Biology subjects

Gazzola, V.

Publications and source records attributed to Gazzola, V..

At least 19 recordsLinked to original sources

bioRxiv2026

Modeling behavior to disentangle motion-related effects in functional ultrasound imaging in awake, head-fixed mice

Functional ultrasound imaging (fUSI) enables brain-wide mapping of hemodynamic activity in awake rodents, offering a powerful bridge between systems neuroscience in animals and human neuroimaging. However, extending fUSI beyond tightly controlled sensory paradigms to more naturalistic behaviors is limited by motion-related confounds arising from locomotion, physiological arousal, and movement-linked neural activity. Here, we introduce a behavior-informed modeling framework that explicitly incorporates continuous measurements of running speed and head motion into a general linear model to account for motion-related variance while preserving interpretable task-related signals. We validate this approach in two head-fixed paradigms with distinct motion profiles: a visual stimulation task with minimal stimulus-driven movement, and a noxious stimulation task in which locomotion and arousal are intrinsic to the behavioral response. In both cases, explicit behavioral modeling recovers neural response patterns that more closely resemble low-motion reference conditions than blind, model-free denoising approaches. Critically, during noxious stimulation, behavior-informed modeling preserves shock-intensity-dependent activity in the primary somatosensory cortex that is attenuated by global component removal. These findings demonstrate that explicit modeling of behavior enables reliable interpretation of brain-wide fUSI signals during naturalistic, high-motion conditions, opening the door to studying affective and cognitive processes that were previously difficult to access with functional ultrasound imaging.

neuroscience↗

bioRxiv2026

Dissociable Effects of Early and Adolescent Adversity on Emotional Contagion

BackgroundEarly-life adversity can alter emotional and social development and increase vulnerability to later life stress. We investigated how early adverse experiences (EAE) and later adverse experiences (LAE) shape adult emotional contagion (EC) responses in female and male rats. MethodsEAE was induced using the limited bedding and nesting model during the first postnatal week. LAE was induced via footshocks during adolescence. In adulthood, male and female rats underwent an EC test in which observers witnessed a conspecific receiving footshocks. ResultsAdolescence-footshock exposed observers showed cingulate cortex-associated increased immobility, proximity, and attention toward distressed conspecifics during adulthood, compared to adult-exposed and sham animals, both in male and female animals. While EAE did alter maternal care, pup stress physiology, and pup weight, we found evidence that it did not alter immobility during EC. However, female demonstrators paired with EAE observers showed increased immobility, linked to a reduced rate and lower frequency of the observers 50-kHz vocalizations. Mediation analysis revealed that a shift toward lower-frequency 50-kHz vocalizations specifically mediated this effect, suggesting a sex-specific pathway by which early adversity shapes social behavior. ConclusionsEarly and adolescent adversity influenced distinct aspects of emotional contagion: EAE mediated an observer-to-demonstrator emotional transfer during EC, while LAE impacted a demonstrator-to-observer transfer, with no evidence of additive effects. Our results highlight developmentally specific and sex-dependent mechanisms by which early and later adversity alter social-affective responses in adulthood.

neuroscience↗

bioRxiv2026

The Intermediate Hippocampus Integrates Shock-Observation and Spatial Information during Observational Fear Memory

Learning where danger lurks by observing others requires linking another individual's distress to one's own representation of space. How the hippocampus implements this mapping is unknown. We recorded Neuropixels activity across the dorsal, intermediate and ventral hippocampus of male rats during contextual fear learning by observation, subsequent rest and recall. Observers showed increased immobility in the context where they had witnessed a conspecific receive footshocks, with substantial inter-individual variability. Pyramidal neurons were recruited by shock observation, with enriched shock-excited cells in the intermediate hippocampus. In the dorsal and intermediate hippocampus, shock-observation responses scaled with baseline place-field firing, revealing a gain-like conjunctive code between observed distress and observer's position. Following learning, shock-context spatial representations were selectively stabilized in the intermediate hippocampus, and post-learning sharp-wave ripples preferentially reactivated shock-context ensembles, especially in animals expressing contextual freezing. These findings identify candidate hippocampal mechanisms by which socially acquired threat information are mapped onto the observer's spatial representation and consolidated into memory.

