Maria Mercedes Piñango

Semantic operations in aphasic comprehension: implications for the cortical organization of language.

We provide data on the neurological basis of two semantic operations at the sentence level: aspectual coercion and complement coercion. These operations are characterized by being purely semantic in nature; that is, they lack morphosyntactic reflections. Yet, the operations are mandatory (i.e., they are indispensable for the semantic well formedness of a sentence). Results indicate that, whereas Brocas patients have little or no trouble understanding sentences requiring these operations (performance was above chance for all conditions), Wernickes patients performed at normal-like levels only for sentences that did not require these operations. These findings suggest that sentence-level semantic operations rely very specifically on the integrity of the cortical area associated with Wernickes aphasia, but not on the region corresponding to Brocas aphasia. In the context of other findings from lesion and imaging studies, this evidence allows a view of the cortical distribution of language capacity that is drawn along a linguistic line, one which distinguishes syntactic from semantic operations.

Slower-than-normal syntactic processing in agrammatic Broca's aphasia: Evidence from Dutch

Abstract Studies of agrammatic Brocas aphasia reveal a diverging pattern of performance in the comprehension of reflexive elements: offline, performance seems unimpaired, whereas online—and in contrast to both matching controls and Wernickes patients—no antecedent reactivation is observed at the reflexive. Here we propose that this difference characterizes the agrammatic comprehension deficit as a result of slower-than-normal syntactic structure formation. To test this characterization, the comprehension of three Dutch agrammatic patients and matching control participants was investigated utilizing the cross-modal lexical decision (CMLD) interference task. Two types of reflexive-antecedent dependencies were tested, which have already been shown to exert distinct processing demands on the comprehension system as a function of the level at which the dependency was formed. Our hypothesis predicts that if the agrammatic system has a processing limitation such that syntactic structure is built in a protracted manner, this limitation will be reflected in delayed interpretation. Confirming previous findings, the Dutch patients show an effect of distinct processing demands for the two types of reflexive-antecedent dependencies but with a temporal delay . We argue that this delayed syntactic structure formation is the result of limited processing capacity that specifically affects the syntactic system.

Understanding the architecture of language: the possible role of neurology

Culicover and Jackendoff have recently described an approach to language representation where semantic structure works, alongside syntax, as a generative system with its own structure and principles of composition. Well-known neurological observations support this view. They show that in the presence of a syntactic impairment, comprehension can take place but only if the sentences semantic structure is rich enough. This would suggest the existence of syntax-independent semantic combinatorial mechanisms, as Culicover and Jackendoffs model proposes.

Reanalyzing the Complement Coercion Effect through a Generalized Lexical Semantics for Aspectual Verbs

Coercion verbs have been taken to include not only aspectual verbs likebegin, start, andfinish but also psychological verbs such as enjoy, endure, andsavorand control verbs liketry andattempt . Their unifying property has been assumed to be that they select for eventive complements (e.g. John began/enjoyed reading the book /the meeting ). On this view, the composition of an entity-denoting expre ssion with any coercion verb obligatorily gives rise to a type-mismatch, w hich can only be resolved by “coercing” the entity-denoting expression into an event-denoting expres sion. The experimental literature has presupposed such an event-selecting lexical semantics for all coercion verbs and interpreted processing and neurological phenomena as being reflexes of entity-to-event type-shifti ng. Recent evidence on the processing properties of coercion ve rbs however shows that when distinct semantic subclasses of coercion verbs are isolated, out of t he two main subclasses (aspectual and psychological verbs), only aspectual verbs trigger the expected p rocessing profile (Katsika et al 2012, Utt., et al., Lai et al., 2014). Crucially, these results call into questi on the standard account for the increased processing cost observed and in doing so they also call into question the linguistic analysis that gives rise to such an account. To address this issue, we focus on aspectual verbs and provid e a new lexical semantic analysis of aspectual verbs. On this analysis, aspectual verbs lexical ly select for structured individuals – entities that can be construed as one-dimensional directed path structur es (K ifka 1998) in some ontological dimension. This analysis has wide empirical coverage: it accounts for t he full range of complements that aspectual verbs legitimately combine with in their transitive uses, a nd it does so without appealing to any coercive entity-to-event type-shifting operations. Finally, the a nalysis allows for a simpler, conceptually grounded interpretation of the observed processing cost as being a re sult of exhaustive lexical retrieval (on the verb) and ambiguity resolution (on the complement).

