
Sylvain BailletMcGill University | McGill · Department of Neurology and Neurosurgery
Sylvain Baillet
Canada Research Chair (Tier 1) Neural Dynamics of Brain Systems / Associate Dean (Research) Faculty of Medicine & Health Sciences.
Council Chair, Organization for Human Brain Mapping
About
329
Publications
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Introduction
I have multidisciplinary interests in systems neuroscience, with the overarching goal of advancing the understanding of integrative mechanisms of neural dynamics in brain systems, in health and disease. My lab has produced >300 publications and obtained >$50M in research funds. We share practical tools through free, open software and data resources with anyone interested. I also have a track record in leading large research units and in the institutional administration of research.
Additional affiliations
February 2019 - September 2024
September 2013 - September 2017
Montreal Neurological Institute
Position
- Managing Director
September 1998 - July 2000
Education
September 1994 - July 1998
September 1990 - May 1994
Publications
Publications (329)
During speech listening, the brain could use contextual predictions to optimize sensory sampling and processing. We asked if such predictive processing is organized dynamically into separate oscillatory timescales. We trained a neural network that uses context to predict speech at the phoneme level. Using this model, we estimated contextual uncerta...
Large, openly available datasets and current analytic tools promise the emergence of population neuroscience. The considerable diversity in personality traits and behaviour between individuals is reflected in the statistical variability of neural data collected in such repositories. Recent studies with functional magnetic resonance imaging (fMRI) h...
Background: Research in healthy young adults shows that characteristic patterns of brain activity define individual "brain-fingerprints" that are unique to each person. However, variability in these brain-fingerprints increases in individuals with neurological conditions, challenging the clinical relevance and potential impact of the approach. Our...
INTRODUCTION
Despite parallel research indicating amyloid‐β accumulation, alterations in cortical neurophysiological signaling, and multi‐system neurotransmitter disruptions in Alzheimer's disease (AD), the relationships between these phenomena remains unclear.
METHODS
Using magnetoencephalography, positron emission tomography, and an atlas of 19...
Animal and computational models of Alzheimer’s disease (AD) indicate that early amyloid-β (Aβ) deposits drive neurons into a hyperactive regime, and that subsequent tau depositions manifest an opposite, suppressive effect as behavioral deficits emerge. Here we report analogous changes in macroscopic oscillatory neurophysiology in the human brain. W...
Neuromodulation therapy comprises a range of non-destructive and adjustable methods for modulating neural activity using electrical stimulations, chemical agents, or mechanical interventions. Here, we discuss how electrophysiological brain recording and imaging at multiple scales, from cells to large-scale brain networks, contribute to defining the...
Background
Recent studies suggest that tau pathology spreads between functionally connected (FC) brain regions. The accumulation of amyloid‐beta (Aß) promotes neural hyper‐activity in asymptomatic older adults, which might enhance tau spreading. We assessed the relationship between band‐specific neurophysiological FC and the rate of tau accumulatio...
Background
Recent studies suggest that tau pathology spreads between functionally connected (FC) brain regions. The accumulation of amyloid‐beta (Aβ) promotes neural hyper‐activity in asymptomatic older adults, which might enhance tau spreading. We assessed the relationship between band‐specific neurophysiological FC and the rate of tau accumulatio...
Perception and production of music and speech rely on auditory–motor coupling, a mechanism which has been linked to temporally precise oscillatory coupling between auditory and motor regions of the human brain, particularly in the beta frequency band. Recently, brain imaging studies using magnetoencephalography (MEG) have also shown that accurate a...
How do neurophysiological traits that characterize individuals evolve across the lifespan? To address this question, we analyzed brief, task-free magnetoencephalographic recordings from over 1,000 individuals aged 4-89. We found that neurophysiological activity is significantly more similar between individuals in childhood than in adulthood, though...
Perception is a function of both stimulus features and active sensory sampling. The illusion of perceptual filling -in occurs when eye gaze is kept still: visual boundary perception may fail, causing adjacent visual features to remarkably merge into one uniform visual surface. Microsaccades–small, involuntary eye movements during gaze fixation–coun...
Parkinson’s disease (PD) is marked by the death of neuromelanin-rich dopaminergic and noradrenergic cells in the substantia nigra (SN) and the locus coeruleus (LC), respectively, resulting in motor and cognitive impairments. Although SN dopamine dysfunction has clear neurophysiological effects, the association of reduced LC norepinephrine signallin...
When the eyes remain still for an extended period of time, visual boundaries can appear to fade. This illusory phenomenon is traditionally attributed to slow neuronal adaptation to stable retinal input. Microsaccades – small, mostly involuntary ocular movements during gaze fixation – counteract fading, but it is unclear exactly how. They might simp...
