Publications

Displaying 1 - 12 of 12
  • FitzPatrick, I., & Indefrey, P. (2016). Accessing Conceptual Representations for Speaking [Editorial]. Frontiers in Psychology, 7: 1216. doi:10.3389/fpsyg.2016.01216.

    Abstract

    Systematic investigations into the role of semantics in the speech production process have remained elusive. This special issue aims at moving forward toward a more detailed account of how precisely conceptual information is used to access the lexicon in speaking and what corresponding format of conceptual representations needs to be assumed. The studies presented in this volume investigated effects of conceptual processing on different processing stages of language production, including sentence formulation, lemma selection, and word form access.
  • Indefrey, P. (2016). On putative shortcomings and dangerous future avenues: response to Strijkers & Costa. Language, Cognition and Neuroscience, 31(4), 517-520. doi:10.1080/23273798.2015.1128554.
  • Weber, K., Christiansen, M., Petersson, K. M., Indefrey, P., & Hagoort, P. (2016). fMRI syntactic and lexical repetition effects reveal the initial stages of learning a new language. The Journal of Neuroscience, 36, 6872-6880. doi:10.1523/JNEUROSCI.3180-15.2016.

    Abstract

    When learning a new language, we build brain networks to process and represent the acquired words and syntax and integrate these with existing language representations. It is an open question whether the same or different neural mechanisms are involved in learning and processing a novel language compared to the native language(s). Here we investigated the neural repetition effects of repeating known and novel word orders while human subjects were in the early stages of learning a new language. Combining a miniature language with a syntactic priming paradigm, we examined the neural correlates of language learning online using functional magnetic resonance imaging (fMRI). In left inferior frontal gyrus (LIFG) and posterior temporal cortex the repetition of novel syntactic structures led to repetition enhancement, while repetition of known structures resulted in repetition suppression. Additional verb repetition led to an
    increase in the syntactic repetition enhancement effect in language-related brain regions. Similarly the repetition of verbs led to repetition enhancement effects in areas related to lexical and semantic processing, an effect that continued to increase in a subset of these regions. Repetition enhancement might reflect a mechanism to build and strengthen a neural network to process novel syntactic structures and lexical items. By contrast, the observed repetition suppression points to overlapping neural mechanisms for native and new language constructions when these have sufficient structural similarities.
  • Weber, K., Luther, L., Indefrey, P., & Hagoort, P. (2016). Overlap and differences in brain networks underlying the processing of complex sentence structures in second language users compared to native speakers. Brain Connectivity, 6(4), 345-355. doi:10.1089/brain.2015.0383.

    Abstract

    When we learn a second language later in life do we integrate it with the established neural networks in place for the first language or is at least a partially new network recruited? While there is evidence that simple grammatical structures in a second language share a system with the native language, the story becomes more multifaceted for complex sentence structures. In this study we investigated the underlying brain networks in native speakers compared to proficient second language users while processing complex sentences. As hypothesized, complex structures were processed by the same large-scale inferior frontal and middle temporal language networks of the brain in the second language, as seen in native speakers. These effects were seen both in activations as well as task-related connectivity patterns. Furthermore, the second language users showed increased task-related connectivity from inferior frontal to inferior parietal regions of the brain, regions related to attention and cognitive control, suggesting less automatic processing for these structures in a second language.
  • Davidson, D. J., & Indefrey, P. (2009). An event-related potential study on changes of violation and error responses during morphosyntactic learning. Journal of Cognitive Neuroscience, 21(3), 433-446. Retrieved from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.2008.21031.

    Abstract

    Based on recent findings showing electrophysiological changes in adult language learners after relatively short periods of training, we hypothesized that adult Dutch learners of German would show responses to German gender and adjective declension violations after brief instruction. Adjective declension in German differs from previously studied morphosyntactic regularities in that the required suffixes depend not only on the syntactic case, gender, and number features to be expressed, but also on whether or not these features are already expressed on linearly preceding elements in the noun phrase. Violation phrases and matched controls were presented over three test phases (pretest and training on the first day, and a posttest one week later). During the pretest, no electrophysiological differences were observed between violation and control conditions, and participants’ classification performance was near chance. During the training and posttest phases, classification improved, and there was a P600-like violation response to declension but not gender violations. An error-related response during training was associated with improvement in grammatical discrimination from pretest to posttest. The results show that rapid changes in neuronal responses can be observed in adult learners of a complex morphosyntactic rule, and also that error-related electrophysiological responses may relate to grammar acquisition.
  • Davidson, D. J., & Indefrey, P. (2009). Plasticity of grammatical recursion in German learners of Dutch. Language and Cognitive Processes, 24, 1335-1369. doi:10.1080/01690960902981883.

