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Although several experiments reported rapid cortical plasticity induced by passive exposure to novel segmental patterns, few studies have devoted attention to the neural dynamics during the rapid learning of novel tonal word-forms in tonal languages, such as Chinese. In the current study, native speakers of Mandarin Chinese were exposed to acoustically matched real and novel segment-tone patterns. By recording their Mismatch Negativity (MMN) responses (an ERP indicator of long-term memory traces for spoken words), we found enhanced MMNs to the novel word-forms over the left-hemispheric region in the late exposure phase relative to the early exposure phase. In contrast, no significant changes were identified in MMN responses to the real word during familiarisation. Our results suggest a rapid Hebbian learning mechanism in the human neocortex which develops long-term memory traces for a novel segment-tone pattern by establishing new associations between the segmental and tonal representations. (C) 2014 Elsevier Inc. All rights reserved.
We used event-related potentials (ERPs) to investigate the neurocognitive mechanisms associated with processing light verb constructions such as "give a kiss". These constructions consist of a semantically underspecified light verb ("give") and an event nominal that contributes most of the meaning and also activates an argument structure of its own ("kiss"). This creates a mismatch between the syntactic constituents and the semantic roles of a sentence. Native speakers read German verb-final sentences that contained light verb constructions (e.g., "Julius gave Anne a kiss"), non-light constructions (e.g., "Julius gave Anne a rose"), and semantically anomalous constructions (e.g., 'Julius gave Anne a conversation"). ERPs were measured at the critical verb, which appeared after all its arguments. Compared to non-light constructions, the light verb constructions evoked a widely distributed, frontally focused, sustained negative-going effect between 500 and 900 ms after verb onset. We interpret this effect as reflecting working memory costs associated with complex semantic processes that establish a shared argument structure in the light verb constructions.
Early acquisition of a second language influences the development of language abilities and cognitive functions. In the present study, we used functional Magnetic Resonance Imaging (fMRI) to investigate the impact of early bilingualism on the organization of the cortical language network during sentence production. Two groups of adult multilinguals, proficient in three languages, were tested on a narrative task; early multilinguals acquired the second language before the age of three years, late multilinguals after the age of nine. All participants learned a third language after nine years of age. Comparison of the two groups revealed substantial differences in language-related brain activity for early as well as late acquired languages. Most importantly, early multilinguals preferentially activated a fronto-striatal network in the left hemisphere, whereas the left posterior superior temporal gyrus (pSTG) was activated to a lesser degree than in late multilinguals. The same brain regions were highlighted in previous studies when a non-target language had to be controlled. Hence the engagement of language control in adult early multilinguals appears to be influenced by the specific learning and acquisition conditions during early childhood. Remarkably, our results reveal that the functional control of early and subsequently later acquired languages is similarly affected, suggesting that language experience has a pervasive influence into adulthood. As such, our findings extend the current understanding of control functions in multilinguals.
Two opposing viewpoints have been advanced to account for morphological productivity, one according to which some knowledge is couched in the form of operations over variables, and another in which morphological generalization is primarily determined by similarity. We investigated this controversy by examining the generalization of Portuguese verb stems, which fall into one of three conjugation classes. In Study 1, an elicited production task revealed that the generalization of 2nd and 3rd conjugation stems is influenced by the degree of phonological similarity between novel roots and existing verbs, whereas the 1st conjugation generalizes beyond similarity. In Study 2, we directly contrasted two distinct computational implementations of conjugation class assignment in how well they matched the human data: a similarity-driven model that captures phonological similarities, and a dual-mechanism model that implements an explicit distinction between context-free and similarity-based generalizations. The similarity-driven model consistently underestimated 1st conjugation responses and overestimated proportions of 2nd and 3rd conjugation responses, especially for novel verbs that are highly similar to existing verbs of those classes. In contrast, the expected proportions produced by the dual-mechanism model were statistically indistinguishable from human responses. We conclude that both context-free and context-sensitive processes determine the generalization of conjugations in Portuguese, and that similarity-based algorithms of morphological acquisition are insufficient to exhibit default-like generalization. (C) 2014 Elsevier Inc. All rights reserved.
