Magnetoencephalography Reveals Mismatch Field Enhancement from Unexpected Syntactic Category Errors in English Sentences

Developmental Language Disorder as Syntactic Prediction Impairment

We provide evidence that children with Developmental Language Disorder (DLD) are impaired in predictive syntactic processing. In the current study, children listened passively to auditorily-presented sentences, where the critical condition included an unexpected "filled gap" in the direct object position of the relative clause verb. A filled gap is illustrated by the underlined phrase in "The zebra that the hippo kissed the camel on the nose…", rather than the expected "the zebra that the hippo kissed [e] on the nose", where [e] denotes the gap. Brain responses to the filled gap were compared to a control condition using adverb-relative clauses with identical substrings: "The weekend that the hippo kissed the camel on the nose [e]…". Here, the same noun phrase is not unexpected because the adverb gap occurs later in the structure. We hypothesized that a filled gap would elicit a prediction error brain signal in the form of an early anterior negativity, as we have previously observed in adults. We found an early (bilateral) anterior negativity to the filled gap in a control group of children with Typical Development (TD), but the children with DLD exhibited no brain response to the filled gap during the same early time window. This suggests that children with DLD fail to predict that a relativized object should correspond to an empty position after the relative clause verb, suggesting an impairment in predictive processing. We discuss how this lack of a prediction error signal can interact with language acquisition and result in DLD.

Native non-prototypicality in vowel perception induces prominent neuromagnetic mismatch intensities in non-native speakers: a pilot study

Neural mismatch response resulting from the difference between prediction and observation is related to change detection and discrimination. Robust neuromagnetic brain activity of auditory mismatch-related perception occurs in response to non-prototypical vowels in across-category contrasts for first-language speakers. However, whether this non-prototypicality effect applies to within-category vowel perception remains to be elucidated. Here, healthy Japanese adults (n = 7) were subjected to magnetoencephalography (MEG) while watching a silent movie, and passively listened to synthesized English vowels /i/. We observed the source-level mismatch effect to the mid-high near-front vowel deviant [ɪ] with the most non-prototypical, unspecified feature in the participants' native language system. The mismatch effect recruited the left posterior superior temporal sulcus with a peak latency of 225 ms post-stimulus onset. We further studied whether a longer F1 distance between vowel pairs would increase mismatch-activated intensities, however, we did not observe neuromagnetic changes when the prototypical anchor standard [i] was compared with three non-prototypical deviants differing in first resonance frequency (F1) values. Our results indicate that an F1 increase in within-category upper front vowel perception is a strong activator of mismatch responses measured by source-level activated intensities for non-native listeners.

Head errors of syntactic dependency increase neuromagnetic mismatch intensities

Mismatch-related brain activation in healthy individuals is an important area of neural investigation. Previously, we evaluated sentence-level syntactic dependencies, composed of a head and a dependent between two syntactically related words in head-initial English structures. We demonstrated that prominent mismatch effects were induced by within-category dependent errors when semantic interpretation was preserved. However, the following issues were not addressed: (1) whether head errors of syntactic dependency in head-final structures would elicit large mismatch field (MMF) intensities, and (2) whether an MMF effect of syntactic errors would be seen in the left superior temporal cortex alone. In this study, auditory MMFs were obtained by magnetocephalography (MEG) from healthy Japanese adults (n = 8) who were subjected to a passive auditory oddball paradigm with syntactically legal or illegal utterances and single words in Japanese. The results demonstrate that the source waveforms had significantly higher MMF cortical activation in response to the head error, which involved altered polarity of the predicate. This resulted in a syntactically incorrect and semantically incomprehensible expression, when compared to the syntactically correct expression and the non-structural lexical item. This mismatch effect, with a peak latency of 164 ms, was confined to the anterior region of the left superior temporal cortex. The current results clearly indicate that the representation of syntactic dependency is stored in long-term memory and tends to be activated in automatic auditory processing.

Local syntactic violations evoke fast mismatch-related neural activity detected by optical neuroimaging

It remains to be investigated whether syntax-related mismatch activity would be evoked in event-related optical signals by syntactic violations that deviate from our language knowledge and expectations. In the current study, we have employed fast optical neuroimaging with a frequency-domain oximeter to examine whether syntactic violations of English bare infinitives in the non-finite complement clause would trigger syntax-related mismatch effects. Recorded sentences of bare or full infinitive structures (without or with the 'to' infinitival marker) with syntactically correct or incorrect versions and non-syntactic lexical items (verbs) were presented to native speakers of English (n = 8) during silent movie viewing as a passive oddball task. The analysis of source strength (i.e., minimum norm current amplitudes) revealed that the syntactic category violations of bare object infinitives led to significantly more robust optical mismatch effects than the other syntactic violation and non-structural, lexical elements. This mismatch response had a peak latency of 186 ms in the left anterior superior temporal gyrus. In combination with our prior MEG report (Kubota et al. in Neurosci Lett 662:195-204, 2018), the present optical neuroimaging findings show that syntactic marking (unmarked-to-marked) violations of the bare object infinitive against the rule of the mental grammar enhance the signal strength exactly in the same manner seen with MEG scanning, including the peak latency of mismatch activity and the activated area of the brain.