    Abstract

    Previous studies have examined cross-serial and embedded complement clauses in West Germanic in order to distinguish between different types of working memory models of human sentence processing, as well as different formal language models. Here, adult plasticity in the use of these constructions is investigated by examining the response of German-speaking learners of Dutch using magnetoencephalography (MEG). In three experimental sessions spanning their initial acquisition of Dutch, participants performed a sentence-scene matching task with Dutch sentences including two different verb constituent orders (Dutch verb order, German verb order), and in addition rated similar constructions in a separate rating task. The average planar gradient of the evoked field to the initial verb within the cluster revealed a larger evoked response for the German order relative to the Dutch order between 0.2 to 0.4 s over frontal sensors after 2 weeks, but not initially. The rating data showed that constructions consistent with Dutch grammar, but inconsistent with the German grammar were initially rated as unacceptable, but this preference reversed after 3 months. The behavioural and electrophysiological results suggest that cortical responses to verb order preferences in complement clauses can change within 3 months after the onset of adult language learning, implying that this aspect of grammatical processing remains plastic into adulthood.
  • Gullberg, M., Indefrey, P., & Muysken, P. (2009). Research techniques for the study of code-switching. In B. E. Bullock, & J. A. Toribio (Eds.), The Cambridge handbook on linguistic code-switching (pp. 21-39). Cambridge: Cambridge University Press.

    Abstract

    The aim of this chapter is to provide researchers with a tool kit of semi-experimental and experimental techniques for studying code-switching. It presents an overview of the current off-line and on-line research techniques, ranging from analyses of published bilingual texts of spontaneous conversations, to tightly controlled experiments. A multi-task approach used for studying code-switched sentence production in Papiamento-Dutch bilinguals is also exemplified.
  • Indefrey, P., & Davidson, D. J. (2009). Second language acquisition. In L. R. Squire (Ed.), Encyclopedia of neuroscience (pp. 517-523). London: Academic Press.

    Abstract

    This article reviews neurocognitive evidence on second language (L2) processing at speech sound, word, and sentence levels. Hemodynamic (functional magnetic resonance imaging and positron emission tomography) data suggest that L2s are implemented in the same brain structures as the native language but with quantitative differences in the strength of activation that are modulated by age of L2 acquisition and L2 proficiency. Electrophysiological data show a more complex pattern of first and L2 similarities and differences, providing some, although not conclusive, evidence for qualitative differences between L1 and L2 syntactic processing.
  • Weber, K., & Indefrey, P. (2009). Syntactic priming in German–English bilinguals during sentence comprehension. Neuroimage, 46, 1164-1172. doi:10.1016/j.neuroimage.2009.03.040.

    Abstract

    A longstanding question in bilingualism is whether syntactic information is shared between the two language processing systems. We used an fMRI repetition suppression paradigm to investigate syntactic priming in reading comprehension in German–English late-acquisition bilinguals. In comparison to conventional subtraction analyses in bilingual experiments, repetition suppression has the advantage of being able to detect neuronal populations that are sensitive to properties that are shared by consecutive stimuli. In this study, we manipulated the syntactic structure between prime and target sentences. A sentence with a passive sentence structure in English was preceded either by a passive or by an active sentence in English or German. We looked for repetition suppression effects in left inferior frontal, left precentral and left middle temporal regions of interest. These regions were defined by a contrast of all non-target sentences in German and English versus the baseline of sentence-format consonant strings. We found decreases in activity (repetition suppression effects) in these regions of interest following the repetition of syntactic structure from the first to the second language and within the second language.
    Moreover, a separate behavioural experiment using a word-by-word reading paradigm similar to the fMRI experiment showed faster reading times for primed compared to unprimed English target sentences regardless of whether they were preceded by an English or a German sentence of the same structure.
    We conclude that there is interaction between the language processing systems and that at least some syntactic information is shared between a bilingual's languages with similar syntactic structures.

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  • Hagoort, P., Indefrey, P., Brown, C. M., Herzog, H., Steinmetz, H., & Seitz, R. J. (1999). The neural circuitry involved in the reading of german words and pseudowords: A PET study. Journal of Cognitive Neuroscience, 11(4), 383-398. doi:10.1162/089892999563490.

    Abstract

    Silent reading and reading aloud of German words and pseudowords were used in a PET study using (15O)butanol to examine the neural correlates of reading and of the phonological conversion of legal letter strings, with or without meaning.
    The results of 11 healthy, right-handed volunteers in the age range of 25 to 30 years showed activation of the lingual gyri during silent reading in comparison with viewing a fixation cross. Comparisons between the reading of words and pseudowords suggest the involvement of the middle temporal gyri in retrieving both the phonological and semantic code for words. The reading of pseudowords activates the left inferior frontal gyrus, including the ventral part of Broca’s area, to a larger extent than the reading of words. This suggests that this area might be involved in the sublexical conversion of orthographic input strings into phonological output codes. (Pre)motor areas were found to be activated during both silent reading and reading aloud. On the basis of the obtained activation patterns, it is hypothesized that the articulation of high-frequency syllables requires the retrieval of their concomitant articulatory gestures from the SMA and that the articulation of lowfrequency syllables recruits the left medial premotor cortex.
  • Indefrey, P., & Levelt, W. J. M. (1999). A meta-analysis of neuroimaging experiments on word production. Neuroimage, 7, 1028.
  • Indefrey, P. (1999). Some problems with the lexical status of nondefault inflection. Behavioral and Brain Sciences, 22(6), 1025. doi:10.1017/S0140525X99342229.

    Abstract

    Clahsen's characterization of nondefault inflection as based exclusively on lexical entries does not capture the full range of empirical data on German inflection. In the verb system differential effects of lexical frequency seem to be input-related rather than affecting morphological production. In the noun system, the generalization properties of -n and -e plurals exceed mere analogy-based productivity.

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