Biomedical subjects

Matthias Schlesewsky

Publications and source records attributed to Matthias Schlesewsky.

18 recordsLinked to original sources

PubMed2007

The role of the posterior superior temporal sulcus in the processing of unmarked transitivity.

Is it living or not? The ability to differentiate between animate and inanimate entities is of considerable value in everyday life, since it allows for the dissociation of individuals that may willfully cause an action from objects that cannot. The present fMRI study aimed to shed light on the neural correlates of animacy at a relational-interpretive level, i.e. on the role of animacy in the establishment of relations between entities that are more or less likely to cause an event and differ in their potential to act volitionally. To this end, we investigated the processing of visually presented transitive German sentences (nominative-accusative structures) in which the factors animacy and argument order were manipulated. The relations between the arguments differed in that the animate subject either acted on an inanimate object (a very natural construction in terms of transitivity) or on an animate object (resulting in a sentence deviating from an unmarked transitive structure). Participants performed an acceptability judgment task. Violations of unmarked transitivity yielded a significant activation increase within the posterior left superior temporal sulcus (pSTS), thus suggesting a specific role of this cortical region in the relational use of animacy information. This result indicates that the influence of animacy as a relational feature differs from the impact of this parameter on the word level and is in line with other neuroimaging studies showing an engagement of the pSTS when a matching between syntax and semantics is required. A comparison between object- and subject-initial conditions further revealed a robust effect of argument order in the pars opercularis of the left inferior frontal gyrus (a subregion of Broca's area), thereby replicating previous findings demonstrating a sensitivity of this region to fine-grained language-specific linearization rules.

Adult↗

PubMed2006

Linguistic prominence and Broca's area: the influence of animacy as a linearization principle.

Previous neuroimaging findings suggest a sensitivity of the pars opercularis of the left inferior frontal gyrus (i.e. a core subregion of Broca's area) to a number of linguistic dependencies governing the linear sequencing of information in a sentence (e.g. subjects should precede objects; the participant role hierarchy should be respected). The present study used event-related fMRI to examine the hitherto untested hypothesis that the violation of a linearization principle that is purely semantic in nature (animate arguments should precede inanimate arguments) would also lead to increased pars opercularis activation. To this end, we manipulated the features animacy and argument order in German sentences and found a significant increase of activation in the pars opercularis for a violation of the animacy principle even when the other factors mentioned above were controlled for. This result therefore calls for a "supra-syntactic" account of pars opercularis function in the real-time understanding of sentences.

Adult↗

PubMed2006

Context-sensitive neural responses to conflict resolution: electrophysiological evidence from subject-object ambiguities in language comprehension.

Reanalysis in language comprehension provides a window on how superficially similar processes of conflict resolution may differ depending on the context in which they are initiated. Thus, previous ERP studies have shown that reanalyses towards object-initial orders in German sentences with dative-active verbs (e.g., folgen, 'to follow') engender N400 effects, while reanalyses with accusative verbs (e.g., besuchen, 'to visit') elicit P600 effects. This difference appears surprising since these two verb classes are both associated with a subject-initial base order. The present paper reports two ERP experiments designed to shed further light on the nature of the conflict resolution processes involved in each case by examining structures in which word order disambiguation is separated from verb class disambiguation. Experiment 1 contrasted dative-active verbs with accusative verbs, while Experiment 2 compared dative-active and dative object-experiencer verbs (which are associated with an object-initial base order). Our results show that the reanalysis pattern for dative-active constructions is context-dependent: when verb class disambiguation precedes word order disambiguation, an N400-P600 pattern results. By contrast, the reanalysis patterns for the other two verb types are context independent: object-experiencer verbs invariably show an N400 and accusative verbs invariably show a P600. We argue that (a) the N400 is a general marker of reanalysis in dative sentences, reflecting an argument reindexation, while (b) the P600 in accusative sentences reflects a structural recomputation. The variable pattern for dative-active sentences reflects the (in)applicability of "good-enough" representations during conflict resolution in garden path sentences.

Adult↗

PubMed2006

Processing linguistic complexity and grammaticality in the left frontal cortex.

