INS Seminar: 10 Jan. 2019 – 14:00 – “Deciphering basal ganglia function using computational models”

From Thursday 10th January 2019 at 14:00
To Thursday 10th January 2019 at 15:00

Location : INS Seminar Room, Campus Timone, Red Wing, 5th Floor

Speaker Jyotika Bahuguna (Forschungszentrum Julich, Germany)
 
Abstract :  Basal ganglia function can be addressed with computational modeling at different levels of abstractions. Here I demonstrate two such examples and an attempt to combine these models. Firsty, we address the question of what is the striatal representation of an motor action.  In order to investigate this issue, we designed a distance dependent spiking neuronal network model of the striatum consisting of D1 and D2 medium spiny neurons (MSNs) and interfaced it to a simulated robot moving in an environment. We demonstrate that this model is able to reproduce key behavioral features (freezing, ambulation and rotation) of 6 out of 7 optogenetic experiments that involved the manipulation of the striatum. The main result of this model was that D1 and D2-MSNs of an action co-operate whereas D1 and D2-MSNs of competing actions inhibit each other during action selection. Basal ganglia being a set of interacting nuclei and forming many functional pathways form a good substrate for degeneracy. This degeneracy might also explain the variability seen in the data in healthy as well as pathological conditions such as Parkinson's disease. In order to investigate this issue, we model the basal ganglia as a firing rate model and perform a parameter search for effective connectivities between its nuclei for healthy and dopamine depleted conditions. The cost function used for constraining this system was derived from empirical firing rates and phase relationships as observed in healthy and dopamine depleted rats. We were able to generate more than 1000 physiological and pathological firing rate models that met the constraints and showed ample variability in the values of effective connectivities. We then projected these models onto a lower dimensional space of dynamical features such as : a) GPi suppression b) Susceptibiity to oscillations. Despite the large variability in effective connectivities, the models clustered together in this space and showed a clear separation between physiological and pathological conditions. This suggests that rather than absolute values of the effective connectivities, it might be their relative values that determine the dynamical state and projecting them on a lower dimensional space of sensible dynamical features might give a better chance at understanding complex pathologies such as Parkinson's disease than a pure structural analysis. And lastly, we use these firing rate models to deconstruct basal ganglia transfer function in response to striatal optogenetic stimulation in order to explain one of the optogenetic experiments that we failed to explain in the first study.
 
For any question, feel free to contact:
Hiba Sheheitli (hiba.sheheitli@univ-amu.fr) or Sophie Chen (sophie.chen@univ-amu.fr)


INS Seminar: 13 Dec. 2018 – 14:00 – “What information dynamics can tell us about brains”

From Thursday 13th December 2018 at 14:00
To Thursday 13th December 2018 at 15:00

Location : INS Seminar Room, Campus Timone, Red Wing, 5th Floor

Speaker: Dr. Joseph T. Lizier, The University of Sydney

Abstract: The space-time dynamics of interactions in neural systems are often described using terminology of information processing, or computation, in particular with reference to information being stored, transferred and modified in these systems. In this talk, we describe an information-theoretic framework -- information dynamics --  that we have used to quantify each of these operations on information, and their dynamics in space and time. Not only does this framework quantitatively align with natural qualitative descriptions of neural information processing, it provides multiple complementary perspectives on how, where and why a system is exhibiting complexity. We will review the application of this framework in computational neuroscience, describing what it can and indeed has revealed in this domain. First, we discuss examples of characterizing behavioral regimes and responses in terms of information processing, including under different neural conditions and around critical states. Next, we show how the space-time dynamics of information storage, transfer and modification directly reveal how distributed computation is implemented in a system, highlighting information processing hot-spots and emergent computational structures, and providing evidence for conjectures on neural information processing such as predictive coding theory. Finally, via applications to several models of dynamical networks and human brain images, we demonstrate how information dynamics relates the structure of complex networks to their function, and how it can invert such analysis to infer structure from dynamics.

