<p class="jove_content"&gt; Financé par néerlandaises NWO / ZonMw subventions 912-03-037 et 911-02-004.</p

1. Plate-forme de mouvement 6DF Stimuli vestibulaires ont été livrés avec une plate-forme de mouvement (voir figure 1) capable de générer des stimuli angulaires et translationnelle à un total de six degrés de liberté (FCS-MOOG, Nieuw-Vennep, Pays-Bas). La plate-forme est déplacé par six actionneurs électromécaniques reliés à un ordinateur personnel avec le logiciel de contrôle dédié. Il génère des mouvements précis avec six degrés de liberté. Les capteurs placés dans les vérins d&#39;une surveillance continue du profil de déplacement de la plate-forme. Le dispositif a &lt;0,5 mm de précision pour linéaire et &lt;0,05 ° pour les mouvements angulaires. Vibrations pendant la stimulation étaient de 0,02 °. La fréquence de résonance du dispositif était&gt; 75 Hz. profil de déplacement de la plate-forme a été reconstituée à partir de l&#39;information de capteur dans les actionneurs à l&#39;aide de la dynamique inverse et envoyé à l&#39;ordinateur de collecte de données. Pour synchroniser plate-forme et les données des mouvements oculaires, un faisceau laser a été monté à l&#39;arrière de la platform et projetée sur une petite cellule (1 mm, le temps de réaction de 10 ps). La tension de sortie de la cellule photoélectrique a été échantillonné à une fréquence de 1 KHz en même temps que les données de mouvement d&#39;oeil et pourvu d&#39;un indicateur en temps réel d&#39;apparition de mouvement avec une précision msec. Lors de l&#39;analyse hors ligne en utilisant Matlab (The MathWorks, Natick, MA), le profil de mouvement reconstruit de la plate-forme basée sur l&#39;information capteur des actionneurs dans la plate-forme a été précisément aligné avec le début du mouvement de la plate-forme. 2. Sujets A. coin Les sujets sont assis sur une chaise montée au centre de la plate-forme (figure 2). Le corps du sujet a été retenu par une ceinture de sécurité à quatre points tel qu&#39;il est utilisé dans les voitures de course. Les ceintures de sécurité ont été ancrés à la base de la plate-forme de mouvement. Le président a été entouré par un cadre cube PVC et a servi de support pour les bobines de champ. Le système de bobines de champ est réglable en hauteur, de telle sorte que le sujLes yeux de ect étaient dans le centre du champ magnétique. B. fixation de la tête La tête est immobilisée à l&#39;aide d&#39;une carte de morsure dentaire-empreinte moulée individuellement, qui a été fixée à la charpente cubique par une barre rigide. Un oreiller vide pliée autour du cou et un anneau attaché à la présidence assurée autre fixation du sujet (Figure 1). En outre, pour surveiller les mouvements de la tête parasites lors de la stimulation, nous avons joint deux capteurs 3D (Analog Devices Inc, Norwood, MA) directement au conseil d&#39;administration de la morsure, l&#39;une pour angulaire et l&#39;autre pour les accélérations linéaires. 3. Système de coordonnées rotations oculaires sont définis dans un système de coordonnées droitier tête fixe (Figure 3). Dans ce système, du point de vue d&#39;une rotation vers la gauche sur l&#39;axe Z (lacet), une rotation vers le bas autour de l&#39;axe Y (tangage) et de la rotation vers la droite sur l&#39;axe des X (roulis) de l&#39;objet sont définies comme positive. Les plans orthogonaux aux axes X, Y et Z des axes de rotation sont respectivement les plans de roulis, de tangage et de lacet (figure 3). 