On the centenary of the first human EEG recording, more than 500 experts reflect on the impact that this discovery has had on our understanding of the brain and behaviour. We document their priorities and call for collective action focusing on validity, democratization and responsibility to realize the potential of EEG in science and society over t...
Rationale: Scalp EEG is a non-invasive technique for studying the brain's electrical activity with high temporal resolution. EEG techniques are used in research and clinical applications, such as diagnosing Alzheimer's disease and epilepsy. EEG allows the monitoring and recording of electrical brain activity from multiple electrodes placed on the s...
Rationale: Stereo-EEG (sEEG) is a powerful tool in neurosurgery that allows seizure analysis and accurate localization of the seizure onset zone (SOZ). Analysis of sEEG data is often done by acquiring pre-implantation MRI (pre-MRI), post-implantation CT (post-CT), and post-surgery MRI (post-MRI) scans. This analysis requires: (1) post-CT to pre-MRI...
Neurophysiological brain activity comprises rhythmic (periodic) and arrhythmic (aperiodic) signal elements, which are increasingly studied in relation to behavioral traits and clinical symptoms. Current methods for spectral parameterization of neural recordings rely on user-dependent parameter selection, which challenges the replicability and robus...
Neurophysiological brain activity underpins cognitive functions and behavioural traits. Here, we sought to establish to what extent individual neurophysiological traits spontaneously expressed in ongoing brain activity are primarily driven by genetic variation. We also investigated whether changes in such neurophysiological features observed across...
Two neuropathological hallmarks of Alzheimer’s disease (AD) are the accumulation of amyloid-β (Aβ) proteins and alterations in cortical neurophysiological signaling. Despite parallel research indicating disruption of multiple neurotransmitter systems in AD, it has been unclear whether these two phenomena are related to the neurochemical organizatio...
Brain processes associated with emotion perception from biological motion have been largely investigated using point-light displays that are devoid of pictorial information and not representative of everyday life. In this study, we investigated the brain signals evoked when perceiving emotions arising from body movements of virtual pedestrians walk...
The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a history of how the standard has developed and grown over time. We outline the principles behind the project, the mechanisms by which it has been extended, and some...
Parkinson's disease (PD) is marked by the death of neuromelanin-rich dopaminergic and noradrenergic cells in the substantia nigra (SN) and the locus coeruleus (LC), respectively, resulting in motor and cognitive impairments. While SN dopamine dysfunction has clear neurophysiological effects, the impact of reduced LC norepinephrine signaling on brai...
Objective
Parkinson's disease (PD) affects the structural integrity and neurophysiological signaling of the cortex. These alterations are related to the motor and cognitive symptoms of the disease. How these changes are related to the neurochemical systems of the cortex is unknown.
Methods
We used T1‐weighted MRI and magnetoencephalography to meas...
Background
Alzheimer’s Disease (AD) is defined by the pathological accumulation of amyloid‐beta (Aβ) and tau in the brain. Regional deposition of these proteins is associated with changes in frequency‐defined neurophysiological activity that can be detected using non‐invasive magnetoencephalography (MEG). Here we examined whether these neurophysiol...
Background
Alzheimer’s Disease (AD) is defined by the pathological accumulation of amyloid‐beta (Aß) and tau in the brain. Regional deposition of these proteins is associated with changes in frequency‐defined neurophysiological activity that can be detected using non‐invasive magnetoencephalography (MEG). Here we examined whether these neurophysiol...
Current theories of attention differentiate exogenous from endogenous orienting of visuospatial attention. While both forms of attention orienting engage different functional systems, endogenous and exogenous attention are thought to share resources, as shown by empirical evidence of their functional interactions. The present study aims to uncover...
Introduction
Conditioned pain modulation (CPM) is an experimental procedure that consists of an ongoing noxious stimulus attenuating the pain perception caused by another noxious stimulus. A combination of the CPM paradigm with concurrent electrophysiological recordings can establish whether an association exists between experimentally modified pai...
Patients with Parkinson’s disease (PD) exhibit multifaceted changes in neurophysiological brain activity, hypothesized to represent a global cortical slowing effect. Using task-free magnetoencephalography and extensive clinical assessments, we found that neurophysiological slowing in PD is differentially associated with motor and non-motor symptoms...
Systematic spatial variation in micro-architecture is observed across the cortex. These micro-architectural gradients are reflected in neural activity, which can be captured by neurophysiological time-series. How spontaneous neurophysiological dynamics are organized across the cortex and how they arise from heterogeneous cortical micro-architecture...
