Biology subjects

Bueti, D.

Publications and source records attributed to Bueti, D..

11 recordsLinked to original sources

bioRxiv2026

How sensory load shapes the neural processing and perception of visual durations

The sensory content and temporal structure of stimuli have been shown to consistently bias duration perception. Temporal intervals filled with continuous sensory input ("filled intervals"), are often perceived as lasting longer than intervals marked only by their onset and offset ("empty intervals"). Despite this robust behavioral finding, it remains unclear whether filled and empty intervals rely on similar or distinct neural mechanisms and, more generally, how sensory format shapes the neural processing of millisecond time. To address this question, we asked twenty-one healthy participants to reproduce visual durations across different stimulus configurations while high-density scalp EEG was recorded. Behavioral results revealed differences in performance across stimulus configurations. Event-related potentials (ERPs) recorded at occipito-parietal and fronto-central electrodes between 0.1 and 0.4 s after duration offset were modulated in amplitude by both stimulus duration and format. These modulations scaled with the sensory load of the stimulus and its duration, suggesting a common underlying mechanism. A Representational Similarity Analysis (RSA) of the ERP data showed that perceived time was represented more strongly than physical time particularly at occipito-parietal electrodes, but only within the 0.2-0.3 s post-offset window, where stimulus format exerted a pronounced effect on the ERP signal. These findings highlight the role of sensory processing in shaping duration perception and its neural coding, and reveal an early neural signature of perceived time in occipito-parietal electrodes. 1 Significance statementOur perception of subsecond durations is distorted by the sensory content of stimuli. Here, we investigated how stimulus configuration shapes the neural correlates of visual duration perception. Specifically, we asked whether temporal intervals filled with continuous sensory input are processed differently from those lacking such content. We found that, between 0.2 and 0.3 s after interval offset, ERP amplitudes were modulated by stimulus content, and in this same temporal window the EEG signal reflected the perceptual bias. These findings support the view that duration processing and perception are deeply rooted in sensory processing.

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bioRxiv2026

Evolution of visual time throughout goal driven action learning

Timing is intimately woven into human cognition and behaviour, underscoring peoples ability of comprehending speech, playing instruments and competing in sports. Converging evidence suggests that our perceptual experience of time is grounded in our ability to control actions: time processing leverages motor control neural machinery, and perceived time is significantly distorted in proximity of action. However, the dynamic interplay between timing and action systems remains unexplored, particularly in goal-directed contexts where action control is gradually refined through practice. Through combined behavioural, neural and modelling approaches, we investigate how time processing gradually evolves as participants gain experience in goal-driven manual reaching actions, varying in terms of action-plan specificity. Participants judged brief visual durations while preparing hand movements aimed at visual targets displayed on a monitor. Subjective time expanded in the foreperiod preceding action onset, and this effect increased over trials, mirroring gradual improvements in action readiness as motor plans became more rapidly and efficiently deployed. Representation Similarity Analysis, integrating electroencephalographic and behavioural data, reveals that actions shape timing through independent mechanisms: planning specific behaviours shapes how duration information is written into timekeeping neural circuits as stimuli unfold (encoding). Parallely, more general aspects of motor engagement and anticipation shape how duration information is read-out from timing circuits following stimulus presentation (decoding). These findings highlight a dynamic, learning-driven coupling between perceptual time and motor control, where subjective time is recalibrated as goal-directed action preparation is optimized, shaped through independent time encoding and decoding mechanisms. Significance statementDespite lacking dedicated sensory and neural systems for duration, humans reveal a highly developed sense of time, for instance when noticing subtle tempo changes in music. We show that perceptual understanding of time is linked to the ability of learning and fine-tuning action: our internal metric of time shifts as action preparation processes are gradually refined, affecting how quickly behaviours are planned and executed. This interaction is mediated by independent neural processes affecting the encoding (online monitoring) and decoding (offline readout) of duration. These findings shift our understanding of timing, from a passive sensory readout to one that is actively constructed and finetuned through action learning, and provide a mechanistic account of neural processes linking action preparation to time processing

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bioRxiv2025

Defining a functional hierarchy of millisecond time: from visual stimulus processing to duration perception

The neural processing of subsecond durations recruits a wide network of areas. Although unimodal tuning has been shown in many of these regions, its role and link to perception remain unclear. Here, we used 7T functional MRI while participants performed a visual duration discrimination task to characterize unimodal responses along the cortical hierarchy. We found topographically-organized neuronal populations tuned to all presented durations in parietal and premotor cortices, and in the caudal supplementary motor area (SMA). In contrast, rostral SMA, inferior frontal cortex, and anterior insula showed neuronal preferences centered around the mean duration, which correlated with the boundary duration participants employed in the task. These differences suggest specialized roles of duration tuning across cortical regions --from discrete to categorical and subjective duration representations. Finally, correlations of neuronal preferences across areas highlighted a hierarchical organization of duration tuning. Together, our findings provide a mechanistic framework for duration perception in vision.

