Event-related potential (ERP) responses to violations of inflectional and derivational rules of Finnish.

Event-related potentials (ERP) were used to investigate the electrophysiological correlates of inflectional and derivational morphology. The participants were presented with visual sentences containing critical words in which either inflectional, derivational or both rules (combined violation) of Finnish were violated. Inflectional anomalies violated a number agreement of a noun with a previous auxiliary word. Derivational violations included a word-internal selectional restriction violation, i.e., a root and suffix category violation. Combined violations contained both a number and a category violation. The phonemic length of the critical words was controlled. Inflectional violations elicited a bilateral negative effect in the 450-550 ms time window, which was interpreted as an anterior negativity (AN) effect. Inflectional violations also elicited a late positivity (P600) effect. Derivational violations elicited an N400-like negativity effect, followed by the P600 effect. The P600 effects in the derivational and inflectional violation conditions summated linearly in the combined violation condition. The results are discussed with respect to the hypothesis that inflectional and derivational processes are independent and elicited in parallel in the online language comprehension.

Electrophysiological correlates of memory processing in early Finnish-Swedish bilinguals.

Event-related desynchronization (ERD) and event-related synchronization (ERS) of the 1-30 EEG frequencies were studied in eight early Finnish-Swedish bilinguals during an auditory bilingual Sternberg memory task using Finnish-Swedish cognates as stimuli. Only subtle differences between languages were expected, since cognates have been assumed to have shared conceptual representations in the bilingual memory. Encoding elicited theta and alpha frequency ERS and beta frequency ERD responses in both languages. Retrieval elicited theta ERS and alpha and beta ERD responses. Some statistically significant differences between encoding and retrieval in Finnish versus Swedish emerged: greater theta and alpha ERS responses were observed during encoding in Swedish than during encoding in Finnish. During between-language retrieval, later-appearing theta ERS and alpha ERD responses were elicited as compared to within-language retrieval. These delayed oscillatory responses might reflect the involvement of central executive attentional functions in relation to language switching.

Modality matters: the effects of stimulus modality on the 4- to 30-Hz brain electric oscillations during a lexical decision task.

The aim of the current study was to assess modality-specific brain oscillatory responses during cognitive processing. Brain oscillatory ERD/ERS responses of the 4- to 30-Hz EEG frequency bands were examined during lexical decision where the task is to identify whether the presented stimulus is a word or a pseudoword. Seven subjects performed the task with visual stimuli and twelve subjects with auditory stimuli. Visual stimuli elicited greater theta ERS responses as compared to the auditory stimuli. Both stimulus modalities elicited alpha and beta frequency ERD, these being greater for the auditory stimuli. Auditory stimuli elicited also later emerging beta ERS responses, absent for the visual stimuli. The lexicality effects (words vs. pseudowords) were greater for the auditory than for the visual stimuli. When studying brain oscillatory correlates of cognitive processing, the stimulus modality matters. Some effects may arise and some vanish depending on in which modality a cognitive experiment is being conducted.

Neurocognitive processing of auditorily and visually presented inflected words and pseudowords: evidence from a morphologically rich language.

The aim of the study was to investigate how the input modality affects the processing of a morphologically complex word. The processing of Finnish inflected vs. monomorphemic words and pseudowords was examined during a lexical decision task, using behavioral responses and event-related potentials. The stimuli were presented in two modalities, visually and auditorily, to two groups of participants. Half of the words and pseudowords carried a case-inflection. At the behavioral level, the inflected words elicited a processing cost with longer decision latencies and higher error rates. At the neural level, pseudowords elicited an N400 effect, which was more pronounced in the visual modality. Inflected words elicited an N400 effect in both modalities, which, however, differed in topography and latency. The N400 effect for inflected words most probably reflects access and possible integration of the stem and suffix. The results suggest that the inflectional processing cost stems from the later, lexical-semantic stage of processing in both modalities. The ERP responses to inflected pseudowords did not differ from the ERP responses to monomorphemic pseudowords in either modality, suggesting that combinatorial case-inflection processing requires a real word stem in order to proceed.