The relationship between structural and functional connectivity in the brain is a key question in connectomics. Here we quantify patterns of structure-function coupling across the neocortex, by comparing structural connectivity estimated using diffusion MRI with functional connectivity estimated using both neurophysiological (MEG-based) and haemody...
Different theories explain how subjective experience arises from brain activity. These theories have independently accrued evidence, yet, confirmation bias and dependence on design choices hamper progress in the field. Here, we present an open science adversarial collaboration which directly juxtaposes Integrated Information Theory (IIT) and Global...
Different theories explain how subjective experience arises from brain activity1,2. These theories have independently accrued evidence, yet, confirmation bias and dependence on design choices hamper progress in the field3. Here, we present an open science adversarial collaboration which directly juxtaposes Integrated Information Theory (IIT)4,5 and...
Decision-making often manifests in behavior, typically yielding overt motor actions. This complex process requires the registration of sensory information with one's internal representation of the current context, before a categorical judgment of the most appropriate motor behavior can be issued. The construct concept of embodied decision-making en...
Difficulty producing intelligible speech is a debilitating symptom of Parkinson’s disease (PD). Yet, both the robust evaluation of speech impairments and the identification of the affected brain systems are challenging. Using task-free magnetoencephalography, we examine the spectral and spatial definitions of the functional neuropathology underlyin...
Parkinson's disease (PD) affects cortical structures and neurophysiology. How these deviations from normative variants relate to the neurochemical systems of the cortex in a manner corresponding to motor and cognitive symptoms is unknown. We measured cortical thickness and spectral neurophysiological alterations from structural magnetic resonance i...
Binocular rivalry is an example of bistable visual perception extensively examined in neuroimaging. Magnetoencephalography (MEG) can track brain responses to phasic visual stimulations of pre‐determined frequency and phase to advance our understanding of perceptual dominance and suppression in binocular rivalry. We used left and right eye stimuli t...
In this study, we investigate the clinical potential of brain-fingerprints derived from electrophysiological brain activity for diagnostics and progression monitoring of Parkinson’s disease (PD). We obtained brain-fingerprints from PD patients and age-matched healthy controls using short, task-free magnetoencephalographic recordings. The rhythmic c...
Systematic spatial variation in micro-architecture is observed across the cortex. These micro-architectural gradients are reflected in neural activity, which can be captured by neurophysiological time-series. How spontaneous neurophysiological dynamics are organized across the cortex and how they arise from heterogeneous cortical micro-architecture...
Objective. We aimed to clarify the pathophysiology of epilepsy involving seizures with apparently generalized onset, progressing to focal ictal rhythm through stereotactic EEG (SEEG) implantation, recording, stimulation and highfrequency oscillation (HFO) analysis.
Methods. We identified two patients with seizures with bilateral electrographic onse...
Objectives
The understanding of the cortical effects of spinal cord stimulation (SCS) remains limited. Multiple studies have investigated the effects of SCS in resting-state electroencephalography. However, owing to the large variation in reported outcomes, we aimed to describe the differential cortical responses between two types of SCS and betwee...
Current theories of attention differentiate exogenous (bottom-up) from endogenous (top-down) orienting of visuospatial attention. While both forms of attentional processing engage different processes, endogenous and exogenous attention are thought to share processing resources, as shown by recent empirical evidence of their functional interactions....
The relationship between structural and functional connectivity in the brain is a key question in connectomics. Here we quantify patterns of structure-function coupling across the neocortex, by comparing structural connectivity estimated using diffusion MRI with functional connectivity estimated using both neurophysiological (MEG-based) and haemody...
Alzheimer's Disease (AD) is characterized by the pathological accumulation of amyloid‐beta (Aβ) and hyperphosphorylated tau proteins in the brain. Animal models have demonstrated that early Aβ accumulation induces neuronal hyperexcitability (Stargardt et al., 2015), whereas later additive effects of Aβ and tau lead to suppression of neuronal activi...
Neurotransmitter receptors support the propagation of signals in the human brain. How receptor systems are situated within macro-scale neuroanatomy and how they shape emergent function remain poorly understood, and there exists no comprehensive atlas of receptors. Here we collate positron emission tomography data from more than 1,200 healthy indivi...
Imaging technologies are increasingly used to generate high-resolution reference maps of brain structure and function. Comparing experimentally generated maps to these reference maps facilitates cross-disciplinary scientific discovery. Although recent data sharing initiatives increase the accessibility of brain maps, data are often shared in dispar...
Macroscopic neural dynamics comprise both aperiodic and periodic signal components. Recent advances in parameterizing neural power spectra offer practical tools for evaluating these features separately. Although neural signals vary dynamically and express non-stationarity in relation to ongoing behaviour and perception, current methods yield static...
