Basque Center on Cognition, Brain and Language

Abstract Brain tumours invade neural tissue, disrupting the functional organisation of neural networks. This disruption can trigger compensatory neuroplastic mechanisms that help preserve cognitive function despite pathological burden. Resting-state functional connectivity (rs-FC) provides a valuable approach for examining these alterations, yet the scope and trajectory of network-level changes remain unclear. In this study, we used rs-FC to characterise compensatory responses induced by left-hemisphere brain tumours affecting the integrity of the language network. The comparison of connectivity patterns at diagnosis and after surgery allowed us to track the temporal progression of these patterns. Relative to healthy participants, patients showed significant deviations in pre-surgical rs-FC, with widespread changes involving the dorsal attention, sensorimotor, frontoparietal, default mode, and cerebellar networks. These differences persisted post-surgically, with no significant longitudinal modifications. Network-level alterations also influenced topological properties: patients showed increased segregation while preserving global integration relative to controls. These properties changed significantly from pre- to postoperative period, with a postoperative increase in segregation and integration towards a pattern more closely resembling that of healthy controls. Furthermore, preoperative network segregation was identified as a predictor of postoperative cognitive recovery. These findings suggest that brain tumours induce network remapping, affecting functional connectivity far beyond the regions strictly related to the affected region. The observed changes in network topological organisation likely reflect the adaptive role of domain-general networks in facilitating homeostatic processes. Surgical strategies aimed at preserving these changes seem to promote sustained cognitive function, regardless of malignancy grade or lesion extent. Key points Presurgical patients show widespread inter- and intrahemispheric rs-FC alterations, reflecting tumour-driven network remapping. Network integration and segregation show longitudinal recovery, approaching neurotypical topology four months post-surgery. Preoperative network segregation predicts postoperative cognitive recovery. Importance of the Study Brain tumours disrupt large-scale brain networks, yet the extent, temporal dynamics, and cognitive relevance of these alterations remain poorly understood. Using resting-state functional connectivity, this study provides a longitudinal, network-level characterisation of tumour-induced neuroplasticity in patients with left-hemisphere lesions affecting language-related regions. Compared with prior work focused on local effects or single networks, our results demonstrate widespread inter- and intrahemispheric connectivity changes involving multiple domain-general resting-state networks, highlighting extensive network remapping beyond lesion boundaries. Importantly, we show that postoperative recovery is accompanied by a rebalancing of network integration and segregation toward a neurotypical configuration. Critically, preoperative network segregation emerges as a predictor of postoperative cognitive recovery, identifying a potential biomarker of resilience. These findings have direct translational relevance, suggesting that preserving and supporting large-scale network organisation during surgical planning may promote cognitive outcomes independently of tumour grade or lesion extent.

Language, a uniquely human higher-order cognitive function, has traditionally been attributed to cortical mechanisms with limited attention given to subcortical contributions. Recent advances in non-invasive neuroimaging have revealed that thalamic activity can be modulated by attention and task demands. Moreover, lesion studies have hinted at the thalamus’s potential role in language processing. Nevertheless, the precise involvement of this structure in language remains unclear. Here, we argue that language-related modulations can occur as early as the sensory thalamic stage, challenging the conventional view of language preprocessing as a predominantly language function. Using functional MRI to image 40 human participants (both female and male) while processing linguistic and non-linguistic stimuli of three main language systems (reading, speech comprehension, and speech production), we demonstrate specific activation of first-order nuclei during targeted language system tasks: lateral geniculate (LGN) for reading, medial geniculate (MGN) for speech comprehension and ventrolateral (VLN) for speech production. Notably, we show linguistic versus non-linguistic stimuli exhibit functional modulations during comprehension tasks (reading and speech) of left MGN and, to a lesser extent, left LGN—in line with prior studies of lateralization of language processes. Multi-voxel classification analysis confirmed left-lateralized linguistic modulation in the MGN, but not in the LGN. Given the complexity of thalamic connectivity and its potential role in integrating sensory and cognitive processes, this work constitutes a relevant first step to further understand thalamic involvement and thalamocortical interactions in language function.