For any question, feel free to contact:
Hiba Sheheitli (hiba.sheheitli@univ-amu.fr) or Sophie Chen (sophie.chen@univ-amu.fr)



INS Seminar – 5 Dec. 2018 – 15:00 : “Resonance of Local Field Potentials in the Connectome”

From Wednesday 5th December 2018 at 15:00
To Wednesday 5th December 2018 at 16:00

Location : INS Seminar Room, Campus Timone, Red Wing, 5th Floor

 Speaker : Joana Cabral (University of Oxford, UK & University of Minho, Portugal)

"Resonance of Local Field Potentials in the Connectome "

 Abstract :  I will describe a mechanistic theory for the transient emergence of macroscopic brain rhythms as collective oscillatory modes emerging transiently from reciprocal interactions between local field potentials in the structural skeleton of the Connectome. This mechanism is grounded on theoretical principles governing the formation of frequency-specific coherent attractors in delay-coupled oscillatory systems. Using a reduced phenomenological network model representing interactions between voltage fluctuations generated locally by neuronal ensembles at 40Hz with realistic wiring and propagation times, numerical simulations reveal the transient emergence of spatially-organized collective oscillatory modes peaking between 0.5-30Hz in line with analytic predictions, matching spectral, spatial and temporal signatures of multimodal neuroimaging data.

For any question, feel free to contact:
Hiba Sheheitli (hiba.sheheitli@univ-amu.fr) or Sophie Chen (sophie.chen@univ-amu.fr)



Keynote Seminar: Virginia Penhune (Montreal)

From Wednesday 31st October 2018 at 14:00
To Wednesday 31st October 2018 at 15:30

Location : INS seminar room (5th floor) Faculty of medecine, La timone Marseille

"Music and auditory-motor integration in the human brain"

Music is a complex system of auditory communication found in all human societies. Most people can move spontaneously to music, and predictable musical structures drive both perception and production. These phenomena suggest a strong interaction between the auditory and motor systems. Structural and functional imaging studies show that brain regions of the auditory dorsal stream network are involved in both music learning and performance. This talk will describe work demonstrating the role of specific regions of the dorsal stream in musical processing, with an emphasis on the role of premotor cortex in linking sound and action.

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com)

 

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Keynote Seminar: Robert Zatorre (Montreal)

From Tuesday 30th October 2018 at 11:00
To Tuesday 30th October 2018 at 12:00

Location : INT Gastaut room Faculty of medecine, La timone Marseille

"Predispositions and Plasticity in Auditory-Motor Learning: Hemispheric Asymmetries"

Our lab has focused on music as a powerful model for understanding plasticity in a human cognitive neuroscience context. This talk will present evidence that musical training modifies auditory and motor networks, and their functional and anatomical relationships, and that important asymmetries exist across the two hemispheres in these systems. We will also discuss evidence that individual differences in learning are related to functional features that may serve as predictors of later learning success. Our goal is to develop a better model of how the large-scale organization and asymmetries of auditory-motor networks relate to the experience-dependent plasticity that underlies complex skills such as playing a musical instrument, which may also have implications for speech.

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com)

 

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INS Seminars :: Lisa Genzel and Francesco Battaglia

From Thursday 27th September 2018 at 11am
To Thursday 27th September 2018 at 2pm

Location : INS Seminar Room

Lisa Genzel:  ''Sleep for Systems Consolidation''

Francesco Battaglia:  ''Finding cell assemblies in brain activity''

 

 Special INS Seminar welcoming two guests at 11am and 2pm:

11.am Seminar  

Lisa Genzel:  ''Sleep for Systems Consolidation''

-abstract: 

''Sleep is important for memory consolidation. More specifically, it is thought that during sleep recent memories are replayed in the hippocampus and prefrontal cortex to allow for abstraction of salient information across events and consolidation from the initial, hippocampal storage to the long-term representation in the cortex.  In this talk data from both humans and rats will be presented, providing evidence for this process.''

 

2.pm Seminar

 Francesco Battaglia:  ''Finding cell assemblies in brain activity''

 

-abstract: 

 ''The brain encodes information in the activity of “cell assemblies”, groups of neurons that are tied together by synaptic plasticity and are likely to activate in a synchronous way. In turn, cell assemblies activate in sequences, reflecting the temporal ordering of the events forming e.g. the memory of an episode. Spontaneous activity (taking place as the subject is inactive) is highly structured, and contains the activation of many cell assemblies, which may reflect stored memories, imagery, or planning of future actions. I present two methods for finding cell assemblies: In the first, we reconstruct the “functional connectivity matrix” by mapping recorded neural data on an  a spin-glass network, and infer the maximum entropy model, in what is known as “reverse Ising inference”. From the connectivity matrix, cell assemblies can be reconstructed and their activity analyzed. 

