Biology subjects

Balestrieri, E.

Publications and source records attributed to Balestrieri, E..

10 recordsLinked to original sources

bioRxiv2025

Neural Oscillations Coordinate Continuous Error Correction During Force Control

Effective motor control depends on the brains ability to monitor performance and make continuous corrections. While many studies focus on discrete errors, everyday actions often require ongoing feedback-based adjustments. Here, we used an isometric force control task with EEG to investigate the neural dynamics supporting real-time error correction. Participants maintained a constant grip force with or without continuous visual feedback. With feedback, behavior showed [~]6 Hz rhythmic fluctuations, consistent with active correction. These fluctuations were mirrored in EEG activity across theta, beta, and alpha bands--oscillations linked to performance monitoring, updating, and attentional control. Without feedback, performance decayed linearly, and the corresponding neural signatures were reduced. These findings suggest that continuous sensory feedback engages a dynamic feedback loop involving distinct neural processes that support adaptive behavior. Our results highlight the importance of oscillatory activity in tracking and correcting moment-to-moment fluctuations in force, offering insight into the neural basis of feedback-loop force control.

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bioRxiv2025

Respiration as a dynamic modulator of sensory sampling

Respiration dynamically modulates sensory perception by orchestrating transient states of the brain and the body. Using simultaneous recordings of high-density magneto-encephalography (MEG), respiration, and pupillometry, we show that human perceptual sensitivity to near-threshold visual stimuli was enhanced during inspiration, coinciding with respiration-modulated increases in arousal neuromodulation and cortical excitability. Participants adapted their breathing patterns to align with predictable stimulus onset, and this adaptive respiratory control correlated with improved performance. We further reveal that respiration-modulated changes in alpha and beta oscillations reflect distinct shifts in sensory and motor excitability, respectively. Crucially, respiration-resolved multivariate Granger causality analyses demonstrate that the breathing rhythm systematically shapes directed information flow within a widespread interoceptive network. This respiration-brain coupling was flexibly adjusted based on stimulus predictability, highlighting a novel mechanism for active sensing which integrates internal bodily rhythms with external sensory demands to optimize perception.

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bioRxiv2024

Neurophysiological correlates of cortical hierarchy across the lifespan

The brain processes information along a hierarchical structure, forming a gradient of cortical hierarchy from sensorimotor areas to transmodal areas. Here, we aim to understand which aspects of neural dynamics characterize this gradient and whether the respective spatial distribution varies across the lifespan. Therefore, we extracted neurophysiological features from magnetoencephalography recordings in 350 participants between 18 and 88 years during rest. Among traditional features related to the power spectrum, delta power (1-4 Hz) showed the most robust association with cortical hierarchy, increasing along this axis. Beyond traditional features, we employed comprehensive time-series characterization and identified a novel hierarchy-sensitive feature capturing the variability of the signals mean over time. This feature increases along the cortical hierarchy, suggesting that higher-level brain areas exhibit more dynamic and context-dependent activity patterns. Furthermore, we highlight changes in the gradient of brain dynamics across the lifespan. Alpha power distribution, for instance, exhibits a posterior-anterior gradient in young adults that becomes less pronounced with increasing age. Further, the change of the autocorrelation and auto mutual information function along the cortical hierarchy is heavily modulated by age. These findings reveal simple but robust neurophysiological markers of cortical hierarchy and highlight the dynamic nature of the brains organization throughout life.

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bioRxiv2024

Extensive MEG time-series phenotyping unveils neural markers predictive of age

Understanding the evolving dynamics of the brain throughout life is pivotal for anticipating and evaluating individual health. While previous research has described age effects on spectral properties of neural signals, it remains unclear which ones are most indicative of age-related processes. This study addresses this gap by analyzing resting-state data obtained from magnetoencephalography in 350 adults (18-88 years). We employed advanced time-series analysis at the brain region level and machine learning to predict age. While traditional spectral features achieved low to moderate accuracy, over a hundred novel time-series features proved superior. Notably, temporal autocorrelation emerged as the most robust predictor of age. Distinct patterns of autocorrelation within the visual and temporal cortex were most informative, offering a versatile measure of age-related signal changes for comprehensive health assessments based on brain activity.

