Our perception and decisions are not only driven by present information, but are also influenced by past information. For instance, previous stimuli can affect the judgement of current ones in an attractive way—a phenomenon known as “serial dependence.” Serial dependence has been shown to occur even across stimuli with different low-level features, suggesting the involvement of high-level computations. Here we further address the level of abstraction at which serial dependence originates by investigating biases across different perceptual dimensions, that is, numerosity and duration—two “magnitude” dimensions that usually bias each other when modulated together. Participants were shown sequences of briefly presented dot-arrays, and asked to reproduce either their duration or the average numerosity computed across the sequence, in separate conditions. We then assessed the influence of duration on numerical estimates, and vice versa, both within the same stimulus (“magnitude integration”) and across successive stimuli (“serial dependence”). Our results show significant influences across the two dimensions, occurring both within the same stimulus and across successive stimuli. Moreover, we show that the strength of serial dependence can be predicted based on the strength of magnitude integration, suggesting a relationship between the two effects. Our findings demonstrate that serial dependence can occur between two different perceptual dimensions when they provide compatible information (i.e., “more” vs. “less”), and thus that serial dependence originates from computations shared across different magnitude dimensions. The relationship between serial dependence and magnitude integration additionally suggests a reliance on similar mechanisms, integrating both past and present magnitude information to build a generalized estimate of magnitude.

Faces and voices provide essential information for recognizing familiar people. The brain regions involved in processing person familiarity through these modalities have typically been studied independently, leaving unclear whether and where the auditory and visual networks overlap. In this study, we developed a novel frequency-tagging-based fMRI paradigm to examine the neural basis of familiarity processing from a multimodal perspective. Our findings indicate that the perception of person familiarity through faces and voices predominantly activates sensory-specific regions-the posterior superior temporal cortex (pSTC) for faces and the anterior superior temporal cortex (aSTC) for voices. Discrete regions in the temporal (posterior superior temporal sulcus, pSTS) and frontal (inferior frontal cortex, IFC) areas showed overlapping multisensory activity. pSTS sits as a spatial boundary between unimodal regions, whereas IFC shows connectivity-driven convergence without boundary constraints. These findings indicate shared neural processes for familiarity processing from faces and voices. All together, these results highlight the presence of distributed unisensory and multisensory networks engaging in recognizing familiar people.

The occipital cortex of people born blind massively enhances its response to sounds, but the brain circuitry supporting such crossmodal plasticity remains elusive. Here we capitalized on ultra-high-field fMRI (7T) coupled with sub-millimetre BOLD and VASO acquisitions to infer whether motion-related information is processed via feedforward or feedback pathways, probing responses to visual motion in sighted participants and auditory motion in both sighted and early blind individuals. By identifying circuitry from layer-dependent activity of the middle temporal cortex (hMT+/V5), we observed that moving, but not static, sounds selectively elicited a feedforward response in the middle layers of hMT+/V5 of blind people, analogous to visual motion processing in sighted individuals. Furthermore, we observed that hMT+/V5 shows enhanced auditory motion-selective connectivity with the Planum Temporale in the sighted and with the cuneus in blind people. These findings reveal that hMT+/V5 implements a feedforward motion selective response profile in sighted and blind individuals, with its sensory input shifting from vision to audition in the absence of visual experience.

Background/Objectives. Human voices convey critical socio-affective information, including emotional states. Although autism has frequently been associated with difficulties in processing vocal emotional cues, findings remain inconsistent, particularly in adults. This study investigated neural and behavioral sensitivity to vocal emotion expressions in autistic adults using an objective auditory frequency-tagging EEG paradigm. Methods. Twenty-five autistic adult men and 25 age- and IQ-matched non-autistic men completed an auditory frequency-tagging EEG task and an auditory and multimodal emotion-recognition assessment. During EEG recording, neutral vocal utterances were presented at 4 Hz, with emotional utterances (fear, anger, happiness, or sadness) inserted every third stimulus, generating an oddball frequency of 1.333 Hz indexing vocal emotion discrimination. Results. No significant group differences were observed in neural or behavioral measures of emotion processing. Robust oddball EEG responses were present in both groups, indicating automatic discrimination of emotional from neutral vocalizations. Fearful and angry vocalizations elicited the strongest neural responses. On the behavioral task, autistic and non-autistic participants showed comparable performance in the auditory modality as well as in the visual and audiovisual modalities, with auditory emotion recognition being the most challenging condition for both groups. Conclusions. These findings provide converging neural and behavioral evidence for intact vocal emotion processing in autistic adult men and are consistent with the view that socio-affective processing differences may attenuate across development. Auditory frequency-tagging EEG shows promise as a sensitive tool for studying individual differences in socio-affective processing.