The second method tackles directly the temporal dimension by defining a distance between spike patterns inspired to the Earth Mover’s distance from Optimal Transportation theory, and then applying density-based clustering on the resulting distance matrix. Application of the method to simulated and real data reconstructs the structure of data and of the behavioral circumstances the animal experiences, in a completely unsupervised fashion. 
I will frame these method in the context of systems neuroscience research, with particular focus on the study of memory systems''

 

Find some information about their work: http://www.memorydynamics.org/

 



INS PhD Defense of Marisa Saggio

From Monday 17th September 2018 at 14
To Monday 17th September 2018 at 16

Marisa Saggio will defend her PhD entitled: 

 "Epidynamics: Seizures in the Unfolding of a High Codimension Singularity ."

The defence will take place on Monday the 17th of Septembre 2018 at 14.00, in the salle de Thèse 1, blue wing, ground floor, at the Faculté de Médecine Campus Timone, 27 bd Jean Moulin - 13005 Marseille : https://medecine.univ-amu.fr/fr/salle-theses-ndeg1
 

Jury Composition:

Rapporteur : BRAZDIL MILAN, Masaryk University, Brno, Czech Republic 
Rapporteur : TERRY JOHN,  University of Exeter, UK
Examinateur : DESTEXHE ALAIN, Unité de Neurosciences, Information & Complexité, Gif-sur-Yvette, France 
Examinateur : MCGONIGAL AILEEN, Hôpital de la Timone, Marseille, France 
Examinateur : BERNARD CHRISTOPHE, Aix-Marseille Université (INS) 
Directeur de thèse : JIRSA VIKTOR, Aix-Marseille Université (INS) 

Abstract

Epilepsy is one of the most common neurological disorders. Around one third of epileptic patients are drug resistant and these patients may be candidates for surgery. Different treatment strategies can be tested computationally using personalized large-scale brain models, providing in silico tools for testing clinical hypothesis and performing virtual surgeries. Electrographic seizures can be classified using knowledge from dynamical system theory in a taxonomy of sixteen possible seizure classes. In this Ph.D. project we created a single model able to produce bursting activity for most of the classes of the taxonomy, with the aim of further personalizing the large-scale brain model using the patient specific class. We validated the taxonomy based on dynamics on a large cohort of human data. Results are consistent with the theoretical framework inspired by our model, which we called Epidynamics, in particular the most surprising finding is that most patients have more than one class of seizures contrary to standard clinic teachings, and that transitions between classes can occur during a single seizure. The Epidynamics framework highlights the role of processes acting on at least three different timescales in the generation, evolution and termination of a seizure. We performed an initial exploration of the impact of the class on recruitment, that is a key feature determining seizure propagation.

 



Topical Seminar: Tomislav Stankovski (Lancaster, UK)

From Thursday 28th June 2018 at 14:00
To Thursday 28th June 2018 at 15:30

Location : INS seminar room Hopital La timone (5th floor, red wing) Marseille

"Coupling functions in neuroscience"

Faculty of Medicine, Ss Cyril and Methodius University, Skopje 1000, Macedonia
Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom

Interacting dynamical systems abound in nature and often the interest is not only to understand if, but also how they interact i.e. to reveal the functions and mechanisms that define and connect them. Coupling functions contain detailed information about the functional mechanisms underlying the interactions and prescribe the physical rule specifying how an interaction occurs [1]. Using a method based on dynamical Bayesian inference [2], we show how one can reconstruct and assess the coupling functions from phase dynamics of oscillatory data. Then, we present number of recent applications in neuroscience – including the neural cross-frequency coupling functions in eyes open/eyes closed resting state [3], and the state of general anaesthesia with two anaesthetics (propofol and sevoflurane) [4]; as we also present bursting neuronal coupling functions from
multielectrode array (MEA) recordings of interacting neurons from rats.