We used event-related functional magnetic resonance imaging to directly compare the hemodynamic responses associated with varying degrees of linguistic complexity with those engendered by the processing of ungrammatical utterances. We demonstrate a dissociation within the left inferior frontal cortex between the deep frontal operculum, which responds to syntactic violations, and a core region of Broca's area, that is, the inferior portion of the left pars opercularis in Brodmann area 44, the activation of which is modulated as a function of the complexity of well-formed sentences. The data demonstrate that different brain regions in the prefrontal cortex support distinct mechanisms in the mapping from a linguistic form onto meaning, thereby separating ungrammaticality from linguistic complexity.

Adult↗

PubMed2006

The extended argument dependency model: a neurocognitive approach to sentence comprehension across languages.

Real-time language comprehension is a principal cognitive ability and thereby relates to central properties of the human cognitive architecture. Yet how do the presumably universal cognitive and neural substrates of language processing relate to the astounding diversity of human languages (over 5,000)? The authors present a neurocognitive model of online comprehension, the extended argument dependency model (eADM), that accounts for cross-linguistic unity and diversity in the processing of core constituents (verbs and arguments). The eADM postulates that core constituent processing proceeds in three hierarchically organized phases: (1) constituent structure building without relational interpretation, (2) argument role assignment via a restricted set of cross-linguistically motivated information types (e.g., case, animacy), and (3) completion of argument interpretation using information from further domains (e.g., discourse context, plausibility). This basic architecture is assumed to be universal, with cross-linguistic variation deriving primarily from the information types applied in Phase 2 of comprehension. This conception can derive the appearance of similar neurophysiological and neuroanatomical processing correlates in seemingly disparate structures in different languages and, conversely, of cross-linguistic differences in the processing of similar sentence structures.

Brain↗

PubMed2005

The resolution of case conflicts from a neurophysiological perspective.

We present two ERP experiments examining the resolution of language processing conflicts involving the multidimensional linguistic feature case, which determines processing in both syntactic and interpretive respects. Ungrammatical German structures with two identically case-marked arguments (double subject or double object constructions) were tested. In earlier studies, double subject constructions have been shown to elicit a biphasic pattern consisting of an N400 effect (a marker of thematic integration problems) followed by a P600 effect (a marker of syntactic ill-formedness). Here, we compare double nominative (subject case) constructions with double datives (indirect object case; Experiment 1) and double accusatives (direct object case; Experiment 2). All types of double case ungrammaticalities elicited a biphasic N400-P600 response. However, double datives differed from double nominatives in that they elicited a larger P600, suggesting that the ill-formedness is more salient in structures with two dative arguments. Double accusatives, by contrast, elicited a stronger N400 in comparison to double nominatives, suggesting that they induce more severe semantic-thematic integration problems. The results demonstrate that the human language comprehension system is sensitive to fine grained linguistic distinctions between different cases and utilizes these in its attempts to solve processing conflicts.

Adolescent↗

PubMed2005

When case meets agreement: event-related potential effects for morphology-based conflict resolution in human language comprehension.

We present event-related potential evidence from language comprehension that processing conflicts arising from the same linguistic domain and appearing within the same time range do not interact when they draw upon distinct underlying neural populations. Thus, a combined violation of two morphosyntactic information types, number-agreement and case, engendered a LAN/N400-P600 pattern, while the corresponding single violations are associated with LAN-P600 and N400-P600 responses, respectively. The absence of an interaction between the two negativities indicates that neuronal resource sharing does not result from a similarity of function, but rather requires an overlap of the underlying neuronal populations.

Adult↗

PubMed2005

Who did what to whom? The neural basis of argument hierarchies during language comprehension.

The present fMRI study aimed at identifying neural correlates of the syntax-semantics interface in language comprehension. This was achieved by examining what we refer to as "argument hierarchy construction", i.e., determining which participant in a sentence is the "Actor" and which is the "Undergoer" of the event expressed by the verb. In order to identify the neural bases of argument hierarchy processing, we manipulated three factors known to influence the complexity of argument hierarchy construction in German, namely argument order, verb class and morphological ambiguity. Increased argument hierarchization demands engendered enhanced activation in a network of inferior frontal, posterior superior temporal, premotor and parietal areas. Moreover, components of this network were differentially modulated by the individual factors. In particular, the left posterior superior temporal sulcus showed an enhanced sensitivity for morphological information and the syntactic realization of the verb-based argument hierarchy, while the activation of the left inferior frontal gyrus (pars opercularis) corresponded to linearization demands and was independent of morphological information. We therefore argue that, for German, posterior superior temporal and inferior frontal regions engage in the extraction of actorhood from morphosyntactic structure and in the sequential realization of hierarchical interpretive dependencies, respectively.

