Portrait de Karim Jerbi

Karim Jerbi

Membre académique associé
Professeur agrégé, Université de Montréal, Département de psychologie
Sujets de recherche
Exploration des données
Neurosciences computationnelles
Systèmes dynamiques
Traitement du langage naturel
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Biographie

Karim Jerbi est professeur agrégé au Département de psychologie de l'Université de Montréal. Il est titulaire de la Chaire de recherche du Canada en neurosciences computationnelles et en neuro-imagerie cognitive et directeur du centre UNIQUE, le centre de recherche en neuro-IA du Québec. Il est membre du Collège de nouveaux chercheurs et créateurs en art et en science de la Société royale du Canada.

Il a obtenu un doctorat en neurosciences cognitives et imagerie cérébrale de l'Université Pierre et Marie Curie à Paris (France) et un diplôme en génie biomédical de l'Université de Karlsruhe (Allemagne). Ses recherches se situent au carrefour des neurosciences cognitives, computationnelles et cliniques. Leur objectif est de sonder le rôle de la dynamique cérébrale à grande échelle dans la cognition d'ordre supérieur et d'étudier les altérations des réseaux cérébraux dans les cas de troubles psychiatriques et neurologiques.

La recherche multidisciplinaire menée dans son laboratoire combine la magnétoencéphalographie (MEG) et l'électroencéphalographie (EEG) du cuir chevelu et intracrânienne avec le traitement avancé des signaux et l'analyse des données, y compris l'apprentissage automatique. Les projets qui y sont en cours utilisent des enregistrements cérébraux électrophysiologiques pour examiner la dynamique des réseaux cérébraux à grande échelle dans une série de processus cognitifs (par exemple la prise de décision et la créativité) et dans différents états de conscience (éveil au repos, sommeil, rêve, anesthésie, méditation et états psychédéliques).

Karim Jerbi est fortement engagé dans la promotion de la justice sociale, de l'équité, de la diversité et de l'inclusion. Il s'intéresse également de près à la convergence entre les sciences du cerveau, l'IA, la créativité et l'art.

Étudiants actuels

Hamza Abdelhedi
Doctorat - UdeM
Site web
Github
Google Scholar
Maryem Benslimane
Maîtrise recherche - UdeM
Samin Mahdipour Aghabagher
Maîtrise professionnelle - UdeM
Site web
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Yorguin Mantilla Ramos
Maîtrise recherche - UdeM
Site web
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Google Scholar

