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The role of network interactions in timing-dependent plasticity within the human motor cortex induced by paired associative stimulationConde Ruiz, Virginia 04 December 2013 (has links) (PDF)
Spike timing-dependent plasticity (STDP) has been suggested as one of the key mechanism underlying learning and memory. Due to its importance, timing-dependent plasticity studies have been approached in the living human brain by means of non-invasive brain stimulation (NIBS) protocols such as paired associative stimulation (PAS). However, contrary to STDP studies at a cellular level, functional plasticity induction in the human brain implies the interaction among target cortical networks and investigates plasticity mechanisms at a systems level.
This thesis comprises of two independent studies that aim at understanding the importance of considering broad cortical networks when predicting the outcome of timing-dependent associative plasticity induction in the human brain. In the first study we developed a new protocol (ipsilateral PAS (ipsiPAS)) that required timing- and regional-specific information transfer across hemispheres for the induction of timing-dependent plasticity within M1 (see chapter 3). In the second study, we tested the influence of individual brain structure, as measured with voxel-based cortical thickness, on a standard PAS protocol (see chapter 4). In summary, we observed that the near-synchronous associativity taking place within M1 is not the only determinant influencing the outcome of PAS protocols. Rather, the online interaction of the cortical networks integrating information during a PAS intervention determines the outcome of the pairing of inputs in M1.
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Investigation de l’effet du polymorphisme Val66Met du gène BDNF sur les mécanismes neurophysiologiques qui sous-tendent les apprentissages moteurs procéduraux et sensorimoteurs, de même que sur le transfert intermanuel des apprentissagesMorin-Moncet, Olivier 12 1900 (has links)
No description available.
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Analýza a klasifikace dat ze snímače mozkové aktivity / Data Analysis and Clasification from the Brain Activity DetectorJileček, Jan January 2019 (has links)
This thesis aims to implement methods for recording EEG data obtained with the neural activity sensor OpenBCI Ultracortex IV headset. It also describes neurofeedback, methods of obtaining data from the motor cortex for further analysis and takes a look at the machine learning algorithms best suited for the presented problem. Multiple training and testing datasets are created, as well as a tool for recording the brain activity of a headset-wearing test subject, which is being visually presented with cognitive challenges on the screen in front of him. A neurofeedback demo app has been developed, presented and later used for calibration of new test subjects. Next part is data analysis, which aims to discriminate the left and right hand movement intention signatures in the brain motor cortex. Multiple classification methods are used and their utility reviewed.
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Steigerung der Effektivität repetitiver Doppelpuls-TMS mit I-Wellen-Periodizität (iTMS) durch individuelle Adaptation des InterpulsintervallsSewerin, Sebastian 01 November 2012 (has links)
Die transkranielle Magnetstimulation (TMS) ist ein nichtinvasives Hirnstimulationsverfahren, mit welchem sowohl die funktionelle Untersuchung umschriebener kortikaler Regionen als auch die Modulation der Erregbarkeit ebendieser sowie die Induktion neuroplastischer Phänomene möglich ist. Sie wurde in der Vergangenheit insbesondere bei der Erforschung des humanen zentralmotorischen Systems angewandt. Dabei zeigte sich, dass ein einzelner über dem primärmotorischen Areal (M1) applizierter TMS-Puls multiple deszendierende Erregungswellen im Kortikospinaltrakt induzieren kann. Von diesen Undulationen besitzt die D-Welle (direkte Welle) die kürzeste Latenz und sie rekurriert auf eine direkte Aktivierung kortikospinaler Neurone, wohingegen I-Wellen (indirekte Wellen) längere Latenzen besitzen und durch transsynaptische Aktivierung dieser Zellen entstehen. Bemerkenswert ist das periodische Auftreten der letztgenannten Erregungswellen mit einer Periodendauer von etwa 1,5 ms. Zwar sind die genauen Mechanismen noch unbekannt, welche der Entstehung dieser I-Wellen sowie dem Phänomen der I-Wellen-Fazilitierung, das sich in geeigneten TMS-Doppelpulsprotokollen offenbart, zugrunde liegen, jedoch existieren hierzu verschiedene Erklärungsmodelle. Im Mittelpunkt der vorliegenden Arbeit steht die repetitive Anwendung eines TMS-Doppelpulsprotokolls, bei dem das Interpulsintervall (IPI) im Bereich der I-Wellen-Periodizität liegt (iTMS) und das gleichsam durch eine Implementierung der I-Wellen-Fazilitierung in der repetitiven TMS charakterisiert ist. Da gezeigt werden konnte, dass iTMS mit einem IPI von 1,5 ms (iTMS_1,5ms) die kortikospinale Erregbarkeit signifikant intra- und postinterventionell zu steigern vermag, und die I-Wellen-Periodizität interindividuellen Schwankungen unterliegt, wurde in der hier vorgestellten Studie an Normalprobanden der Einfluss einer individuellen Anpassung des IPIs (resultierend in der iTMS_adj) auf die intrainterventionelle kortikospinale Erregbarkeit untersucht. In der Tat stellte sich heraus, dass die iTMS_adj der iTMS_1,5ms diesbezüglich überlegen ist. Dieses Ergebnis unterstreicht das Potential einer Individualisierung der interventionellen TMS für erregbarkeitsmodulierende Effekte und macht dasjenige der ohnehin auf physiologische Prozesse abgestimmten iTMS explizit, was insbesondere für klinische Anwendungen relevant sein mag.