4. Les enregistrements des mouvements oculaires Les mouvements oculaires des deux yeux ont été enregistrées avec des bobines de recherche scléraux 3D (Skalar, Delft, Pays-Bas) 4 à l&#39;aide d&#39;un kHz système basé sur la méthode de détection d&#39;amplitude de Robinson (Modèle EMP3020, Skalar médicale, Delft, Pays-Bas) standard de 25 deux bobine de champ 5. Les signaux de la bobine ont été passés à travers un filtre passe-bas analogique avec une fréquence de coupure de 500 Hz et échantillonnées en ligne et stockés sur le disque dur à une fréquence de 1 kHz avec 16 précision de bits (système CED course Spike2 v6, Cambridge conception de circuits électroniques , Cambridge). 5. Recherche Coil Calibration Avant les essais, la sensibilité et la non-orthogonalité de direction et de torsion bobines a été vérifiée in vitro par le montage de la bobine sur un Fick giSystème mbal placé au centre du champ magnétique. En faisant tourner le système à cardan sur tous les axes cardinaux nous nous sommes assurés que toutes les bobines utilisées dans les expériences étaient symétrique pour toutes les directions à l&#39;intérieur de 2%. In vivo, les signaux horizontaux et verticaux des deux bobines ont été calibrés individuellement en demandant au sujet de fixer successivement une série de cinq objectifs (objectif central et une cible à 10 degrés à gauche, à droite, de haut en bas) pendant cinq secondes chacune. Les cibles d&#39;étalonnage ont été projetées sur un écran translucide à 186 cm de distance. l&#39;analyse de l&#39;expérience post des données de calibrage a abouti à la sensibilité et les valeurs des bobines compensée chaque recherche. Ces valeurs ont ensuite été utilisés dans les procédures d&#39;analyse écrits en Matlab 3. 6 Stimulation A. stimulation sinusoïdale La plate-forme livrée rotations sinusoïdales l&#39;ensemble du corps (1 Hz, A = 4 °) sur les trois cardiaxes internes: L&#39;axe rostrale-caudale ou vertical (lacet), l&#39;axe interauriculaire (tangage) et de l&#39;axe du nez-occipitale (roulis), et sur les axes horizontaux intermédiaires incrémenté par pas de 22,5 ° entre roulis et de tangage. Stimuli sinusoïdaux ont été livrés à la lumière et l&#39;obscurité. Dans la lumière, les sujets fixés sur une cible visuelle allumé en permanence (une LED rouge, 2 mm de diamètre) situé à 177 cm en avant du sujet au niveau des yeux (figure 1C panneau de gauche). Head a été positionné de telle sorte que la ligne de Reid était base (la ligne imaginaire reliant le conduit auditif externe avec le cantus orbitale inférieure) était à 6 degrés par rapport à la terre horizontale). Lors d&#39;une stimulation sinusoïdale dans l&#39;obscurité, la cible visuelle a été brièvement présentée (2 sec) lorsque la plate-forme était stationnaire pendant chaque intervalle entre deux stimuli consécutifs. Pour éviter les mouvements oculaires spontanés pendant la stimulation, les sujets ont été invités à fixer le lieu imaginaire de la cible fixe dans l&#39;espace au cours de sinusoïdeal stimulation après la cible avait été éteint juste avant l&#39;apparition du mouvement. Nous avons vérifié que le type d&#39;instruction réduit principalement les mouvements oculaires effectués dans les ténèbres, et a eu que peu d&#39;effet sur le gain (&lt;10%). Cette variabilité a eu lieu dans toutes les composantes (horizontale, verticale et de torsion) simultanément. B. stimulation Impulse Courte durée des impulsions du corps entiers ont été livrées dans un environnement faiblement éclairé. Le seul stimulus visible à la disposition du sujet était une cible visuelle situé à 177 cm en avant du sujet au niveau des yeux. Chaque impulsion a été répétée six fois et remis dans un ordre aléatoire et avec une synchronisation aléatoire d&#39;apparition mouvement (intervalles varier entre 2,5 et 3,5 sec.) Le profil des impulsions est une accélération constante de 100 ° -2 sec pendant les 100 premières millisecondes de l&#39;impulsion, suivie d&#39;une diminution progressive de l&#39;accélération linéaire. Cette relance a entraîné une augmentation linéaire de la vitesse pour atteindre un veloction de 10 ° s -1 après 100 ms. Mouvements de la tête aberrantes pendant la stimulation vestibulaire mesurées par la vitesse angulaire et les dispositifs d&#39;accélération linéaire sont à moins de 4% de l&#39;amplitude de stimulation. La vitesse de pointe des mouvements de l&#39;oeil en réponse à ces impulsions est 100 fois supérieur au niveau de bruit des signaux de la bobine. 