neuroscience↗

bioRxiv2025

Heightened Play following Play Observation in the Absence of 22KHz Calls in Juvenile Rats

Emotional contagion, the process leading to emotional state matching between individuals is considered a cornerstone for the proper functioning of social groups, via its contribution to group coordination and cohesion, the ability to learn from others and engage in prosocial behaviors. However, to date, most studies of emotional contagion investigate the transfer of negative emotional states thereby bypassing the neurobiology of positive affect sharing. In this study, we aimed to leverage on the innately rewarding and salient nature of play behaviour, to investigate the potential contagiousness of positive affective states in juvenile rats. Observers that had been moderately socially deprived for varying durations first witnessed highly-playful (Play) or non-playful (Control) demonstrator rats prior to being reunited and given the opportunity to freely interact. Surprisingly, we observed the emission of negatively-valenced 22 kHz calls in a subset of sessions which was also associated with heightened play behavior of the demonstrators. We found that the reunited observers showed an increase in play behavior following observation in the Play condition compared to the Control condition, but only after short social isolation and in sessions without 22 kHz calls. In addition, an overall higher number of positively-valenced 50 kHz calls were emitted in the Play condition, again in sessions without 22 kHz emissions. Despite the limitations of the experimental procedure, our results highlight the complex nature of positive emotional sharing and provide encouraging first indications of using social play observation to study positive emotional contagion. Highlights- Social deprivation positively modulates play behavior and USV emission in reunited juvenile rats - Heightened play is associated with 22 kHz USVs following social deprivation - Heightened play was observed following play observation in the absence of 22 kHz USVs - Play observation was associated with an overall increased number of 50 kHz calls emissions - Play observation as an encouraging approach to study positive emotional contagion in rat

animal behavior and cognition↗

bioRxiv2025

Representational geometry of emotional empathy in the ventromedial prefrontal cortex and in the mid-posterior insula.

Facial expressions provide rapid and informative cues about others emotional and mental states, playing a critical role in social interactions. However, whether distinct emotional expressions reflect discrete neural processes or arise from varying combinations of underlying affective dimensions such as arousal and valence remains a subject of investigation. Crucially, these accounts need not be mutually exclusive: different brain regions may encode emotional expressions along both categorical and dimensional axes to varying degrees. To test this hypothesis, we probed different brain systems involved in emotion recognition - the ventral attentional network and the cortical limbic system centered on the ventromedial prefrontal cortex (vmPFC) - to investigate the extent to which these networks and their subregions encode emotional facial expressions in terms of (1) perceived arousal, (2) arousal+valence, or (3) six discrete emotion categories (anger, disgust, fear, happiness, pain, sadness). To this aim, we modelled the fMRI signal from perceiving movies of facial emotional expressions with ratings for either arousal, arousal+valence or emotion category using representational similarity analysis (RSA) - a method that aims at assessing which ratings model better represents how the perception of facial expressions is reflected by the fMRI parameter estimates across all the voxels within a brain region. This analysis showed that regions in the vmPFC network, including the subgenual cingulate and the medial OFC, are sensitive to ratings for distinct emotion category and for arousal+valence - significantly more so for the former - while they fail to show sensitivity for arousal ratings alone. In the ventral attentional network, the mid-posterior insula showed a similar profile, while the most posterior and ventral insular show evidence of encoding arousal+valence, but not for emotion category or arousal alone. Our findings support the idea that the vmPFC and the mid-posterior insula play a role in encoding emotion-specific and valence representations beyond general arousal processing. These results contribute to understanding how integrative brain regions support emotional empathy and social cognition.

neuroscience↗

bioRxiv2025

Ultrasound Transparent Neural Interfaces for Multimodal Interaction

Neural interfaces that unify diagnostic and therapeutic functionalities hold particular promise for advancing both fundamental neuroscience and clinical neurotechnology. Functional ultrasound imaging (fUSI) has recently emerged as a powerful modality for high-resolution, non-invasive monitoring of brain function and structure. However, conventional metal-based microelectrodes typically impede ultrasound propagation, limiting compatibility with fUSI. Here, we present flexible, ultrasound-transparent neural interfaces that retain practical metal thicknesses while achieving high acoustic transparency. We introduce a theoretical and simulation-based framework to investigate the conditions under which commonly used polymers and metals in neural interfaces can become acoustically transparent. Based on these insights, we propose design guidelines that maximize ultrasound transmission through soft neural interfaces. We experimentally validate our approach through immersion experiments and by demonstrating the acoustic transparency of a suitably engineered interface using fUSI in phantom and in vivo experiments. Finally, we discuss the potential extension of this approach to therapeutic focused ultrasound (FUS). This work establishes a foundation for the development of multimodal neural interfaces with enhanced diagnostic and therapeutic capabilities, enabling both scientific discovery and translational impact.

