Event Related Potentials

Spelling errors are ubiquitous in all writing systems. Most studies exploring spelling errors focused on the phonological plausibility of errors. However, unlike typical pseudohomophones, spelling errors occur in naturally produced written language. We investigated the time course of recognition of the most frequent orthographic errors in Russian (error in an unstressed vowel in the root) and the effect of word frequency on this process. During event-related potentials (ERP) recording, 26 native Russian speakers silently read high-frequency correctly spelled words, low-frequency correctly spelled words, high-frequency words with errors, and low-frequency words with errors. The amplitude of P200 was more positive for correctly spelled words than for misspelled words and did not depend on the frequency of the words. In addition, in the 350–500-ms time window, we found a more negative response for misspelled words than for correctly spelled words in parietal–temporal-occipital regions regardless of word frequency. Considering our results in the context of a dual-route model, we concluded that recognizing misspelled high-frequency and low-frequency words involves common orthographic and phonological processes associated with P200 and N400 components such as whole word orthography processing and activation of phonological representations correspondingly. However, at the 500–700 ms stage (associated with lexical-semantic access in our study), error recognition depends on the word frequency. One possible explanation for these differences could be that at the 500–700 ms stage recognition of high-frequency misspelled and correctly spelled words shifts from phonological to orthographic processes, while low-frequency misspelled words are accompanied by more prolonged phonological activation. We believe these processes may be associated with different ERP components P300 and N400, reflecting a temporal overlap between categorization processes based on orthographic properties for high-frequency words and phonological processes for low-frequency words. Therefore, our results complement existing reading models and demonstrate that the neuronal underpinnings of spelling error recognition during reading may depend on word frequency.

This study aimed to examine the behavioral and neural correlates of facial emotion recognition in young women with subsyndromal panic disorder (SPD). In the experiment 15 non-medicated women with SPD and 17 matched healthy controls were tasked with recognizing angry, fearful, happy, and neutral facial expressions, and accuracy, reaction time (RT), and event-related potentials (ERPs) were recorded. Significant between-group differences in behavioral characteristics (accuracy of emotion recognition and RT) were not found, however, the SPD subjects demonstrated a slower response to fearful expressions compared to neutral and happy expressions. More distinct between-group differences were observed for the EPRs. The SPD subjects demonstrated increased amplitudes of the P100 ERP component in the occipital area and the P200 component over the occipital and temporal regions. In the frontal regions the SPD group showed a greater amplitude of the N200 component and also an increased negativity 350−450 ms after stimulus presentation. According to the dipole source modeling data, the SPD subjects showed enhanced activation in the extra-striate cortex which increased in intensity when angry and fearful faces were presented. Thus, young women with SPD which manifested in infrequent panic attacks showed significant alterations in ERP characteristics of emotional processing, which may be considered as a more sensitive indicator of early-stage panic disorder than the observed behavioral measures.