Biology subjects

Tieri, G.

Publications and source records attributed to Tieri, G..

5 recordsLinked to original sources

bioRxiv2024

Taking the perspective of an embodied avatar modulates the temporal dynamics of vicarious pain and pleasure: a combined Immersive Virtual Reality and EEG study

Observing negative and positive valence virtual stimuli can influence the onlookers subjective and brain reactivity. However, the relationship between vicarious pain and pleasure, observers perspective taking and cerebral activity remains underexplored. To address this gap, we asked 24 healthy participants to passively observe pleasant, painful, and neutral stimuli delivered to a virtual hand seen from a first-person (1PP) or third-person perspective (3PP) while undergoing time and time-frequency EEG recording. Participants reported a stronger sense of ownership over the virtual hand seen from a 1PP, rated pain and touch valence appropriately, and more intense than the neutral ones. Distinct EEG patterns emerged across early (N2, early posterior negativity, EPN), late (late positive potential, LPP) event-related potentials, and EEG power. The N2 and EPN components showed greater amplitudes for pain and pleasure than neutral stimuli, particularly in 1PP. The LPP component exhibited lower amplitudes for pleasure than pain and neutral stimuli. Further, theta-band power increased, and alpha power decreased for pain and pleasure stimuli viewed from a 1PP versus a 3PP perspective. In the ultra-late time window, we observed decreased theta, alpha, and beta-band power specifically associated with pleasure stimuli. Our study provides novel evidence that perspective-taking modulates the temporal dynamics of vicarious pain and pleasure.

neuroscience↗

bioRxiv2022

Selective influence of dopamine on electrocortical signatures of error monitoring: a combined EEG and immersive virtual reality study in Parkinson's disease

Detecting errors in ones own and others actions is likely linked to the discrepancy between intended or expected and produced or observed output. To detect and process the occurrence of salient events seems associated to the release of dopamine, the balance of which is profoundly altered in Parkinsons disease (PD). EEG studies in healthy participants indicate that the occurrence of errors in observed actions triggers a variety of electrocortical indices (like mid-frontal theta activity, error-related delta and the Error Positivity, oPe), that seem to map different aspects of error detection and performance monitoring. Whether these indices are differently modulated by dopamine in the same individual has never been investigated. To explore this issue, we recorded EEG markers of error detection by asking healthy controls (HCs) and PD patients to observe ecological reach-to-grasp a glass actions performed by a virtual arm seen in first person perspective. PD patients were tested under their dopaminergic medication ( on-condition), and after dopaminergic withdrawal ( off-condition). HCs showed a clear oPe and an increase of delta and theta power during the observation of erroneous vs. correct actions. In PD patients, oPe and delta responses were always preserved. Crucially, however, an error-related increase of theta power was found in on but not in off state PD patients. Thus, different EEG error signatures may index the activity of independent systems and error related theta power is selectively modulated by dopamine depletion. Our findings may pave the way to the discovery of dopamine-related biomarkers of higher-order motor cognition dysfunctions that may have crucial theoretical and clinical implications. Significance StatementDopaminergic neurons respond to salient events during performance monitoring. Yet, the impact of dopamine depletion on the human reactivity to observed errors is still unclear. We recorded EEG in patients with Parkinsons Disease (PD) under dopaminergic treatment ( on-condition) and medication withdrawal ( off-condition) while they observed correct and erroneous goal-related actions performed by a virtual limb. Analysis of Error Positivity (oPe) and theta and delta power increase, markers of physiological error-monitoring, indicates that while the formers were intact, the latter was preserved in the on and altered in the off condition. Thus, different EEG markers of error monitoring likely rely on independent circuits. Moreover, mid-frontal theta activity alterations may represent a marker of dopamine-related neurophysiological impairments of higher-order cognition.

neuroscience↗

bioRxiv2021

Midfrontal theta tACS facilitates motor coordination in dyadic human-avatar motor interactions