Not only the apples
(2014)
Focus sensitive particles highlight the relevance of contextual alternatives for the interpretation of a sentence. Two experiments tested whether this leads to better encoding and therefore, ultimately, better recall of focus alternatives. Participants were presented with auditory stimuli that introduced a set of elements ("context sentence") and continued in three different versions: the critical sentences either contained the exclusive particle nur ("only"), the inclusive particle sogar ("even"), or no particle (control condition). After being exposed to blocks of ten trials, participants were asked to recall the elements in the context sentence. The results show that both particles enhanced memory performance for the alternatives to the focused element, relative to the control condition. The results support the assumption that information-structural alternatives are better encoded in memory in the presence of a focus sensitive particle.
Schlucken ist ein lebensnotwendiger Prozess, dessen Diagnose und Therapie eine enorme Herausforderung bedeutet. Die Erkennung und Beurteilung von Schlucken und Schluckstörungen erfordert den Einsatz von technisch aufwendigen Verfahren, wie Videofluoroskopie (VFSS) und fiberoptisch-endoskopische Schluckuntersuchung (FEES), die eine hohe Belastung für die Patienten darstellen. Beide Verfahren werden als Goldstandard in der Diagnostik von Schluckstörungen eingesetzt. Die Durchführung obliegt in der Regel ärztlichem Personal. Darüber hinaus erfordert die Auswertung des Bildmaterials der Diagnostik eine ausreichend hohe Erfahrung. In der Therapie findet neben den klassischen Therapiemethoden, wie z.B. diätetische Modifikationen und Schluckmanöver, auch zunehmend die funktionelle Elektrostimulation Anwendung. Ziel der vorliegenden Dissertationsschrift ist die Evaluation eines im Verbundprojekt BigDysPro entwickelten Bioimpedanz (BI)- und Elektromyographie (EMG)-Messsystems. Es wurde geprüft, ob sich das BI- und EMG-Messsystem eignet, sowohl in der Diagnostik als auch in der Therapie als eigenständiges Messsystem und im Rahmen einer Schluckneuroprothese eingesetzt zu werden. In verschiedenen Studien wurden gesunde Probanden für die Überprüfung der Reproduzierbarkeit (Intra-und Interrater-Reliabilität), der Unterscheidbarkeit von Schluck- und Kopfbewegungen und der Beeinflussung der Biosignale (BI, EMG) durch verschiedene Faktoren (Geschlecht der Probanden, Leitfähigkeit, Konsistenz und Menge der Nahrung) untersucht. Durch zusätzliche Untersuchungen mit Patienten wurde einerseits der Einfluss der Elektrodenart geprüft. Andererseits wurden parallel zur BI- und EMG-Messung auch endoskopische (FEES) und radiologische Schluckuntersuchungen (VFSS) durchgeführt, um die Korrelation der Biosignale mit der Bewegung anatomischer Strukturen (VFSS) und mit der Schluckqualität (FEES) zu prüfen. Es wurden 31 gesunde Probanden mit 1819 Schlucken und 60 Patienten mit 715 Schlucken untersucht. Die Messkurven zeigten einen typischen, reproduzierbaren Signalverlauf, der mit anatomischen und funktionellen Änderungen während der pharyngalen Schluckphase in der VFSS korrelierte (r > 0,7). Aus dem Bioimpedanzsignal konnten Merkmale extrahiert werden, die mit physiologischen Merkmalen eines Schluckes, wie verzögerter laryngealer Verschluss und Kehlkopfhebung, korrelierten und eine Einschätzung der Schluckqualität in Übereinstimmung mit der FEES ermöglichten. In den Signalverläufen der Biosignale konnten signifikante Unterschiede zwischen Schluck- und Kopfbewegungen und den Nahrungsmengen und -konsistenzen nachgewiesen werden. Im Gegensatz zur Nahrungsmenge und -konsistenz zeigte die Leitfähigkeit der zu schluckenden Nahrung, das Geschlecht der Probanden und die Art der Elektroden keinen signifikanten Einfluss auf die Messsignale. Mit den Ergebnissen der Evaluation konnte gezeigt werden, dass mit dem BI- und EMG-Messsystem ein neuartiges und nicht-invasives Verfahren zur Verfügung steht, das eine reproduzierbare Darstellung der pharyngalen Schluckphase und ihrer Veränderungen ermöglicht. Daraus ergeben sich vielseitige Einsatzmöglichkeiten in der Diagnostik, z.B. Langzeitmessung zur Schluckfrequenz und Einschätzung der Schluckqualität, und in der Therapie, z.B. der Einsatz in einer Schluckneuroprothese oder als Biofeedback zur Darstellung des Schluckes, von Schluckstörungen.