Congenital sensory loss reveals how experience shapes the brain organization, yet most accounts of such plasticity have focused on cortex rather than the thalamic systems that link sensory input, cortical development, and distributed networks. Here, we tested whether primary and higher-order thalamic nuclei show distinct relationships with thalamocortical organization after early sensory loss. In congenital blindness, structural differences were focal to the lateral geniculate nucleus (LGN), the primary thalamic nucleus of the visual system, with individual differences in LGN volume associated with areal features of primary visual cortex morphology. Functional differences, by contrast, involved altered relationships between visual cortex and higher-order cortical and thalamic systems, including stronger functional similarity between visual cortex and control-related networks at rest and during active nonvisual cognition. A parallel analysis of congenital deafness showed no detectable volumetric difference in the medial geniculate nucleus, the primary thalamic nucleus of the auditory system, but revealed altered functional relationships between auditory cortex and higher-order cortical and thalamic systems. These findings suggest that primary thalamic pathways are associated with modality-specific structural consequences of early sensory loss, whereas higher-order thalamocortical systems contribute to convergent functional reorganization of affected sensory cortices across sensory modalities.

While eye movements have been shown to track the speech envelope, it is unknown whether this reflects a hard-wired mechanism or one shaped by (lifetime) audiovisual experience. Further, questions remain about whether ocular tracking is modulated by speech intelligibility and which brain regions drive these synchronized eye movements. Here, we investigate ocular speech tracking in 47 (20 male), blindfolded early blind, late blind, and sighted individuals using magnetoencephalography and source-reconstructed oculomotor signals while participants listened to narrative speech of varying intelligibility. We find that oculomotor activity tracks acoustic speech features; however, while neural speech tracking is modulated by intelligibility, ocular tracking patterns remain ambiguous. Interestingly, we find effects reflected in two frequency-specific components: a low-frequency (∼1 Hz) effect present across all groups, indicating that visual experience is not required, and a high-frequency (∼6 Hz) effect reduced in early and late blind individuals. Moreover, this finding is not driven by cerebro-ocular connectivity, as late blind individuals exhibit stronger connectivity between the eyes and the left temporal cortices without a corresponding increase in ocular tracking. In conclusion, ocular speech tracking seems to respond selectively to acoustic features of speech, and does not require visual experience to develop. It may thus represent a hard-wired oculomotor mechanism within the oculo-cerebral network involved in speech processing.

Exploring our environment through touch often entails integration of tactile input with auditory and/or visual cues. The mechanisms by which mechanosensation integrates with other sensory modalities during active touch remain poorly understood, despite their ecological importance. Here, we investigated auditory-tactile integration in the context of edge localization during active tactile exploration. We assessed how accurately participants could determine the position of their moving finger in relation to the onsets of tactile, auditory, and auditory-tactile stimuli with respect to a visually displayed midline. We hypothesized that localization precision would be improved in the presence of combined auditory-tactile stimulation. In Experiment 1, the auditory, tactile, and auditory-tactile conditions were presented in separate blocks, while in Experiment 2, they were interleaved within blocks. For both experiments, we found that concurrent auditory-tactile stimulation did not increase localization precision. We also observed across all modalities an inclination to localize the finger position towards the right, possibly due to a shift induced by the left-to-right finger movement. This bias was reduced in the auditory-tactile condition of the second experiment, suggesting that when modality was not predictable, integration of auditory and tactile input may have led to a more accurate representation of finger position at stimulation onset. In conclusion, we show that combined auditory-tactile input may reduce biases in reconstructing the spatial location of a tactile stimulus generated by sliding the finger onto a flat surface. These observations have potential implications for the design of haptic technologies involving active touch.

