Biology subjects

Tomassini, A.

Publications and source records attributed to Tomassini, A..

11 recordsLinked to original sources

bioRxiv2026

Neural and behavioural manifold dynamics align across interacting individuals

Coordinating actions with others is fundamental for social behaviour, requiring the nervous system to continuously adapt motor output to a partner's evolving behaviour. Yet the neural population principles supporting such coordination remain poorly understood. To address this, we investigated interpersonal coordination across two dual-EEG studies comprising 44 dyads (88 participants) engaged in either instructed finger movement synchronization or spontaneous face-to-face interaction. Combining kinematics-informed deep contrastive learning with dynamical-systems modelling, we identified low-dimensional neural manifolds. These manifolds aligned geometrically and temporally across interacting partners, mirrored their coordinated behaviour, and uncovered interpersonal alignment not captured by traditional synchrony measures. Importantly, these manifolds exhibited flexible attractor-like organization consistent with a synergistic, dynamical account of motor control, with attractor properties that were co-regulated across partners. Collectively, we propose a novel mechanism in which interpersonal coordination emerges through the intermittent updating of internally organized dynamics by a partner's movements. More broadly, our results establish movement-informed latent-space modeling as a framework for uncovering the low-dimensional population dynamics linking neural activity, neuromuscular control and interpersonal coordination.

neuroscience↗

bioRxiv2026

Evidence of predictive information compression in latent space in humans during speech listening

Speech perception requires transforming acoustic input into neural representations that support linguistic understanding, yet its underlying computational principles remain unclear. Classical efficient coding theories posit optimal compression of sensory input, whereas alternative accounts propose that neural systems preferentially encode information that supports prediction. A key open question is whether such predictive encoding operates on fixed inputs or on flexible internal representations. We instantiated three hypothesis models of speech processing: (i) optimal compression with deep autoencoders, (ii) predictive reconstruction with predictive autoencoders, and (iii) predictive information representation via latent-space prediction using contrastive learning. We compared resulting speech latent representations to electroencephalographic (EEG) activity during speech listening. Representations learned under the predictive information objective best explained neural latents. Crucially, only representations that selectively compressed predictive information predicted behavioral performance, suggesting that neural speech representations are structured to encode predictive information in latent space rather than to maximize compression or input prediction.

neuroscience↗

bioRxiv2026

Microscopic Motor Alterations in Psychosis and Chronic Cannabis Use

Background and HypothesisMotor alterations represent an important component of psychotic disorders. Chronic cannabis use, a key risk factor for psychosis, is also associated with sensorimotor dysfunctions. Yet, the hypothesis of a common sensorimotor disturbance remains underinvestigated. Study Design.In this study, we examined submovements, elementary units of motor output, to search for common subclinical impairments in these populations. Patients with psychosis (n = 17), heavy cannabis users (n = 21), and healthy controls (n = 17) performed a continuous visuomotor synchronization task, consisting in tracking a dot moving on a screen with a finger. Study Results.Individuals with psychosis and cannabis users exhibited less frequent and more variable submovements compared with healthy controls. Furthermore, when interacting with a pre-recorded human kinematic profile, both groups exhibited attenuated responses to the observed submovements. This alteration was found to be more pronounced in patients with psychosis. Conclusions.These findings suggest that submovement analysis may reveal subtle, shared alterations in sensorimotor integration in psychosis and chronic cannabis use, providing an objective window onto motor dysfunction not readily captured by current clinical tools.

neuroscience↗

bioRxiv2025

Alpha and beta cortico-motor synchronization shape visuomotor control on a single-trial basis

A central question in sensorimotor neuroscience is how sensory inputs are mapped onto motor outputs to enable swift and accurate responses, even in the face of unexpected environmental changes. In this study, we leverage cortico-motor phase synchronization as a window into the dynamics of sensorimotor loops and explore how it relates to online visuomotor control. We recorded brain activity using electroencephalography (EEG) while participants performed an isometric tracking task that involved transient, unpredictable visual perturbations. Our results show that synchronization between cortical activity and motor output (force) in the alpha band (8-13 Hz) is associated with faster motor responses, while beta-band synchronization (18-30 Hz) promotes more accurate control, which is in turn linked to a higher likelihood of obtaining rewards. Both effects are most pronounced immediately before perturbation onset, underscoring the predictive value of cortico-motor phase synchronization for sensorimotor performance. Single-trial analyses further reveal that deviations from the preferred cortico-motor phase relationship are associated with longer reaction times and larger errors, and these phase effects are independent of power effects. Thus, beta-band synchronization may reflect a cautious, reward-oriented control strategy, while alpha-band synchronization enables quicker, though not necessarily efficient, motor responses, indicating a complementary, more reactive control mode. These results highlight the finely tuned nature of sensorimotor control, where different aspects of sensory-to-motor transformations are governed by frequency-specific neural synchronization on a moment-to-moment basis. By linking neural dynamics to motor output, this study sheds light on the spectrotemporal organization of sensorimotor networks and their distinct contribution to goal-directed behavior.