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bioRxiv2024

Beyond oscillations - A novel feature space for characterizing brain states

Our moment-to-moment conscious experience is paced by transitions between states, each one corresponding to a change in the electromagnetic brain activity. One consolidated analytical choice is to characterize these changes in the frequency domain, such that the transition from one state to the other corresponds to a difference in the strength of oscillatory power, often in pre-defined, theory-driven frequency bands of interest. Today, the huge leap in available computational power allows us to explore new ways to characterize electromagnetic brain activity and its changes. Here we leveraged an innovative set of features on an MEG dataset with 29 human participants, to test how these features described some of those state transitions known to elicit prominent changes in the frequency spectrum, such as eyes-closed vs eyes-open resting-state or the occurrence of visual stimulation. We then compared the informativeness of multiple sets of features by submitting them to a multivariate classifier (SVM). We found that the new features outperformed traditional ones in generalizing states classification across participants. Moreover, some of these new features yielded systematically better decoding accuracy than the power in canonical frequency bands that has been often considered a landmark in defining these state changes. Critically, we replicated these findings, after pre-registration, in an independent EEG dataset (N=210). In conclusion, the present work highlights the importance of a full characterization of the state changes in the electromagnetic brain activity, which takes into account also other dimensions of the signal on top of its description in theory-driven frequency bands of interest.

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bioRxiv2022

Alpha-band lateralization and microsaccades elicited by exogenous cues do not track attentional orienting

We explore the world by constantly shifting our focus of attention towards salient stimuli, and then disengaging from them in search of new ones. The alpha rhythm (8-13 Hz) has been suggested as a pivotal neural substrate of these attentional shifts, due to its local synchronization and desynchronization that suppresses irrelevant cortical areas and facilitates relevant areas, a phenomenon called alpha lateralization. Whether alpha lateralization tracks the focus of attention from orienting toward a salient stimulus to disengaging from it is still an open question. In this study, we addressed this question by leveraging the well-established phenomenon of Inhibition of Return (IOR), consisting of an initial facilitation in response times (RTs) for target stimuli appearing at an exogenously cued location, followed by a suppression of that location. Our behavioral data showed a typical IOR effect with both early facilitation and subsequent inhibition. By contrast, alpha was lateralized only in the cued direction, but never re-lateralized in a manner compatible with the behavioral inhibition effect. Importantly, also the initial lateralization towards the cue ocurred too late to account for the behavioral facilitation effect. Furthermore, we analyzed the interaction between alpha lateralization and microsaccades: at the same time when alpha was lateralized towards the cued location, microsaccades were mostly oriented away from the cued location. Crucially, the two phenomena showed a significant positive correlation. These results indicate that alpha lateralization reflects primarily the processing of salient stimuli, challenging the view that alpha lateralization is directly involved in exogenous attentional orienting per se. We discuss the relevance of the present findings for an oculomotor account of alpha lateralization as a modulator of cortical excitability in preparation of a saccade.

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bioRxiv2022

Distinct cortical networks subserve spatio-temporal sampling in vision through different oscillatory rhythms

Although visual input arrives continuously, sensory information is segmented into discrete events. Here, the neural correlates of spatiotemporal binding in male/female human subjects were investigated with MEG using two tasks where separate flashes were presented on each trial but were perceived, in a bi-stable way, as either a single, or two separate, events. The first task (two-flash fusion: TFF) involved judging one versus two flashes while in the second task (apparent motion: AM) participants judged coherent motion versus two stationary flashes. Results indicate two different functional networks underlying two unique aspects of visual temporal binding. In the TFF task, involving an integration window of {approx}50 ms, evoked responses differed as a function of perceptual interpretation by {approx}25 ms after stimuli presentation. Multivariate decoding of subjective perception based on prestimulus oscillatory phase was significant for alpha-band activity in the right medial temporal (MT) area, with the strength of pre-stimulus connectivity between early visual areas and MT being predictive of performance. In contrast, the longer integration window ({approx}130 ms) for AM showed evoked field differences only {approx}250 ms after stimuli onset. Phase decoding of the perceptual outcome in the AM task was strongest for theta-band activity, localized to a right intra-parietal sulcus (IPS) source. Pre-stimulus connectivity between MT and IPS seeds in the theta band best predicted perceptual outcome. Overall, these results show a strong relationship between specific spatiotemporal binding windows and specific oscillations, linked to the information flow between different areas of the "where" and "when" visual processing pathways. Significance StatementMultiple neural rhythms seem relevant for sampling visual information across space and time, but the cortical networks underlying these fundamental computational principles of the visual system remain unexplored. We filled this gap by employing source-level multivariate decoding and connectivity analyses of magnetoencephalographic data recorded during an integration/segregation task of temporal and spatio-temporal events. We identified a first and faster network involving early visual areas (V2 to MT/V5) that determines the basic temporal resolution of visual perception at the speed of the alpha rhythm, and a second slower network involving parietal regions (IPS) that had a key role in the integration of more complex spatiotemporal events at a theta speed. These findings elucidate the neural mechanisms that transfer sensory information into temporal sequences.

