Brain and Language

Humans routinely encounter speech in languages they have never heard, yet how the brain responds to such input and whether bilingual experience shapes this response remains unknown. Here, we used electroencephalography (EEG) and temporal response function (TRF) modeling to examine cortical tracking of the speech envelope in 24 English-monolingual and 24 English-Mandarin bilingual adults. Participants listened to naturally produced continuous speech in three languages: English (familiar to all), Mandarin (familiar to bilinguals only), and Vietnamese (unfamiliar to all). We report two main findings. First, both monolinguals and bilinguals showed enhanced cortical tracking for unfamiliar relative to familiar languages, evidenced by higher EEG prediction accuracy (PA). Monolinguals showed enhanced tracking for both Mandarin and Vietnamese, whereas bilinguals showed enhancement only for Vietnamese, consistent with Mandarin being a familiar language for this group. This finding suggests that enhanced cortical encoding of unfamiliar speech is a general property of the listening brain, not a signature of listening to a non-native language or reduced language proficiency. Second, bilinguals strikingly showed stronger cortical tracking than monolinguals overall, in both PA and TRF peak weights, with the TRF peak weight advantage present across all three languages, suggesting a difference in how bilingual experience shapes the neural encoding of speech. These findings have implications for understanding how the brain navigates the linguistic diversity of everyday life in an increasingly global, multilingual world.

Developmental dyslexia is associated with impaired cortical tracking of continuous speech and difficulties in perceiving within-word prosodic structure in children and adults. For adults and continuous speech, both low-frequency delta- and theta-band impairments and high-frequency gamma- and beta-band differences are found. To date, perceptual difficulties with intra-word prosody have not been studied in direct relation to neural speech encoding. Here neurotypical adults and adults with dyslexia listened to multisyllabic words. EEG was recorded, and cortical encoding was quantified using temporal response function (TRF) modelling. Four speech representations were explored: lexical stress pattern (intra-word prosodic prominence), the low-frequency speech envelope, word onsets and syllable onsets. Adults with dyslexia showed significantly reduced encoding of intra-word prosodic prominence (delta band) and of the speech envelope (delta and theta bands). In contrast, encoding of word and syllable onsets was preserved. Pinpointing delta-band cortical tracking as central to encoding intra-word prosodic prominence opens new avenues for research.

Reading behaviour is sensitive to contextual demands. For example, when reading to study or answer questions, readers strategically allocate more attention to goal-relevant sections, read slower, and regress more frequently to extract specific information based on task demands. This suggests that readers flexibly adapt their strategies according to goals and situational constraints. However, the neurocognitive mechanisms supporting this flexibility remain unclear. To test this, we combined eye-tracking with EEG during naturalistic reading and examined how short-term reading goals modulated the neural tracking of hierarchical linguistic features at the orthographic (orthographic neighbourhood size), lexical (word frequency), and contextual-semantic (Surprisal) levels. Forty native English speakers read narratives in three goal conditions: Baseline (no goal), Proofreading (detect spelling errors), and Comprehension (attend to content). Fixation-aligned word-level EEG activity was modelled using multivariate temporal response function to estimate the strength of feature-specific neural tracking. Orthographic tracking was significantly enhanced during Proofreading relative to Baseline, and predicted better Proofreading accuracy. Conversely, stronger frequency tracking predicted better Comprehension accuracy. Contextual-semantic tracking was not modulated by task goal. These findings suggest that reading goals selectively bias neural processing towards linguistic features (sublexical vs. lexical) that support successful task performance, providing evidence for short-term functional plasticity in linguistic processing and supporting a flexible predictive processing account of goal-directed reading.