neuroscience↗

bioRxiv2024

ASPYRE-Lung: Validation of a simple, fast, robust and novel method for multi-variant genomic analysis of actionable NSCLC variants in tissue

Genomic variant testing of tumors is a critical gateway for patients to access the full potential of personalized oncology therapeutics. Current methods such as next-generation sequencing are costly and challenging to interpret, while PCR assays are limited in the number of variants they can cover. We developed ASPYRE(R) (Allele-Specific PYrophosphorolysis REaction) technology to address the urgent need for rapid, accessible and affordable diagnostics informing actionable genomic target variants of a given cancer. The targeted ASPYRE-Lung panel for non-small cell carcinoma covers 114 variants in 11 genes (ALK, BRAF, EGFR, ERBB2, KRAS, RET, ROS1, MET & NTRK1/2/3) to robustly inform clinical management. The assay detects single nucleotide variants, insertions, deletions, and gene fusions from tissue-derived DNA and RNA simultaneously. We tested the limit of detection, specificity, analytical accuracy and analytical precision of ASPYRE-Lung using FFPE lung tissue samples from patients with non-small cell lung carcinoma, variant-negative FFPE tissue from healthy donors, and FFPE-based contrived samples with controllable variant allele fractions. The sensitivity of ASPYRE-Lung was determined to be [≤] 3% variant allele fraction for single nucleotide variants and insertions or deletions, 100 copies for fusions, and 200 copies for MET exon 14 skipping. The specificity was 100% with no false positive results. The analytical accuracy test yielded no discordant calls between ASPYRE-Lung and expected results for clinical samples (via orthogonal testing) or contrived samples, and results were replicable across operators, reagent lots, runs, and real-time PCR instruments with a high degree of precision. The technology is simple and fast, requiring only four reagent transfer steps using standard laboratory equipment (PCR and qPCR instruments) with analysis via a cloud-based analysis algorithm. The ASPYRE-Lung assay has the potential to be transformative in facilitating access to rapid, actionable molecular profiling of tissue for patients with non-small cell carcinoma.

cancer biology↗

bioRxiv2021

Prefrontal cortical connectivity mediates locus coeruleus noradrenergic regulation of inhibitory control in older adults

Response inhibition is a core executive function enabling adaptive behaviour in dynamic environments. Human and animal models indicate that inhibitory control and control networks are modulated by noradrenaline, arising from the locus coeruleus. The integrity (i.e., cellular density) of the locus coeruleus noradrenergic system can be estimated from magnetization transfer sensitive magnetic resonance imaging, in view of neuromelanin present in noradrenergic neurons of older adults. Noradrenergic psychopharmacological studies indicate noradrenergic modulation of prefrontal and frontostriatal stopping-circuits in association with behavioural change. Here we test the noradrenergic hypothesis of inhibitory control, in healthy adults. We predicted that locus coeruleus integrity is associated with age-adjusted variance in response inhibition, mediated by changes in connectivity between frontal inhibitory control regions. In a preregistered analysis, we used magnetization transfer MRI images from N=63 healthy adults aged above 50 years who performed a stop-signal task, with atlas-based measurement of locus coeruleus contrast. We confirm that better response inhibition is correlated with locus coeruleus integrity and stronger connectivity between pre-supplementary motor area and right inferior frontal gyrus, but not volumes of the cortical regions. We confirmed a significant role of prefrontal connectivity in mediating the effect of individual differences in the locus coeruleus on behaviour, whereby this effect was moderated by age, over and above adjustment for the mean effects of age. Our results support the hypothesis that in normal populations, as in clinical settings, the locus coeruleus noradrenergic system regulates inhibitory control.

neuroscience↗

bioRxiv2021

Interpersonal synchronization of movement intermittency

Most animal species group together and coordinate their behavior in quite sophisticated manners for mating, hunting or defense purposes. In humans, coordination at a macroscopic level (the pacing of movements) is evident both in daily life (e.g., walking) and skilled (e.g., music and dance) behaviors. By examining the fine structure of movement, we here show that interpersonal coordination is established also at a microscopic - sub-movement - level. Natural movements appear as marked by recurrent (2-3 Hz) speed breaks, i.e., submovements, that are traditionally considered the result of intermittency in (visuo)motor control. In a series of interpersonal motor coordination tasks, we demonstrate that submovements are not independent between interacting partners but produced in a tight temporal relation that reflects the directionality in the partners informational coupling. These findings unveil a potential core mechanism for behavioral coordination that is based on between-persons synchronization of the intrinsic dynamics of action-perception cycles.

