Biology subjects

Mattioni, S.

Publications and source records attributed to Mattioni, S..

12 recordsLinked to original sources

bioRxiv2026

Parallel control of conjunctive and compositional representations supports dynamic task preparation

People can dynamically and adaptively update task goals in the face of task uncertainty. In this fMRI study, we aimed to investigate the modulation of neural task representations that subserve such flexible task control. On each trial, we asked people to perform one of nine image categorization tasks. During task preparation, participants had to actively infer varying levels of task uncertainty and dynamically modulate their task preparation accordingly. Multivariate pattern analyses demonstrated dissociable uncertainty-driven modulations of conjunctive and compositional task representations in the right frontoparietal network. Specifically, different sub-regions showed diminished conjunctive task representations when task uncertainty increased during task preparation. At the same time, we observed an active maintenance of compositional task representations, suggesting an adaptive cognitive strategy in facilitating compositional task reconfiguration. These findings suggest a mechanism of parallel control on conjunctive and compositional representations that allows for maximizing the advantages of both representational formats, offering new insights into the neural mechanisms underpinning human flexible task preparation.

neuroscience↗

bioRxiv2025

Representation of emotional expressions across the face and voice brain networks

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.

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bioRxiv2025

Two time scales of adaptation in human learning rates

Different situations may require radically different information updating speeds (i.e., learning rates). Some demand fast learning rates, while others benefit from using slower ones. To adjust learning rates, decision makers could rely on either global, meta-learned differences between environments, or faster but transient adaptations to locally experienced prediction errors. Here, we introduce a new paradigm that allows researchers to measure and empirically disentangle both forms of adaptations. Participants performed short blocks of trials of a continuous estimation task - fishing for crabs - on six different islands that required different optimal (initial) learning rates. Across two experiments, participants showed fast adaptations in learning rate within a block. Critically, participants also learned global environment-specific learning rates over the time course of the experiment, as evidenced by computational modelling and by the learning rates calculated on the very first trial when revisiting an environment (i.e., unconfounded by transient adaptations). Using representational similarity analyses of fMRI data, we found that differences in voxel pattern responses in the central orbitofrontal cortex correlated with differences in these global environment-specific learning rates. Our findings show that humans adapt learning rates at both slow and fast time scales, and that the central orbitofrontal cortex may support meta-learning by representing environment-specific task-relevant features such as learning rates.

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bioRxiv2025

Neural and computational evidence for a predictive learning account of the testing effect

Testing enhances memory more than studying. Although numerous studies have demonstrated the robustness of this classic effect, its neural and computational origin remains debated. Predictive learning is a potential mechanism behind this phenomenon: Because predictions and prediction errors (mismatch between predictions and feedback) are more likely to be generated in testing (relative to in studying), testing can benefit more from predictive learning. We shed light on the testing effect from a multi-level analysis perspective via a combination of cognitive neuroscience experiments (fMRI) and computational modeling. Behaviorally and computationally, only a model incorporating predictive learning can account for the full breadth of behavioral patterns and the robust testing effect. At the neural level, testing and prediction error both activate the canonical reward-related brain areas in the ventral striatum, insula, and midbrain. Crucially, back sorting analysis revealed that activation in the ventral striatum, insula, and midbrain can enhance declarative memory. These results provide strong and converging evidence for a predictive learning account of the testing effect. Significance StatementAn exam is not a neutral measurement of memory. The testing effect entails that a test (e.g., an exam), is more effective than study for learning and memory. The same effect can be harnessed also before events of significance take place, rendering it an important aspect of an active learning strategy. Nevertheless, its origin remains unknown. We propose a novel predictive learning account, which posits that testing (vs studying) facilitates predictions about study material and promotes learning from prediction errors. Computationally, the testing effect was explained through a predictive-learning-based neural network. Neurally, testing and prediction error activate common neural areas, which in turn enhance declarative memory. This account may extend beyond testing to support active learning.

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bioRxiv2024

Impact of a transient neonatal visual deprivation on the development of the ventral occipito-temporal cortex in humans

How does experience shape the development of visual brain regions? We demonstrate that a transient period of visual deprivation early in life in humans leads to permanent alteration in the function of the early visual cortex (EVC), while leaving the categorical coding of downstream ventral occipito-temporal cortex (VOTC) mostly unaffected. We used fMRI to characterize the brain response to five categories (faces, bodies, objects, buildings and words) in a rare group of cataract-reversal individuals who experienced a transient period of blindness early in life, and in matched participants with typical visual development. We show that the encoding of low-level visual properties is impaired in EVC in cataract-reversal participants, while the categorical response in the VOTC is preserved. When altering the visual properties of our stimuli to mimic in controls the deficit of EVC response of the cataract, we observe a cascading alteration of the categorical coding from EVC to VOTC that is not observed in the cataract-reversal group. Our results show that a typical visual categorical organization develops in VOTC despite a period of visual deprivation early in life and in the presence of impaired processing in EVC. A deep neural network exposed to a visual diet that emulates the experience of our participants reproduced our brain observations within an artificial system. These findings emphasize how specific visual regions are differently affected by a period of visual deprivation early in life, with information encoded in EVC being permanently affected, while the categorical coding in VOTC shows resilience to deprivation.

