Papers by Paolo Belardinelli
Journal of Neuroscience Methods, Sep 1, 2022
Frontiers in Human Neuroscience, Jun 21, 2021
Background: Theta-band neuronal oscillations in the prefrontal cortex are associated with several... more Background: Theta-band neuronal oscillations in the prefrontal cortex are associated with several cognitive functions. Oscillatory phase is an important correlate of excitability and phase synchrony mediates information transfer between neuronal populations oscillating at that frequency. The ability to extract and exploit the prefrontal theta rhythm in real time in humans would facilitate insight into neurophysiological mechanisms of cognitive processes involving the prefrontal cortex, and development of brain-statedependent stimulation for therapeutic applications. Objectives: We investigate individual source-space beamforming-based estimation of the prefrontal theta oscillation as a method to target specific phases of the ongoing theta oscillations in the human dorsomedial prefrontal cortex (DMPFC) with real-time EEGtriggered transcranial magnetic stimulation (TMS). Different spatial filters for extracting the prefrontal theta oscillation from EEG signals are compared and additional signal quality criteria are assessed to take into account the dynamics of this cortical oscillation. Methods: Twenty two healthy participants were recruited for anatomical MRI scans and EEG recordings with 18 composing the final analysis. We calculated individual spatial filters based on EEG beamforming in source space. The extracted EEG signal was then used to simulate real-time phase-detection and quantify the accuracy as compared to post-hoc phase estimates. Different spatial filters and triggering parameters were compared. Finally, we validated the feasibility of this approach by actual real-time triggering of TMS pulses at different phases of the prefrontal theta oscillation. Results: Higher phase-detection accuracy was achieved using individualized sourcebased spatial filters, as compared to an average or standard Laplacian filter, and also by detecting and avoiding periods of low theta amplitude and periods containing a phase reset. Using optimized parameters, prefrontal theta-phase synchronized TMS of DMPFC was achieved with an accuracy of ±55 • .
Brain Stimulation, Mar 1, 2019
Results: Despite the lack of intervention, a significant number of participants were classified a... more Results: Despite the lack of intervention, a significant number of participants were classified as responders (21-71%). Conclusion: This study highlights the large Type I error associated with responder analyses when MEP data are di-or trichotomised. Our data suggest that at best, 20% of the participants classified as responders are done so erroneously. Therefore, a control group is essential with these analyses as these methods are prone to overestimation of response rates.
Clinical Neurophysiology, Apr 1, 2020
bioRxiv (Cold Spring Harbor Laboratory), Sep 25, 2018
Brain Stimulation, Mar 1, 2022
Background: Prefrontal theta oscillations are involved in neuronal information transfer and reten... more Background: Prefrontal theta oscillations are involved in neuronal information transfer and retention. Phases along the theta cycle represent varied excitability states, whereby high-excitability states correspond to high-frequency neuronal activity and heightened capacity for plasticity induction, as demonstrated in animal studies. Human studies corroborate this model and suggest a core role of prefrontal theta activity in working memory (WM). Objective/Hypothesis: We aimed at modulating prefrontal neuronal excitability and WM performance in healthy humans, using real-time EEG analysis for triggering repetitive transcranial magnetic stimulation (rTMS) theta-phase synchronized to the left dorsomedial prefrontal cortex. Methods: 16 subjects underwent 3 different rTMS interventions on separate days, with pulses triggered according to the individual's real-time EEG activity: 400 rTMS gamma-frequency (100 Hz) triplet bursts applied during either the negative peak of the prefrontal theta oscillation, the positive peak, or at random phase. Changes in cortical excitability were assessed with EEG responses following single-pulse TMS, and behavioral effects by using a WM task. Results: Negative-peak rTMS increased single-pulse TMS-induced prefrontal theta power and thetagamma phase-amplitude coupling, and decreased WM response time. In contrast, positive-peak rTMS decreased prefrontal theta power, while no changes were observed after random-phase rTMS. Conclusion: Findings point to the feasibility of EEG-TMS technology in a thetaegamma phaseeamplitude coupling mode for effectively modifying WM networks in human prefrontal cortex, with potential for therapeutic applications.