Publications

Criticality of resting-state EEG predicts perturbational complexity and level of consciousness during anesthesia.
Charlotte Maschke
Jordan O'Byrne
Michele Angelo Colombo
Melanie Boly
Olivia Gosseries
Steven Laureys
Mario Rosanova
Karim Jerbi
Stefanie Blain-Moraes
Consciousness has been proposed to be supported by electrophysiological patterns poised at criticality, a dynamical regime which exhibits ad… (voir plus)aptive computational properties, maximally complex patterns and divergent sensitivity to perturbation. Here, we investigated dynamical properties of the resting-state electroencephalogram of healthy subjects undergoing general anesthesia with propofol, xenon or ketamine. We then studied the relation of these dynamic properties with the perturbational complexity index (PCI), which has shown remarkably high sensitivity in detecting consciousness independent of behavior. All participants were unresponsive under anesthesia, while consciousness was retained only during ketamine anesthesia (in the form of vivid dreams)., enabling an experimental dissociation between unresponsiveness and unconsciousness. We estimated (i) avalanche criticality, (ii) chaoticity, and (iii) criticality-related measures, and found that states of unconsciousness were characterized by a distancing from both the edge of activity propagation and the edge of chaos. We were then able to predict individual subjects’ PCI (i.e., PCImax) with a mean absolute error below 7%. Our results establish a firm link between the PCI and criticality and provide further evidence for the role of criticality in the emergence of consciousness.
2023-10-30
bioRxiv (prépublication)
doi.org
Class imbalance should not throw you off balance: Choosing the right classifiers and performance metrics for brain decoding with imbalanced data
Philipp Thölke
Yorguin-Jose Mantilla-Ramos
Hamza Abdelhedi
Charlotte Maschke
Arthur Dehgan
Yann Harel
Anirudha Kemtur
Loubna Mekki Berrada
Myriam Sahraoui
Tammy Young
Antoine Bellemare Pépin
Clara El Khantour
Mathieu Landry
Annalisa Pascarella
Vanessa Hadid
Etienne Combrisson
Jordan O'Byrne
Karim Jerbi
Machine learning (ML) is increasingly used in cognitive, computational and clinical neuroscience. The reliable and efficient application of … (voir plus)ML requires a sound understanding of its subtleties and limitations. Training ML models on datasets with imbalanced classes is a particularly common problem, and it can have severe consequences if not adequately addressed. With the neuroscience ML user in mind, this paper provides a didactic assessment of the class imbalance problem and illustrates its impact through systematic manipulation of data imbalance ratios in (i) simulated data and (ii) brain data recorded with electroencephalography (EEG), magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI). Our results illustrate how the widely-used Accuracy (Acc) metric, which measures the overall proportion of successful predictions, yields misleadingly high performances, as class imbalance increases. Because Acc weights the per-class ratios of correct predictions proportionally to class size, it largely disregards the performance on the minority class. A binary classification model that learns to systematically vote for the majority class will yield an artificially high decoding accuracy that directly reflects the imbalance between the two classes, rather than any genuine generalizable ability to discriminate between them. We show that other evaluation metrics such as the Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC), and the less common Balanced Accuracy (BAcc) metric - defined as the arithmetic mean between sensitivity and specificity, provide more reliable performance evaluations for imbalanced data. Our findings also highlight the robustness of Random Forest (RF), and the benefits of using stratified cross-validation and hyperprameter optimization to tackle data imbalance. Critically, for neuroscience ML applications that seek to minimize overall classification error, we recommend the routine use of BAcc, which in the specific case of balanced data is equivalent to using standard Acc, and readily extends to multi-class settings. Importantly, we present a list of recommendations for dealing with imbalanced data, as well as open-source code to allow the neuroscience community to replicate and extend our observations and explore alternative approaches to coping with imbalanced data.
2023-07-31
NeuroImage (publié)
doi.org
Aperiodic brain activity and response to anesthesia vary in disorders of consciousness
Charlotte Maschke
Catherine Duclos
Adrian M. Owen
Karim Jerbi
Stefanie Blain-Moraes
Stefanie Blain-Moraes
The analysis of human EEG has traditionally focused on oscillatory power, which is characterized by peaks above an aperiodic component in th… (voir plus)e power spectral density. This study investigates the aperiodic EEG component of individuals in a disorder of consciousness (DOC); how it changes in response to exposure to anesthesia; and how it relates to the brain’s information richness and criticality. High-density EEG was recorded from 43 individuals in a DOC, with 16 of these individuals undergoing a protocol of propofol anesthesia. The aperiodic component was defined by the spectral slope of the power spectral density. Our results demonstrate that the EEG aperiodic component is more informative about the participants’ level of consciousness than the oscillatory component. Importantly, the pharmacologically induced change in the spectral slope from 30-45 Hz positively correlated with individual’s pre-anesthetic level of consciousness. The pharmacologically induced loss of information-richness and criticality was associated with individual’s pre-anesthetic aperiodic component. During exposure to anesthesia, the aperiodic component was correlated with 3-month recovery status for individuals with DOC. The aperiodic EEG component has been historically neglected; this research highlights the necessity of considering this measure for the assessment of individuals in DOC and future research that seeks to understand the neurophysiological underpinnings of consciousness.
2022-12-31
NeuroImage (publié)
doi.org
Differential and Overlapping Effects between Exogenous and Endogenous Attention Shape Perceptual Facilitation during Visual Processing.
Mathieu Landry
Jason da Silva Castanheira
Karim Jerbi
Visuospatial attention is not a monolithic process and can be divided into different functional systems. In this framework, exogenous attent… (voir plus)ion reflects the involuntary orienting of attention resources following a salient event, whereas endogenous attention corresponds to voluntary orienting based on the goals and intentions of individuals. Previous work shows that these attention processes map onto distinct functional systems, yet evidence suggests that they are not fully independent. In the current work, we investigated the differential and overlapping effects of exogenous and endogenous attention on visual processing. We combined spatial cueing of visuospatial attention, EEG, and multivariate pattern analysis to examine where and when the effects of exogenous and endogenous attention were maximally different and maximally similar. Critically, multivariate pattern analysis provided new insights by examining whether classifiers trained to decode the cueing effect for one attention process (e.g., exogenous attention) can successfully decode the cueing effect for the other attention process (e.g., endogenous attention). These analyses uncovered differential and overlapping effects between exogenous and endogenous attention. Next, we combined principal component analyses, single-trial ERPs, and mediation analysis to determine whether these effects facilitate perception, as indexed by the behavioral spatial cueing effects of exogenous and endogenous attention. This approach revealed that three EEG components shape the cueing effects of exogenous and endogenous attention at various times after target onset. Altogether, our study provides a comprehensive account about how overlapping and differential processes of endogenous and exogenous relate to perceptual facilitation in the context of visuospatial attention.
2022-12-31
Journal of Cognitive Neuroscience (inconnu)
doi.org
Optimizing deep learning for Magnetoencephalography (MEG): From sensory perception to sex prediction and brain fingerprinting
Arthur Dehgan
Irina Rish
Karim Jerbi
2021-12-31
2022 Conference on Cognitive Computational Neuroscience (publié)
doi.org
Processing visual ambiguity in fractal patterns: Pareidolia as a sign of creativity
Antoine Bellemare-Pepin
Yann Harel
Jordan O'Byrne
Geneviève Mageau
Arne Dietrich
Karim Jerbi

Creativity is a highly sought after and multifaceted skill. Unfortunately, we only have a loose grasp on its cognitive underpinnings. Emp… (voir plus)irical research typically probes creativity by estimating the potential for problem solving and novel idea generation, a process known as “divergent thinking”. Here, by contrast, we examine creativity through the lens of perceptual abilities. In particular, we ask whether creative individuals are better at perceiving recognizable forms in noisy or ambiguous stimuli, a phenomenon known as pareidolia. To this end, we designed a visual perception task in which 50 participants, with various levels of creativity, were presented with ambiguous stimuli and asked to identify as many recognizable forms as possible. The stimuli consisted of cloud-like images with various levels of complexity, which we controlled by manipulating fractal dimension (FD) and contrast level. We found that pareidolic perceptions arise more often and more rapidly in individuals that are more creative. Furthermore, the emergence of pareidolia in individuals with lower creativity scores was more restricted to images with a narrow range of FD values, suggesting a wider repertoire for perceptual abilities in creative individuals. Our findings suggest that pareidolia may be used as a perceptual proxy of idea generation abilities, a key component of creative behavior. In sum, we extend the established body of work on divergent thinking, by introducing divergent perception as a complementary manifestation of the creative mind. These findings expand our understanding of the perception-creation link and open new paths in studying creative behavior in humans.

2021-11-27
iScience (publié)
doi.org