7. Analyse des données signaux de bobines ont été converties en angles Fick, puis exprimé en tant que vecteurs de rotation 6,7. A partir des données de fixation de la cible tout droit, nous avons déterminé la désalignement de la bobine dans l&#39;oeil par rapport aux bobines de champ magnétique primaire orthogonales. Les signaux ont été corrigées pour cette décalage axial par rotation contre trois dimensions. Il a également été vérifié qu&#39;aucun glissement de la bobine avait eu lieu au cours de l&#39;expérience en vérifiant la sortie de position lors de la fixation de la cible avant chaque début de mouvement. Pour exprimer les mouvements oculaires 3D dans le domaine de vitesse,nous avons converti des données de vecteur de rotation en arrière dans la vitesse angulaire. Avant la conversion de vecteur de rotation à vitesse angulaire, nous avons lissé les données de phase de zéro avec un filtre numérique avant et arrière avec une fenêtre gaussienne de 20 points (durée 20 ms). 8. Les réponses sinusoïdales Un gain. Le gain de chaque élément et le gain de vitesse de l&#39;oeil 3D a été calculée en ajustant une sinusoïde avec une fréquence égale à la fréquence de la plate-forme, par l&#39;intermédiaire des composants de vitesse angulaire verticales et horizontales torsion. Le gain de chaque composant défini comme le rapport entre la vitesse de l&#39;oeil du pic du composant et de la vitesse de pointe de plate-forme est calculée séparément pour chaque oeil. B désalignement. L&#39;alignement entre l&#39;axe de la vitesse des yeux 3D et l&#39;axe de vitesse de tête a été calculé en utilisant la méthode de Aw et ses collègues 8,9. A partir du produit scalaire de deux vecteurs, l&#39;alignement a été calculée comme étant la insangle tantaneous en trois dimensions entre l&#39;inverse de la vitesse de l&#39;axe de l&#39;oeil et de l&#39;axe de vitesse de tête. Le gain de vitesse angulaire et le désalignement 3D pour chaque orientation en azimut ont été comparés au gain et le désalignement prédit à partir du vecteur somme de 0 ° (rouleau) et 90 ° (pitch) azimut composants 10. A partir de ce vecteur somme il résulte que, lorsque les gains de vitesse de roulis et de tangage sont égales, l&#39;orientation de l&#39;axe de rotation de l&#39;oeil soit aligné avec l&#39;axe de rotation de la tête, lorsque les deux sont différents, l&#39;écart maximal entre le stimulus et l&#39;axe de rotation de l&#39;oeil est prévu à 45 ° azimut. 9. réponses impulsionnelles Traces de données œil gauche et à droite de six présentations pour chaque direction de mouvement ont été analysés séparément. Parce que les valeurs de l&#39;œil gauche et droite étaient presque identiques, les données de l&#39;oeil gauche et de droite ont été moyennées pour déterminer le gain de vitesse de l&#39;œil en réponse à la stimulation d&#39;impulsion. Toutes les traces étaientinspecté individuellement sur l&#39;écran d&#39;ordinateur. Lorsque le sujet a fait un clin d&#39;œil ou saccade lors de l&#39;impulsion qui trace a été écartée manuellement. Composantes de la vitesse angulaire (N = 5 à 6) pendant les 100 premières millisecondes après le début du mouvement a été calculée dans les poubelles de temps de 20 ms (fournissant un filtrage passe-bas efficace) et tracés en fonction de la vitesse de la plate-forme 11,12.