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bioRxiv2024

The mechanisms and neural signature of average numerosity perception

The human brain is endowed with an intuitive sense of number allowing to perceive the approximate quantity of items in a scene, or "numerosity." This ability is not limited to items distributed in space, but also to events unfolding in time and to the average numerosity of dynamic scenes. How the brain computes and represents the average numerosity over time however remains mostly unclear. Here we investigate the mechanisms and electrophysiological (EEG) signature of average numerosity perception. To do so, we used dynamic stimuli composed of 3-12 arrays presented for 50 ms each, and asked participants to judge the average numerosity of the sequence. Our results first show that the weight of different arrays in the sequence in determining the judgement is subject to both primacy and recency effects, depending on the length of the sequence. Moreover, we show systematic perceptual adaptation effects across trials, with the bias on numerical estimates depending on both the average numerosity and length of the preceding stimulus. The EEG results show numerosity-sensitive brain responses starting very early after stimulus onset, and that activity around the offset of the sequence can predict both the accuracy and precision of judgments. Additionally, we show a neural signature of the adaptation effect at around 300 ms, whereby the amplitude of brain responses can predict the strength of the bias. Overall, our findings support the existence of a dedicated, low-level perceptual mechanism involved with the computation of average numerosity, and highlight the processing stages involved with such process.

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bioRxiv2024

Magnitude processing and integration entail perceptual processes independent from the task

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 interaction across dimensions, or "magnitude integration" effects, arise from low-level perceptual processes that are independent from the task performed, or whether they instead arise from high-level decision-making processes. We address this question with two experiments in which participants watched a series of dot-array stimuli modulated in numerosity, duration, and item size. In experiment 1 (task condition), the task required participants to either judge the numerosity, duration, or size of each stimulus. In experiment 2 (passive condition), instead, a separate group of participants passively watched the stimuli. The behavioral results obtained in the task show robust magnitude integration effects across all three dimensions. Then, we identify a neural signature of magnitude integration by showing that event-related potentials at several latency windows (starting at [~]100-200 ms after stimulus onset) can predict the effect measured behaviorally. In the passive condition, we demonstrate an almost identical modulation of brain responses, occurring at the same processing stages as during the task. Importantly, using a cross-condition multivariate decoding analysis, we demonstrate that brain responses to magnitude in the task condition can predict the response in the passive condition at specific latency windows. These results thus suggest that magnitude processing and integration likely occurs via automatic perceptual processes that are engaged irrespective of the task-relevance of the stimuli, and independently from decision making.

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bioRxiv2024

The link between space and time along the human cortical hierarchy

In humans, very few studies have directly tested the link between the neural coding of time and space. Here we combined ultra-high field functional magnetic resonance imaging with neuronal-based modeling to investigate how and where the processing and the representation of a visual stimulus duration is linked to that of its spatial location. Results show a transition in the neural response to duration: from monotonic and spatially-dependent in early visual cortex, to unimodal and spatially-invariant in frontal cortex. This transition begins in extrastriate areas V3AB, and it fully displays in the intraparietal sulcus (IPS), where both unimodal and monotonic responses are present and where neuronal populations are selective to either space, time or both. In IPS, space and time topographies show a specific relationship, although along the cortical hierarchy duration maps compared to spatial ones are smaller in size, less clustered and more variable across participants. These results help to identify the mechanisms through which humans perceive the duration of a visual object with a specific spatial location and precisely characterize the functional link between time and space processing, highlighting the importance of space-time interactions in shaping brain responses.

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bioRxiv2022

The neural signature of magnitude integration between time and numerosity

Magnitude dimensions such as time and numerosity are fundamental components of our visual experience, allowing us to understand the environment and interact with it. Different magnitudes are however not processed independently from each other, but show a relationship whereby the perception of one dimension depends on the others ("magnitude integration"). In this study, we use electroencephalography (EEG) to address whether such integration may arise from a shared brain processing stage where different dimensions are integrated together, or from independent parallel processes interfering with each other. In the experiment, participants judged either the average numerosity or duration of dynamic dot-array stimuli concurrently modulated in both dimensions. First, the behavioural results show a magnitude integration effect in both tasks, with duration affecting the judgement of numerosity and vice versa. The EEG results further show that both numerosity and duration significantly modulate event-related potentials at several distinct latencies. Crucially, however, we identified a significant interaction between numerosity and duration emerging in a specific latency window (360-460 ms) irrespective of the task performed by participants. In this latency window, the modulation of ERPs provided by the interfering magnitude dimension can be predicted by the strength of the behavioural bias. Our results thus support the idea of different magnitude dimensions converging onto a shared perceptual processing stage mediating their integration. Overall, our results demonstrate a clear electrophysiological signature of magnitude integration between numerosity and time, and provide new evidence for a shared representational system encompassing different magnitude dimensions.