Comprehending spoken language requires extracting syntactic structure and meaning from a continuous acoustic signal. Psycholinguistic evidence points to a key role for prosody in this process. However, because interactions between prosody and syntax are typically demonstrated using carefully controlled sentence constructions, it remains unclear whether such interactions constitute a general, default property of spoken language processing. Addressing this question requires naturalistic, broad-coverage data. Here, we combined experimental psycholinguistics with naturalistic neuroscience to investigate the joint neural encoding of syntax and prosody in MEG recordings of 26 participants (19 female) listening to narrative speech. Linguistic annotations revealed that strong prosodic boundaries tend to coincide with syntactic phrase closures, and that the strength of prosodic boundaries scales with the number of phrases closed. Using time-resolved regression with temporal response functions, we modeled how these features relate to delta-band neural activity during continuous speech processing. Our results reveal a bidirectional interaction between syntax and prosody. Prosodic marking modulates the neural processing of syntax, with phrase closures being encoded more strongly when accompanied by strong prosodic boundaries. Conversely, syntactic structure shapes prosodic encoding, such that boundary strength is neurally encoded primarily at points of syntactic phrase closure. These findings demonstrate that syntax and prosody are encoded not independently, but in a context-dependent and mutually constraining manner, highlighting their joint role in guiding structure building during naturalistic spoken language comprehension.

Understanding how the brain represents meaning at different levels of specificity, from general categories (bird) through combined phrases (nocturnal bird) to specific exemplars (owl), is a central question in semantic cognition and its disorders. The anterior temporal lobes (ATL) have been implicated in both activating stored conceptual representations and combining them, yet whether these two routes to conceptual content engage the ATL in the same way remains an open question. We recorded concurrent MEG-EEG from 36 participants reading 100 conceptual triads varying parametrically in specificity: general words (bird), adjective-noun phrases (nocturnal bird), and specific words (owl). Source analyses revealed a non-linear pattern in bilateral ATL (400-520ms): high-specificity concepts elicited greater activity than both low-specificity words and mid-specificity phrases. Bilateral inferior frontal cortex showed this effect with similar timing (430-630ms). N400 amplitude and ATL source activity showed a functional dissociation in their sensitivity to word frequency, ruling out a purely frequency account of the ATL and IFC effects. Results imply that accessing high-specificity concepts requires individuating stored representations among competitors, whereas phrases construct meaning through a different route. These findings extend the unified semantic hub account by revealing that computational operations within the ATL vary depending on task and stimulus demands.

Naming pictures from the same semantic category can interfere with subsequent word retrieval. Although the left inferior frontal gyrus (LIFG) has been implicated in resolving this semantic interference, its causal role in this process remains unclear. Across three experiments, we investigated the contribution of the LIFG to interference resolution during blocked-cyclic naming. Experiment 1 tested whether continuous theta-burst stimulation over the LIFG increased semantic interference relative to vertex stimulation. Although the overall interference effect did not differ significantly between stimulation sites, exploratory analyses revealed an unexpected pattern based on the initial context (related vs. unrelated) with which items were named, suggesting that LIFG disruption affected retrieval of previously related items even when they were subsequently named in unrelated contexts. This observation motivated two further experiments examining the consequences of prior naming context more directly. Experiment 2 established that, without stimulation, interference observed in related blocks was no longer evident after the items were redistributed into unrelated blocks. Experiment 3 combined this design with cathodal or sham transcranial direct current stimulation (tDCS) over the LIFG. Planned comparisons showed that cathodal stimulation slowed naming of initially related items both within related blocks and after redistribution into unrelated blocks; corresponding comparisons for items named consistently in unrelated blocks were not significant. The similar patterns across two stimulation methods suggest that LIFG-mediated control may influence both selection under current competition and subsequent retrieval of previously competing words. These findings could be accommodated within a hybrid account in which working memory supports context-guided selection and selection-related control helps recalibrate lexical accessibility, limiting the carryover of interference into subsequent naming.