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Nous n&#39;avons rien à révéler.

Ce document décrit une méthode permettant de mesurer avec précision 3D VOR angulaire en réponse aux rotations du corps entier chez l&#39;homme. L&#39;avantage de cette méthode est qu&#39;elle donne des informations quantitatives sur le gain et le désalignement de la 3D VOR angulaire dans les trois dimensions. Le procédé est utile pour la recherche fondamentale et dispose également d&#39;une valeur potentielle par exemple cliniques pour tester les patients ayant des problèmes de canaux verticaux ou les...

<table border="1">
 <tbody>
		<tr>
			<td>Electric Motion Base MB-E-6DOF/24/1800KG * (Formerly E-CUE 624-1800)</td>
			<td>FCS-MOOG, Nieuw-Vennep, The Netherlands</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic field with detector, Model EMP3020</td>
			<td>Skalar Medical, Delft, The Netherlands</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CED power 1401, running Spike2 v6</td>
			<td>Cambridge Electronic Design, Cambridge</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electromagnetic search coils</td>
			<td>Chronos Vision, Berlin, Germany</td>
			<td></td>
			<td></td>
		</tr>
 </tbody>
	</table>

three dimensional vestibular ocular reflex testing using a six degrees of freedom motion platform

The vestibular organ is a sensor that measures angular and linear accelerations with six degrees of freedom (6DF). Complete or partial defects in the vestibular organ results in mild to severe equilibrium problems, such as vertigo, dizziness, oscillopsia, gait unsteadiness nausea and/or vomiting. A good and frequently used measure to quantify gaze stabilization is the gain, which is defined as the magnitude of compensatory eye movements with respect to imposed head movements. To test vestibular function more fully one has to realize that 3D VOR ideally generates compensatory ocular rotations not only with a magnitude (gain) equal and opposite to the head rotation but also about an axis that is co-linear with the head rotation axis (alignment). Abnormal vestibular function thus results in changes in gain and changes in alignment of the 3D VOR response.
Here we describe a method to measure 3D VOR using whole body rotation on a 6DF motion platform. Although the method also allows testing translation VOR responses 1, we limit ourselves to a discussion of the method to measure 3D angular VOR. In addition, we restrict ourselves here to description of data collected in healthy subjects in response to angular sinusoidal and impulse stimulation.
Subjects are sitting upright and receive whole-body small amplitude sinusoidal and constant acceleration impulses. Sinusoidal stimuli (f = 1 Hz, A = 4&deg;) were delivered about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5&deg; in azimuth. Impulses were delivered in yaw, roll and pitch and in the vertical canal planes. Eye movements were measured using the scleral search coil technique 2. Search coil signals were sampled at a frequency of 1 kHz.
The input-output ratio (gain) and misalignment (co-linearity) of the 3D VOR were calculated from the eye coil signals 3.
Gain and co-linearity of 3D VOR depended on the orientation of the stimulus axis. Systematic deviations were found in particular during horizontal axis stimulation. In the light the eye rotation axis was properly aligned with the stimulus axis at orientations 0&deg; and 90&deg; azimuth, but gradually deviated more and more towards 45&deg; azimuth.
The systematic deviations in misalignment for intermediate axes can be explained by a low gain for torsion (X-axis or roll-axis rotation) and a high gain for vertical eye movements (Y-axis or pitch-axis rotation (see Figure 2). Because intermediate axis stimulation leads a compensatory response based on vector summation of the individual eye rotation components, the net response axis will deviate because the gain for X- and Y-axis are different.
In darkness the gain of all eye rotation components had lower values. The result was that the misalignment in darkness and for impulses had different peaks and troughs than in the light: its minimum value was reached for pitch axis stimulation and its maximum for roll axis stimulation.
Case Presentation
Nine subjects participated in the experiment. All subjects gave their informed consent. The experimental procedure was approved by the Medical Ethics Committee of Erasmus University Medical Center and adhered to the Declaration of Helsinki for research involving human subjects.
Six subjects served as controls. Three subjects had a unilateral vestibular impairment due to a vestibular schwannoma. The age of control subjects (six males and three females) ranged from 22 to 55 years. None of the controls had visual or vestibular complaints due to neurological, cardio vascular and ophthalmic disorders.
The age of the patients with schwannoma varied between 44 and 64 years (two males and one female). All schwannoma subjects were under medical surveillance and/or had received treatment by a multidisciplinary team consisting of an othorhinolaryngologist and a neurosurgeon of the Erasmus University Medical Center. Tested patients all had a right side vestibular schwannoma and underwent a wait and watch policy (Table 1; subjects N1-N3) after being diagnosed with vestibular schwannoma. Their tumors had been stabile for over 8-10 years on magnetic resonance imaging.

Lumière de stimulation sinusoïdale Figure 4 (en haut) montre pour le groupe de contrôle le gain moyen des composantes de vitesse angulaire horizontaux, verticaux et de torsion pour toutes les stimulations sinusoïdales testés dans le plan horizontal à la lumière. Torsion était maximale à l&#39;azimut 0 °, alors que vertical a son maximum à 90 °. Figure 5 montre le gain de vitesse de l&#39;oeil 3D dans la lumière. Gain varié entre 0,99 ± 0,12 (pitc...

