Pierre Vassiliadis

Pierre Vassiliadis
École Polytechnique Fédérale de Lausanne | EPFL · Center for Neuroprosthetics CNP

MD
Joint PhD Student at EPFL and UCLouvain

About

25
Publications
3,647
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140
Citations

Publications

Publications (25)
Article
Full-text available
Reward timing, that is, the delay after which reward is delivered following an action is known to strongly influence reinforcement learning. Here, we asked if reward timing could also modulate how people learn and consolidate new motor skills. In 60 healthy participants, we found that delaying reward delivery by a few seconds influenced motor learn...
Article
Full-text available
Besides relying heavily on sensory and reinforcement feedback, motor skill learning may also depend on the level of motivation experienced during training. Yet, how motivation by reward modulates motor learning remains unclear. In 90 healthy subjects, we investigated the net effect of motivation by reward on motor learning while controlling for the...
Article
Background: Latencies of motor evoked potentials (MEP) can provide insights into the motor neuronal pathways activated by transcranial magnetic stimulation (TMS). Notwithstanding its clinical relevance, accurate, unbiased methods to automatize latency detection are still missing. Objective: We present a novel open-source algorithm suitable for M...
Preprint
Dual–site transcranial magnetic stimulation (TMS) has been widely exploited to probe the influence of cortical structures on the primary motor cortex (M1). However, several issues remain open, notably regarding the use of this approach on areas of the medial frontal cortex – including the supplementary motor area (SMA) and the ventromedial prefront...
Preprint
Full-text available
Reward can improve motor learning and the consolidation of motor memories. Identifying the features of reward feedback that are critical for motor learning is a necessary step for successful integration into rehabilitation programs. One central feature of reward feedback that may affect motor learning is its timing, that is, the delay after which r...
Preprint
Full-text available
Besides relying heavily on sensory and reinforcement feedback, motor skill learning may also depend on the level of motivation experienced during training. Yet, how motivation by reward modulates motor learning remains unclear. In 90 healthy subjects, we investigated the net effect of motivation by reward on motor learning while controlling for the...
Article
Full-text available
Training can improve motor skills and modify neural activity at rest and during movement execution. Learning-related modulations may also concern motor preparation but the neural correlates and the potential behavioral relevance of such adjustments remain unclear. In humans, preparatory processes have been largely investigated using transcranial ma...
Article
Full-text available
The mere possibility of earning a reward induces substantial improvements in the way we choose and execute actions. This observation has raised hope for rehabilitation: reward is regarded as a promising means to magnify the positive effects of practice on motor control. Yet, this branch of research is only burgeoning, and neuroscientists have yet t...
Article
Full-text available
The motor system displays strong changes in neural activity during action preparation. In the past decades, several techniques, including transcranial magnetic stimulation (TMS), electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), have allowed us to gain insights into the functional role of such preparatory activity in hu...
Preprint
Full-text available
Training can improve motor skills and modify neural activity at rest and during movement execution. Learning-related modulations may also concern motor preparation but the neural correlates and the potential behavioral relevance of such adjustments remain unclear. In humans, preparatory processes have been largely investigated using transcranial ma...
Article
Full-text available
Motor and reinforcement learning have been classically linked to functionally independent brain networks centered on the cerebellum and the basal ganglia respectively. In a recent study published in eNeuro, Therrien et al. (2018) showed that increasing motor noise in healthy subjects disrupts reinforcement learning. However, this impairment remaine...
Conference Paper
Full-text available
Transcranial magnetic stimulation (TMS) allows stimulating targeted cortical areas non-invasively in humans. When applied over primary motor cortex (M1), TMS can yield electrical responses in contralateral hand muscles, called motor-evoked potentials (MEPs). Comparing MEPs in different contexts has allowed to identify various neural processes, incl...
Article
Full-text available
Transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1), elicits motor-evoked potentials (MEPs) in contralateral limb muscles which are valuable indicators of corticospinal excitability (CSE) at the time of stimulation. So far, most studies have used single-coil TMS over one M1, yielding MEPs in muscles of a single limb –...
Article
Background: For several decades, Transcranial magnetic stimulation (TMS) has been used to monitor corticospinal ex-citability (CSE) changes in various contexts. Habitually, single-coil TMS is applied over one primary motor cortex (M1), eliciting motor-evoked potentials (MEPs) in a contralateral limb muscle, usually a hand effector. However, in many...
Poster
Full-text available
Transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1) elicits motor-evoked potentials (MEPs) which provide a temporally precise and muscle-specific readout of the state-changes in the motor output system. For more than twenty years, many studies have used this method to investigate corticospinal excitability (CSE) chang...
Conference Paper
Full-text available
Transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1) elicits motor-evoked potentials (MEPs) which provide a temporally precise and muscle-specific readout of the state-changes in the motor output system. For more than twenty years, many studies have used this method to investigate corticospinal excitability (CSE) chang...
Conference Paper
Transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1) elicits motor-evoked potentials (MEPs) which provide a temporally precise and muscle-specific readout of state-changes in the motor output system. Many studies have used TMS over M1 to investigate corticospinal excitability changes occurring when choosing which hand...
Conference Paper
Full-text available
When one makes the decision to act in the physical world, the neural activity in primary motor cortex (M1) encodes the competition between potential action choices. Traditional approaches have viewed this activity as reflecting the unfolding of the outcome of a decision process taking place upstream. However, a recently emerging theoretical framewo...

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Projects

Projects (2)
Project
In the last decade, some studies have evidenced that decision-related signals might drive changes in the activity of motor neural structures (e.g., the primary motor cortex [M1]; Donner et al., 2009, Curr Biol; Hare et al., 2011, PNAS; Thura and Cisek, 2014 & 2017, Neuron), which suggests that these structures might contribute to decision processes. The goal of the present project is to better understand the role of different motor structures (e.g., M1, the pre-supplementary motor area, the basal ganglia) in motor decision-making.
Project
Testing if a double-coil TMS method where the two M1 are stimulated with a 1ms inter-pulse interval (double-coil1ms) is a reliable method to measure corticospinal excitability bilaterally.