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In the present study, we propose to explore the Event-Related Potentials components elicited in reading disabled (RD) and normal readers (NR) children by phonological and semantic processes using an auditory sentence comprehension task, that manipulate both phonological and semantic expectancies. Reading deficiencies in both these processes have been demonstrated in RD children, thus similar problems might also be expected for oral language in these children. Twenty-two male children (9-12 years old) with normal IQ, were classified by Neuropsychological Battery for Reading Disabilities into two groups: Normal Readers (NR, n=11) and Reading Disabled (RD, n=11). ERPs were recorded from 19 derivations of the I.S. 10-20. Children were presented with spoken sentences that ended with a word that was either (a) semantically congruent, and phonologically expected, (b) semantically incongruent, but beginning with the same initial phonemes as the congruent completion, or (c) semantically incongruent, and phonologically unexpected. For each type of sentence, ERP were analyzed in two time windows: early time window (330-430 ms) related to phonological processing, as well as a later N400 window (515-615 ms) that would reflect the semantic processing. In both groups, the three types of sentences elicited a negative waveform with an onset at 200 ms that lasted until approximately 900 ms. This negative waveform had greater amplitude in response to semantically incongruent, compared to semantically congruent sentences. Results revealed a probably anomalous phonological processing in RD children, reflected by a greater ERP response to expected, than to unexpected, words in a given sentential context. However, both the N400 responses related to semantic processing, and the behavioral responses related to the correctness of sentences, were comparable between RD and NR children.

In the present study, we assessed phonological priming during a visual lexical decision task (LDT) in patients with Parkinson’s disease (PD). This study was performed because phonological deficiencies have been reported in patients with PD, and such processes are critical predictors of reading performance. We tested for phonological priming effects using homonyms (zarjento – SARGENTO), where the prime differed from the target orthographically but with complete phonological overlap, and rhymes (cadera – MADERA), where the last two syllables of both the prime and the target are identical. Both types of priming were compared to the non-rhyme baseline condition (mercader – CUCHILLA) to assess the size of the priming effect. The results indicated that patients with PD exhibited a smaller phonological priming effect than controls in the homophonic condition. Patients with PD also displayed a lower percentage of correct responses and longer Reaction Times (RTs) than controls on both rhyme and homophone pairings. No group differences were found in the non-rhyme experimental condition. We concluded that phonological processing in patients with PD is important for lexical access during visual word recognition.

It is important to understand learning disabilities (LD) because they are prevalent worldwide. Currently there is great controversy about LD definition, as some studies focus on the discrepancy between intelligence and academic skills, while others focus only on academic skill assessments. The DSM-IV-TR provides the most commonly used definition for LD, which includes specific learning disabilities (reading, writing, arithmetic) and unspecified learning disabilities. For specific one would expect a significant discrepancy between academic skills and IQ, in contrast, significant discrepancies should not be observed in the unspecified. The literature also reports comorbidities among LD types. The objective of this study was to evaluate reading, writing, and arithmetic task performance profiles in 127 public elementary school children. Based on DSM-IV-TR criteria, we determined academic skill profiles, the presence of LD, LD type, and potential comorbidities in our sample. Using normalized test scores for reading, writing, and arithmetic, we applied a hierarchical cluster analysis to identify academic skill patterns. The results showed the following clusters among school children: 1) children with normal academic skills (n = 80), 2) children with unspecified LD including deficiencies in all three academic processes (n = 27), and 3) children with specific reading LD including arithmetic and writing deficiencies (n = 20). These classification types may later help identify specific neuropsychological characteristics underlying a specific disability, and subsequently facilitate treatments. Key words: Learning disabilities, reading disabilities, LD subtypes, hierarchical-clusters.