Inhibitory control deficits have long been proposed as a central neurocognitive mechanism underlying childhood Attention Deficit/Hyperactivity Disorder (ADHD). However, neuroimaging findings remain heterogeneous, partly due to methodological variability across developmental samples and experimental paradigms. The present study aimed to characterize the neural architecture of motor response inhibition in typically developing (TD) children and identify reproducible functional abnormalities associated with pediatric ADHD using stringent, developmentally specific inclusion criteria. We conducted two coordinate-based meta-analyses using Activation Likelihood Estimation (ALE). Following a systematic literature search (up to August 2026), we identified 23 task-based fMRI studies reporting inhibitory-control-related activation in TD children (237 foci) and 17 studies comparing children with ADHD and TD peers (114 foci) during the Stop-Signal Task or Go/No-Go Task. All participants were younger than 18 years of age. Statistical significance was determined using cluster-level family-wise error (FWE) correction. In TD children, ALE revealed a robust inhibitory-control network encompassing the bilateral anterior insula (AI), inferior frontal gyrus (IFG), and the midline pre-supplementary motor area (preSMA) and anterior cingulate cortex (ACC). This spatial organization closely resembled the canonical inhibitory-control network consistently observed in adults, suggesting that the core neural architecture supporting motor inhibition is already detectably organized during development. In the between-group analysis, children with ADHD exhibited significant hypoactivation primarily within the preSMA. Notably, this region demonstrated striking spatial overlap with the preSMA cluster reliably recruited in TD children during motor inhibition. These findings provide convergent support for inhibitory-control models of ADHD and identify altered preSMA recruitment as one of the most consistent functional abnormalities associated with pediatric ADHD. While the neural infrastructure supporting inhibitory control is broadly established during childhood, children with ADHD exhibit reduced recruitment of a key cortical node within this network during motor inhibition demands.

We investigated how auditory and visual presentation of small numerical magnitudes and non- numerical magnitudes are passively processed at the neural level. Earlier research suggests automatic processing of quantities occurs rapidly in the brain. However, there are no studies on passive, pre-attentive change detection of magnitudes utilizing mismatch negativity (MMN) across sensory modalities in same participants, important to understand amodal processing of magnitudes. We recorded EEG in passive auditory and visual multi-feature oddball and control paradigms from the same adult individuals (N=104/105, respectively). In the auditory paradigm, the standard stimulus was a 2-part sound, while the deviant stimuli varied in frequency, intensity, gap length, and number of sounds (1-part and 3-part stimuli). In the visual paradigm, the standard stimulus was a dot array containing two medium-sized dots, while the deviant stimuli varied in numerosity (1 or 3 dots) and dot size (small or large). The results for the auditory paradigm showed significant MMN across all features, including comparisons with deviant-alone control stimuli, except for the 2-part vs. 1-part contrast. The results for the visual paradigm suggested differences in processing across all features apart from large and medium-size stimuli. These results replicate earlier MMN findings that the brain distinguishes pre-attentively changes in sound frequency, amplitude and gap. Auditorily presented small numerical magnitudes also showed pre-attentive processing but less robustly to the contrast 2 vs. 1. Visual pre-attentive processing of small numerical magnitudes was also observed. Together these findings could be interpreted to support the existence of abstract, pre- attentive processing of numerical magnitudes. Highlights* Auditory and visual processing of numerical and non-numerical magnitudes was examined with EEG * Auditory non-numerical magnitudes and medium vs. small dots replicated earlier MMN studies * aMMN and vMMN showed pre-attentive processing of changes in small numerosities 2 vs. 3 and 2 vs. 1 * 2 vs. 1 tone processing was less robust than 2 vs. 3 or the processing of the visual contrasts * The brain processes changes in small non-symbolic magnitudes pre-attentively

The development of speech in human children is a protracted process that depends on social experience. From early life, young children produce vocalizations in the presence of others, which affords unique opportunities for feedback about how to communicate successfully. However, for feedback to happen, young childrens speech needs to effect change in the brains of their caregivers. Using dual-brain functional near-infrared spectroscopy (fNIRS) to measure real-time communication between caregivers and their 2- to 3-year-old children (n = 56), we found that children's vocalizations selectively modulated caregivers' brain activity. Parents' brains showed a rapid response to children's production of speech that was communicatively advanced (multiword utterances) vs. less advanced (babble). The findings imply that if part of learning to talk is figuring out how to get your communication partner to listen, then early conversations likely present continuous opportunities for feedback that guide children toward advances in spoken language.

