Biology subjects

Pisoni, A.

Publications and source records attributed to Pisoni, A..

6 recordsLinked to original sources

bioRxiv2025

Cortical markers of PAS-induced long-term potentiation and depression in the motor system: A TMS-EEG Registered Report

Paired associative stimulation (PAS), a neuromodulation protocol combining transcranial magnetic stimulation (TMS) pulses to the primary motor cortex (M1) with electrical median nerve stimulation, promotes synaptic plasticity (long-term potentiation - LTP, long-term depression - LTD) in the human motor system following Hebbian associative plasticity induction. To date, PAS effects have been mainly investigated at the corticospinal level. In the present Registered Report, we leveraged TMS and electroencephalography (TMS-EEG) co-registration to track the cortical dynamics related to M1-PAS, aiming to characterize the neurophysiological substrates better, grounding the effectiveness of such protocol. In two within-subject sessions, 30 healthy participants underwent the standard M1-PAS protocols inducing LTP (PASLTP) and LTD (PASLTD) while measuring motor-evoked potentials (MEPs) and TMS-evoked potentials (TEPs) from M1 stimulation before, immediately after, and 30 minutes from the end of the PAS, applied both at supra- (i.e., 110%) and sub- (i.e., 90%) resting motor threshold intensities. Besides replicating MEPs enhancement and inhibition after PASLTP and PASLTD, our results showed that the P30 and N100 M1-TEPs components were significantly modulated immediately following PASLTP and PASLTD administration. These effects were detectable only in suprathreshold conditions, suggesting that M1 subthreshold stimulation could not be optimal for tracking cortical effects of PAS. Furthermore, exploratory analyses showed that P60 amplitude at baseline successfully predicted the magnitude of P30 modulations after PASLTP administration. Our findings provide compelling evidence about the specificity of early TEP components in reflecting changes in M1 reactivity underpinning PAS effects and associative plasticity induction within the motor system. From a broader perspective, our study fosters evidence about using TMS-EEG biomarkers to track complex plastic changes induced in the human brain, exploiting neuromodulatory non-invasive brain stimulation protocols based on associative mechanisms, like PAS. Preregistered Stage 1 protocol: https://osf.io/detjc (date of in-principle acceptance: 15/01/2024) Recommended Stage 2 manuscript: https://rr.peercommunityin.org/articles/rec?id=1031

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bioRxiv2025

Frontal connectivity dynamics encode contextual information during action preparation

The context in which we perform motor acts shapes our behavior, with movement speed and accuracy modulated by contingent factors, such as the occurrence of cues that trigger or inhibit our actions. This flexibility relies on network interactions encompassing premotor and prefrontal regions, including the supplementary motor area (SMA) and the right inferior frontal gyrus (rIFG). However, the dynamic interplay between these regions during action preparation and execution based on contextual demands remains unclear. Here, we demonstrate that contextual information is encoded in SMA and rIFG interareal connectivity before action. Using Transcranial Magnetic Stimulation (TMS) and electroencephalography (EEG) during Go/No- Go tasks with varying target probabilities, we found that, during the preparatory stages of action, -band rIFG connectivity increased in contexts where motor responses were more frequently withheld. In contrast, SMA exhibited a reversed pattern only near the target onset. Finally, {beta}-band connectivity encoded proactive inhibition processes, increasing when action likelihood was low. Accordingly, during response implementation, both areas exhibited greater {beta}-band connectivity when action was withheld compared to when a motor response was required, further supporting its role in inhibitory control. Our results demonstrate that - and {beta}-band oscillatory network dynamics support context-sensitive adaptations, illustrating how premotor and prefrontal regions synergistically modulate their interactions as they transition from preparation to response. These findings advance understanding of how the brain integrates predictive information to dynamically organize motor and cognitive resources before an action unfolds, revealing that connectivity encodes critical information driving behavior. Significance statementAdaptive behavior relies on the brains ability to anticipate and adjust actions based on contextual cues. Using Transcranial Magnetic Stimulation and electroencephalography (TMS-EEG), we show that the supplementary motor area (SMA) and the right inferior frontal gyrus (IFG) dynamically modulate their functional connectivity based on target predictability during action preparation and initiation. We reveal distinct oscillatory mechanisms by which SMA enhances motor readiness and IFG supports inhibitory control before action execution. These findings provide new insights into how frontal networks integrate probabilistic information to optimize action outputs in predictable contexts, with implications for disorders involving deficits in motor planning and control.

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bioRxiv2024

M1 Large-scale Network Dynamics Support Human Motor Resonance and Its Plastic Reshaping

Motor resonance - the activation of the observers motor system when viewing others actions - grounds the intertwined nature of action perception and execution, with profound implications for social cognition and action understanding. Despite extensive research, the neural underpinnings supporting motor resonance emergence and rewriting remain unexplored. In this study, we investigated the role of sensorimotor associative learning in motor resonance neural mechanisms. To this aim, we applied cross-systems paired associative stimulation (PAS) to induce novel visuomotor associations in the human brain. This protocol, which repeatedly pairs transcranial magnetic stimulation (TMS) pulses over the primary motor cortex (M1) with visual stimuli of actions, drives the emergence of an atypical, PAS-conditioned motor resonance response. Using TMS and electroencephalography (EEG) co-registration during action observation, we tracked the M1 functional connectivity profile during this process to map the inter-areal connectivity profiles associated with typical and PAS-induced motor resonance phenomena. Besides confirming, at the corticospinal level, the emergence of newly acquired motor resonance responses at the cost of typical ones after PAS administration, our results reveal dissociable aspects of motor resonance in M1 interregional communication. On the one side, typical motor resonance effects acquired through the lifespan are associated with prominent M1 alpha-band and reduced beta-band connectivity, which might facilitate the corticospinal output while integrating visuomotor information. Conversely, the atypical PAS-induced motor resonance is linked to M1 beta-band cortical connectivity modulations, only partially overlapping with interregional communication patterns related to the typical mirroring responses. This evidence suggests that beta-phase synchronization may be the critical mechanism supporting the formation of motor resonance by coordinating the activity of motor regions during action observation, which also involves alpha-band top-down control of frontal areas. These findings provide new insights into the neural dynamics underlying (typical and newly acquired) motor resonance, highlighting the role of large-scale interregional communication in sensorimotor associative learning within the action observation network.