Abstract The human brain processes sensory information through a hierarchical system, from primary to higher-level regions, integrating inputs across modalities to support perception and cognition. While early sensory loss triggers widespread neuroplastic changes, its impact on integration across the cortical hierarchy remains unclear. Here, we examined the cortical reorganization of individuals with early blindness and deafness using a sensory integration framework that quantifies how brain regions prioritize different sensory inputs across the hierarchy. We found that early sensory deprivation drives highly localized reorganization adjacent to the deprived primary cortical areas: extrastriate cortex in early blindness and the superior temporal cortex in early deafness. These findings were further corroborated by analysis of the functional gradients, which found reorganization within these sensory regions. Notably, the hierarchy was largely preserved across groups. However, the sensory integration framework uniquely detected reorganization in language-related regions in deaf individuals with knowledge of a visual communication system known as cued speech. The specific differences between early deaf and hearing individuals remained restricted to superior temporal cortex. Together, our findings demonstrate that early sensory deprivation drives targeted reorganization adjacent to the affected primary sensory cortex, while preserving the overall hierarchy of cortical integration.

How early visual cortex (EVC) supports language and semantic processing in sighted and congenitally blind individuals remains debated. Some predict that blindness induces radical functional reorganization of EVC, whereas others suggest more modest scaling-up changes of a neurofunctional architecture present in sighted individuals. We recorded whole-head MEG in 19 early blind (EB) and 21 sighted adults (SC) listening to spoken adjectives belonging to different semantic categories (i.e., abstract, concrete visual, concrete non-visual) and performing lexical and semantic decision tasks. In the lexical task, lexical information (i.e., word vs pseudoword) could be reliably decoded in perisylvian language areas and the EVC of both groups, with group differences (EB > SC) localized to occipital areas between 0.4 and 0.8 s after word onset. During the semantic task, semantic category information could be decoded in a network overlapping with the canonical semantic system and encompassing the EVC of both groups, with group differences (EB > SC) localized to occipital areas between 0.9 and 1 s after stimulus onset. We further characterized EVC properties and showed that i) EVC semantic information decoding is task sensitive, with no above-chance decoding in EB or SC in the lexical task ii) in the blind EVC it was possible to decode abstract from concrete concepts but not visual from non-visual concepts, a profile similar to that of posterior cingulate areas, but different to anterior cingulate cortex which showed above chance classification for all semantic categories. These results suggest that deprived EVC is integrated into a distributed lexical-semantic network carrying behaviourally relevant semantic information, although to a different extent.

Moving events on the skin can be perceived through vision and touch. How does the brain create a unified multisensory representation of motion directions initially acquired in different coordinate systems? Using functional magnetic resonance imaging, we demonstrate that individually and functionally defined hMT+/V5 shows univariate preference for both visual and tactile motion and encodes motion directions across hand postures. Unlike somatosensory regions, information about tactile directions is enhanced in right hMT+/V5 when mapped using an external rather than a somatotopic frame of reference. Crossmodal decoding reveals alignment between tactile and visual motion directions in the right hMT+/V5 (both in MT and MST) only when tactile motion is defined in external space. A whole-brain searchlight analysis extends this aligned representation to parietal and frontal regions. Our findings reveal a network involving right hMT+/V5 and fronto-parietal regions that encodes motion directions in vision and touch using a common external frame of reference.

Most written systems share basic shape features with natural objects such as line junctions, a commonality thought to be at the basis of fluent reading. Studies that compared reading acquisition for different scripts used line-based scripts and investigated them in terms of complexity, novelty, or associations of stimuli from different categories. Here, we directly compared visual Braille, a script that only includes patterns of dots and no line junctions, to Line Braille, a novel, custom-made script based on line junctions drawn between Braille dots. For four consecutive days, two groups of participants (each N = 40) underwent online training of either one of the scripts, during which they first mapped new letters onto the Latin alphabet and then trained on full words. Each day, participants were tested by asking them to transcribe a set of stimuli (words and pseudowords) from the novel to the Latin script. Across sessions, we found no significant differences between scripts in the overall transcription accuracy nor in the time required to transcribe words. We only found a small delay in the learning trajectory of the Braille group represented through an interaction between group and session in overall accuracy, and slightly higher sensitivity for stimulus length in the Braille group. Overall, these results show that line junctions only provide a small and temporary benefit when learning a new script, contrasting with the idea that line junctions is a core visual features for learning orthography.