Language processing does not occur in a vacuum. Language comprehension and production have its own temporal organization, and it unfolds against ongoing neural. We examined whether the base organization persists from rest into sentence processing, and we further examined how it relates to evoked responses and semantic decisions. Sentences crossed linguistic argument versus adjunct completions with semantic plausibility. Anomalies elicited a centroparietal late positivity from 600 to 900 ms (+0.628 microvolt, 95% CI 0.349-0.907). Channel-wise autocorrelation timescales formed person-specific topographies: own-person rest-task similarity exceeded mismatched-person similarity (Fisher-z advantage = 0.463, permutation P = 5.00 x 10^-6), identifying 78.6% of participants against 7.1% chance. The advantage survived Cz re-referencing and surface-Laplacian transformation. In separate ERP predictor tests, longer absolute task timescales accompanied a smaller anomaly effect (cross-fitted Spearman rho = -0.486, Holm-adjusted P = 0.030). Stronger topographic continuity also accompanied greater anomaly-related decision slowing, although the behavioral association fell short of correction across six endpoints (rho = 0.547, familywise P = 0.054). Supporting analyses evaluated larger eligible samples and an eyes-closed subset. The findings place persistent, person-specific temporal organization within sentence processing and link absolute task timescale to the neural response to semantic anomaly.

Comprehending a narrative requires continuously updating a model of the discourse, and beta-band activity is thought to signal when that model should be held versus changed. Whether beta also grades how much to update, and whether that index is carried by discrete bursts beyond sustained power, is unknown for naturalistic comprehension. We recorded MEG from 61 human participants (22 men, 39 women) while they listened to naturalistic Hebrew narratives, detected beta bursts in the continuous signal, and quantified the semantic shift between successive sentences from sentence embeddings. Beta burst rate decreased after sentence boundaries, and regression-based deconvolution separated a pre-onset maintenance phase from a graded post-onset response whose magnitude scaled with semantic shift (peak ~0.9 s). This response was independent of lexical surprisal, the acoustic envelope, and referent introduction, largely robust to dependency structure, though it shared variance with propositional quantity. Burst occurrence carried a component of the effect beyond the accompanying amplitude change: applying that change as a pure gain to each participant's envelope and re-running the identical detection predicts only 75% of the observed burst-rate reduction (excess p = .038), the effect survived an amplitude-invariant threshold, and a Poisson model reproduced it as a graded reduction in burst-initiation rate. The effect held in both participant groups, which heard differently framed narratives, and was decisively supported (BF10 > 250). Beta bursts thus provide a graded signal of semantic updating during continuous comprehension, expressed in the rate of burst occurrence over and above the accompanying change in sustained power.

The relationship between neural processes supporting perception, deviance processing, and post-perceptual task demands during auditory processing is not well understood. We used multitone masking and a no-report inattentional deafness paradigm to dissociate neural correlates of auditory perceptual awareness, deviance processing, and task demands. Evoked responses to physically identical target-tone pairs were recorded across three phases differing only in task instructions. In Phase A, human participants remained nave to (and thus unaware of) the target tones. In Phase B, participants were informed about (and thus aware of) the target tones. In Phase C, participants remained aware of the target tones and judged the duration of the silent gap between them, rendering them task-relevant. When participants were aware of them, target tones elicited an auditory awareness negativity and an increased positivity in the P3 window), with larger responses when target tones were additionally task-relevant. Furthermore, though largest in Phase C, deviant stimuli elicited a mismatch negativity across all task conditions, while a significant P3 to deviants was only observed in Phase C. Thus, early and late responses can be independently modulated by awareness, deviance, and task-relevance, indicating that they do not necessarily rely on shared neural mechanisms despite overlapping spatiotemporal profiles.