Adult↗

PubMed2005

Detection of early cognitive processing by event-related phase synchronization analysis.

In order to investigate the temporal characteristics of cognitive processing, we apply multivariate phase synchronization analysis to event-related potentials. The experimental design combines a semantic incongruity in a sentence context with a physical mismatch (color change). In the ERP average, these result in an N400 component and a P300-like positivity, respectively. Synchronization analysis shows an effect of global desynchronization in the theta band around 288 ms after stimulus presentation for the semantic incongruity, while the physical mismatch elicits an increase of global synchronization in the alpha band around 204 ms. Both of these effects clearly precede those in the ERP average. Moreover, the delay between synchronization effect and ERP component correlates with the complexity of the cognitive processes.

Adult↗

PubMed2005

The emergence of the unmarked: a new perspective on the language-specific function of Broca's area.

A number of neuroimaging studies have implicated an involvement of Broca's area, particularly of the pars opercularis of the left inferior frontal gyrus (IFG), in the processing of complex (permuted) sentences. However, functional interpretations of this region's role range from very general (e.g., in terms of working memory) to highly specific (e.g., as supporting particular types of syntactic operations). A dissociation of these competing accounts is often impossible because in most cases, the language internal complexity of permuted sentence structures is accompanied invariably by increasing costs of a more general cognitive nature (e.g., working memory, task difficulty, and acceptability). We used functional magnetic resonance imaging to explore the precise nature of the pars opercularis activation in the processing of permuted sentences by examining the permutation of pronouns in German. Although clearly involving a permutation operation, sentences with an initial object pronoun behave like simple, subject-initial sentences (e.g., in terms of acceptability) because of a rule stating that pronouns should generally precede non-pro-nominal arguments. The results of the experiment show that in contrast to non-pro-nominal permutations, sentences with a permuted pronoun do not engender enhanced pars opercularis activation. Our findings therefore speak against both language-related working memory and transformation-based accounts of this region's role in sentence comprehension. Rather, we argue that the pars opercularis of the left IFG supports the language-specific linearization of hierarchical linguistic dependencies.

Adult↗

PubMed2004

Fractionating language comprehension via frequency characteristics of the human EEG.

We present a new analysis technique for EEG research on language comprehension, which dissociates superficially indistinguishable event-related potential (ERP) components. A frequency-based analysis differentiated between two apparently identical but functionally distinct N400 effects in terms of activity in separable frequency bands, and whether the activity stemmed from increased power or phase locking. Whereas linguistic problem detection is associated with theta band activity (approximately 3.5-7.5 Hz), conflict resolution correlates with activity in the delta band (1-3 Hz). The data further differentiate between the neuronal processing mechanisms involved in different types of conflict resolution on the basis of frequency characteristics (power vs phase locking).

Conflict, Psychological↗

PubMed2004

"Capacity" reconsidered: interindividual differences in language comprehension and individual alpha frequency.

The influence of interindividual differences in cognitive mechanisms on language comprehension remains controversial not only due to conflicting experimental findings, but also in view of the difficulty associated with determining which measure should be used in participant classification. Here, we address the latter problem by proposing that an electrophysiological measure, individual alpha frequency (IAF), may be a suitable means of classifying interindividual differences in sentence processing. Interindividual differences in IAF have been shown to correlate with performance on memory tasks and speed of information processing. In two experiments using event-related brain potentials (ERPs), IAF-based participant groups differed systematically with regard to the processing of ambiguous sentences such that the low-IAF group showed a sustained positivity in the ambiguous region, while the high-IAF group did not. These interindividual differences were independent of whether the ambiguity was syntactic (Experiment 1) or sentence-level semantic (Experiment 2). Moreover, they were reliable only when participants were classified according to IAF, but not in classifications based on reading span, speed of processing (reaction time), or accuracy of processing (error rate).

Adult↗

PubMed2003

The neurophysiological basis of word order variations in German.