Brain Stimulation, Mar 1, 2017
stimulation (rTMS), to test if dorsolateral prefrontal cortex (DLPFC) stimulation might prevent c... more stimulation (rTMS), to test if dorsolateral prefrontal cortex (DLPFC) stimulation might prevent cocaine use in humans. Method: Thirty-two cocaine-addicted patients were randomly assigned to either the experimental group (rTMS) on the left DLPFC, or to a control group (pharmacological agents) during a 29-day study (Stage 1). This was followed by a 63-day follow-up (Stage 2), during which all participants were offered rTMS treatment. Amongst the patients who completed Stage 1, 16 were in the rTMS group (100%) and 13 in the control group (81%). Results: No significant adverse events were noted. During Stage 1, there were a significantly higher number of cocaine-free urine drug tests in the rTMS group compared to control (p¼0.004). Craving for cocaine was also significantly lower in the rTMS group compared to the controls (p¼0.038). Out of 13 patients who completed Stage 1 in the control group, 10 patients received rTMS treatment during Stage 2 and showed significant improvement with favorable outcomes becoming comparable to those of the rTMS group. Conclusion: The present preliminary findings support the safety of rTMS in cocaine-addicted patients, and suggest its potential therapeutic role for rTMS-driven PFC stimulation in reducing cocaine use, providing a strong rationale for developing larger placebo-controlled studies.
Clinical Neurophysiology, Mar 1, 2017
perceived pain of the first and every 10th heat stimulation using a numeric rating scale 0-100. T... more perceived pain of the first and every 10th heat stimulation using a numeric rating scale 0-100. TSP was calculated as the difference between the lowest rating and the rating of the last stimulus and was compared among 4 conditions. Results: Condition IV yielded the largest TSP effect (20 ± 3.1; mean ± SEM), which was higher than TSP effect of condition I (7.9 ± 2.2; p = 0.03) and II (6.8 ± 1.5; p = 0.012; Fig. 1). TSP effects of condition III and IV were comparable, however condition IV caused discomfort and intolerable pain in 9 participants; no one complained about discomfort during other conditions. Conclusion: The protocol with high number of repeated stimuli and short pulse duration (<1.0 s) is feasible to reproduce TSP phenomenon. Heat stimulation with long pulse durations and high stimulation temperatures are not feasible in experimental human pain research.
Brain Stimulation, Mar 1, 2017
Brain Stimulation, Mar 1, 2017
Brain Stimulation, Mar 1, 2017
Results: "Montage B" induces substantially higher electric field levels than "Montage A" and "Mon... more Results: "Montage B" induces substantially higher electric field levels than "Montage A" and "Montage C" at the genital level. Moreover, the comparison between the two female models shows current density amplitudes and temperature increases higher in the younger subject than in the adult. However, the maxima levels found across the three models and the three montages are widely lower than the limits leading to tissue damage by heating. Significance: This modelling study represents the first contribution that gives quantitative information about genital safety during tsDCS.