Watch this Scientific Journal Video about Three Dimensional Vestibular Ocular Reflex Testing Using a Six Degrees of Freedom Motion Platform at JoVE.com

Three Dimensional Vestibular Ocular Reflex Testing Using a Six Degrees of Freedom Motion Platform

On décrit une méthode pour mesurer tridimensionnelles réflexes oculaires VESTIBULO (3D VOR) chez l&#39;homme en utilisant une période de six degrés de liberté (6DF) du simulateur de mouvement. Le gain et le désalignement de la VOR angulaire 3D fournissent une mesure directe de la qualité de la fonction vestibulaire. Des données représentatives sur les sujets sains sont fournis

Tridimensionnelle vestibulaire oculaire Test Reflex aide d&#39;un Six degrés de plate-forme de mouvement de la liberté

The vestibular organ is a sensor that measures angular and linear accelerations with six degrees of freedom (6DF). Complete or partial defects in the ...

three-dimensional-vestibular-ocular-reflex-testing-using-six-degrees

Research

JoVE Journal

Neuroscience

15.8K vues.  Erasmus MC. On décrit une méthode pour mesurer tridimensionnelles réflexes oculaires VESTIBULO (3D VOR) chez l'homme en utilisant une période de six degrés de liberté (6DF) du simulateur de mouvement. Le gain et le désalignement de la VOR angulaire 3D fournissent une mesure directe de la qualité de la fonction vestibulaire. Des données représentatives sur les sujets sains sont fournis

Vidéo: Three Dimensional Vestibular Ocular Reflex Testing Using a Six Degrees of Freedom Motion Platform

MPI CyberMotion Simulator: Implementation of a Novel Motion Simulator to Investigate Multisensory Path Integration in Three Dimensions

Path integration is a process in which self-motion is integrated over time to obtain an estimate of one's current position relative to a starting point 1. Humans can do path integration based exclusively on visual 2-3, auditory 4, or inertial cues 5. However, with multiple cues present, inertial cues - particularly kinaesthetic - seem to dominate 6-7. In the absence of vision, humans tend to overestimate short distances (&lt;5 m) and turning angles (&lt;30&deg;), but underestimate longer ones 5. Movement through physical space therefore does not seem to be accurately represented by the brain.
Extensive work has been done on evaluating path integration in the horizontal plane, but little is known about vertical movement (see 3 for virtual movement from vision alone). One reason for this is that traditional motion simulators have a small range of motion restricted mainly to the horizontal plane. Here we take advantage of a motion simulator 8-9 with a large range of motion to assess whether path integration is similar between horizontal and vertical planes. The relative contributions of inertial and visual cues for path navigation were also assessed.
16 observers sat upright in a seat mounted to the flange of a modified KUKA anthropomorphic robot arm. Sensory information was manipulated by providing visual (optic flow, limited lifetime star field), vestibular-kinaesthetic (passive self motion with eyes closed), or visual and vestibular-kinaesthetic motion cues. Movement trajectories in the horizontal, sagittal and frontal planes consisted of two segment lengths (1st: 0.4 m, 2nd: 1 m; &plusmn;0.24 m/s2 peak acceleration). The angle of the two segments was either 45&deg; or 90&deg;. Observers pointed back to their origin by moving an arrow that was superimposed on an avatar presented on the screen.
Observers were more likely to underestimate angle size for movement in the horizontal plane compared to the vertical planes. In the frontal plane observers were more likely to overestimate angle size while there was no such bias in the sagittal plane. Finally, observers responded slower when answering based on vestibular-kinaesthetic information alone. Human path integration based on vestibular-kinaesthetic information alone thus takes longer than when visual information is present. That pointing is consistent with underestimating and overestimating the angle one has moved through in the horizontal and vertical planes respectively, suggests that the neural representation of self-motion through space is non-symmetrical which may relate to the fact that humans experience movement mostly within the horizontal plane.

An efficient way to gain insight into how humans navigate themselves in three dimensions is described. The method takes advantage of a motion simulator capable of moving observers in ways unattainable by traditional simulators. Results confirm that movement in the horizontal plane is underestimated, while vertical movement is overestimated.

MPI CyberMotion Simulator: la mise en œuvre d&#39;un simulateur de mouvement Novel pour étudier l&#39;intégration multisensorielle chemin en trois dimensions

Path integration is a process in which self-motion is integrated over time to obtain an estimate of one's current position relative to a starting point 1. ...