Complement Coercion as the Processing of Aspectual Verbs: Evidence from Self-Paced Reading and fMRI

The so-called coercion verbs have been taken to select for an event as their complement, and to coerce an entity-denoting complement into an event as a resolution to the predictable type mismatch. This process is reported to manifest as additional processing cost that unpredictably has been associated with more than one cortical recruitment locus. Recent work has challenged the traditional view showing that the processing effect is observed only for aspectual verbs (e.g., begin) but not psychological verbs (e.g., enjoy) (Katsika et al. 2012), and that contra the traditional assumption aspectual verbs not only select for events but also for entity-denoting complements (Pinango and Deo 2015 ). Here, we test the hypothesis that aspectual verbs require their complement to be conceptualized as a structured individual. These verbs encode a set of functions that allow the construal of the structured individual as an axis along a dimension (e.g. spatial, eventive) afforded by the complement. The processing cost associated with the composition of the “coercion configuration” (animate subject + aspectual verb + entity-denoting complement) emerges from (A) exhaustive retrieval of the verbs’ lexical functions and (B) resolution of dimension ambiguity. Results from a self-paced reading and an fMRI experiment confirm that processing aspectual-verb sentences is more costly than psychological-verb counterparts, and that consistently with previous findings, comprehension is associated with both a Wernicke’s area and a left inferior frontal cortex activation. Crucially, this activation pattern tracks the necessary exhaustive lexical retrieval of the functions at the verb (Wernicke’s area) and the subsequent ambiguity resolution of the dimension at the complement (LIFG) required for the interpretation of the aspectual-verb utterance.

The Localization of Long-Distance Dependency Components: Integrating the Focal-lesion and Neuroimaging Record

In the sentence “The captain who the sailor greeted is tall,” the connection between the relative pronoun and the object position of greeted represents a long-distance dependency (LDD), necessary for the interpretation of “the captain” as the individual being greeted. Whereas the lesion-based record shows preferential involvement of only the left inferior frontal (LIF) cortex, associated with Brocas aphasia, during real-time comprehension of LDDs, the neuroimaging record shows additional involvement of the left posterior superior temporal (LPST) and lower parietal cortices, which are associated with Wernickes aphasia. We test the hypothesis that this localization incongruence emerges from an interaction of memory and linguistic constraints involved in the real-time implementation of these dependencies and which had not been previously isolated. Capitalizing on a long-standing psycholinguistic understanding of LDDs as the workings of an active filler, we distinguish two linguistically defined mechanisms: GAP-search, triggered by the retrieval of the relative pronoun, and GAP-completion, triggered by the retrieval of the embedded verb. Each mechanism is hypothesized to have distinct memory demands and given their distinct linguistic import, potentially distinct brain correlates. Using fMRI, we isolate the two mechanisms by analyzing their relevant sentential segments as separate events. We manipulate LDD-presence/absence and GAP-search type (direct/indirect) reflecting the absence/presence of intervening islands. Results show a direct GAP-search—LIF cortex correlation that crucially excludes the LPST cortex. Notably, indirect GAP-search recruitment is confined to supplementary-motor and lower-parietal cortex indicating that GAP presence alone is not enough to engage predictive functions in the LIF cortex. Finally, GAP-completion shows recruitment implicating the dorsal pathway including: the supplementary motor cortex, left supramarginal cortex, precuneus, and anterior/dorsal cingulate. Altogether, the results are consistent with previous findings connecting GAP-search, as we define it, to the LIF cortex. They are not consistent with an involvement of the LPST cortex in any of the two mechanisms, and therefore support the view that the LPST cortex is not crucial to LDD implementation. Finally, results support neurocognitive architectures that involve the dorsal pathway in LDD resolution and that distinguish the memory commitments of the LIF cortex as sensitive to specific language-dependent constraints beyond phrase-structure building considerations.

Pronoun Resolution to Commanders and Recessors: A View from Event-Related Brain Potentials

We present results from an online experiment designed to probe the cognitive underpinnings of intra-sentential pronoun resolution. Event-related brain potentials were used to test the hypothesis that the processing of anaphoric links established between pronouns and non commanding antecedents demands more cognitive resources than the processing of anaphoric links to commanding antecedents. The experimental results obtained show, among others, a major N400-like effect elicited by the pronouns resolved to the non-commanding antecedent. This enhanced negativity suggests that, as hypothesized, resolving a pronoun to a non commanding antecedent is a more resource demanding process than resolving it to an antecedent in a commanding position. Our results can be interpreted within a theoretical framework for anaphor resolution that distinguishes two processing routes: a more resource-demanding discourse-based route and a less taxing syntax-only route.