Synchronous interpersonal motor interactions require moment-to-moment predictions and proactive monitoring of the partners actions. Neurophysiologically, this is highlighted by an enhancement of midfrontal theta activity. In the present study we explored the causal role of midfrontal theta for interpersonal motor interactions employing transcranial alternating current stimulation (tACS). We implemented a realistic human-avatar interaction task in immersive virtual reality (IVR) where participants controlled a virtual arm and hand to press a button synchronously with a virtual partner. Participants completed the task while receiving theta (Experiment 1) or beta (control frequency, Experiment 2) EEG-informed tACS over the frontal midline, as well as sham stimulation as a control. Results showed that frontal theta tACS significantly improved behavioural performance (by reducing interpersonal asynchrony) and participants motor strategies (by increasing movement times and reducing reaction times), while beta tACS had no effect on these measures. These results suggest that theta tACS over frontal areas facilitates action monitoring and motor abilities supporting interpersonal interactions.

neuroscience↗

bioRxiv2021

The monitoring system is attuned to others' actions during dyadic motor interactions

Successful interpersonal motor interactions necessitate the simultaneous monitoring of our own and our partners actions. To characterize the dynamics of the action monitoring system for tracking self and other behaviors during dyadic synchronous interactions, we combined EEG recordings and immersive Virtual Reality in two tasks where participants were asked to coordinate their actions with those of a Virtual Partner (VP). The two tasks differed in the features to be monitored: the Goal task required participants to predict and monitor the VPs reaching goal; the Spatial task required participants to predict and monitor the VPs reaching trajectory. In both tasks, the VP performed unexpected movement corrections to which the participant needed to adapt. By comparing the neural activity locked to the detection of unexpected changes in the VP action (other-monitoring) or to the participants action-replanning (self-monitoring), we show that during interpersonal interactions the monitoring system is more attuned to others than to ones own actions. Additionally, distinctive neural responses to VPs unexpected goals and trajectory corrections were found: goal corrections were reflected both in early fronto-central and later posterior neural responses while trajectory deviations from the expected movement were reflected only in later and posterior responses. Since these responses were locked to the partners behavior and not to ones own, our results indicate that during interpersonal interactions the action monitoring system is dedicated to evaluating the partners movements. Hence, our results reveal an eminently social role of the monitoring system during motor interactions. Significance StatementNon-verbal synchronous interpersonal interactions require the monitoring of both our actions and those of our partners. Understanding the neural underpinnings of this ability with a focus on the dynamics between self- and other-monitoring is fundamental to the comprehension of social coordination. By combining EEG and immersive Virtual Reality we demonstrate that the monitoring system is more attuned to others actions than to our own. In two tasks, we show that the neural activity associated with unexpected corrections in the goal or the trajectory of an action are locked to the partners actions rather than to the participants subsequent adaptation. This pattern of results highlights a social mode adopted by the monitoring system to handle motor interactions.

neuroscience↗

bioRxiv2018

Frontal and occipito-temporal Theta activity as marker of error monitoring in Human-Avatar joint performance.

Discrepancies between sensory predictions and action outcome are at the base of error coding. However, these phenomena have mainly been studied focusing on individual performance. Here, we explored prediction errors during a human-avatar motor interaction and focused on both the classical frontal error-related brain responses and the activity of the action observation network. Our motor interaction paradigm required healthy individuals to synchronize their reach-to-grasp movements with those of a virtual partner in conditions that did (Interactive) or did not require (Cued) movement prediction and adaptation to the partners actions. Crucially, in 30% of the trials the virtual partner suddenly and unpredictably changed its movement trajectory thereby violating the human participants expectation. These changes elicited error-related neuromarkers (ERN/Pe - Theta/Alpha modulations) over fronto-central electrodes mainly during the Interactive condition. Source localization and connectivity analyses showed that the frontal Theta activity induced by violations of the expected interactive movements was in phase with occipito-temporal Theta activity. These results expand current knowledge about the neural correlates of on-line motor interactions linking the frontal error-monitoring system to visual, body motion-related, responses.

neuroscience↗