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bioRxiv2022

Different modality-specific mechanisms mediate perceptual history effects in vision and audition

Perceptual history plays an important role in sensory processing and decision making, shaping how we perceive and judge external objects and events. Indeed, past stimuli can bias what we are currently seeing in an attractive fashion, making a current stimulus to appear more similar to its preceding one than it actually is. Such attractive effects across successive stimuli appear to be ubiquitous, affecting almost every aspect of perception - from very basic visual attributes (i.e., orientation) to more complex features (i.e., face identity) - suggesting that they may reflect a fundamental principle of brain processing. However, it is unclear whether the ubiquitous nature of these effects is due to an underlying centralised mechanism mediating all of them, or by the existence of separate mechanisms implemented independently in different perceptual pathways. Here we address this question by assessing the behavioural and neural signature of perceptual history in audition and vision, in the context of time perception. Our results first show a double dissociation between the two modalities, whereby the behavioural effect of perceptual history shows opposite patterns of selectivity for the features and position of the stimuli. Electroencephalography results further support a difference between audition and vision, demonstrating that the signature of perceptual history unfolds according to different dynamics in the two modalities and show different relations with the behavioural effect. Overall, our results suggest that the effect of perceptual history may be mediated by different and at least partially independent mechanisms based on the same computational principle, implemented in different sensory pathways. SIGNIFICANCE STATEMENTThe recent history of stimulation, or perceptual history, plays a fundamental role in perception, shaping what we see according to what we saw in the past. The brain mechanisms mediating the integration of past and present perceptual information are however still unclear. In this study we asked whether perceptual history operates via a centralized mechanism shared across sensory modalities, or via distinct modality-specific mechanisms. Our findings show a double dissociation in attractive perceptual history effects across vision and audition, while EEG data show neural signatures of perceptual history with distinct dynamics and properties. Overall, we thus demonstrate that perceptual history affects sensory processing starting from the earliest level of processing, within distinct modality-specific sensory pathways.

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bioRxiv2020

Subjective time is predicted by local and early visual processing

Time is as pervasive as it is elusive to study, and how the brain keeps track of millisecond time is still unclear. Here we studied the mechanisms underlying duration perception by looking for a neural signature of subjective time distortion induced by motion adaptation. We recorded electroencephalographic signals in human participants while they were asked to discriminate the duration of visual stimuli after translational motion adaptation. Our results show that distortions of subjective time can be predicted by the amplitude of the N200 event-related potential and by the activity in the Beta band frequency spectrum. Both effects were observed from occipital electrodes contralateral to the adapted stimulus. Finally, a multivariate decoding analysis highlights the impact of motion adaptation throughout the visual stream. Overall, our findings show the crucial involvement of local and low-level perceptual processes in generating a subjective sense of time.

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bioRxiv2020

Topographic Connectivity in a Duration Selective Cortico-Cerebellar Network

How does the human brain represent millisecond unit of time? A recent neuroimaging study revealed the existence in the human premotor cortex of a topographic representation of time i.e., neuronal units selectively responsive to specific durations and topographically organized on the cortical surface. By using high resolution functional Magnetic Resonance Images here, we go futher this previous work, showing duration preferences across a wide network of cortical and subcortical brain areas: from cerebellum to primary visual, parietal, premotor and prefrontal cortices. Most importantly, we identify the functional connectivity structure between these different brain areas and their duration selective neural units. The results highlight the role of the cerebellum as the network hub and that of medial premotor cortex as the final stage of duration recognition. Interstingly, when a specific duration is presented, only the communication between the units selective to that duration become particularly "active". These findings identify duration tuning and topographic connectivity as possible mechanisms underlying our capacity of telling time.

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bioRxiv2018

Chronotopic Maps in Human Medial Premotor Cortex

Time is a fundamental dimension of everyday experiences. We can unmistakably sense its passage and adjust our behavior accordingly. Despite its ubiquity, the neuronal mechanisms underlying the capacity to perceive time remains unclear. Here, in two experiments using ultra-high-field 7-Tesla functional magnetic resonance imaging, we show that in the medial premotor cortex of the human brain, neural units tuned to different durations are orderly mapped in contiguous portions of the cortical surface, so as to form chronomaps. The response of each portion in a chronomap is enhanced by preferred and neighboring durations and suppressed by non-preferred durations represented in distant portions of the map. These findings identify duration-sensitive tuning as a neural mechanism underlying the recognition of time and demonstrate for the first time that the representation of an abstract feature such as time can be instantiated by a topographical arrangement of duration-sensitive neural populations.

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