In addition to sensory decline, age-related losses in auditory perception also reflect impairments in attentional modulation of perceptual saliency. Using an attention and intensity-modulated dichotic listening paradigm, we investigated electrophysiological correlates of processing conflicts between attentional focus and perceptual saliency in 25 younger and 26 older adults. Participants were instructed to attend to the right or left ear, and perceptual saliency was manipulated by varying the intensities of both ears. Attentional control demand was higher in conditions when attentional focus and perceptual saliency favored opposing ears than in conditions without such conflicts. Relative to younger adults, older adults modulated their attention less flexibly and were more influenced by perceptual saliency. Our results show, for the first time, that in younger adults a late negativity in the event-related potential (ERP) at fronto-central and parietal electrodes was sensitive to perceptual-attentional conflicts during auditory processing (N450 modulation effect). Crucially, the magnitude of the N450 modulation effect correlated positively with task performance. In line with lower attentional flexibility, the ERP waveforms of older adults showed absence of the late negativity and the modulation effect. This suggests that aging compromises the activation of the frontoparietal attentional network when processing the competing and conflicting auditory information.
The aim of the present thesis is to answer the question to what degree the processes involved in sentence comprehension are sensitive to task demands. A central phenomenon in this regard is the so-called ambiguity advantage, which is the finding that ambiguous sentences can be easier to process than unambiguous sentences. This finding may appear counterintuitive, because more meanings should be associated with a higher computational effort. Currently, two theories exist that can explain this finding.
The Unrestricted Race Model (URM) by van Gompel et al. (2001) assumes that several sentence interpretations are computed in parallel, whenever possible, and that the first interpretation to be computed is assigned to the sentence. Because the duration of each structure-building process varies from trial to trial, the parallelism in structure-building predicts that ambiguous sentences should be processed faster. This is because when two structures are permissible, the chances that some interpretation will be computed quickly are higher than when only one specific structure is permissible. Importantly, the URM is not sensitive to task demands such as the type of comprehension questions being asked.
A radically different proposal is the strategic underspecification model by Swets et al. (2008). It assumes that readers do not attempt to resolve ambiguities unless it is absolutely necessary. In other words, they underspecify. According the strategic underspecification hypothesis, all attested replications of the ambiguity advantage are due to the fact that in those experiments, readers were not required to fully understand the sentence.
In this thesis, these two models of the parser’s actions at choice-points in the sentence are presented and evaluated. First, it is argued that the Swets et al.’s (2008) evidence against the URM and in favor of underspecification is inconclusive. Next, the precise predictions of the URM as well as the underspecification model are refined. Subsequently, a self-paced reading experiment involving the attachment of pre-nominal relative clauses in Turkish is presented, which provides evidence against strategical underspecification. A further experiment is presented which investigated relative clause attachment in German using the speed-accuracy tradeoff (SAT) paradigm. The experiment provides evidence against strategic underspecification and in favor of the URM. Furthermore the results of the experiment are used to argue that human sentence comprehension is fallible, and that theories of parsing should be able to account for that fact. Finally, a third experiment is presented, which provides evidence for the sensitivity to task demands in the treatment of ambiguities. Because this finding is incompatible with the URM, and because the strategic underspecification model has been ruled out, a new model of ambiguity resolution is proposed: the stochastic multiple-channel model of ambiguity resolution (SMCM). It is further shown that the quantitative predictions of the SMCM are in agreement with experimental data.
In conclusion, it is argued that the human sentence comprehension system is parallel and fallible, and that it is sensitive to task-demands.
Object and action naming in Russian- and German- speaking monolingual and bilingual children*
(2014)
The present study investigates the influence of word category on naming performance in two populations: bilingual and monolingual children. The question is whether and, if so, to what extent monolingual and bilingual children differ with respect to noun and verb naming and whether a noun bias exists in the lexical abilities of bilingual children. Picture naming of objects and actions by Russian-German bilingual children (aged 4-7 years) was compared to age-matched monolingual children. The results clearly demonstrate a naming deficit of bilingual children in comparison to monolingual children that increases with age. Noun learning is more fragile in bilingual contexts than is verb learning. In bilingual language acquisition, nouns do not predominate over verbs as much as is seen in monolingual German and Russian children. The results are discussed with respect to semantic-conceptual aspects and language-specific features of nouns and verbs, and the impact of input on the acquisition of these word categories.