bioengineering↗

bioRxiv2025

Selective-plane Functional Ultrasound Neuroimaging

Functional ultrasound (fUS) is a sensitive neuroimaging technique that uses high frame rate ultrasound to monitor brain hemo-dynamics as a proxy for neural activity. Recent studies have demonstrated its potential for brain-machine interfaces (BMIs) in both primates and humans. However, current 2D fUS approaches are limited to a single brain slice, restricting the ability to decode widespread neural activity. While 3D fUS could overcome this, it demands high data throughput, increased computation, and higher temperature increases due to the requirement of a higher number of transmitted waves. To address this, we present selective-plane fUS, a method that leverages the wide field of view of row-column addressed (RCA) transducer arrays to capture activity in targeted brain regions without moving the probe. By electronically selecting imaging planes, this approach achieves higher spatio-temporal resolution with lower data and pulse repetition rate compared to 3D fUS, while preserving sensitivity to neurovascular signals. Our pipeline begins with a 3D functional activation scan to guide plane selection, followed by high frame rate focused wave (FW) imaging in coronal or sagittal slices. This method offers robust detection of visually evoked responses in rodents and reduces signal variability compared to 3D fUS. By imaging only functional regions of interest, selective-plane fUS cuts computational load by an order of magnitude, enables continuous 1000 Hz recordings, and reduces functional signal variability fivefold. We envision that this method will allow tailored continuous functional imaging of widespread neuronal activity in the human brain in a BMI context.

neuroscience↗

bioRxiv2025

Adaptive transcranial ultrasound Doppler imaging of the brain

The development of fully noninvasive, transcranial functional ultrasound (fUS) would increase the translatability and clinical potential of this neuroimaging modality. Unfortunately, transcranial fUS is hindered by skull-induced aberrations which degrade power Doppler image quality and lower sensitivity. As a result, a majority of fUS imaging studies rely on craniotomies or acoustically transparent cranial windows. To advance fUS technology further, we present an adaptive aberration correction method based on ray-tracing through 4 tissue layers (transducer lens, gel & skin, bone and brain tissue). Our method segments these layers, and estimates ultrasound wave speeds in each layer iteratively. Once a velocity model of the imaging plane of interest is retrieved, ultrafast power Doppler imaging of the brain is performed using a ray-tracing beamformer that accounts for wave refraction. We tested our method in three adult rats, and estimated wave speeds for the skin/gel layer (1628 {+/-} 7 m/s), skull bone (3247 {+/-} 110 m/s), and brain tissue (1526 {+/-} 55 m/s). After aberration correction, we measured an average adult rat skull thickness of 388 {+/-} 41 m in agreement with anatomical records. The largest improvements in Doppler imaging quality were observed in cortical brain layers adjacent to the skull, specifically lateral spatial resolution was improved by 32%. Our method consistently outperformed Doppler imaging based on traditional delay-and-sum (DAS) beamforming, which assumes a uniform sound speed.

neuroscience↗

bioRxiv2025

Acoustic pH sensor for dynamic ultrasound imaging of cellular acidification

Genetically encoded pH sensors based on fluorescent proteins enable dynamic optical imaging of cellular processes such as endocytosis and exocytosis. To date, light scattering in thick tissue as well as photobleaching of fluorescent proteins prevent deep cellular imaging over sustained periods of time. To visualize intracellular pH variations across opaque organs, we introduce a genetically encoded acoustic pH sensor dubbed pHonon. We modified the outer gas vesicle protein (GvpC) of echogenic protein nanostructures via histidine point mutations. At low pH, engineered gas vesicles exhibit an increased shell stiffness which switched their acoustic response from nonlinear to linear. By combining pHonons with nonlinear ultrasound imaging, we captured dynamic deep tissue images of lysosomal acidification by macrophages in murine liver. The combination of pHonon with nonlinear ultrasound creates the possibility for basic studies of endo- and exocytic activity in deep tissue of living opaque organisms.