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bioRxiv2024

Phonological representations of auditory and visual speech in the occipito-temporal cortex and beyond

Speech is a multisensory signal that can be extracted from the voice and the lips. Previous studies suggested that occipital and temporal regions encode both auditory and visual speech features but their precise location and nature remain unclear. We characterized brain activity using fMRI (in male and female) to functionally and individually define bilateral Fusiform Face Areas (FFA), the left Visual Word Form Area (VWFA), an audio-visual speech region in the left Superior Temporal Sulcus (lSTS) and control regions in bilateral Para-hippocampal Place Areas (PPA). In these regions, we performed multivariate patterns classification of corresponding phonemes (speech sounds) and visemes (lip movements). We observed that the VWFA and lSTS represent phonological information from both vision and sounds. The multisensory nature of phonological representations appeared selective to the anterior portion of VWFA, as we found viseme but not phoneme representation in adjacent FFA or even posterior VWFA, while PPA did not encode phonology in any modality. Interestingly, cross-modal decoding revealed aligned phonological representations across the senses in lSTS, but not in VWFA. A whole-brain cross-modal searchlight analysis additionally revealed aligned audio-visual phonological representations in bilateral pSTS and left somato-motor cortex overlapping with oro-facial articulators. Altogether, our results demonstrate that auditory and visual phonology are represented in the anterior VWFA, extending its functional coding beyond orthography. The geometries of auditory and visual representations do not align in the VWFA as they do in the STS and left somato-motor cortex, suggesting distinct multisensory representations across a distributed phonological network. Significance statementSpeech is a multisensory signal that can be extracted from the voice and the lips. Which brain regions encode both visual and auditory speech representations? We show that the Visual Word Form Area (VWFA) and the left Superior Temporal Sulcus (lSTS) both process phonological information from speech sounds and lip movements. However, while the lSTS aligns these representations across the senses, the VWFA does not, indicating different encoding mechanisms. These findings extend the functional role of the VWFA beyond reading. An additional whole-brain approach reveals shared representations in bilateral superior temporal cortex and left somato-motor cortex, indicating a distributed network for multisensory phonology.

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bioRxiv2021

Structural and functional network-level reorganization in the coding of auditory motion directions and sound source locations in the absence of vision

hMT+/V5 is a region in the middle occipito-temporal cortex that responds preferentially to visual motion in sighted people. In case of early visual deprivation, hMT+/V5 enhances its response to moving sounds. Whether hMT+/V5 contains information about motion directions and whether the functional enhancement observed in the blind is motion specific, or also involves sound source location, remains unsolved. Moreover, the impact of this crossmodal reorganization of hMT+/V5 on the regions typically supporting auditory motion processing, like the human Planum Temporale (hPT), remains equivocal. We used a combined functional and diffusion MRI approach and individual in-ear recordings to study the impact of early blindness on the brain networks supporting spatial hearing, in male and female humans. Whole-brain univariate analysis revealed that the anterior portion of hMT+/V5 responded to moving sounds in sighted and blind people, while the posterior portion was selective to moving sounds only in blind participants. Multivariate decoding analysis revealed that the presence of motion directions and sound positions information was higher in hMT+/V5 and lower in hPT in the blind group. While both groups showed axis-of-motion organization in hMT+/V5 and hPT, this organization was reduced in the hPT of blind people. Diffusion MRI revealed that the strength of hMT+/V5 - hPT connectivity did not differ between groups, whereas the microstructure of the connections was altered by blindness. Our results suggest that the axis-of-motion organization of hMT+/V5 does not depend on visual experience, but that blindness alters the response properties of occipito-temporal networks supporting spatial hearing in the sighted. Significance StatementSpatial hearing helps living organisms navigate their environment. This is certainly even more true in people born blind. How does blindness affect the brain network supporting auditory motion and sound source location? Our results show that the presence of motion directions and sound positions information was higher in hMT+/V5 and lower in hPT in blind relative to sighted people; and that this functional reorganization is accompanied by microstructural (but not macrostructural) alterations in their connections. These findings suggest that blindness alters crossmodal responses between connected areas that share the same computational goals.

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bioRxiv2020

The balanced act of crossmodal and intramodal plasticity for processing sound categories in early and late onset blindness

How does blindness onset impact on the organization of cortical regions coding for the deprived and the remaining senses? We show that the coding of sound categories in the occipital cortex is enhanced and more stable within and across blind individuals when compared to sighted controls, while a reverse group difference is found in the temporal cortex. Importantly, occipital and temporal regions share a more similar representational structure in blind people, suggesting an interplay between the reorganization of occipital and temporal regions following visual deprivation. We suggest that early, and to some extent late blindness, induces network-level reorganization of the neurobiology of auditory categories by concomitantly increasing/decreasing the respective computational load of occipital/temporal regions. These results highlight the interactive nature of regional brain development in case of sensory deprivation.