How does sensory experience shape the development of the visual brain? To answer this eluding question, we examine brain responses to visual categories in a rare group of cataract-reversal individuals who experienced a short transient period of early blindness. Encoding of low-level visual properties is impaired in the early visual cortex (EVC) of cataract-reversal participants, whereas categorical responses in downstream ventral occipito-temporal cortex (VOTC) are preserved. In controls, degrading visual input to mimic the visual deficits of cataracts produces cascading disruptions extending from EVC to VOTC, unlike in the cataract group. A deep neural network trained on altered visual input reproduces this dissociation, supporting the brain findings. These results demonstrate that while EVC is permanently affected by early deprivation, categorical coding in VOTC shows resilience, highlighting different sensitive periods for specific brain regions and computations.

Recognizing emotion expressions from facial and vocal signals is crucial for optimal social interactions. We comprehensively characterized regions within the face and voice processing networks to probe their contribution to unimodal and crossmodal emotion representation. Using multivariate pattern classification analyses, we found that emotional expressions could be reliably decoded from the dominant sensory modality in all individually defined face- and voice-selective regions. Emotion expressions from the non-dominant modality (vocal expressions in the face networks, and vice versa) could also be decoded in all areas except the occipital face areas. A shared neural code for facial and vocal emotions is implemented in the temporal voice areas (TVA), the posterior superior temporal sulcus (pSTS) and the precentral gyrus (PCG). The simultaneous presentation of congruent facial and vocal expressions elicited distinct activity patterns across most regions, highlighting that multisensory inputs reshape brain responses relative to unisensory stimulation across the entire face and voice brain network. These findings suggest that face and voice-selective regions broadly encode emotion expressions within and even across the senses, relying on a multisensory gradient that converges in temporo-frontal regions where their distributed multisensory responses align to create a supramodal representation of specific emotion expressions. ### Competing Interest Statement The authors have declared no competing interest. Belgian Excellence of Science program - EOS project, 30991544 Flag-ERA HBP PINT-MULTI, R.8008.19 mandate d’impulsion scientifique (MIS-FNRS) National Fund for Scientific Research of Belgium (FRS-FNRS)

Exploratory movements are a key component of tactile sensing to extract haptic information from the external world. While much of the research in the somatosensory field has employed artificial tactile stimuli delivered in passive touch conditions, more recently, much interest has been put in the study of active, dynamic touch. An ecological study of tactile processing during active touch comes with several challenges, particularly with regard to electrophysiological techniques, such as scalp electroencephalography. Here, we report a novel experimental setup to record somatosensory evoked potentials in conditions of active, dynamic touch, where participants performed voluntary and minimally controlled exploratory finger-sliding movements against a surface to come into contact with an edged haptic stimulus. Our results showed that it is possible to record cortical responses to a physical, transient haptic stimulus. The pattern of responses revealed early-latency components with a contralateral topography, consistent with activity originating from the primary somatosensory cortex, followed by later components displaying a more central/bilateral pattern of activity, consistent with activity originating from higher-order areas. In summary, our results reveal the feasibility of recording time-locked cortical responses to tactile stimuli in conditions of active touch, with important implications to study somatosensory processing related to active tactile sensing.

The magnitude dimensions of visual stimuli, such as their numerosity, duration, and size, are intrinsically linked, leading to mutual interactions across them. However, it remains debated whether such interactions, or "magnitude integration" effects, arise from perceptual processes that are independent from the task performed, or whether they arise from high-level decision-making processes. We address this question with two electroencephalography (EEG) experiments in which participants watched a series of dot-array stimuli modulated in numerosity, duration, and item size, in two separate conditions. In the "magnitude task" condition, participants judged either the numerosity, duration, or size of each stimulus. In the "contrast task" condition, instead, a separate group of participants performed a contrast oddball task, never attending or judging the magnitude of the stimuli. The results of the magnitude task first show robust integration effects across the three dimensions. Then, we compare the neural responses to magnitude across the two task conditions. This comparison shows very similar brain responses irrespective of the task, within a series of latency windows whereby the modulation of response amplitude can predict the behavioral magnitude integration effect (~150 and ~250 ms post-onset for numerosity and size; ~300 ms post-offset for the effect of duration). To better assess the similarity of brain responses to magnitude irrespective of the task, we use a cross-condition multivariate decoding analysis. This analysis demonstrates that brain responses in the magnitude task can predict the responses in the contrast task, at multiple latencies starting from early processing stages (~120 ms). These results suggest that magnitude processing and integration likely involve perceptual processes that are engaged irrespective of the task, thus independently from decision making, although the effect of duration on other magnitudes may also involve post-perceptual processes such as working memory.