References:
[1] Stankovski et al., Rev. Mod. Phys., (2017)
[2] Stankovski et al., Phys. Rev. Lett. (2012)
[3] Stankovski et al., Front. Syst. Neurosci. (2017)
[4] Stankovski et al., Philos. Trans. Royal Soc. A (2016)

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com) or Adam Williamson (adam.WILLIAMSON@univ-amu.fr)

 

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Keynote Seminar: Mary Pat McAndrews (Toronto, Canada)

From Thursday 7th June 2018 at 14:00
To Thursday 7th June 2018 at 15:30

Location : INS new seminar room on 5th floor Faculty of medecine, La timone Marseille

"What are best practices in using fMRI to assess cognitive integrity and predict post-operative morbidity in temporal lobe epilepsy ?"

The use of fMRI to understand how cognitive processes such as language and memory are disrupted by neurological disorders is starting to bear fruit in clinical care. In the case of temporal-lobe epilepsy, the focus is identifying imaging features that will assist with diagnosis and prognosis in the service of surgical planning. While much of the early translational work was concerned with focal task-related activation, it is becoming clear that network properties and connectivity amongst brain regions may be a more sensitive and appropriate biomarker of functional integrity of brain networks that support complex cognitive operations, and that predicting the impact of focal damage or surgery requires an appreciation of those networks. Against this background, I will discuss analyses of resting state functional MRI (rsfMRI) as an emerging technique to address clinically-relevant questions about memory and language in the context of medial temporal lobe epilepsy.

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com) or Adam Williamson (adam.WILLIAMSON@univ-amu.fr)

 

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Keynote Seminar: Kristina Malmgren (Göteborg)

From Thursday 3rd May 2018 at 14:00
To Thursday 3rd May 2018 at 15:30

Location : INS temporary seminar room (5th floor) Faculty of medecine, La timone Marseille

"What do we know about the comprehensive long-term outcomes of epilepsy surgery – the Swedish contribution"

Epilepsy surgery is a recognized option in the management of adults and children with drug-resistant epilepsy. Advances in investigational techniques have widened the spectrum of surgical candidates. In the short term, rates of seizure freedom are relatively high, but seizure recurrence can still occur in the long term. There are methodological hurdles to overcome when assessing longer-term seizure outcomes. Patients and parents have hopes for improvements that are not limited to seizure control but pertain to many other areas of life - e g cognition, neurodevelopment, academic and vocational outcomes, and quality of life – which are of importance when determining whether a treatment is beneficial. In a number of these areas longer-term data are scarce or missing. Most patients are young when operated and they need counseling about the long-term perspective in order to make an informed decision about surgery. The Swedish National Epilepsy Surgery Register has prospectively included all patients in Sweden who have undergone epilepsy surgery since 1990. Hence the register is population based in a setting where this specialized treatment is public health care financed, which renders the data more generalisable than single center follow-ups. We have structured follow-ups up to 20 years after surgery encompassing information on seizures, antiepileptic drug treatment, work, and driving. We also pursue long-term cognitive follow-up studies of patients after temporal lobe resection; survey studies and qualitative interview studies in specified national patient/parent cohorts identified through the register. Results from these outcome studies will be presented concerning long-term seizure outcome, antiepileptic drug treatment outcome, vocational outcome, cognitive outcome and quality of life. From the interview studies data on patients’ expectations and experiences of epilepsy surgery will be presented. This knowledge is important in the counseling process, in order for patients to have realistic expectations on what they can gain from epilepsy surgery.

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com) or Adam Williamson (adam.WILLIAMSON@univ-amu.fr)

 

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Keynote Seminar: F-Xavier Alario (Marseille)

From Thursday 12th April 2018 at 14:00
To Thursday 12th April 2018 at 15:30

Location : INS temporary seminar room (5th floor) Faculty of medecine, La timone Marseille

"Neuro-physiological evaluation of psycho-linguistic hypothesis: A personal account"

Psycholinguistic models describe the cognitive processes that allow speakers to produce and comprehend language. These language processes are undoubtedly generated by neuro-physiological activities. Yet, despite the available evidence, much work remains to be done to understand the functions that link cognition and neuro-physiology, particularly in what concerns the ability to produce language. In recent years, we have used intra-cerebral neuro-physiological data to test cognitive hypothesis about language production. In the talk, I will discuss a few difficulties we have faced and how we have addressed them in our investigation of word selection processes. References: 1.Dubarry, A.-S., Llorens, A., Trébuchon, A., Carron, R., Liégeois-Chauvel, C., Bénar, C.*, & Alario, F.-X.* Estimating Parallel Processing in a Language Task Using Single-Trial Intracerebral Electroencephalography. Psychol. Sci. 28, 414–426 (2017). 2.Llorens, A. Dubarry, A.-S., Trébuchon, A., Chauvel, P., Alario, F.-X., & Liégeois-Chauvel, C. Contextual modulation of hippocampal activity during picture naming. Brain Lang. 159, (2016).