Cognitive decline with age is associated with brain atrophy and reduced brain activations, but the underlying neurophysiological mechanisms are unclear, especially in deeper brain structures primarily affected by healthy aging or neurodegenerative processes. Here, we characterize time-resolved, resting-state magnetoencephalography activity of the h...
Using magnetoencephalographic imaging and extensive clinical and neuropsychological assessments, we show that patients with Parkinson's disease (PD; N = 79) exhibit a slowing of neurophysiological activity relative to healthy adults (N = 65), which relates to motor and cognitive abilities. Importantly, the association between neurophysiological slo...
Whole-brain neural communication is typically estimated from statistical associations among electromagnetic or haemodynamic time-series. The relationship between functional network architectures recovered from these 2 types of neural activity remains unknown. Here, we map electromagnetic networks (measured using magnetoencephalography (MEG)) to hae...
Background: Poorly-defined cases (PDCs) of focal epilepsy are cases with no/subtle MRI abnormalities or have abnormalities extending beyond the lesion visible on MRI. Here, we evaluated the utility of Arterial Spin Labeling (ASL) MRI perfusion in PDCs of pediatric focal epilepsy. Methods: ASL MRI was obtained in 25 consecutive children presenting w...
Cognitive decline with age is associated with brain atrophy and reduced brain activations, but the underlying neurophysiological mechanisms are unclear, especially in deeper brain structures primarily affected by healthy aging or neurodegenerative processes. Here, we characterize time-resolved, resting-state magnetoencephalography activity of the h...
Prevailing accounts of visuospatial attention differentiate exogenous orienting, which corresponds to involuntary shifts of attention, from endogenous orienting, which reflects the voluntary control of attention. While these different forms of attention are functionally separable, evidence shows that they can nevertheless interact with each other....
Difficulty producing intelligible speech is a common and debilitating symptom of Parkinson's disease (PD). Yet, both the robust evaluation of speech impairments and the identification of the affected brain systems are challenging. We examine the spectral and spatial definitions of the functional neuropathology underlying reduced speech quality in p...
Conscious perceptual experiences are expected to correlate with content-specific brain activity. A veridicality problem arises when attempting to disentangle unconscious and conscious brain processes if conscious perceptual contents accurately match the physical nature of the stimulus. We argue that perceptual filling-in, a phenomenon whereby visua...
Processing auditory sequences involves multiple brain networks and is crucial to complex perception associated with music appreciation and speech comprehension. We used time-resolved cortical imaging in a pitch change detection task to detail the underlying nature of human brain network activity, at the rapid time scales of neurophysiology. In resp...
The frontoparietal network is involved in multiple tasks, such as visual mental rotation, working memory, or arithmetic. Whether those different cognitive processes are supported by the same supramodal network or distinct, but overlapping, functional systems is unresolved. We investigate whether frontoparietal activity can be selectively entrained...
Imaging technologies are increasingly used to generate high-resolution reference maps of brain structure and function. Modern scientific discovery relies on making comparisons between new maps (e.g. task activations, group structural differences) and these reference maps. Although recent data sharing initiatives have increased the accessibility of...
Macroscopic neural dynamics comprise both aperiodic and periodic components. Recent advances in parameterizing neural power spectra offer practical tools for evaluating these features separately. Although neural signals vary dynamically and express non-stationarity in relation to ongoing behaviour and perception, current methods yield static spectr...
Many brain functions are difficult to localize, as they involve distributed networks that reconfigure themselves on short timescales. One example is the integration of oculomotor and visual signals that occurs with each eye movement: The brain must combine motor signals about the eye displacement with retinal signals, to infer the structure of the...
Imaging technologies are increasingly used to generate high-resolution reference maps of brain structure and function. Modern scientific discovery relies on making comparisons between new maps (e.g. task activations, group structural differences) and these reference maps. Although recent data sharing initiatives have increased the accessibility of...
We present both a scientific overview and conceptual positions concerning the challenges and assets of electrophysiological measurements in the search for the nature and functions of the human connectome. We discuss how the field has been inspired by findings and approaches from functional magnetic resonance imaging (fMRI) and informed by a small n...
The principle of resting-state paradigms is appealing and practical for collecting data from impaired patients and special populations, especially if data collection times can be minimized. To achieve this goal, researchers need to ensure estimated signal features of interest are robust. In electro- and magnetoencephalography (EEG, MEG) we are not...
Background: Poorly-defined cases (PDCs) of focal epilepsy are cases with no/subtle MRI abnormalities or have abnormalities extending beyond the lesion visible on MRI. Here, we evaluated the utility of Arterial Spin Labeling (ASL) MRI perfusion in PDCs of pediatric focal epilepsy. Methods: ASL MRI was obtained in 25 consecutive children presenting w...