Learning to read assigns linguistic value to an abstract visual code. Whether regions of the reading network tune to visual properties common to most scripts or code for more abstracted units of language remains debated. Here, we investigate this question using visual Braille, a script developed for touch that does not share the typical explicit shape information of other alphabets, yet maps onto the same phonology and lexicon as other more regular scripts. First, we compared univariate responses in visual Braille readers and a naïve control group and found that individually localized visual word form area (VWFA) was selectively activated for visual Braille when compared with scrambled Braille only in expert Braille readers. Multivariate analyses showed that linguistic properties can be decoded from Latin script in both groups and from Braille script in expert readers in an extended network of brain regions including the early visual cortex (V1), the lateral occipital (LO) region, the VWFA, and the left posterior temporal (l-PosTemp) area. These results suggest that the tuning of an extended reading network to orthography relies more on the linguistic content of the script rather than their specific visual features (e.g., line junctions). Nevertheless, cross-scripts generalization was significantly lower than within-script decoding and failed to reveal common representations across Latin and Braille in experts in all regions except the l-PosTemp. These results suggest that V1, LO, and VWFA encode orthographic representations in a script-specific manner, whereas l-PosTemp encodes abstracted linguistic information.

The human cortex is organized along continuous functional gradients that capture systematic transitions in functional connectivity across the brain. These gradients describe large-scale organizational principles, including hierarchical transitions from unimodal to transmodal regions. Here, we provide the first characterization of cortical gradients in a large sample of congenitally blind (n = 41) and sighted (n = 44) adults to assess the relative contributions of intrinsic (genetic) and experiential factors to cortical gradient organization. Using resting-state fMRI, we compared functional connectome gradients and their association with cortical structure. Both groups exhibited similar principal gradients: unimodal to transmodal, somatosensory to visual, and frontoparietal segregation, demonstrating that the fundamental scaffold of cortical organization emerges largely independently of visual experience. However, blindness altered specific features of the functional connectome: the visual network was more segregated from the sensorimotor network and more integrated with transmodal and frontoparietal networks. Moreover, blind individuals showed reduced canonical hierarchical ordering within early visual areas, weaker structure–function coupling in visual and temporal regions, and altered functional areal boundaries in V1. These findings suggest that the development of large-scale cortical gradients reflects a genetically guided scaffold that is subsequently refined by sensory experience.

Blindness has been shown to induce changes in the structural and functional organization of the brain. However, few studies have investigated the relationship between these structural and functional changes. In this study, we examined cortical thickness within occipital regions of interest in 38 early blind individuals and explored its relationship to functional activation during linguistic processing. Participants engaged in tactile Braille reading and auditory processing tasks involving words, pseudowords, and control conditions to assess various aspects of linguistic processing. Linear mixed models revealed a significant association between cortical thickness and functional activation in the occipital cortex during linguistic tasks. Specifically, lower cortical thickness in the middle occipital gyrus, the calcarine sulcus, and the parieto-occipital sulcus were linked to increased activation during orthographic processing in blind participants (Braille pseudowords vs. Braille nonsense-symbols). Similarly, lower cortical thickness in the calcarine sulcus and parieto-occipital sulcus was associated with greater functional activation during phonological processing (auditory pseudowords vs. auditory control). These findings align with prior research suggesting that structural and functional adaptations in the visual cortex of blind individuals may be influenced by developmental mechanisms such as pruning or myelination. This study highlights the interplay between cortical structure and functional reorganization in the blind brain.