bioengineering↗

bioRxiv2024

Nonlinear sound-sheet microscopy: imaging opaque organs at the capillary and cellular scale

Light-sheet fluorescence microscopy has revolutionized biology by visualizing dynamic cellular processes in three dimensions. However, light scattering in thick tissue and photobleaching of fluorescent reporters limit this method to studying thin or translucent specimens. Here we show that non-diffractive ultrasonic beams used in conjunction with a cross-amplitude modulation sequence and nonlinear acoustic reporters enable fast and volumetric imaging of targeted biological functions. We report volumetric imaging of tumor gene expression at the cm3 scale using genetically encoded gas vesicles, and localization microscopy of currently uncharted cerebral capillary networks using intravascular microbubble contrast agents. Nonlinear sound-sheet microscopy provides a [~]64x acceleration in imaging speed, [~]35x increase in imaged volume and [~]4x increase in classical imaging resolution compared to the state-of-the-art in biomolecular ultrasound.

bioengineering↗

bioRxiv2023

Endogenous opioid receptor system mediates costly altruism in the human brain

Functional neuroimaging studies suggest that a large-scale brain network transforms others pain into its vicarious representation in the observer, potentially modulating helping behaviour. The neuromolecular basis of individual differences in vicarious pain and helping, however, have remain poorly understood. Here we investigated the role of the endogenous -opioid receptor (MOR) system - known for its role in analgesia and sociability - in altruistic costly helping. MOR density was measured with high-affinity agonist radioligand [11C]carfentanil. In a separate fMRI experiment, participants could choose to donate money to reduce the pain of the confederate who was subjected to electric shocks of varying intensity. We found that subjects were in general willing to engage in costly helping, and haemodynamic activity in amydala, anterior insula, anterior cingulate cortex, striatum, primary motor cortex, primary somatosensory cortex, and thalamus increased when participants witnessed the pain of others. These haemodynamic responses were negatively associated with MORs availability in the striatolimbic and cortical emotion circuits. In turn, haemodynamic responses during helping were positively associated with MOR availability in the anterior cingulate cortex and hippocampus. Altogether these data suggest that the endogenous MOR system modulates the processing of altruistic behaviour and costly helping in the human brain.

neuroscience↗

bioRxiv2023

Neural mechanisms of costly helping in the general population and mirror-pain synesthetes

Helping others often comes with a cost to ourselves. It has been argued that experiencing the pain of others motivates helping. Here we investigate how individuals that report somatically feeling the pain of others (mirror-pain synesthetes) differ from those that do not, when deciding to help and reduce someones pain conveyed through different modalities. Mirror-pain synesthetes and participants who do not report such everyday life experiences witnessed a confederate expressing pain and could decide to reduce the intensity by donating money. Measuring brain activity using fMRI confirmed our initial hypothesis: self-reported mirror-pain synesthetes increased their donation more steeply, as the intensity of the observed pain increased, and their somatosensory brain activity (in SII and the adjacent IPL) activity was more tightly associated with donation when the pain of other was conveyed by the reactions of the pain-receiving hand. For all participants, in a condition where the pain was conveyed by facial expressions, activation in insula, SII and MCC correlated with the trial by trial donation made, while SI and MTG activation was correlated with the donation in the Hand condition. These results further inform us about the role of empathy in costly helping, the underlying neural mechanism, and individual variability.

neuroscience↗

bioRxiv2022

Predictive coding during action observation - an Electrocorticographic study

Predictive coding is a theoretical framework that has received much attention for its ability to generate testable hypotheses on how multiple brain regions integrate information during cognitive functions. Given relatively large sensorimotor delays, during social interactions, predicting the behavior of others is crucial to enable joint actions or provide competitive advantages. The action observation network (AON) has been extensively studied, but how information is integrated across its main nodes remains poorly understood. Here we leverage the high spatial and temporal resolution of intracranial Electrocorticography (ECoG), to characterize how the key nodes of the AON - including precentral, supramarginal and visual areas - exchange information. We found more top-down beta oscillation from precentral to supramarginal contacts during the observation of predictable actions while more bottom-up gamma oscillation from visual to supramarginal contacts were measured for unpredictable actions. These results, in line with predictive coding, provide critical evidence towards an understanding of how nodes of the AON integrate information to process the actions of others.

neuroscience↗

bioRxiv2022

Investigating the mechanistic role of painful self-experience in emotional contagion: an effect of auto-conditioning?

