas of the reading network. This study, together with the previously published VBM study (Brambati, S.M., Termine, C., Ruffino, M., Stella, G., Fazio, F., Cappa, S.F. and Perani, D., Regional reductions of gray matter volume in familial dyslexia, Neurology, 63 (2004) 742-5), provides a multiple modality evaluation of familial dyslexia. The neuropsychological assessment showed cognitive deficits associated with dyslexia that persist also in subjects with compensated reading deficit. Both the anatomical and the functional study point out a deficit in the posterior areas of the reading network.

Real-word repetition as a predictor of grammatical competence in Italian children with typical language development

BACKGROUND Non-word repetition in children is a skill related to, but separable from grammatical ability. Lexical skill may bridge the gap between these two abilities. AIMS The main aim was to determine whether real-word-repetition tasks could be better as predictors of grammatical ability than non-word-repetition tasks in children with typical language. This proposal was pursued because lexical knowledge was assumed to make performance in repetition tasks more representative of other language abilities, whereas non-word-repetition tasks are heavily influenced by phonological short-term memory. METHODS & PROCEDURES In order to investigate this possibility, three repetition tasks (two real-word lists characterized by different lexical knowledge and one non-word list), were compared in three groups of three- to four-year-olds with typical language (42 children). Grammatical ability was tested through probes for third-person plural inflection and direct-object critic use. OUTCOMES & RESULTS Real words were repeated more accurately than non-words and the non-words were more sensitive to Syllable length than real words. Performance on all repetition tasks was correlated with grammatical ability, but real words predicted variance in grammatical ability to a greater extent than non-words. CONCLUSIONS & IMPLICATIONS Given the lexical information contained in real words, repetition of such words was a better predictor of grammatical ability than non-word repetition. Future research should replicate and extend these results. Tasks using real words may also have considerable clinical potential; for this reason, these tasks might also be included in studies of children with language impairment.

Response inhibition and adaptations to response conflict in 6- to 8-year-old children: Evidence from the Simon effect

Several studies have shown that the Simon effect, which is the advantage of spatial correspondence between stimulus and response locations when the stimulus location is task-irrelevant, decreases with increasing response times and is affected by preceding-trial correspondence. These modulations suggest the existence of control mechanisms that adapt our behavior to current goals by responding to the conflict experienced within a trial and by preventing the recurrence of a conflict in the subsequent trial. The aim of the present study was to assess whether these control mechanisms, which are well consolidated in adults and in children older than 8 years of age, are present in children between 6 and 8 years old. To this end, we tested 32 first-grade (6–7 years) and 34 second-grade (7–8 years) children on a Simon task in which correspondence sequence was manipulated on a trial-by-trial basis. The Simon effect was larger for first- than for second-graders and decreased with increasing response times only in second-graders. Crucially, for both groups, the effect was reduced when the preceding trial was noncorresponding, and the reductions were comparable for the two groups, indicating that trial-by-trial control mechanisms are already present in first-grade children and may be dissociated from within-trial control adjustments.

Cortical sources of resting state EEG rhythms are abnormal in dyslexic children

OBJECTIVE Previous studies have been inconclusive whether dominant resting state alpha rhythms differ in amplitude in dyslexic subjects when compared to control subjects, being these rhythms considered as a reflection of effective cortical neural synchronization and cognition. Here we used a validated EEG source estimation to test the hypothesis that resting state alpha rhythms are abnormal in dyslexic subjects and are related to reading deficits. METHODS Eyes-closed resting state electroencephalographic (EEG) data were recorded in 26 dyslexics (12 males, mean age of 11 years ± 0.5 standard error of mean, SEM) and 11 age-matched normal control subjects (8 males, mean age of 11 years ± 0.7 SEM). EEG rhythms of interest, based on individual alpha frequency peak, were the following: about 2-4 Hz (delta), 4-6 Hz (theta), 6-8 Hz (alpha 1), 8-10 Hz (alpha 2), and 10-12 Hz (alpha 3). For the higher frequencies, we selected beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-40 Hz). Cortical EEG sources were estimated by low resolution electromagnetic tomography (LORETA). LORETA solutions were normalized across all voxels and frequencies. RESULTS Compared to the control children, the dyslexics showed lower amplitude of parietal, occipital, and temporal alpha 2 and alpha 3 sources. In the dyslexics, some of these sources were correlated to reading time of pseudo-words (parietal alpha 2, r=-0.56, p=0.02; parietal alpha 3, r=-0.58, p=0.02; temporal alpha 3, r=-0.57, p=0.02); the higher the alpha power, the shorter the reading time. CONCLUSIONS Dyslexic children are characterized by limited abnormalities of resting state EEG rhythms as to topography (posterior regions) and frequency (alpha), which were related to phonological encoding (pseudo-words reading). SIGNIFICANCE Dyslexia may be associated to some functional impairment of cortical neuronal synchronization mechanisms involved in the resting state condition.

A new approach for the quantitative evaluation of drawings in children with learning disabilities.

A new method for a quantitative and objective description of drawing and for the quantification of drawing ability in children with learning disabilities (LD) is hereby presented. Twenty-four normally developing children (N) (age 10.6 ± 0.5) and 18 children with learning disabilities (LD) (age 10.3 ± 2.4) took part to the study. The drawing tasks were chosen among those already used in clinical daily experience (Denver Developmental Screening Test). Some parameters were defined in order to quantitatively describe the features of the childrens drawings, introducing new objective measurements beside the subjective standard clinical evaluation. The experimental set-up revealed to be valid for clinical application with LD children. The parameters highlighted the presence of differences in the drawing features of N and LD children. This paper suggests the applicability of this protocol to other fields of motor and cognitive valuation, as well as the possibility to study the upper limbs position and muscle activation during drawing.

Age-Related Cortical Thickness Reduction in Non-Demented Down's Syndrome Subjects

The aim of this study was to investigate the characteristic pattern of age‐related cortical thinning in patients with Down Syndrome (DS), as assessed by MRI and automatic cortical thickness measurements.

Silent reading fluency: Implications for the assessment of adults with developmental dyslexia

Introduction: Understanding silent reading fluency (SRF) is of a paramount importance, given that silent reading is the principal manner of reading for capable readers. But the assessment of SRF is not commonly useful for identifying students with reading difficulties and monitoring their progress. The paper presents the SRF scores of adults with dyslexia compared to SRF scores of skilled readers and discusses the power of the SRF measure in identifying adults with specific learning disorders with impairment in reading. Method: Participants recruited were 68 dyslexic and age-matched skilled adult readers (18–48 years old). Among them, 24 were skilled readers with a university degree (GRS), 22 were skilled readers with a high school diploma (DSR), and 22 participants had been diagnosed with dyslexia (DR). We used a standardized oral reading fluency (ORF) test and an original SRF task to measure the reading fluency. Results: All participants increased their reading fluency in silent mode (p < .001). Nonetheless, the average speed of the oral reading was 7.19 syllables per second (syl/s) for the GSR group, 7.11 syl/s for the DSR group, and 4.95 syl/s for the DR group. The average speed of the silent reading was 11.62 syl/s and 10.75 syl/s for GSR and DSR, respectively, and 6.15 syl/s for DR. The reading fluency differential (Δf) between ORF and SRF was significantly different among the dyslexic participants and the other two groups. Conclusions: Our results strongly suggest that dyslexic readers are less capable of significantly improve their reading speed when they read silently. Thus SRF could be considered a suitable parameter for identifying older students and adults with impairment in reading. A broader investigation of the issues surrounding silent reading is needed.