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Neurosciences

Protocol for Three-dimensional Confocal Morphometric Analysis of Astrocytes

As glial cells in the brain, astrocytes have diverse functional roles in the central nervous system. In the presence of harmful stimuli, astrocytes modify their functional and structural properties, a condition called reactive astrogliosis. Here, a protocol for assessment of the morphological properties of astrocytes is presented. This protocol includes quantification of 12 different parameters i.e. the surface area and volume of the tissue covered by an astrocyte (astrocyte territory), the entire astrocyte including branches, cell body, and nucleus, as well as total length and number of branches, the intensity of fluorescence immunoreactivity of antibodies used for astrocyte detection, and astrocyte density (number/1,000 &#181;m2). For this purpose three-dimensional (3D) confocal microscopic images were created, and 3D image analysis software such as Volocity 6.3 was used for measurements. Rat brain tissue exposed to amyloid beta1-40 (A&#946;1-40) with or without a therapeutic&#160;intervention was used to present the method. This protocol can also be used for 3D morphometric analysis of other cells from either in vivo or in vitro conditions.

Astrocytes in the CNS change their functional and structural properties in response to harmful stimuli. This report presents a protocol for assessment of three-dimensional astrocyte morphology in diseased conditions or after therapeutic interventions.

Protocole pour tridimensionnelle confocale Analyse morphométrique des astrocytes

As glial cells in the brain, astrocytes have diverse functional roles in the central nervous system. In the presence of harmful stimuli, astrocytes modify ...

A Rat Model of Central Fatigue Using a Modified Multiple Platform Method

In this article, we introduced a rat model of central fatigue using the modified multiple platform method (MMPM). The Multiple Platform box was designed as a water tank with narrow platforms on the bottom. The model rats were put into the tank and stood on the platforms for 14 h (18:00 - 8:00) per day for a consecutive 21 days, with a blank control group set for contrast. At the end of modeling, rats in the model group showed an obvious fatigued appearance. To assess the model, we performed several behavioral tests, including the open field test (OFT), the elevated plus maze (EPM) test, and the exhaustive swimming (ES) test. The results showed that anxiety, spatial cognition impairment, poor muscle performance, and declined voluntary activity presented in model rats confirm the diagnosis of&#160;central fatigue. Changes of the central neurotransmitters also verified the result. In conclusion, the model successfully simulated central fatigue, and future study with the model may help reveal the pathological mechanism of the disease.

Here, we present a protocol to introduce a rat model of central fatigue using the modified multiple platform method (MMPM).

Un Rat Model of Fatigue centrale utilisant une mis à jour le méthode de plate-forme Multiple

In this article, we introduced a rat model of central fatigue using the modified multiple platform method (MMPM). The Multiple Platform box was designed ...

Large-scale Three-dimensional Imaging of Cellular Organization in the Mouse Neocortex

The mammalian neocortex is composed of many types of excitatory and inhibitory neurons, each with specific electrophysiological and biochemical properties, synaptic connections, and in vivo functions, but their basic functional and anatomical organization from cellular to network scale is poorly understood. Here we describe a method for the three-dimensional imaging of fluorescently-labeled neurons across large areas of the brain for the investigation of the cortical cellular organization. Specific types of neurons are labeled by the injection of fluorescent retrograde neuronal tracers or expression of fluorescent proteins in transgenic mice. Block brain samples, e.g., a hemisphere, are prepared after fixation, made transparent with tissue clearing methods, and subjected to fluorescent immunolabeling of the specific cell types. Large areas are scanned using confocal or two-photon microscopes equipped with large working distance objectives and motorized stages. This method can resolve the periodic organization of the cell type-specific microcolumn functional modules in the mouse neocortex. The procedure can be useful for the study of three-dimensional cellular architecture in the diverse brain areas and other complex tissues.

Here we describe a procedure for tissue clearing, fluorescent labeling, and large-scale imaging of mouse brain tissue which, thereby, enables visualization of the three-dimensional organization of cell types in the neocortex.

Imagerie tridimensionnelle à grande échelle de l’organisation cellulaire dans le néocortex de souris

The mammalian neocortex is composed of many types of excitatory and inhibitory neurons, each with specific electrophysiological and biochemical ...

Three-Dimensional Shape Modeling and Analysis of Brain Structures

Statistical shape analysis of brain structures has been used to investigate the association between their structural changes and pathological processes. We have developed a software package for accurate and robust shape modeling and group-wise analysis. Here, we introduce an pipeline for the shape analysis, from individual 3D shape modeling to quantitative group shape analysis. We also describe the pre-processing and segmentation steps using open software packages. This practical guide would help researchers save time and effort in 3D shape analysis on brain structures.

We introduce a semi-automatic protocol for shape analysis on brain structures, including image segmentation using open software, and further group-wise shape analysis using an automated modeling package. Here, we demonstrate each step of the 3D shape analysis protocol with hippocampal segmentation from brain MR images.