Clinical Neurophysiology, Mar 1, 2017
The Journal of Physiology
Frontiers in Neuroscience, 2019
Neurologic music therapy in rehabilitation of stroke patients has been shown to be a promising su... more Neurologic music therapy in rehabilitation of stroke patients has been shown to be a promising supplement to the often strenuous conventional rehabilitation strategies. The aim of this study was threefold: (i) replicate results from a previous study with a sample from one clinic (henceforth called Site 1; N = 12) using an already established recording system, and (ii) conceptually replicate previous findings with a less costly hand-tracking system in Site 2 (N = 30), and (iii) compare both sub-studies' outcomes to estimate the efficiency of neurologic music therapy. Stroke patients in both sites were randomly assigned to treatment or control groups and received daily training of guided sequential upper limb movements additional to their standard stroke rehabilitation protocol. Treatment groups received sonification (i.e., changes in musical pitch) of their movements when they moved their affected hand up and down to reproduce a sequence of the first six notes of a C major scale. Controls received the same movement protocol, however, without auditory feedback. Sensors at the upper arm and the forearm (Xsens) or an optic sensor device (Leapmotion) allowed to measure kinematics of movements and movement smoothness. Behavioral measures pre and post intervention included the Fugl-Meyer assessment (FMA) and the Stroke Impact Scale (SIS) and movement data. Bayesian regression did not show evidence supporting an additional effect of sonification on clinical mobility assessments. However, combined movement data from both sites showed slight improvements in movement smoothness for the treatment group, and an advantage for one of the two motion capturing systems. Exploratory analyses of EEG-EMG phase coherence during movement of the paretic arm in a subset of patients suggested increases in cortico-muscular phase coherence specifically in the ipsilesional hemisphere after sonification therapy, but not after standard rehabilitation therapy. Our findings show that musical sonification
Clinical Neurophysiology, 2020
Introduction: Rotation of a static magnet over the primary motor cortex (M1) generates a transcra... more Introduction: Rotation of a static magnet over the primary motor cortex (M1) generates a transcranial alternating magnetic field (tAMF) and induces alternating electrical fields in the underlying tissue. Objectives: The aim of this transcranial magnetic stimulation (TMS) study is to investigate whether such alternating magnetic fields are able to influence M1 excitability, and whether these effects are similar to the ones induced by the trans cranial alternating current stimulation (tACS). Materials and methods: Fourteen healthy volunteers received 20?Hz tAMF stimulation over the M1, over the vertex, and 20 Hz tACS over the 1C, each with a duration of 15 min. TMS assessments were performed before and after the interventions. Changes in motor evoked potentials (MEP), short interval intra-cortical inhibition (SICI) and intra-cortical facilitation (ICF) were evaluated. Results: The tACS and the tAMF stimulation over the M1 affected cortical excitability in a different way. After tAMF stimulation MEP amplitudes and ICF decreased and the effect of SICI increased. After tACS MEP amplitudes increased and there were no effects on SICI and ICF. Conclusions: The recorded single and paired pulse MEPs indicate a general decrease of M1 excitability following 15 min of tAMF stimulation. These effects demonstrate that devices based on rotating agents are potentially suited as novel brain stimulation tools in clinical neurophysiology.
ABSTRACT A set of different algorithms was involved to analyze the anomalous motor control in fou... more ABSTRACT A set of different algorithms was involved to analyze the anomalous motor control in four young hemi-paretic patients with pre-and perinatally acquired brain lesions. The effects of a peculiar cerebral reorganization allow the patients to move the paretic arm. Patients performed a pinch grip using their paretic and non-paretic hands alternatively. EMG was simultaneously recorded as a basis for coherence calculations. 3D coherence mapping was performed in the beta frequency range. Such approach evidenced the relocation of motor functions from the lesioned (left) to the contralesional (right) hemisphere. While in case of left, non-paretic pinch grip, coherent activity originated from contralateral (right) Ml exclusively, right (paretic) grip, produced coherent activity in ipsilateral Ml as well as significant coherence of ipsilateral cerebellum. Coupling direction analysis demonstrated that throughout pinch grip the coupling direction goes from Ml to cerebellum.
Cognitive Processing, Jan 21, 2006
Computational and Mathematical Methods in Medicine, 2012
Resting state functional connectivity of MEG data was studied in 29 children (9-10 years old). Th... more Resting state functional connectivity of MEG data was studied in 29 children (9-10 years old). The weighted phase lag index (WPLI) was employed for estimating connectivity and compared to coherence. To further evaluate the network structure, a graph analysis based on WPLI was used to determine clustering coefficient (C) and betweenness centrality (BC) as local coefficients as well as the characteristic path length (L) as a parameter for global interconnectedness. The network's modular structure was also calculated to estimate functional segregation. A seed region was identified in the central occipital area based on the power distribution at the sensor level in the alpha band. WPLI reveals a specific connectivity map different from power and coherence. BC and modularity show a strong level of connectedness in the occipital area between lateral and central sensors. C shows different isolated areas of occipital sensors. Globally, a network with the shortest L is detected in the alpha band, consistently with the local results. Our results are in agreement with findings in adults, indicating a similar functional network in children at this age in the alpha band. The integrated use of WPLI and graph analysis can help to gain a better description of resting state networks.
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Papers by Paolo Belardinelli