Psycholinguistic research has become increasingly reliant on online experimentation, making it an attractive approach for studying speech production. However, concerns remain about data quality and participant engagement in online settings. In this preregistered study, we used two tasks-picture naming and reading aloud-to test whether the lexical frequency effect (low-frequency words having shorter speech onset times than high-frequency words) could be reliably detected in the online environment (run at home), both with and without experimenter supervision. Participants completed the same two tasks at home and in the lab. Half of the participants performed both tasks with supervision and the other half unsupervised. In the naming task, all conditions yielded consistent frequency effects (~27-41 ms), comparable to previous online and lab findings. In the reading aloud task, lexical frequency effect emerged in all conditions except for the home-supervised, where the effect was in the expected direction but nonsignificant (~12 ms). Notably, participants were overall faster at home than in the lab (~10 ms), and unsupervised settings yielded the largest effect sizes. This suggests that experimenter presence may inadvertently dampen subtle effects, possibly due to increased self-monitoring or reduced comfort. Such findings indicate the reliability of online platforms for speech production research in psycholinguistics and highlight the nuanced influence of supervision on speech outcomes.

In sign languages, linguistic information is transmitted through the simultaneous movement of several bodily articulators. This study investigates cortical tracking of sign language and whether experience and knowledge of sign language can modulate the tracking. We used a camera with a depth sensor to record videos of semispontaneous sign language narratives while tracking articulators' movement in 3D space. These videos served to characterize the temporal periodicity of the sign language visual signal and as stimuli for the experiment. Using magnetoencephalography (MEG), we recorded the neurophysiological activity of two groups of hearing participants-proficient signers and sign-naive individuals-while they watched videos in a known and unknown sign language. Coherence between the preprocessed MEG data and the visual linguistic signal extracted from different articulators was used as measure of brain-language tracking. The results show that neural activity tracks sign language input in delta frequency band (0.5 to 2.5 Hz), reflecting the slower periodicity associated with articulator movements. Both groups of participants show similar tracking in occipital areas, reflecting low-level visual processing of the videos. Proficient signers show stronger synchronization compared to sign-naive controls for linguistically relevant articulators in the right temporal cortex. Proficient signers also show greater tracking for the known compared to the unknown sign language. These findings confirm that cortical tracking of language is a feature of language processing beyond the auditory domain, and is modulated by language experience.

Reading is a rapid process. Within hundreds of milliseconds, perceptual input from the eyes is integrated by the early visual cortex and processed by higher-order visual and language networks, including the ventral occipitotemporal cortex (vOTC) and the inferior frontal gyrus (IFG). Electrophysiological evidence has shown that the IFG becomes active during reading within 200 milliseconds. This early-stage activation suggests the presence of direct white-matter connections between visual territories and the IFG. Previous research has identified four major white-matter tracts linking the vOTC and IFG, however, the detailed connectivity profiles between subregions of these visual and language circuits remain poorly characterized, partly due to the limitations of diffusion-weighted imaging (DWI). In this study, we used a high-quality diffusion MRI dataset (N=66, plus 31 retested) to investigate white-matter connectivity patterns between subregions of the ventral visual pathway and the IFG (pars opercularis, triangularis and orbitalis). To address methodological challenges, we applied a novel approach combining two tract reconstruction algorithms: ROI-to-ROI streamlines and whole-brain tractography. This approach allowed us to delineate subregion-specific white-matter connections without compromising their anatomical accuracy. Our results revealed that the pars opercularis is primarily connected to the anterior vOTC dorsally via the arcuate and superior longitudinal fasciculi. In contrast, the pars orbitalis exhibited exclusive ventral connectivity to the vOTC through the inferior fronto-occipital and inferior longitudinal fasciculi. The pars triangularis displayed a mixed connectivity pattern, with the posterior vOTC connecting ventrally and the anterior vOTC dorsally. In sum, our findings provide a detailed characterization of the structural connectivity underlying reading networks, offering a framework for exploring the white-matter connectivity and functional connectivity, and providing insights into the computational theories of reading.