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bioRxiv2023

State-dependent effectiveness of cathodal transcranial direct current stimulation on cortical excitability

The extensive use of transcranial direct current stimulation (tDCS) in experimental and clinical settings does not correspond to an in-depth understanding of its underlying neurophysiological mechanisms. In previous studies, we employed an integrated system of Transcranial Magnetic Stimulation and Electroencephalography (TMS-EEG) to track the effect of tDCS on cortical excitability. At rest, anodal tDCS (a-tDCS) over the right Posterior Parietal Cortex (rPPC) elicits a widespread increase in cortical excitability. In contrast, cathodal tDCS (c-tDCS) fails to modulate cortical excitability, being indistinguishable from sham stimulation. Here we investigated whether an endogenous task-induced activation during stimulation might change this pattern, improving c-tDCS effectiveness in modulating cortical excitability. In Study 1, we tested whether performance in a Visuospatial Working Memory Task (VWMT) and a modified Posner Cueing Task (mPCT), involving rPPC, could be modulated by c-tDCS. Thirty-eight participants were involved in a two-session experiment receiving either c-tDCS or sham during tasks execution. In Study 2, we recruited sixteen novel participants who performed the same paradigm but underwent TMS-EEG recordings pre- and 10 minutes post-sham and c-tDCS. Behavioral results showed that c-tDCS significantly modulated mPCT performance compared to sham. At a neurophysiological level, c-tDCS significantly reduced cortical excitability in a frontoparietal network involved in task execution. Taken together, our results provide evidence of the state dependence of c-tDCS in modulating cortical excitability effectively. The conceptual and applicative implications are discussed.

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bioRxiv2021

Top-down contribution to motor network reorganization during action preparation

BACKGROUNDIt is unclear whether the Bereitschaftspotential (BP) recorded in humans during action preparation mirrors motor areas activation escalation, or if its early and late phases reflect the engagement of different functional networks. OBJECTIVEHere, we aimed at recording the TMS evoked-potentials (TEP) stimulating the supplementary motor area (SMA) to assess whether and how cortical excitability and functional connectivity of this region change as the BP increases. We hypothesize that, at later stages, the SMA functional network should become more connected to regions relevant for the implementation of the final motor plan. METHODSWe performed TMS-EEG recordings on fourteen healthy subjects during the performance of a visuomotor Go/No-go task, eliciting and recording cortical activity and functional connectivity at -700 ms and -300 ms before the onset of visual stimuli over the SMA. RESULTSWhen approaching stimulus onset, and thus BP peak, the SMA increased its functional connectivity with movement-related structures in the gamma and alpha bands, indicating a regional top-down preparation to implement the motor act. Beta-band connectivity, instead, was maintained constant for the whole BP time-course, being potentially related to sustained attention required by the experimental task. CONCLUSIONThese findings reveal that the BP is not a mere result of increased activation of the SMA, but the functional networks in which this region is involved qualitatively changes over time, becoming more related to the execution of the motor act.

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bioRxiv2018

TMS orientation and pulse waveform manipulation activates different neural populations: direct evidence from TMS-EEG

Monophasic and biphasic TMS pulses and coil orientations produce different responses in terms of motor output and sensory perception. Those differences have been attributed to the activation of specific neural populations. However, up to date, direct evidence supporting this hypothesis is still missing since studies were mostly based on indirect measures of cortical activation, i.e., motor evoked potentials or phosphenes. Here, we investigated for the first time the impact of different coil orientations and waveforms on a non-primary cortical area, namely the premotor cortex, by measuring TMS evoked EEG potentials (TEPs). We aimed at determining whether TEPs produced by differently oriented biphasic and monophasic TMS pulses diverge and whether these differences are underpinned by the activation of specific neural populations. To do so, we applied TMS over the right premotor cortex with monophasic or biphasic waveforms oriented perpendicularly (in the anterior-posterior direction and vice-versa) or parallel (latero-medial or medio-laterally) to the target gyrus. EEG was concurrently recorded from 60 electrodes. We analyzed TEPs at the level of EEG sensors and cortical sources both in time and time-frequency domain. Biphasic pulses evoked larger early TEP components, which reflect cortical excitability properties of the underlying cortex, in both parallel directions when compared to the perpendicular conditions. Conversely, monophasic pulses, when oriented perpendicularly to the stimulated gyrus, elicited a greater N100, which is a reliable TEP component linked to GABAb-mediated inhibitory processes, than when parallel to the gyrus. Our results provide direct evidence supporting the hypothesis that TMS pulse waveform and TMS coil orientations affect which neural population is engaged.

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