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bioRxiv2021

Spontaneous alpha-band oscillations bias subjective contrast perception

Perceptual decisions depend both on the features of the incoming stimulus and on the ongoing brain activity at the moment the stimulus is received. Specifically, trial-to-trial fluctuations in cortical excitability have been linked to fluctuations in the amplitude of pre-stimulus alpha oscillations ({approx}8-13 Hz), which are in turn are associated with fluctuations in subjects tendency to report the detection of a stimulus. It is currently unknown whether alpha oscillations bias post-perceptual decision making, or even bias subjective perception itself. To answer this question, we used a contrast discrimination task in which subjects reported which of two gratings - one in each hemifield - was perceived as having a stronger contrast. Our EEG analysis showed that subjective contrast was reduced for the stimulus in the hemifield represented in the hemisphere with relatively stronger pre-stimulus alpha amplitude, reflecting reduced cortical excitability. Furthermore, the strength of this spontaneous hemispheric lateralization was strongly correlated with the magnitude of individual subjects biases, suggesting that the spontaneous patterns of alpha lateralization play a role in explaining the intersubject variability in contrast perception. These results indicate that spontaneous fluctuations in cortical excitability, indicted by patterns of pre-stimulus alpha amplitude, affect perceptual decisions by altering the phenomenological perception of the visual world. Significance StatementOur moment to moment perception of the world is shaped by the features of the environment surrounding us, as much as by the constantly evolving states that characterize our brain activity. Previous research showed how the ongoing electrical activity of the brain can influence whether a stimulus has accessed conscious perception. However, evidence is currently missing on whether these electrical brain states can be associated to the subjective experience of a sensory input. Here we show that local changes in patterns of electrical brain activity preceding visual stimulation can bias our phenomenological perception. Importantly, we show that the strength of these variations can help explaining the great inter-individual variability in how we perceive the visual environment surrounding us.

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bioRxiv2021

Respiration aligns perception with neural excitability

Recent studies from the field of interoception have highlighted the link between bodily and neural rhythms during action, perception, and cognition. The mechanisms underlying functional body-brain coupling, however, are poorly understood, as are the ways in which they modulate behaviour. We acquired respiration and human magnetoencephalography (MEG) data from a near-threshold spatial detection task to investigate the trivariate relationship between respiration, neural excitability, and performance. Respiration was found to significantly modulate perceptual sensitivity as well as posterior alpha power (8 - 13 Hz), a well-established proxy of cortical excitability. In turn, alpha suppression prior to detected vs undetected targets underscored the behavioural benefits of heightened excitability. Notably, respiration-locked excitability changes were maximised at a respiration phase lag of around - 30{degrees} and thus temporally preceded performance changes. In line with interoceptive inference accounts, these results suggest that respiration actively aligns sampling of sensory information with transient cycles of heightened excitability to facilitate performance.

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bioRxiv2019

Shared resources between visual attention and visual working memory are allocated through rhythmic sampling

Attention and Visual Working Memory (VWM) are among the most theoretically detailed and empirically tested constructs in human cognition. Nevertheless, the nature of the interrelation between selective attention and VWM still presents a fundamental controversy: do they rely on the same cognitive resources or not? The present study aims at disentangling this issue by capitalizing on recent evidence showing that attention is a rhythmic phenomenon, oscillating over short time windows. Using a dual-task approach, we combined a classic VWM task with a detection task in which we densely sampled detection performance during the time between the memory and the test array. Our results show that an increment in VWM load was related to a worse detection of near threshold visual stimuli and, importantly, to the presence of an oscillatory pattern in detection performance at [~]5 Hz. Furthermore, our findings suggest that the frequency of this sampling rhythm changes according to the strategic allocation of attentional resources to either the VWM or the detection task. This pattern of results is consistent with a central sampling attentional rhythm which allocates shared attentional resources both to the flow of external visual stimulation and also to the internal maintenance of visual information.

neuroscience↗