An interesting fact about language cognition is that stimulation involving incongruence in the merge operation between verb and complement has often been related to a negative event-related potential (ERP) of augmented amplitude and latency of ca. 400 ms -the N 400 . Using an automatic ERP latency and amplitude estimator to facilitate the recognition of waves with a low signal-to-noise ratio, the objective of the present study was to study the N 400 statistically in 24 volunteers. Stimulation consisted of 80 experimental sentences (40 congruous and 40 incongruous), generated in Brazilian Portuguese, involving two distinct local verb-argument combinations (nominal object and pronominal object series). For each volunteer, the EEG was simultaneously acquired at 20 derivations, topographically localized according to the 10-20 International System. A computerized routine for automatic N 400 -peak marking (based on the ascendant zero-cross of the first waveform derivative) was applied to the estimated individual ERP waveform for congruous and incongruous sentences in both series for all ERP topographic derivations. Peak-to-peak N 400 amplitude was significantly augmented (P < 0.05; one-sided Wilcoxon signed-rank test) due to incongruence in derivations F 3 , T 3 , C 3 , C z , T 5 , P 3 , P z , and P 4 for nominal object series and in P 3 , P z and P 4 for pronominal object series. The results also indicated high inter-individual variability in ERP waveforms, suggesting that the usual procedure of grand averaging might not be considered a generally adequate approach. Hence, signal processing statistical techniques should be applied in neurolinguistic ERP studies allowing waveform analysis with low signal-to-noise ratio.
IntroductionAlthough several electrophysiological studies have demonstrated the role of theta band during the execution of different visuospatial attention tasks, this study is the first to directly investigate the role of theta power during the planning, execution and cognitive control of SEM.ObjectiveSaccadic eye movements (SEMs) represent the first stage of visual sensorimotor integration and are relevant for the visuospatial attention. The current study aims to address this issue by investigating absolute theta power over the frontal cortex during the execution of stimulus- and memory-driven SEMs.Methods12 healthy volunteers (3 male; mean age: 26.25), performed two tasks involving different conditions in the planning, execution and cognitive control of SEMs while their brain activity pattern is recorded using quantitative electroencephalography.ResultsWe found an interaction between SEM condition (memory- vs stimulus-driven) and electrode (F3, F4, Fz), and a main effect of time point and electrode. Our key finding revealed that the stimulus presentation induces different patterns over frontal theta power increase between the left and right hemisphere.ConclusionsWe conclude that right and left frontal regions are an important factor to discriminate between memory- versus stimulus-driven SEMs, and speculate on their role for different levels within the visuospatial attention.
Resumo: A referencialidade é um tópico que sempre renova o interesse da linguística teórica e experimental. Isso porque as referências são recursos fundamentais das línguas naturais que estabelecem uma relação entre a língua no cérebro e as coisas do mundo lá fora. Este experimento investiga duas condições referentes a mecanismos de referencialidade: uma relaciona-se a um NP não específico na posição do sujeito e a outra se relaciona a um NP que denota tipo influenciado por um contexto especial de Conhecimento do Mundo. A comparação entre as duas condições nas suas versões congruente e incongruente revelou que a Condição do Conhecimento do Mundo apresentou um ERP (N 400 ) com latência mais curta. Já que as sentenças são percebidas em uma ordem linear e que o sujeito em português (língua SVO) vem na frente, aqui se propõe que o acesso ao sujeito pragmaticamente saliente na sua posição sentença-inicial abre, logo de início, uma moldura pragmática e pode Revista de Estudos da Linguagem, Belo Horizonte, v.25, n.3, p.1433-1461, 2017 1434 restringir a seleção no verbo-complemento, fazendo com que o merge verbo-objeto se dê de forma mais rápida. Isso pode explicar porque o N 400 relacionado aos estímulos do Conhecimento do Mundo apareceu mais cedo do que na Condição de Controle. Adicionalmente, encontrouse um ERP positivo em torno dos 600 ms apenas presente nos estímulos da Condição de Conhecimento do Mundo e ausente na Condição de Controle. A interpretação deste achado é que o pleno acesso ao conteúdo pragmático que está no sujeito só ocorre após o merge do complemento ao verbo. Palavras-chave: hipótese sintaxe-primeiro; pragmática no processamento de sentenças; extração de potenciais relacionados a evento; N 400 -P 600 . Abstract:Referring is a permanently hot topic in theoretical and experimental linguistics since references establish the fundamental relationship between parts of language in the brain and things out there in the world. This experiment investigates two conditions pertaining to reference mechanisms: one relates to a generic NP in the subject position and the other to an NP that is influenced by a special World Knowledge context. The comparison between the two conditions in their congruous and incongruous versions depicts a shorter latency for the N 400 ERPs of the World Knowledge stimuli. Since linguistic input gradually reaches the reader from left to right, we propose that the access to a pragmatically salient subject in its sentence-initial position, by opening a window into World Knowledge, may restrict selections in the verb-complement merge more speedily than pragmatically unmarked subjects. This may explain why the N 400 related to the World Knowledge stimuli appeared earlier than that of the Control Condition. Additionally, we found a later positive ERP around the 600ms only present in the World Knowledge stimuli and absent in the Control condition. The interpretation of this finding is that full access to the pragmatic contents of the subject only takes place after the verb complement merge.
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