Modélisation et analyse tridimensionnelles de la forme des structures cérébrales

Statistical shape analysis of brain structures has been used to investigate the association between their structural changes and pathological processes. ...

In Vivo Three-Dimensional Two-Photon Microscopy to Study Conducted Vascular Responses by Local ATP Ejection Using a Glass Micro-Pipette

Maintenance of normal brain function requires a sufficient and efficient supply of oxygen and nutrition by a complex network of vessels. However, the regulation of cerebral blood flow (CBF) is incompletely understood, especially at the capillary level. Two-photon microscopy is a powerful tool widely used to study CBF and its regulation. Currently, this field is limited by the lack of in vivo two-photon microscopy studies examining (1) CBF responses in three-dimensions, (2) conducted vascular responses, and (3) localized interventions within the vascular network. Here, we describe a 3D in vivo method using two-photon microscopy to study conducted vascular responses elicited by&#160;local ejection of ATP with a glass micro-pipette. Our method uses fast and repetitive hyperstack two-photon imaging providing precise diameter measurements by maximal intensity projection of the obtained images. Furthermore, we show that this method can also be used to study 3D astrocytic calcium responses. We also discuss the advantages and limitations of glass micro-pipette insertion and two-photon hyperstack imaging.

We present an optimized local ejection procedure using a glass micro-pipette and a fast two-photon hyperstack imaging method, which allows precise measurement of capillary diameter changes and investigation of its regulation in three dimensions.

In Vivo Tri-Dimensional Two-Photon Microscopy to Study Conducted Vascular Responses by Local ATP Ejection Using a Glass Micro-Pipette In Vivo Tri-Dimensional Two-Photon Microscopy to Study Conducted Vascular Responses by Local ATP Ejection Using a Glass Micro-Pipette In Vivo

Maintenance of normal brain function requires a sufficient and efficient supply of oxygen and nutrition by a complex network of vessels. However, the ...

Three-Dimensional Motor Nerve Organoid Generation

A fascicle of axons is one of the major structural motifs observed in the nervous system. Disruption of axon fascicles could cause developmental and neurodegenerative diseases. Although numerous studies of axons have been conducted, our understanding of formation and dysfunction of axon fascicles is still limited due to the lack of robust three-dimensional in vitro models. Here, we describe a step-by-step protocol for the rapid generation of a motor nerve organoid (MNO) from human induced pluripotent stem (iPS) cells in a microfluidic-based tissue culture chip. First, fabrication of chips used for the method is described. From human iPS cells, a motor neuron spheroid (MNS) is formed. Next, the differentiated MNS is transferred into the chip. Thereafter, axons spontaneously grow out of the spheroid and assemble into a fascicle within a microchannel equipped in the chip, which generates an MNO tissue carrying a bundle of axons extended from the spheroid. For the downstream analysis, MNOs can be taken out of the chip to be fixed for morphological analyses or dissected for biochemical analyses, as well as calcium imaging and multi-electrode array recordings. MNOs generated with this protocol can facilitate drug testing and screening and can contribute to understanding of mechanisms underlying development and diseases of axon fascicles.

This protocol provides a comprehensive procedure to fabricate human iPS cell-derived motor nerve organoid through spontaneous assembly of a robust bundle of axons extended from a spheroid in a tissue culture chip.

Génération organoïde tridimensionnelle de nerf moteur

A fascicle of axons is one of the major structural motifs observed in the nervous system. Disruption of axon fascicles could cause developmental and ...

Measuring the Influence of Magnetic Vestibular Stimulation on Nystagmus, Self-Motion Perception, and Cognitive Performance in a 7T MRT

Strong magnetic fields induce dizziness, vertigo, and nystagmus due to Lorentz forces acting on the cupula in the semi-circular canals, an effect called magnetic vestibular stimulation (MVS). In this article, we present an experimental setup in a 7T MRT scanner (MRI scanner) that allows the investigation of the influence of strong magnetic fields on nystagmus as well as perceptual and cognitive responses. The strength of MVS is manipulated by altering the head positions of the participants. The orientation of the participants&#39; semicircular canals with respect to the static magnetic field is assessed by combining a 3D magnetometer and 3D constructive interference in steady-state (3D-CISS) images. This approach allows to account for intra- and inter-individual differences in participants&#8217; responses to MVS. In the future, MVS can be useful for clinical research, for example, in the investigation of compensatory processes in vestibular disorders. Furthermore, it could foster insights into the interplay between vestibular information and cognitive processes in terms of spatial cognition and the emergence of self-motion percepts under conflicting sensory information. In fMRI studies, MVS can elicit a possible confounding effect, especially in tasks influenced by vestibular information or in studies comparing vestibular patients with healthy controls.

