Biology subjects

Marcantoni, E.

Publications and source records attributed to Marcantoni, E..

3 recordsLinked to original sources

bioRxiv2024

Immediate TMS-EEG responses reveal motor cortex excitability

BackgroundCombined transcranial magnetic stimulation and electroencephalography (TMS-EEG) is widely used to probe cortical excitability at the network level, but technical challenges have prevented its application to investigate local excitability of the stimulated area. A recent study revealed immediate TMS-evoked potentials (i-TEPs) after primary motor cortex (M1) stimulation, suggesting that it may represent a local response. Here, we aimed at testing if this activity is physiological in nature and what it represents. MethodsWe analyzed a TMS-EEG dataset from 28 healthy participants recorded at 9.6 kHz including two M1 stimulation conditions with opposite biphasic current directions. We localized the brain sources of i-TEPs, calculated the immediate TMS-related power (i-TRP) to distinguish between two oscillatory components that may contribute to i-TEPs, and investigated the relationship between i-TRP and motor-evoked potentials (MEPs). In an additional recording, we stimulated a control site evoking a muscular response to understand the contribution of the TMS-related muscle artifact. ResultsResults confirmed i-TEPs with similar characteristics as previously described. The i-TRP revealed strong activity in two ranges 600-800 Hz and 100-200 Hz; The former was positively associated with MEPs amplitude for both current direction conditions. Moreover, i-TEPs were localized in the precentral gyrus of the stimulated hemisphere and the muscular response generated by the control stimulation site differed from i-TEPs and i-TRP. DiscussionThese findings provide first evidence on the physiological nature of i-TEPs and i-TRP following M1 stimulation and that i-TRP represents a direct measure of excitability of the stimulated cortex.

neuroscience↗

bioRxiv2024

Investigating visuo-tactile mirror properties in Borderline Personality Disorder: a TMS-EEG study

Patients with Borderline Personality Disorder (pw-BPD) are characterized by lower levels of cognitive empathy compared to healthy controls (HCs), indicating difficulties in understanding others perspective. A candidate neural mechanism subtending empathic abilities is represented by the Tactile Mirror System (TaMS), which refers to mirror-like mechanisms in the somatosensory cortices. However, little is known about TaMS alterations in BPD, specifically in terms of brain connectivity within this network. Here, we aimed at providing novel insights on TaMS as neurophysiological candidate for BPD empathic deficits, with a special focus on TaMS connectivity by means of the combined use of transcranial magnetic stimulation and electroencephalography (TMS-EEG). Twenty pw-BPD and 20 HCs underwent a thorough investigation: we collected measures of empathic abilities obtained from self-report questionnaires, behavioral performance in a visuo-tactile spatial congruency task, and TMS-evoked potentials (TEPs) as effective connectivity indexes. In the TMS-EEG session, TMS was delivered over the right primary somatosensory cortex (S1) following the presentation of real touches and visual touches, while 74-channel EEG was continuously recorded. In the visuo-tactile spatial congruency task and the TMS-EEG recording, control conditions with visual touches on objects instead of body parts enabled to disentangle the involvement of TaMS from non-specific effects. The study is the first one employing TMS-EEG in pw-BPD and it has been preregistered before data collection. Consistent with previous findings, results show that pw-BPD reported significantly lower levels of cognitive empathy. Moreover, pw-BPD made significantly more errors than controls in the visuo-tactile spatial congruency task during visual touches on human body parts and not on objects. Finally, pw-BPD displayed a different connectivity pattern from S1-TEPs that was not specific for TaMS: they showed a lower P60 component during touch observation, as well as reduced amplitude of later TEPs responses (after [~]100 ms) during real touches. Overall, the present study shows behavioral evidence of TaMS impairment and a more general alteration in the connectivity pattern of the somatosensory network in pw-BPD.

neuroscience↗

bioRxiv2022

Reliability of M1-P15 as a cortical marker for transcallosal inhibition: a preregistered TMS-EEG study

BackgroundIn a recently published study combining transcranial magnetic stimulation and electroencephalography (TMS-EEG), we provided first evidence of M1-P15, an early component of TMS-evoked potentials, as a measure of transcallosal inhibition between motor cortices. However, considering the technical challenges of TMS-EEG recordings, further evidence is needed before M1-P15 can be considered a reliable index. ObjectiveHere, we aimed at validating M1-P15 as a cortical index of transcallosal inhibition, by replicating previous findings on its relationship with the ipsilateral silent period (iSP) and with performance in bimanual coordination. Moreover, we aimed at inducing a task-dependent modulation of transcallosal inhibition. MethodsA new sample of 32 healthy right-handed participants underwent behavioral motor tasks and TMS-EEG recording, in which left and right M1 were stimulated during bimanual tasks and during an iSP paradigm. Hypotheses and methods were preregistered before data collection. ResultsWe successfully replicated our previous findings on the positive relationship between M1-P15 amplitude and the iSP normalized area. However, we did not confirm the relationship between M1-P15 latency and bimanual coordination. Finally, we show a task-dependent modulation of M1-P15 amplitude, which was affected by the characteristics of the bimanual task the participants were performing, but not by the contralateral hand activity during the iSP paradigm. ConclusionsThe present results corroborate our previous findings in validating the M1-P15 as a reliable cortical marker of transcallosal inhibition, and provide novel evidence of its task-dependent modulation. Importantly, we demonstrate the feasibility of a preregistration approach in the TMS-EEG field to increase methodological rigor and transparency.

neuroscience↗