Neuroimaging studies identify the superior temporal sulcus (STS) as an anatomical and functional target in autism spectrum disorder (ASD). Yet, the STS is a heterogeneous structure containing unique subregions, such as the superior temporal asymmetrical pit (STAP), which is a recently identified human-specific landmark. To date, no study has compared the STAP between ASD individuals and neurotypical controls (NTs) in a large sample. Here, we analyzed the mean intra-hemispheric sulcal depth and inter-hemispheric laterality of the STAP, as well as the anterior and posterior portions of the STS (aSTS, pSTS), in 100 NTs and 100 ASD male individuals (ages 5-18) using a discovery-replication design. Across samples, the STAP and pSTS showed rightward asymmetry, while the aSTS showed leftward asymmetry within groups. All features of the STAP, aSTS, or pSTS did not differ significantly between groups. However, pSTS laterality related to individual differences in social cognition, which was further supported by a meta-analysis across over 200 studies showing that neurocognitive functional differences associated with social cognition and ASD are restricted to portions of the STS outside of the STAP. Together, these findings provide fine-grained insight into prior studies showing coarse morphological differences of the STS between individuals with ASD and NTs, as well as open up new questions and new neuroanatomical targets of the heterogeneous STS in future studies of brain structure, brain function, and cognition in ASD, as well as other neurodevelopmental disorders targeting the superior temporal cortex.

Language can be experienced in highly serial form, as in speech, or in fully parallel form, as in text, yet how our brains adapt to differences in seriality is not understood. Here, we held modality constant (visual) and examined whether processing mechanisms underlying grammaticality detection are similar under Rapid Serial Visual Presentation (RSVP) and Rapid Parallel Visual Presentation (RPVP). To identify shared neural representations of grammaticality, we trained a classifier on magnetoencephalography (MEG) responses to grammatical and ungrammatical three-word phrases in one presentation mode and tested its generalization to the other. Behaviorally, accuracy was higher and reaction times faster for grammatical vs. ungrammatical phrases across presentation modes. Neurally, cross-presentation decoding revealed shared representations of grammaticality at word 2 across train-test directions--albeit with different latencies and durations--and an early shared representation at word 3 when trained on RPVP. We take the bidirectional representations at word 2 to capture distinct but presentation-invariant combinatorial processes and the asymmetry at word 3 as reflecting stronger global structure encoding in RPVP.

Working memory (WM), a core executive function that supports learning and reasoning, undergoes rapid development during early childhood years. Neural activation patterns underlying WM have been extensively studied in both adults and children, revealing increasing involvement of the frontoparietal network (FPN) with age and coordinated interactions with the default mode network (DMN). However, relatively little is known about how these network interactions develop in children, particularly within the visuospatial domain. The present study investigated the influence of age and task performance on effective connectivity within the FPN and its interactions with DMN hubs during a visuospatial WM task in early childhood. Functional MRI data were collected during a visual n-back task with two WM load levels (0-back and 2-back) in 120 typically developing children aged 5-8 years. Dynamic Causal Modeling (DCM) with parametric empirical Bayes was used to estimate effective connectivity among eight regions of interest spanning the FPN and DMN. Behaviorally, age-related gains were steepest under high-load for accuracy, and under low-load for reaction time, suggesting WM capacity is a demand-sensitive marker of development at this age. At the network level, high-load robustly engaged the FPN, whereas low-load was associated with relatively greater engagement of DMN and episodic memory-related regions. Baseline effective connectivity was dominated by parietal-to-frontal drive and strong self-inhibition in the anterior cingulate cortex. Age-related effects on this architecture were sparse, involving asymmetric interhemispheric frontal coupling and reduced parieto-cingulate coupling, whereas accuracy-related effects were larger in magnitude, particularly at self-connections. More accurate children showed greater excitability in frontal and parietal FPN nodes alongside increased self-inhibition in the precuneus, a DMN hub, consistent with a neural efficiency account in which better performance reflects more selective, rather than more global, network engagement. Task load further shaped connectivity in distinct ways: low-load elicited widespread inter-regional modulation, whereas high-load predominantly modulated self-connections, with age and accuracy effects on this modulation dissociating by load. These findings suggest that, in primary school children, current task performance was associated with more pronounced differences in frontoparietal effective connectivity than was age, and that WM-related network engagement becomes increasingly selective and load-dependent across this developmental window.