neuroscience↗

bioRxiv2020

Cortico-motor control dynamics orchestrates visual sampling

Movements overtly sample sensory information, making sensory analysis an active-sensing process. In this study, we show that visual information sampling is not just locked to the (overt) movement dynamics, but it is structured by the internal (covert) dynamics of cortico-motor control. We asked human participants to perform an isometric motor task - based on proprioceptive feedback - while detecting unrelated near-threshold visual stimuli. The motor output (Force) shows zero-lag coherence with brain activity (recorded via electroencephalography) in the beta-band, as previously reported. In contrast, cortical rhythms in the alpha-band systematically forerun the motor output by 200ms. Importantly, visual detection is facilitated when cortico-motor alpha (not beta) synchronization is enhanced immediately before stimulus onset, namely at the optimal phase relationship for sensorimotor communication. These findings demonstrate an automatic gating of visual inputs by the ongoing motor control processes, providing evidence of an internal and alpha-cycling visuomotor loop.

neuroscience↗

bioRxiv2019

On the evolution of neural decisions from uncertain visual input to uncertain actions

Behavior can be conceived as the result of a sequence in which the outcomes of perceptual decisions inform decisions on which action to take. However, the relationship between these processes, and spatiotemporal dynamics of the visual-to-motor transformation remains unclear. Here, we combined accumulation-to-threshold models and electro-magnetoencephalography, to trace neural correlates of sensorimotor decisions in space, time and frequency. We challenge the assumption of sequential decisions, with evidence that visuomotor processing unfolds through a continuous flow of information from sensory to motor regions. Action selection is initiated before regional visual decisions are completed. By linking behavior and physiology through theoretical decision models, we identify simultaneous forward and backward flow of information for visuomotor decisions between sensory and motor regions, in beta and gamma ranges. The model of integrated visuomotor decisions provides a powerful approach to investigate behavioral disorders that impair the ability to use sensory inputs to guide appropriate actions.

neuroscience↗

bioRxiv2019

Cortical tracking of speech reveals top-down reconstructive processes

Cortical entrainment to the (quasi-) rhythmic components of speech seems to play an important role in speech comprehension. It has been suggested that neural entrainment may reflect top-down temporal predictions of sensory signals. Key properties of a predictive model are its anticipatory nature and its ability to reconstruct missing information. Here we put both these two properties to experimental test. We acoustically presented sentences and measured cortical entrainment to both acoustic speech envelope and lips kinematics acquired from the speaker but not visible to the participants. We then analyzed speech-brain and lips-brain coherence at multiple negative and positive lags. Besides the well-known cortical entrainment to the acoustic speech envelope, we found significant entrainment in the delta range to the (latent) lips kinematics. Most interestingly, the two entrainment phenomena were temporally dissociated. While entrainment to the acoustic speech peaked around +0.3 s lag (i.e., when EEG followed speech by 0.3 s), entrainment to the lips was significantly anticipated and peaked around 0-0.1 s lag (i.e., when EEG was virtually synchronous to the putative lips movement). Our results demonstrate that neural entrainment during speech listening involves the anticipatory reconstruction of missing information related to lips movement production, indicating its fundamentally predictive nature and thus supporting analysis by synthesis models.

neuroscience↗

bioRxiv2017

Accumulation of sensory evidence is impaired in Parkinson’s disease with visual hallucinations

Models of hallucinations across disorders emphasise an imbalance between sensory input and top-down influences over perception. However, the psychological and mechanistic correlates of this imbalance remain underspecified. Visual hallucinations in Parkinsons disease (PD) are associated with impairments in lower level visual processes and attention, accompanied by over activity and connectivity in higher-order association brain networks. PD therefore provides an attractive framework to explore the relative contributions of bottom-up versus top-down disturbances in hallucinations. Here, we characterised sensory processing in PD patients with and without visual hallucinations, and in healthy controls, by fitting a hierarchical drift diffusion model (hDDM) to an attentional task. The hDDM uses Bayesian estimates to decompose reaction time and response output into parameters reflecting drift rates of evidence accumulation, decision thresholds and non-decision time. We observed slower drift rates in PD patients with hallucinations, which were insensitive to changes in task demand. In contrast, wider decision boundaries and shorter non-decision times relative to controls were found in PD regardless of hallucinator status. Inefficient and less flexible sensory evidence accumulation emerge as unique features of PD hallucinators. We integrate these results with current models of hallucinations, suggesting that slow and inefficient sensory input in PD is less informative, and may therefore be down-weighted leading to an over reliance on top-down influences. Our findings provide a novel computational framework to better specify the impairments in dynamic sensory processing that are a risk factor for visual hallucinations.

neuroscience↗