Biology subjects

Marcantoni, E.

Publications and source records attributed to Marcantoni, E..

7 recordsLinked to original sources

bioRxiv2026

Assessing the longevity of the Theta-induced Memory Effect (TIME)

Theta-phase synchronisation between visual and auditory rhythmically modulated sensory stimuli during encoding has been shown to enhance associative memory, an effect known as Theta-Induced Memory Effect (TIME). However, whether this advantage is short-lived or persists over time remains unknown. To address this, we examined the TIME effect in 52 participants randomly assigned to a short-delay group (immediate retrieval) or a long-delay group (retrieval after 24 hours). Electroencephalography (EEG) was recorded during incidental encoding of audio-video pairs. The luminance of the video clips and the amplitude of the sounds were modulated at theta frequency (4 Hz) and presented either in-synchrony (0{degrees} phase offset between audio and video) or out-of-synchrony (the sound 180{degrees} phase-shifted relative to the video). Source reconstruction was used to estimate the actual phase difference between visual and auditory cortices for every trial. At the behavioural level, no significant difference in memory accuracy was found between the synchronous and asynchronous conditions in either group. However, after reconstructing the actual phase difference at the source level, the TIME effect was replicated in the short-delay group, with significantly higher memory accuracy at the optimal reconstructed theta phase compared to out-of-phase. In contrast, the long-delay group showed a reversed pattern, with higher accuracy in the asynchronous condition, though this difference did not reach significance. These findings suggest that the TIME effect is time-limited and may not survive or even reverse after overnight consolidation.

neuroscience↗

bioRxiv2026

Audiovisual stimulation using wearable shutter glasses robustly evokes 40 Hz neuronal activity but does not modulate associative memory

Audiovisual stimulation is a promising approach for studying and modulating human neuronal gamma (>30 Hz) oscillations and associated memory processes. Portable setups can increase ecological validity and therapeutic potential, but options remain limited. See-through shutter glasses are a new mobile technology that adds a visual flicker effect to what the user naturally sees. Here, we validated this method in a multisensory, cognitively relevant setting. We leveraged a previous experimental design from our lab, aiming to A) characterise the neuronal gamma activity evoked by shutter glasses, and B) conceptually replicate the previously reported effect of audiovisual gamma stimulation on memory accuracy, in line with a Spike Timing Dependent Plasticity model. We recorded high-density Electroencephalography (EEG) from 24 healthy participants during an associative memory task. Video-sound pairs were presented with the sound amplitude-modulated at 40 Hz and 40 Hz visual flicker elicited by the shutter glasses, with a phase offset between both modalities. The visual flicker preceded the auditory modulation by 90 or 270 degrees. Participants were asked to remember the video-sound associations. They also underwent a visual-only condition and an electrically equivalent control condition. EEG evoked power and phase coherence were reconstructed at source level and analysed along with behavioural accuracy. As expected, the shutter glasses robustly increased EEG evoked power and phase coherence at 40 Hz compared to the control condition. Effects were widespread and stronger than in a previous study not using shutter glasses. However, we did not replicate the previously reported effects of audiovisual phase offsets on memory accuracy. This could be due to reduced statistical power or methodological differences. Nonetheless, the validation of shutter glasses in a multisensory setting and the EEG analysis software, now improved and open source, enable important further investigations of audiovisual gamma stimulation in research and clinical settings.

neuroscience↗

bioRxiv2026

Non-invasive tracking of hippocampal theta oscillations

Hippocampal theta oscillations play a crucial role in the formation of episodic memories by binding multisensory information into coherent episodes. Brain stimulation studies suggest that memory performance can be modulated by targeting these oscillations, offering a potential way of treating memory disorders. However, to effectively engage these rhythms, precise knowledge about their presence, frequency, phase and location is required, which has been a challenge, particularly for non-invasive methods such as magnetoencephalography (MEG). Here, we first asked if hippocampal signals are detectable in MEG recordings. Using simultaneous MEG-intracranial EEG (iEEG) data, we show that invasively recorded hippocampal activity is reflected in MEG sensor signals, demonstrating the feasibility of detecting deep-brain activity non-invasively. Building on this, we introduce a MEG-based analysis pipeline to track hippocampal theta frequency over time. Applied across three independent datasets, the pipeline captured characteristic hippocampal theta frequency patterns in both rodents and humans, and MEG-derived hippocampal frequencies were consistent with those observed simultaneously in intracranial EEG. These findings provide evidence that MEG can reliably track individual hippocampal oscillatory dynamics, paving the way for future non-invasive closed-loop interventions that adapt stimulation frequency and timing to ongoing oscillations.

neuroscience↗

bioRxiv2025

Pre-stimulus alpha power modulates trial-by-trial variability in theta rhythmic multisensory entrainment strength and theta-induced memory effect

Binding multisensory information into episodic memory depends partly on the timing of the hippocampal theta rhythm which provides time windows for synaptic modification. In humans, theta rhythmic sensory stimulation (RSS) enhances episodic memory when the stimuli are synchronised across the visual and auditory domain compared to when they are out-of-synchrony. However, recent studies show mixed evidence if the improvement in episodic memory is the result of modulating hippocampal theta activity. In the current study, we investigated whether pre-stimulus brain state could explain part of this variance in the neural and behavioural effects induced by the RSS, via recording participants brain activity with MEG during a multisensory theta RSS memory paradigm. Our findings suggest that pre-stimulus alpha power modulates entrainment strength in sensory regions, which in turn predicts subsequent memory formation. These findings suggest that for non-invasive brain stimulation tools to be effective it is crucial to consider brain-state dependent effects.

neuroscience↗

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↗