In this article, we describe the experimental setup, material, and procedures to assess reflexive eye movements, self-motion perception, and cognitive tasks under magnetic vestibular stimulation, as well as the anatomical orientation of the vestibular organs, in a 7 Tesla Magnetic resonance tomography (7T-MRT) scanner.

Mesure de l’influence de la stimulation vestibulaire magnétique sur le nystagmus, la perception du mouvement de soi et les performances cognitives dans un MRT 7T

Strong magnetic fields induce dizziness, vertigo, and nystagmus due to Lorentz forces acting on the cupula in the semi-circular canals, an effect called ...

Production of Human Neurogenin 2-Inducible Neurons in a Three-Dimensional Suspension Bioreactor

The derivation of neuronal lineage cells from human induced pluripotent stem cells (hiPSCs) marked a milestone in brain research. Since their first advent, protocols have been continuously optimized and are now widely used in research and drug development. However, the very long duration of these conventional differentiation and maturation protocols and the increasing demand for high-quality hiPSCs and their neural derivatives raise the need for the adoption, optimization, and standardization of these protocols to large-scale production. This work presents a fast and efficient protocol for the differentiation of genetically modified, doxycycline-inducible neurogenin 2 (iNGN2)-expressing hiPSCs into neurons using a benchtop three-dimensional (3D) suspension bioreactor.
In brief, single-cell suspensions of iNGN2-hiPSCs were allowed to form aggregates within 24 h, and neuronal lineage commitment was induced by the addition of doxycycline. Aggregates were dissociated after 2 days of induction and cells were either cryopreserved or replated for terminal maturation. The generated iNGN2 neurons expressed classical neuronal markers early on and formed complex neuritic networks within 1 week after replating, indicating an increasing maturity of neuronal cultures. In summary, a detailed step-by-step protocol for the fast generation of hiPSC-derived neurons in a 3D environment is provided that holds great potential as a starting point for disease modeling, phenotypic high-throughput drug screenings, and large-scale toxicity testing.

This article describes a protocol for the generation of human induced pluripotent stem cell-derived neurons in a benchtop 3D suspension bioreactor.

Production de neurones 2-inductibles de neurogénine humaine dans un bioréacteur en suspension tridimensionnel

The derivation of neuronal lineage cells from human induced pluripotent stem cells (hiPSCs) marked a milestone in brain research. Since their first ...

In vivo Imagerie du cerveau entier des larves de poisson-zèbre

In Vivo Whole-Brain Imaging of Zebrafish Larvae Using Three-Dimensional Fluorescence Microscopy

As a vertebrate model animal, larval zebrafish are widely used in neuroscience and provide a unique opportunity to monitor whole-brain activity at the cellular resolution. Here, we provide an optimized protocol for performing whole-brain imaging of larval zebrafish using three-dimensional fluorescence microscopy, including sample preparation and immobilization, sample embedding, image acquisition, and visualization after imaging. The current protocol enables in vivo imaging of the structure and neuronal activity of a larval zebrafish brain at a cellular resolution for over 1 h using confocal microscopy and custom-designed fluorescence microscopy. The critical steps in the protocol are also discussed, including sample mounting and positioning, preventing bubble formation and dust in the agarose gel, and avoiding motion in images caused by incomplete solidification of the agarose gel and paralyzation of the fish. The protocol has been validated and confirmed in multiple settings. This protocol can be easily adapted for imaging other organs of a larval zebrafish.

Pleins feux sur l’auteur : Imagerie in vivo de l’ensemble du cerveau des larves de poisson-zèbre à l’aide de la microscopie à fluorescence tridimensionnelle  

Presented here is a protocol for in vivo whole-brain imaging of larval zebrafish using three-dimensional fluorescence microscopy. The experimental procedure includes sample preparation, image acquisition, and visualization.

In vivo Imagerie du cerveau entier de larves de poisson-zèbre à l’aide de la microscopie à fluorescence tridimensionnelle

As a vertebrate model animal, larval zebrafish are widely used in neuroscience and provide a unique opportunity to monitor whole-brain activity at the ...