The posterior semantic asymmetry (PSA): specific to written not auditory semantic word processing (original) (raw)
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Brain and cognition, 2018
This study replicates and extends the findings of Koppehele-Gossel, Schnuerch, and Gibbons (2016) of a posterior semantic asymmetry (PSA) in event-related brain potentials (ERPs), which closely tracks the time course and degree of semantic activation from single visual words. This negativity peaked 300 ms after word onset, was derived by subtracting right- from left-side activity, and was larger in a semantic task compared to two non-semantic control tasks. The validity of the PSA in reflecting the effort to activate word meaning was again attested by a negative correlation between the meaning-specific PSA increase and verbal intelligence, even after controlling for nonverbal intelligence. Extending prior work, current source density (CSD) transformation was used. CSD results were consistent with a left temporo-parietal cortical origin of the PSA. Moreover, no PSA was found for pictorial material, suggesting that the component reflects early semantic processing specific to verbal st...
A brain electrical signature of left-lateralized semantic activation from single words
Brain and Language, 2016
Lesion and imaging studies consistently indicate a left-lateralization of semantic language processing in human temporo-parietal cortex. Surprisingly, electrocortical measures, which allow a direct assessment of brain activity and the tracking of cognitive functions with millisecond precision, have not yet been used to capture this hemispheric lateralization, at least with respect to posterior portions of this effect. Using event-related potentials, we employed a simple single-word reading paradigm to compare neural activity during three tasks requiring different degrees of semantic processing. As expected, we were able to derive a simple temporo-parietal left-right asymmetry index peaking around 300 ms into word processing that neatly tracks the degree of semantic activation. The validity of this measure in specifically capturing verbal semantic activation was further supported by a significant relation to verbal intelligence. We thus posit that it represents a promising tool to monitor verbal semantic processing in the brain with little technological effort and in a minimal experimental setup.
The lateral distribution of event-related potentials during sentence processing
Neuropsychologia, 1982
Event-related brain potentials (ERPs) were recorded from adults as they lead 160 different sentences. half of which ended with a semantically anomalous word. These deviant words elicited a broad. negative component (N400). Measured in the difference wave between ERPs to incongruous and congruous endings, the N400 was slightly larger and more prolonged over the right than the left hemisphere and diminished in amplitude over the course of the experiment. A left-greater-than-right asymmetry was again observed in the slow. positive ERP elicited by the first six uords in the sentences, being most pronounced for subjects having no lek-handers in their immediate family.
Hemispheric Asymmetry in Interpreting Novel Literal Language: An Event-Related Potential Study
Neuropsychologia, 2013
Conceptual mapping, or making connections between conceptual structure in different domains, is a key mechanism of creative language use whose neural underpinnings are not well understood. The present study involved the combination of event-related potentials (ERPs) with the divided visual field presentation technique to explore the relative contributions of the left and right hemispheres (LH and RH) to the construction of novel meanings in fully literal language. Electroencephalogram (EEG) was recorded as healthy adults read sentences that supported either a conventional literal reading of the sentence final word (‘‘His main method of transportation is a boat,’’), or a novel literal meaning derived from conceptual mapping (‘‘The clever boys used a cardboard box as a boat,’’). The novel and conventional conditions were matched for cloze probability (a measure of predictability based on the sentence context), lexical association between the sentence frame and the final word (using latent semantic analysis), and other factors known to influence ERPs to language stimuli. To compare effects of novelty to previously reported effects of predictability, a high-cloze conventional condition (‘‘The only way to get around Venice is to navigate the canals in a boat.’’) was included. ERPs were time-locked to sentence final words (‘‘boat’’) presented in either the left visual field, to preferentially stimulate the RH (lvf/RH), or in the right visual field, targeting the LH (rvf/LH). The N400 component of the ERP was affected by predictability in both presentation sides, but by novelty only in rvf/LH. Two distinct late frontal positive effects were observed. Word predictability modulated a frontal positivity with a LH focus, but semantic novelty modulated a frontal positivity focused in RH. This is the first demonstration that the frontal positivity may be composed of multiple overlapping components with distinct functional and anatomical characteristics. Extending contemporary accounts of the frontal positivity, we suggest that both frontal positivities reflect learning mechanisms involving prediction based on statistical regularities in language (LH) and world knowledge (RH).
Using event-related potentials to examine hemispheric differences in semantic processing
Brain and Cognition, 2003
Event-related potentials (ERPs) were used as the dependent measure in a divided visual field study examining the processing of lexically ambiguous words in the cerebral hemispheres. The goal was to determine if the N400 ERP component is sensitive measure of hemispheric differences in semantic processing. ERP waveforms were examined for lateralized target words that were related to either the dominant (MONEY) or subordinate (RIVER) meanings of ambiguous words (BANK). These waveforms were compared to trials where the prime-target pairs were unrelated. Reliable N400s, reflecting a significant difference between related and unrelated trials, were seen when targets were presented to the right visual field/left hemisphere. However, there were no N400s observed for either the dominant or subordinate conditions when targets were presented to the left visual field/right hemisphere.
Behavioural Brain Research, 2006
Most of literature on language has shown how different word-classes activate distinct neural networks within linguistic cortical areas. The present investigation aimed to demonstrate that, by means of slow evoked potentials and using the same set of words in different tasks, it is possible to activate cortical networks that are spatially and temporally distinguished. Twenty healthy subjects had to evaluate, in a word pair matching session, whether two words rhymed (phonological task), were semantically related (semantic task) or were written in the same letter case (orthographic task). Slow wave amplitude was computed in three relevant time windows: the last 0.5 s of first word presentation (W1), the initial contingent negative variation (iCNV) and the terminal CNV (tCNV). During W1 and iCNV intervals, both the orthographic and the phonological tasks were left lateralized. Furthermore, the phonological task was more lateralized than the orthographic because of a greater inhibition of the right hemisphere, whereas the orthographic task was characterized by a greater bilateral posterior activation. During the tCNV, only the phonological task remained left lateralized while orthographic and semantic were bilaterally distributed. Although the use of the same set of words tends to activate widely overlapped networks, in the present research task manipulation was effective in demonstrating task dependent differences in brain lateralization. Thus, the present paradigm and the adopted tasks are especially suited for studying deficit and recovery of language in patients affected by linguistic disorders such as developmental dyslexia and aphasia.
Symmetry, 2021
Language-induced asymmetry to single word reading has been well investigated in past research. Less known are the complex processes and related asymmetries occurring when a word is compared with the previous one, according to specific tasks. To this end, we used a paradigm based on 80 sequential word pair comparisons and three blocked tasks: phonological, semantic and orthographical matching judgment. Participants had to decide whether the target word (W2) did or did not match the prime word (W1), presented 2 sec before, according to the task. The event-related potentials (ERPs) evoked by W2 in 20 participants have been analyzed. The first negative wave, the Recognition Potential (RP), peaking at about 120 ms over parietal sites, showed greater amplitude at left sites in all tasks, thus revealing the typical left-lateralization. At frontal sites, only the phonological task showed left lateralization. The following N400 (300–450 ms) showed an interesting interaction: Match trials eli...