N170

In the literature of ERPs/EEG, the specialization for reading has been characterized by the P1 – N1 components. The visual P1 is an early occipital component, with maximum amplitude at 100ms (CLARK, FAN, HILLYARD, 1995; DI RUSSO et al., 2002b). It is usually the earliest observed component, known to be sensitive to many low-level properties of visual stimuli (REGAN, 1989). The N1 component, also known as N170, is an occipito-temporal negative component, peaking at ~170ms (BENTIN et al., 1996). Traditionally recognized as a face-sensitive component, N170 shows the largest amplitude to faces at right lateral occipito-temporal electrode sites (ROSSION, JACQUES, 2008). However, the N170 has also been more recently elicited in response to written words when compared to low- level control stimuli, such as symbol strings, forms, alphanumeric symbols, shapes and dots (HASKO et al., 2013). The relatively larger amplitudes for letter strings, thus, marks print sensitivity in fluent readers. However, differently from N170 components in facial recognition, which tend to be either bilateral or right lateralized, the sensitivity to the N170 in response to grapheme type stimuli is left lateralized.

The development of a left-lateralized N170 component in response to visual word presentation shows differences when comparing different age groups, thus, accompanying the development of literacy. In a study carried out with pre-literate children, for example, there were no apparent differences in amplitudes in response to words as compared to symbols (i.e. false fonts). Pre-literate children with high familiarity with letters, on the other hand, did show slight differences (MAURER, BREM, et al., 2015). For second-graders this difference became considerably larger, with much higher amplitudes for word stimuli (MAURER et al., 2008). In fifth graders and adult expert readers the difference became more attenuated (MAUER et al., 2011; MAURER, ROSSION, McCANDLISS, 2008; MAURER et al., 2006). The print sensitive N170 component has been elicited not only with alphabetic print, but also with Japanese syllabic and logographic scripts (MAUER et al., 2008), as well as Chinese characters (ZHAO et al., 2012).

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SOTO, M.; GOMES, J. N.; FRANÇA, A. I.; MANHÃES, A. G. Neurophysiology of grapheme decoding: The N170 as A Predictive and Descriptive Tool. Revista da ABRALIN, v. 17, n. 1, p. 402-433, 30 mar. 2019.