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bioRxiv2020

Direct structural connections between auditory and visual motion selective regions in humans

In humans, the occipital middle-temporal region (hMT+/V5) specializes in the processing of visual motion, while the Planum Temporale (hPT) specializes in auditory motion processing. It has been hypothesized that these regions might communicate directly to achieve fast and optimal exchange of multisensory motion information. In this study, we investigated for the first time in humans the existence of direct white matter connections between visual and auditory motion-selective regions using a combined functional- and diffusion-MRI approach. We found reliable evidence supporting the existence of direct white matter connections between individually and functionally defined hMT+/V5 and hPT. We show that projections between hMT+/V5 and hPT do not overlap with large white matter bundles such as the Inferior Longitudinal Fasciculus (ILF) nor the Inferior Frontal Occipital Fasciculus (IFOF). Moreover, we did not find evidence for the existence of reciprocal projections between the face fusiform area and hPT, supporting the functional specificity of hMT+/V5 - hPT connections. Finally, evidence supporting the existence of hMT+/V5 - hPT connections was corroborated in a large sample of participants (n=114) from the human connectome project. Altogether, this study provides first evidence supporting the existence of direct occipito-temporal projections between hMT+/V5 and hPT which may support the exchange of motion information between functionally specialized auditory and visual regions and that we propose to name the middle (or motion) occipito-temporal track (MOTT).

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bioRxiv2019

Similar categorical representation from sound and sight in the occipito-temporal cortex of sighted and blind

Is vision necessary for the development of the categorical organization of the Ventral Occipito-Temporal Cortex (VOTC)? We used fMRI to characterize VOTC responses to eight categories presented acoustically in sighted and early blind individuals, and visually in a separate sighted group. We observed that VOTC reliably encodes sound categories in sighted and blind people using a representational structure and connectivity partially similar to the one found in vision. Sound categories were, however, more reliably encoded in the blind than the sighted group, using a representational format closer to the one found in vision. Crucially, VOTC in blind represents the categorical membership of sounds rather than their acoustic features. Our results suggest that sounds trigger categorical responses in the VOTC of congenitally blind and sighted people that partially match the topography and functional profile of the visual response, despite qualitative nuances in the categorical organization of VOTC between modalities and groups.

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bioRxiv2018

Representation of auditory motion directions and sound source locations in the human planum temporale

The ability to compute the location and direction of sounds is a crucial perceptual skill to efficiently interact with dynamic environments. How the human brain implements spatial hearing is however poorly understood. In our study, we used fMRI to characterize the brain activity of male and female humans listening to left, right, up and down moving as well as static sounds. Whole brain univariate results contrasting moving and static sounds varying in their location revealed a robust functional preference for auditory motion in bilateral human Planum Temporale (hPT). Using independently localized hPT, we show that this region contains information about auditory motion directions and, to a lesser extent, sound source locations. Moreover, hPT showed an axis of motion organization reminiscent of the functional organization of the middle-temporal cortex (hMT+/V5) for vision. Importantly, whereas motion direction and location rely on partially shared pattern geometries in hPT, as demonstrated by successful cross-condition decoding, the responses elicited by static and moving sounds were however significantly distinct. Altogether our results demonstrate that the hPT codes for auditory motion and location but that the underlying neural computation linked to motion processing is more reliable and partially distinct from the one supporting sound source location.\n\nSIGNIFICANCE STATEMENTIn comparison to what we know about visual motion, little is known about how the brain implements spatial hearing. Our study reveals that motion directions and sound source locations can be reliably decoded in the human Planum Temporale (hPT) and that they rely on partially shared pattern geometries. Our study therefore sheds important new lights on how computing the location or direction of sounds are implemented in the human auditory cortex by showing that those two computations rely on partially shared neural codes. Furthermore, our results show that the neural representation of moving sounds in hPT follows a \"preferred axis of motion\" organization, reminiscent of the coding mechanisms typically observed in the occipital hMT+/V5 region for computing visual motion.

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bioRxiv2017

Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

The occipital cortex of early blind individuals (EB) activates during speech processing, challenging the notion of a hard-wired neurobiology of language. But, at what stage of speech processing do occipital regions participate in EB?Here we demonstrate that parieto-occipital regions in EB enhance their synchronization to acoustic fluctuations in human speech in the theta-range (corresponding to syllabic rate), irrespective of speech intelligibility. Crucially, enhanced synchronization to the intelligibility of speech was selectively observed in primary visual cortex in EB, suggesting that this region is at the interface between speech perception and comprehension. Moreover, EB showed overall enhanced functional connectivity between temporal and occipital cortices sensitive to speech intelligibility and altered directionality when compared to the sighted group. These findings suggest that the occipital cortex of the blind adopts an architecture allowing the tracking of speech material, and therefore does not fully abstract from the reorganized sensory inputs it receives.

neuroscience↗