Emotional contagion refers to the transmission of emotions from one conspecific to another. Previous research in rodents has demonstrated that the self-experience of footshocks enhances how much an observer is affected by the emotional state of a conspecific in pain or distress. We hypothesized auditory auto-conditioning to contribute to this enhancement: during the observers own experience of shocks, the animal associates its own audible nocifensive responses, i.e. its pain squeaks, with the negative affective state induced by the shock. When the animal later witnesses a cage mate receive shocks and hears it squeak, the previously strengthened connection between fear and squeaks could be a mechanism eliciting the enhanced fearful response in the observer. As hypothesized, in a first study, we found pre-exposure to shocks to increase freezing and 22 kHz vocalizations associated with distress upon the playback of pain squeaks. Freezing was also increased during the playbacks of phase-scrambled squeaks, but 22 kHz calls were more frequent during the playback of regular squeaks. Core to the notion of auto-conditioning is that the effect of pre-exposure is due to the pairing of a pain-state with hearing ones own pain squeaks. In a second study, we therefore compared the response to squeak playbacks after animals had been pre-exposed to pairings of a CO2 laser with a squeak playback against three control groups that were pre-exposed to the CO2 laser alone, to squeak playbacks alone or to neither of these conditions. We however could not find any differences in freezing or 22 kHz calls among all experimental groups. In summary, we demonstrate the sufficiency of pain squeaks to trigger fear in a way that critically depends on the nature of an animals prior experience and discuss why the pairing of a CO2 laser with pain squeaks cannot substitute footshock pre-exposure.

animal behavior and cognition↗

bioRxiv2022

A multivariate brain signature for reward

The processing of rewards and losses are crucial for learning to adapt to an ever changing environment. Dysregulated reward processes are prevalent in mental health and substance use disorders. While many human brain measures related to reward have been based on activity in individual brain regions, recent studies indicate that many affective and motivational processes are encoded in distributed systems that span multiple regions. Consequently, decoding these processes using individual regions yields small effect sizes and limited reliability, whereas predictive models based on distributed patterns yield much larger effect sizes and excellent reliability. To create such a predictive model for the processes of rewards and losses, from now on termed the Brain Reward Signature (BRS), we trained a LASSO-PCR model to predict the signed magnitude of monetary rewards and losses on the Monetary Incentive Delay task (MID; N = 39) and achieved a high significant decoding performance (92% for decoding rewards versus losses). We subsequently demonstrate the generalizability of our signature on another version of the MID in a different sample (92% decoding accuracy for rewards versus losses; N = 12) and on a gambling task from a large sample (73% decoding accuracy for rewards versus losses, N = 1084) from the Human Connectome Project. Lastly, we also provided preliminary evidence for specificity to rewarding outcomes by illustrating that the signature map generates estimates that significantly differ between rewarding and negative feedback (92% decoding accuracy) but do not differ for conditions that differ in disgust rather than reward in a novel Disgust-Delay Task (N = 39). We thus created a BRS that can be used to make specific, generalizable and reproducible predictions about brain responses to rewards and losses.

neuroscience↗

bioRxiv2021

Commanding or being a simple intermediary: how does it affect moral behavior and related brain mechanisms?