Communication is inherently interactive, yet most neuroimaging studies examine individuals in isolation. Here, we used functional near-infrared spectroscopy (fNIRS) hyperscanning to investigate interbrain synchrony (IBS) during naturalistic communication. In Study 1, 13 healthy familiar dyads completed Joint Singing, Joint Reading, and Picture Guessing tasks. IBS was quantified using wavelet transform coherence across bilateral frontal and temporoparietal regions. Joint Singing produced higher IBS than the other tasks in several regions, including the dorsolateral prefrontal cortex and temporoparietal junction, and selected effects were greater in true than pseudo-dyads. In Study 2, we applied the same paradigm to five individuals with chronic post-stroke aphasia interacting with trained speech-language pathologists. IBS could be estimated in all dyads after lesion-informed channel exclusion, although regional coverage varied with lesion location. These findings demonstrate that fNIRS hyperscanning can capture task-dependent interpersonal neural coupling during spoken interaction and can be extended to communication involving individuals with aphasia. This approach provides a foundation for studying how neural coordination between communication partners relates to functional communication and partner-supported interaction.

Multi-echo functional magnetic resonance imaging (fMRI) acquires signals with distinct contrast profiles across echo times (TEs). Empirical evidence suggests that different TEs capture distinct signal contributions with varying sensitivity to BOLD and non-BOLD processes from long to short TEs (Stroman, 2002; Krishnamurthy, 2023; Dong, 2024). Previous literature has not yet examined how brain states extracted from temporal dynamic functional connectivity (dFNC) evolve across TEs. Here we present a methodological and empirical study of TE-dependent evolution of dynamic connectivity states, with a phenomenological two-component model for interpretation. Multiple echoes were acquired with an echo planar time-resolved imaging (EPTI) sequence. TE-specific components were extracted via atlas-based group ICA (Neuromark 1.0), and brain connectivity states were generated via windowed dFNC and spatial ICA clustering of windows. Within-subject and group-level states evolved across TEs in network organization and variance. States exhibited TE-dependent variance profiles, with distinct peak echo times; and group-level points of state transition were independently mapped to TE-dependent transitions in variance. We modified a bi-exponential model to simulate and model changes in the dFNC time-course across TEs. The bi-exponential model revealed high consistency with subject states (R2 fit=0.86, res. error=0.55, 86% model convergence rate), suggesting a two-component signal system contributing to dynamic TE-dependent connectivity changes in state. A significant correlation between relative model terms was estimated on a cell-wise basis across states (r(24) = -0.43, p=0.03, 95% CI [-0.70, -0.04]). This suggests that specific bi-exponential signal parameters (i.e., short FNC1,TE=0, long FNC2,TE=0, and long FNC2,decay) were associated with the observed TE-dependent variations in connectivity states across TEs. In sum, our analyses provide downstream implications for TE-aware state analysis dependent on connectivity magnitude (FNCTE=0) and rate of connectivity decay (FNCdecay), in a two-component signal model, with future implications for TE-dependent state biomarkers.

Free recall of naturalistic stimuli, such as films and stories, reveals what people remember and how they organize it. Scoring such recall requires matching each recalled utterance to the encoded stimulus, and doing this manually often makes large studies impractical. Existing automated methods mostly return similarity or aggregate scores rather than explicit matches between recalled and stimulus content. Here we introduce an open-source, model-agnostic pipeline that uses a large language model (LLM) to divide the stimulus and the recall into information units and to match units between the two texts. The output is a table of unit-to-unit matches with accuracy labels, from which standard analysis scripts compute recall measures. We validated the pipeline with four LLMs (Claude Sonnet 4.5, GPT 5.4, Gemini 2.5 Pro, and Gemini 2.5 Flash) on three datasets. On typed recall of four short stories, agreement between each model and two trained raters ({phi} = .73-.79) was close to the agreement between the raters themselves ({phi} = .77). A second run reproduced each model's matches ({phi} = .91-.97) more closely than the raters agreed with each other. On spoken recall of 10 films, every model attributed recall to the correct film with high agreement. On uncorrected speech-to-text recall of a television episode, agreement varied more across models. The median cost was under $1 per participant for every model. These results suggest that the pipeline can serve as a reliable, low-cost alternative to manual scoring of free recall.

