Event related potentials during the visual discrimination of words and pseudowords by children

Abstract

-Event related potentials (ERPs) in reading were studied in children in a word and pseudoword discriminating task. Seventy-nine children (9 to 11 year old), all with no elements suggesting brain injury and with school perf o rmance compatible with their age were studied. The ERP were re g i s t e red as there w e re presented, visually, successively and in a random manner, 100 words and 100 pseudowords. For each stimulus the child pressed a key corresponding to the discrimination between word and pseudoword. The register was carried out for the electrodes of the 10-20 system and the mean amplitudes and latency peaks m e a s u red and also the amplitude from 200 to 550 milliseconds. The most significant diff e rences between the ERPs occurred in Cz, with greater negativity for the mean of the amplitude between 425 and 550 milliseconds for pseudowords (N400). The N400 was more precocious in 11 year old. The influence of age was thus evident and also the differences in ERPs between words and pseudowords.KEY WORDS: event-related potential, pseudowords, lexical decision, child, EEG.Potenciais evocados cognitivos na discriminação visual entre palavras e pseudopalavras em crianças RESUMO -Foram estudadas 79 crianças (9 a 11 anos) sem elementos sugestivos de comprometimento cerebral e com desempenho escolar compatível com a idade. Os PCL foram registrados enquanto eram apresentados, visualmente, sucessivamente e de modo aleatório, 100 palavras e 100 pseudopalavras. Para cada estímulo a criança acionava uma tecla correspondente à discriminação entre palavra e pseudopalavra. O registro foi realizado para os eletrodos do sistema 10-20 e foram feitas medidas de médias de amplitude e de latências de pico e de amplitude de 200 a 550 milissegundos. Em Cz ocorreram as diferenças mais significativas entre os PCL, com maior negatividade da média de amplitude entre 425 e 550 milissegundos para pseudopalavras (N400). O N400 foi mais precoce nas crianças com 11 anos. Evidenciou-se assim a influência da idade e as diferenças no PCL entre palavras e pseudopalavras. PALAVRAS-CHAVE: potenciais evocados cognitivos, decisão lexical, EEG, pseudopalavras.It is possible to register event-related potentials (ERPs) in reading tasks. The ERPs for reading show prolonged latency and consist of a sequence of waves, the most important of which are one with positivity at about 300 ms (P300) and another with negativity between 400 and 450 ms 1 , 2 . The ERPs have shown peculiarities in tasks involving: semantic and phonological congruence and incongru e n c e 1 -5 , syntax anomalies 6 , word categories in context 7 , word f requency and length 8 and specifically in the re a ding of words and pseudoword s 9 . In the event re l a ted model for reading/writing, two basic pro c e s s e s can be characterised using the "information pro c e s sing" approach: reading by way of phonological mediation and visual re a d i n g 1 0 -1 2 . In reading by way of phonological mediation the written word is re c o gnised as if it had been heard whilst in dire...

Benign childhood epilepsy with centrotemporal spikes: word and pseudoword discrimination

“…No relationship was found between performance in Benign childhood epilepsy Fonseca et al the DWPT and the total number of epileptic seizures and use of antiepileptic medication, which is in agreement with the studies in relation to these aspects and neuropsychological alterations 1,3,5,9,11,18,25 . The onset age for epilepsy was not a significant factor for performance in the DWPT, and was also found to be non-significant in language tests and school performance in other studies 5,28 .…”

“…With respect to the discrimination of PW, a lower percentage of hits is understandable since, not being well constituted in a lexical system, some pseudowords could be confounded with W or be labeled as such, due to a lack of certainty in the limits of their lexical system. Thus the longer response times for PW can also be explained by the activation, in addition to the cerebral areas involved more directly in processing W, of other areas that participate in the discrimination of PW, according to neurophysiological and functional imaging findings 16,25 .…”

“…100 words (W) and 100 pseudowords (PW), disyllables paired with respect to the number of letters and consonant and vowel compositions, were presented in a random manner. High frequency words were used, taken from the Pinheiro child first readers 25 . A pseudoword was considered to be a group of letters forming a pronounceable unit, but with no meaning, and they were obtained by exchanging graphemes or making other alterations to real words.…”

Repeated Exposure to “meaningless” Pseudowords Modulates LPC, but Not N(FN)400

“…Specifically, meaningless stimuli, like pseudowords, have been found to produce more negative amplitudes than meaningful stimuli, such as words, on the N400 component. This differential effect of the two types of stimuli has been observed in different tasks such as semantic categorization (Ziegler et al 1997), semantic decision (Bentin et al 1999), and lexical decision tasks (Carreiras et al 2005;Fonseca et al 2006;Wang and Yuan 2008). It can thus be concluded that the N400 component reflects differences in semantic processing between words and pseudowords.…”

Cognição e eletrofisiologia: uma revisão crítica das perspectivas nacionais

“…Este demonstrou uma correlação entre a ausência desse efeito com a presença de comprometimento cognitivo resultante de esclerose múltipla. Quanto aos três estudos encontrados na literatura nacional que investigaram o componente N400, um investigou variáveis metodológicas referentes à análise desse componente (Cagy & cols., 2006); outro, variáveis sintáticas através da extração do componente (França, Lemle, Cagy, Constant & Infantosi, 2004) e outro examinou a manifestação desse componente em crianças por meio de uma tarefa de decisão lexical (Fonseca, Tedrus & Gilbert, 2006). É importante destacar que os estudos nacionais que investigaram MMN e N400 adicionam dados importantes para a literatura em PRE e processamento da linguagem.…”