This paper aims to dissociate grammatical and general cognitive (e.g., working-memory based) accounts of the processing costs elicited by word order variations in German. To this end, we present a study using event-related brain potentials (ERPs), in which dislocated arguments were instantiated either by non-pronominal or by pronominal noun phrases. This manipulation allows for a dissociation of the two competing accounts, since only a dislocation of non-pronominal arguments gives rise to a non-canonical structure. The results show that (a) in sentences with non-pronominal arguments, the determiner of a non-canonical noun phrase elicited a broadly distributed negativity, and (b) in sentences with pronominal arguments, no differences were observed for object- vs. subject-initial word orders. These findings show that the human parser is sensitive to fine-grained grammatical regularities. We therefore argue that the negativity is a reflection of a local syntactic mismatch, rather than of an increase in working-memory load.

Adult↗

PubMed2003

Contextual information modulates initial processes of syntactic integration: the role of inter- versus intrasentential predictions.

The authors demonstrate that intersentential context may influence syntactic integration processes during online sentence comprehension, although this influence appears to be restricted to cases in which a contextual requirement must be fulfilled. By applying event-related brain potentials to the processing of clause-medial word order variations in German, the authors show that the local processing difficulty (a negativity from 300 to 450 ms) observed for object-initial sentences in a neutral context is also obtained in a (behaviorally) facilitating context in which the object is contextually given. By contrast, the processing pattern for a focused (questioned) initial object does not differ from that for a focused subject: both elicit a parietal positivity (280-480 ms) post-onset of the focused phrase. The authors interpret this early positivity as a general marker of focus integration, a process that appears to briefly supersede sentence-internal requirements.

Adult↗

PubMed2002

Beyond syntax: language-related positivities reflect the revision of hierarchies.

On the basis of an experiment using event-related brain potentials (EPRs), we argue that a characterisation of language-related positivities as necessarily syntax-related is too restrictive. Our data show that, in verb-final German clauses, the processing of a verb which disconfirms the expectations with regard to the hierarchical thematic structure of a sentence (who is doing what to whom) gives rise to an early (200-600 ms) parietal positivity. Thus, positive ERP components elicited during language processing appear to be related to operations (most often revisions) applying to hierarchically structured linguistic information in general, rather than to syntactic structure in particular.

Adult↗

PubMed2002

Grammar overrides frequency: evidence from the online processing of flexible word order.

We show that online processing difficulties induced by word order variations in German cannot be attributed to the relative infrequency of the constructions in question, but rather appear to reflect the application of grammatical principles during parsing. Event-related brain potentials revealed that dative-marked objects in the initial position of an embedded sentence do not elicit a neurophysiologically distinct response from subjects, whereas accusative-marked objects do. These differences are predictable on the basis of grammatical distinctions (i.e. underlying linguistic properties), but not on the basis of frequency information (i.e. a superficial linguistic property). We therefore conclude that the former, but not the latter, guides syntactic integration during online parsing.

Adult↗

PubMed2002

The P600 as an indicator of syntactic ambiguity.

In a study using event-related brain potentials, we show that the current characterization of the P600 component as an indicator of revision processes (reanalysis and repair) in sentence comprehension must be extended to include the recognition of syntactic ambiguity. By comparing the processing of ambiguous and unambiguous sentence constituents in German, we show that the P600 is elicited when our language processing system has syntactic alternatives at a certain item given in the input string. That the P600 is sensitive to syntactic ambiguity adds crucial evidence to current debates in psycholinguistic modelling, as the results clearly favour parallel models of syntactic processing which assume that ambiguity is recognized and costly.

Adult↗

PubMed2002

Why a "word order difference" is not always a "word order" difference: a reply to Weyerts, Penke, Münte, Heinze, and Clahsen.

We present evidence that the supposed processing advantage for an SVfinO word order over an SOVfin word order in German argued for by Weyerts, Penke, Münte, Heinze, and Clahsen (2002) is supported by neither experimental nor theoretical evidence. Specifically, we show (a) that the frontocentral negativity for an SOVfin in comparison to an SVfinO word order in Weyerts et al.'s Experiments 2 and 3 is reducible to more general differences in the electrophysiological responses elicited by nouns versus verbs in a sentence context, and (b) that the P600 difference between the two word orders in Experiment 2, as well as the reading time differences in Experiment 1, result from the fact that the two supposedly ungrammatical conditions actually differ in their degree of ill-formedness. We conclude that there is no evidence for a processing disadvantage for SOVfin, thus reconciling Weyerts et al.'s results on German sentence processing with the grammatical regularities of German.

Evoked Potentials↗