Syntax processing impairment is a defining feature of primary progressive aphasia (PPA), particularly in the nonfluent/agrammatic variant. However, current models are derived largely from Indo-European languages, and it remains unclear whether the cognitive and neuroanatomical mechanisms of syntax processing generalize to Chinese, an analytic, pro-drop language that encodes grammatical relationships primarily through word order and function words rather than inflectional morphology. Participants were recruited from the international Chinese Language Assessment in PPA cohort and included 64 individuals with PPA (19 logopenic, 15 nonfluent/agrammatic, 15 semantic, and 15 unclassifiable/mixed) and 60 cognitively healthy controls. Participants completed sentence comprehension and production tasks with systematically manipulated syntactic features. Item-level linguistic determinants were examined using ridge regression, diagnostic performance using receiver operating characteristic analyses, and neuroanatomical correlates using voxel-based morphometry of structural MRI. Performance on sentence comprehension and production was influenced by grammatical and lexical features. Subject-relative clauses, passive constructions, a higher proportion of function words, longer character length, and greater lexical content were associated with poorer performance among participants with PPA. Sentence comprehension was impaired in the logopenic, nonfluent/agrammatic, and semantic variants, even when isolated to the syntactic component of the sentence comprehension task. Similarly, sentence production was impaired across all PPA variants (all P < 0.01 versus controls). No significant differences were observed among PPA variants. Adjusted receiver operating characteristic analyses demonstrated high discrimination between each PPA variant and controls, with areas under the curve ranging from 0.87 to 0.97 for sentence comprehension-syntax and from 0.91 to 0.97 for sentence production. However, pairwise comparisons showed no significant differences in discriminative performance among PPA variants after correction for multiple comparisons. Both sentence comprehension-syntax and sentence production showed associations with semantic and repetition measures in addition to motor speech measures. Voxel-based morphometry showed that higher sentence comprehension-syntax scores were associated with greater grey matter volume in left frontotemporal and cingulate regions, whereas higher sentence production scores were additionally associated with greater gray matter volume in frontostriatal structures, including the caudate, putamen, and thalamus. Syntactic processing impairment in Chinese-speaking individuals with PPA extends beyond the nonfluent/agrammatic variant and is associated with distributed frontotemporal and frontostriatal regions, as well as lexical-semantic and auditory verbal short term memory mechanisms. These findings suggest that the cognitive and neural manifestations of syntactic impairment may be shaped by language-specific typological properties, underscoring the need for linguistically informed approaches to the assessment and interpretation of PPA.

PurposeDuring speech planning, the brain predicts the auditory consequences of its movements and modulates the auditory system--a process called pre-speech auditory modulation (PSAM). We investigated the link between PSAM and behavioral error correction and determined how aging influences these mechanisms. MethodsSeventeen young adults (18-32 years) and 13 older adults (50-85 years) performed a speaking task involving auditory feedback perturbations and a silent reading control. We measured electrophysiological responses (N1/P2) to auditory probes during speech planning and correlated these modulations with the magnitude of participants subsequent behavioral corrective responses. ResultsBoth groups showed significant modulation of N1 and P2. However, N1 modulation correlated with corrective responses only in young adults. Older adults showed reduced behavioral corrections and smaller, delayed P2 components. Despite these age-related behavioral differences and the loss of the modulation-correction correlation, older adults maintained modulation magnitudes comparable to those of younger adults. ConclusionsN1 modulation serves as a neural index of the brains predictive processes during speech planning. Aging appears to selectively disrupt the integration of these signals into motor output rather than the internal generation of the predictions themselves.