• Speakers named novel objects to aid native and non-native listeners' word learning. • Speakers named those objects in comprehension, pronunciation, and writing tasks. • Speakers adapted acoustic features based on the tasks and the listener's profile. • Non-native directed speech appears to serve a didactic purpose. Speakers adapt acoustic features to factors such as listeners’ linguistic profiles. For instance, addressing a non-native listener elicits Non-Native Directed Speech (NNDS). However, whether these speech adaptations vary depending on the speakers’ didactic goals, in interaction with the listeners' profiles (i.e., native vs. non-native), remains unknown. We recorded native Spanish speakers naming novel objects to aid their listeners’ performance in comprehension, pronunciation, and writing tasks. Each speaker interacted with a native (Native Directed Speech, NDS) and a non-native (NNDS) Spanish listener. We extracted measures of vowel hyperarticulation, duration, intensity, speech rate, and F0 to assess listener- and task-specific speech adjustments. Our results showed that speakers hyperarticulated vowels to a greater extent in the writing condition compared to the comprehension condition, and during NNDS compared to NDS. Listener profile and task also impacted speakers’ F0 height, intensity, and vowel duration production. Therefore, speakers adjust acoustic features in their speech to achieve their didactic goals and accommodate their listener's profile. Also, speakers’ overall greater adaptation in NNDS than in NDS suggests that NNDS serves a didactic purpose.

The development of robust frameworks to understand how the human brain represents conscious and unconscious perceptual contents is paramount to make progress in the neuroscience of consciousness. Recent functional MRI studies using multi-voxel pattern classification analyses showed that unconscious contents could be decoded from brain activity patterns. However, decoding does not imply a full understanding of neural representations. Here we re-analysed data from a high-precision fMRI study coupled with representational similarity analysis based on convolutional neural network models to provide a detailed information-based approach to neural representations of both unconscious and conscious perceptual content. The results showed that computer vision model representations strongly predicted brain responses in ventral visual cortex and in fronto-parietal regions to both conscious and unconscious contents. Moreover, this pattern of results generalised when the models were trained and tested with different participants. Remarkably, these observations results held even when the analysis was restricted to observers that showed null perceptual sensitivity. In light of the highly distributed brain representation of unconscious information, we suggest that the functional role of fronto-parietal cortex in conscious perception is unlikely to be related to the broadcasting of information, as proposed by the global neuronal workspace theory, and may instead relate to the generation of meta-representations as proposed by higher-order theories.

Subcortical plasticity has mainly been studied using invasive electrophysiology in animals. Here, we leverage precision functional mapping (PFM) to study motor plasticity in the human subcortex during 2weeks of upper-extremity immobilization with daily resting-state and motor task fMRI. We found previously that, in the cortex, limb disuse drastically impacts disused primary motor cortex functional connectivity (FC) and is associated with spontaneous fMRI pulses. It remains unknown whether disuse-driven plasticity pulses and FC changes are cortex specific or whether they could also affect movement-critical nodes in the thalamus and striatum. Tailored analysis methods now show spontaneous disuse pulses and FC changes in the dorsal posterior putamen and central thalamus (centromedian [CM], ventral-intermediate [VIM], and ventroposterior-lateral nuclei), representing a motor circuit-wide plasticity phenomenon. The posterior putamen effects suggest plasticity in stimulus-driven habit circuitry. Importantly, thalamic plasticity effects are focal to nuclei used as deep brain stimulation targets for essential tremor/Parkinson's disease (VIM) and epilepsy/coma (CM).