Neural mechanisms of anaphoric reference revealed by FMRI

Fractionating difficulty during sentence comprehension using functional neuroimaging

Sentence comprehension is highly practiced and largely automatic, but this belies the complexity of the underlying processes. We used functional neuroimaging to investigate garden-path sentences that cause difficulty during comprehension, in order to unpack the different processes used to support sentence interpretation. By investigating garden-path and other types of sentences within the same individuals, we functionally profiled different regions within the temporal and frontal cortices in the left hemisphere. The results revealed that different aspects of comprehension difficulty are handled by left posterior temporal, left anterior temporal, ventral left frontal, and dorsal left frontal cortices. The functional profiles of these regions likely lie along a spectrum of specificity to generality, including language-specific processing of linguistic representations, more general conflict resolution processes operating over linguistic representations, and processes for handling difficulty in general. These findings suggest that difficulty is not unitary and that there is a role for a variety of linguistic and non-linguistic processes in supporting comprehension.

Neural correlates of pronoun processing: An activation likelihood estimation meta-analysis

Pronouns are unique linguistic devices that allow for the expression of referential relationships. Despite their communicative utility, the neural correlates of the operations involved in reference assignment and/or resolution, are not well-understood. The present study synthesized the neuroimaging literature on pronoun processing to test extant theories of pronoun comprehension. Following the PRISMA guidelines and thebest-practice recommendations for neuroimaging meta-analyses, a systematic literature search and record assessment were performed. As a result, 16 fMRI studies were included in the meta-analysis, and were coded in Scribe 3.6 for inclusion in the BrainMap database. The activation coordinates for the contrasts of interest were transformed into Talairach space and submitted to an Activation Likelihood Estimation (ALE) meta-analysis in GingerALE 3.0.1. The results indicated that pronoun processing had functional convergence in the left posterior middle and superior temporal gyri, potentially reflecting the retrieval, prediction and integration roles of these areas for pronoun processing.

Differential Tracking of Linguistic vs. Mental State Content in Naturalistic Stimuli by Language and Theory of Mind (ToM) Brain Networks

Language and social cognition, especially the ability to reason about mental states, known as theory of mind (ToM), are deeply related in development and everyday use. However, whether these cognitive faculties rely on distinct, overlapping, or the same mechanisms remains debated. Some evidence suggests that, by adulthood, language and ToM draw on largely distinct-though plausibly interacting-cortical networks. However, the broad topography of these networks is similar, and some have emphasized the importance of social content / communicative intent in the linguistic signal for eliciting responses in the language areas. Here, we combine the power of individual-subject functional localization with the naturalistic-cognition inter-subject correlation approach to illuminate the language-ToM relationship. Using functional magnetic resonance imaging (fMRI), we recorded neural activity as participants (n = 43) listened to stories and dialogues with mental state content (+linguistic, +ToM), viewed silent animations and live action films with mental state content but no language (-linguistic, +ToM), or listened to an expository text (+linguistic, -ToM). The ToM network robustly tracked stimuli rich in mental state information regardless of whether mental states were conveyed linguistically or non-linguistically, while tracking a +linguistic / -ToM stimulus only weakly. In contrast, the language network tracked linguistic stimuli more strongly than (a) non-linguistic stimuli, and than (b) the ToM network, and showed reliable tracking even for the linguistic condition devoid of mental state content. These findings suggest that in spite of their indisputably close links, language and ToM dissociate robustly in their neural substrates-and thus plausibly cognitive mechanisms-including during the processing of rich naturalistic materials.

Decoding the silence: Neural bases of zero pronoun resolution in Chinese

Chinese is one of many languages that can drop subjects. We report an fMRI study of language comprehension processes in these "zero pronoun" cases. The fMRI data come from Chinese speakers who listened to an audiobook. We conducted both univariate GLM and multivariate pattern analysis (MVPA) on these data. We found increased left Temporal Lobe activity for zero pronouns compared to overt subjects, suggesting additional effort searching for an antecedent during zero pronoun resolution. MVPA further revealed that the intended referent of a zero pronoun can be decoded in the Parahippocampal Gyrus and the Precuneus shortly after its presentation. This highlights the role of memory and discourse-level processing in resolving referential expressions, including unspoken ones, in naturalistic language comprehension.