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Ipsi- and contralateral corticospinal influences in uni- and bimanual movements in humansDuval, Laura 04 1900 (has links)
Il existe des projections corticospinales (CS) vers les motoneurones (MNs) aussi bien contra- (c)
qu’ipsilatérales (i). Les influences CSc sur les MNs du poignet sont connues pour être modulées
entre autres par la position du poignet et les afférences cutanées. Pour cette raison, notre objectif
était de vérifier si ces caractéristiques sont aussi valides pour les influences CSi. En utilisant la
stimulation transcrânienne magnétique au niveau du cortex primaire droit, nous avons tout
d’abord comparé les influences CSi sur les MNs des fléchisseurs du poignet à des positions
maintenues de flexion et d’extension durant une tâche uni-manuelle ainsi que deux tâches bimanuelles,
ceci chez des sujets droitiers (n=23). Nous avons ensuite comparé les influences CSi
dans cinq tâches bi-manuelles de tenue d’objet durant lesquelles les sujets avaient à tenir entre
leurs mains un bloc à la surface soit lisse, soit rugueuse, dont le poids était supporté ou non, ceci
en position de flexion (n=21). Dans une tâche, un poids était ajouté au bloc lisse en condition non
supportée pour amplifier les forces de préhension requises. Une modulation positiondépendante
était observée au niveau des potentiels évoqués moteurs (iPEM), mais seulement
lors de la tâche bi-manuelle quand les deux mains interagissaient via un bloc (p= 0.01). Une
modulation basée sur la texture était également présente, quel que soit le support de poids, et le
bloc lisse était associé avec des iPEMs plus importants en comparaison avec le bloc rugueux (p=
0.001). Ainsi, les influences CSi sur les MNs n’étaient modulées que lors des tâches bi-manuelles
et dépendaient de la manière dont les mains interagissaient. De plus, les afférences cutanées
modulaient les influences CSi facilitatrices et pourraient ainsi participer à la prise en main des
objets. Il en est conclu que les hémisphères droit et gauche coopèrent durant les tâches bimanuelles
impliquant la tenue d’objet entre les mains, avec la participation potentielle de
projections mono-, et poly-synaptiques, transcallosales inclues. La possibilité de la contribution
de reflexes cutanés et d’étirement (spinaux et transcorticaux) est discutée sur la base de la notion
que tout mouvement découle du contrôle indirect, de la « référence » (referent control). Ces
résultats pourraient être essentiels à la compréhension du rôle des interactions interhémisphériques
chez les sujets sains et cliniques. / There are both contra- (c) and ipsilateral (i) corticospinal (CS) projections to motoneurons (MNs).
There is evidence that cCS influences on wrist MNs are modulated by wrist position and
cutaneous afferents. Thus, we aimed to test whether these findings are valid for iCS influences as
well. Using transcranial magnetic stimulation applied over the right primary motor cortex, we first
compared iCS influences on wrist flexor MNs at actively maintained flexion and extension wrist
positions in one uni- and two bimanual tasks in right-handed subjects (n=23). We further
compared iCS influences in five bimanual holding tasks in which subjects had to hold a smooth or
coarse block between their hands, with or without its weight being supported, in flexion position
(n=21). In one task, a weight was added to the unsupported smooth block to increase load forces.
A position-dependent modulation of the short-latency motor evoked potential (iMEP) was
observed, but only in the bimanual task when the two hands interacted through a block (p=0.01).
A texture-dependent modulation was present regardless of the weight supported, and the
smooth block was associated with larger iMEPs in comparison to the coarse block (p=0.001).
Hence, iCS influences on MNs were modulated only in bimanual tasks and depended on how the
two hands interacted. Furthermore, cutaneous afferents modulated facilitatory iCS influences
and thus may participate to grip forces scaling and maintaining. It is concluded that the left and
right cortices cooperate in bimanual tasks involving holding an object between the hands, with
possible participation of mono- and poly-synaptic, including transcallosal projections to MNs. The
possible involvement of spinal and trans-cortical stretch and cutaneous reflexes in bimanual tasks
when holding an object is discussed based on the notion that indirect, referent control underlies
motor actions. Results might be essential for the understanding of the role of intercortical
interaction in healthy and neurological subjects.
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The role of network interactions in timing-dependent plasticity within the human motor cortex induced by paired associative stimulationConde Ruiz, Virginia 07 November 2013 (has links)
Spike timing-dependent plasticity (STDP) has been suggested as one of the key mechanism underlying learning and memory. Due to its importance, timing-dependent plasticity studies have been approached in the living human brain by means of non-invasive brain stimulation (NIBS) protocols such as paired associative stimulation (PAS). However, contrary to STDP studies at a cellular level, functional plasticity induction in the human brain implies the interaction among target cortical networks and investigates plasticity mechanisms at a systems level.
This thesis comprises of two independent studies that aim at understanding the importance of considering broad cortical networks when predicting the outcome of timing-dependent associative plasticity induction in the human brain. In the first study we developed a new protocol (ipsilateral PAS (ipsiPAS)) that required timing- and regional-specific information transfer across hemispheres for the induction of timing-dependent plasticity within M1 (see chapter 3). In the second study, we tested the influence of individual brain structure, as measured with voxel-based cortical thickness, on a standard PAS protocol (see chapter 4). In summary, we observed that the near-synchronous associativity taking place within M1 is not the only determinant influencing the outcome of PAS protocols. Rather, the online interaction of the cortical networks integrating information during a PAS intervention determines the outcome of the pairing of inputs in M1.
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Long-term effects of sports concussionDe Beaumont, Louis 10 1900 (has links)
No description available.
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Contributions des voies vestibulospinale et corticospinale au contrôle des mouvements du brasRaptis, Alkisti Helli 03 1900 (has links)
No description available.
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