History has shown that fractioning operations between several individuals along a hierarchical chain allows diffusing responsibility between components of the chain, which has the potential to disinhibit antisocial actions. Here, we present two studies, one using fMRI (Study 1) and one using EEG (Study 2), designed to help understand how commanding or being in an intermediary position impacts the sense of agency and empathy for pain. In the age of military drones, we also explored whether commanding a human or robot agent influences these measures. This was done within a single behavioral paradigm in which participants could freely decide whether or not to send painful shocks to another participant in exchange for money. In Study 1, fMRI reveals that activation in social cognition and empathy-related brain regions was equally low when witnessing a victim receive a painful shock while participants were either commander or simple intermediary transmitting an order, compared to being the agent directly delivering the shock. In Study 2, results indicated that the sense of agency did not differ between commanders and intermediary, no matter if the executing agent was a robot or a human. However, we observed that the neural response over P3 was higher when the executing agent was a robot compared to a human. Source reconstruction of the EEG signal revealed that this effect was mediated by areas including the insula and ACC. Results are discussed regarding the interplay between the sense of agency and empathy for pain for decision-making.

neuroscience↗

bioRxiv2021

Depth-resolved intersubject functional correlation of 7T BOLD signals reveals increased stimulus related information sharing across deep layers in premotor and parietal nodes for predictable actions

While the brain regions involved in action observation are relatively well documented in humans and primates, how these regions communicate to help understand and predict actions remains poorly understood. Traditional views emphasized a feed-forward architecture in which visual features are organized into increasingly complex representations that feed onto motor programs in parietal and then premotor cortices where the matching of observed actions upon the observers own motor programs contributes to action understanding. Predictive coding models place less emphasis on feed-forward connections and propose that feed-back connections from premotor regions back to parietal and visual neurons represent predictions about upcoming actions that can supersede visual inputs when actions become predictable, with visual input then merely representing prediction errors. Here we leverage the notion that feed-back connections target specific cortical layers to help adjudicate across these views. Specifically, we test whether observing sequences of hand actions in their natural order, which permits participants to predict upcoming actions, triggers more feed-back input to parietal regions than seeing the same actions in a scrambled sequence that hinders making predictions. Using submillimeter fMRI acquisition at 7T, we find that watching predictable sequences triggers more action-related activity (as measured using intersubject functional correlation) in the parietal cortical area PFt at depths receiving feed-back connections (layers III and V/VI) than watching the exact same actions in scrambled and hence unpredictable sequence. In addition, functional connectivity analysis performed using intersubject functional connectivity confirms that these increased action-related signals in PFt could originate from ventral premotor region BA44. This data showcases the utility of intersubject functional correlation in combination with 7T MRI to explore the architecture of social cognition under more naturalistic conditions, and provides evidence for models that emphasize the importance of feed-back connections in action prediction.

neuroscience↗

bioRxiv2021

Intracortical human recordings reveal intensity coding for the pain of others in the insula

Based on neuroimaging data, the insula is considered important for people to empathize with the pain of others, whether that pain is perceived through facial expressions or the sight of limbs in painful situations. Here we present the first report of intracranial electroencephalographic (iEEG) recordings from the insulae collected while 7 presurgical epilepsy patients rated the intensity of a womans painful experiences viewed in movies. In two separate conditions, pain was deduced from seeing facial expressions or a hand being slapped by a belt. We found that broadband activity in the 20-190 Hz range correlated with the trial-by-trial perceived intensity in the insula for both types of stimuli. Using microwires at the tip of a selection of the electrodes, we additionally isolated 8 insular neurons with spiking that correlated with perceived intensity. Within the insula, we found a patchwork of locations with differing selectivities within our stimulus set, some representing intensity only for facial expressions, others only for the hand being hit, and others for both. That we found some locations with intensity coding only for faces, and others only for hand across simultaneously recorded locations suggests that insular activity while witnessing the pain of others cannot be entirely reduced to a univariate salience representation. Psychophysics and the temporal properties of our signals indicate that the timing of responses encoding intensity for the sight of the hand being hit are best explained by kinematic information; the timing of those encoding intensity for facial expressions are best explained by shape information in the face. In particular, the furrowing of the eyebrows and the narrowing of the eyes of the protagonist in the movies suffice to predict both the rating of and the timing of the neuronal response to the facial expressions. Comparing the broadband activity in the iEEG signal with spiking activity and an fMRI experiment with similar stimuli revealed a consistent spatial organization for the representation of intensity from our hand stimuli, with stronger intensity representation more anteriorly and around neurons with intensity coding. In contrast, for the facial expressions, we found that the activity at the three levels of measurement do not coincide, suggesting a more disorganized representation. Together, our intracranial recordings indicate that the insula encodes, in a partially intermixed layout, both static and dynamic cues from different body parts that reflect the intensity of pain experienced by others.

neuroscience↗