Direct object pronoun sentence processing in Spanish-English children with/without Specific Language Impairment and adults: A cross-modal priming study

PURPOSE

This paper examines whether bilingual children with Specific Language Impairment (SLI) showed limited comprehension of Direct Object (DO) pronoun sentences and/or morphosyntactic priming compared to children with Typical Language Development (TLD) and adults. We analyzed the relation of these morphosyntactic processes to other psycholinguistic abilities, according to the MUC (Memory-Unification-Control) model.

METHOD

Ten bilingual native Spanish-speaking children with SLI (8;3-10;6) and 10 age-matched children with TLD (7;6-10;10) received a psycholinguistic evaluation in Spanish-English. The 20 children and 10 adults (19-34) performed an on-line cross-modal pronoun task. They listened to long distance animate DO pronoun sentences, and filler sentences without any pronoun. At the offset of the pronoun in each pronoun sentence, a picture of an animal for the antecedent (match condition), another animal for the second noun (mismatch), or an unrelated object (neutral) was displayed on the screen. In the filler sentences, a picture of an object that depicted the first noun, appeared at the offset of another later noun. Participants decided whether that pictured item was "alive"/"not alive" by pressing two keys on the computer keyboard. Immediately after, they answered an oral comprehension question about the DO pronoun sentence.

RESULTS

Bilingual children with SLI showed significantly poorer comprehension of DO pronoun sentences than bilingual children with TLD. Pronoun sentence understanding in the overall children correlated significantly with oral sentence completion, expressive vocabulary abilities, auditory story comprehension, and the non-word repetition task, all in Spanish. Adults showed significantly the highest pronoun sentence comprehension, and the fastest animacy decisions across conditions; it was the only group showing a significant behavioral morphosyntactic priming effect. All groups exhibited high accuracy in the animacy decisions across conditions, although children with SLI showed lower accuracy and more variability.

CONCLUSION

Bilingual Spanish-English children with SLI showed significant limitations in understanding long distance animate DO pronoun sentences. The deficits were also related to weak morphosyntactic, lexical, and/or phonological representations stored in their memory. These processes may be harder to combine in the unification process, and also to control for answering the comprehension questions. Clinical and educational implications are discussed.

On-line processing and comprehension of direct object pronoun sentences in Spanish-speaking children with Specific Language Impairment

Eleven native Spanish-speaking children with Specific Language Impairment (SLI) (8;3-10;11) and 11 typically developing children (8;7-10;8) received a comprehensive psycholinguistic evaluation. Participants listened to either Direct Object (DO) pronoun sentences or filler sentences without any pronoun, and they decided whether a picture on the screen (depicting the antecedent, another noun in the sentence, or an unrelated object) was 'alive'. They answered comprehension questions about pronoun sentences. Children with SLI showed significantly poorer comprehension of DO pronoun sentences when answering comprehension questions than children with Typical Language Development (TLD). This poor pronoun sentence understanding correlated significantly with poor auditory sentence completion, non-word repetition task and expressive vocabulary skills. Children with SLI were significantly slower in the animacy decisions than children with TLD across all pronoun and filler sentence conditions. Both groups exhibited high accuracy in the animacy decisions for any conditions. Clinical implications are discussed.

The role of gender information in pronoun resolution: evidence from Chinese

Although previous studies have consistently demonstrated that gender information is used to resolve pronouns, the mechanisms underlying the use of gender information continue to be controversial. The present study used event-related potentials (ERPs) to investigate whether working memory modulates the effect of gender information on pronoun resolution. The critical pronoun agreed or disagreed with its antecedent in gender. Moreover, the distance between a pronoun and its antecedent was varied to assess the influence of working memory. Compared with the congruent pronouns, the incongruent pronouns elicited an N400 effect in the short distance condition and a P600 effect in the long distance condition. The results suggest that the effect of gender information on pronoun comprehension is modulated by working memory.