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com) or Adam Williamson (adam.WILLIAMSON@univ-amu.fr)

 

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Keynote Seminar: Fabrice Wendling (Rennes)

From Thursday 5th April 2018 at 14:00
To Thursday 5th April 2018 at 15:30

Location : INS seminar room (5th floor) Faculty of medecine, La timone Marseille

"Neurostimulation for diagnosis and therapy in epilepsy: from “in silico” models to “in vivo” applications"

Diagnosis. Neurostimulations can be used to probe neuronal circuits. Using a computational modeling approach in combination with in vivo and in vitro electrophysiological recordings, we showed that extracellular local bipolar stimulation at low intensity allows preferential activation of GABAergic interneurons. From this procedure, we devised a quantitative index that reflects the excitability of locally-stimulated neuronal networks (the neuronal network excitability index or NNEI). The NNEI is computed from stimulation-induced responses recorded as extracellular signals (Local Field Potentials, LFPs) evoked with optimally-tuned intensity and frequency parameters. The proposed probing method can be used to identify hyperexcitable brain regions in patients with focal epilepsy.

Therapy. We study the effects of local direct current stimulation (LDCS) effects on hyperexcitable tissue, by i) analyzing the impact of electrical currents locally applied on epileptogenic brain regions, and ii) characterizing currents achieving an “anti-epileptic” effect (excitability reduction). First, a neural mass model of hippocampal circuits was extended to accurately reproduce the features of hippocampal paroxysmal discharges (HPDs) observed in a mouse model of epilepsy. Second, model predictions regarding current intensity and stimulation polarity were confronted to in vivo mice recordings during LDCS. Simulations showed that significant decrease of simulated HPDs (in duration and occurrence rate, not in amplitude) could be obtained for specific configurations (electrode position, polarity, intensity). Predictions were successfully verified experimentally in epileptic mice. Results provide support for further model-guided design of neuromodulation therapy.

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com) or Adam Williamson (adam.WILLIAMSON@univ-amu.fr)

 

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Topical Seminar: Véronique Boulenger (Lyon)

From Thursday 29th March 2018 at 14:00
To Thursday 29th March 2018 at 15:30

Location : INS temporary seminar room (5th floor) Faculty of medecine, La timone Marseille

"Brain oscillations during natural speech perception: the case of speech rate variations"

Oscillation-based models of speech perception suggest a close correspondence between speech rhythm and cortical oscillations: neural oscillations would synchronize to the quasi-regular temporal cues in speech across multiple timescales, therefore facilitating the partitioning of the acoustic stream into relevant linguistic units crucial for language comprehension (Ghitza, 2011; Giraud & Poeppel, 2012; Peelle & Davis, 2012; Poeppel, 2003). EEG/MEG studies have convincingly demonstrated coupling between auditory cortical oscillations and slow modulations in the temporal envelope of speech in the theta band (e.g., Ahissar et al., 2001; Gross et al., 2013; Luo & Poeppel, 2007; Peelle et al., 2013), namely in a frequency range which coincides with the average syllabic rate of speakers across languages (Pellegrino et al., 2011). Here I will present some MEG data in adults as well as in typically-developing children (8-13 years old) showing changes in the properties of cortico-acoustic coupling when natural speech perception shifts from normal to fast syllabic rate (with natural or artificial acceleration). Source-level coherence analyses indeed revealed entrainment of neuronal oscillations that followed the changes in speech envelope (though in adults only) as well as in fundamental frequency (both in adults and children) with increasing speech rate. Children data furthermore showed alignment of theta oscillatory activity in left (pre)motor regions when speech was naturally accelerated. I will discuss these findings in light of multi-time resolution models of speech perception as well as the role of the motor system in speech perception.

For any question, feel free to contact:
Benjamin Morillon (bnmorillon@gmail.com) or Adam Williamson (adam.WILLIAMSON@univ-amu.fr)

 

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