A Neural Network Model for Temporal Sequence Learning and Motor Programming

International audienceAbstraet-A neural network model for fast learning and storage of temporal sequences is presented. The recall of a learned sequence is triggered by the occurrence of an item relating to its identity, and one of the main distinctive features of this model is that the speed at which a sequence is repeated can be freely modulated by a control subsystem. The possible applications of the model are illustrated by applying it to the production of motor forms. It is shown that any spatial shape memorized in exteroceptive terms can be reproduced in terms of movement by any of the effector systems of the body, and in particular by a simulated jointed arm, at any point in its working space and at any suitable size scale. Our theoretical approach reinforces the idea that the structures responsible for planning a movement in the central nervous system might be largely independent of the motor systems performing this movement

Chapitre 4 : Traiter des données de langage écrit recueillies avec tablette graphique

L'étude de la graphonomie (Graphonomics) dans le domaine du langage écrit est le pendant de l'étude de la parole dans le domaine du langage oral. Mais contrairement à la parole où le processus de production sonore caractérise la performance, la performance d'écriture s'étudie à partir de l'analyse conjointe du produit, c'est-à-dire de la trace écrite, et du processus, mouvement qui génère cette trace. Les tablettes graphiques, utilisées avec un ordinateur, ou les tablettes numériques, véritables ordinateurs portables sous forme d'écrans tactiles sans clavier, permettent de recueillir les coordonnées spatiales de la pointe du stylo, la pression exercée par la pointe du stylo sur la tablette, et l'inclinaison latérale et antéro-postérieure du stylo. Grâce à l'enregistrement de ces variables toutes les 5 ou 10 ms (selon la fréquence d'acquisition de 200 ou 100 Hz, respectivement), il est possible de calculer des variables spatiales relatives à la trace écrite, ainsi que des variables temporelles, cinématiques et dynamiques relatives au mouvement d'écriture. Ce chapitre expose les problématiques relatives à l'utilisation des tablettes et décrit la manière d'acquérir et d'analyser l'ensemble des variables de l'écriture manuscrite grâce à un logiciel gratuit et en libre accès que nous avons développé

Chapitre 4 : Traiter des données de langage écrit recueillies avec tablette graphique

L'étude de la graphonomie (Graphonomics) dans le domaine du langage écrit est le pendant de l'étude de la parole dans le domaine du langage oral. Mais contrairement à la parole où le processus de production sonore caractérise la performance, la performance d'écriture s'étudie à partir de l'analyse conjointe du produit, c'est-à-dire de la trace écrite, et du processus, mouvement qui génère cette trace. Les tablettes graphiques, utilisées avec un ordinateur, ou les tablettes numériques, véritables ordinateurs portables sous forme d'écrans tactiles sans clavier, permettent de recueillir les coordonnées spatiales de la pointe du stylo, la pression exercée par la pointe du stylo sur la tablette, et l'inclinaison latérale et antéro-postérieure du stylo. Grâce à l'enregistrement de ces variables toutes les 5 ou 10 ms (selon la fréquence d'acquisition de 200 ou 100 Hz, respectivement), il est possible de calculer des variables spatiales relatives à la trace écrite, ainsi que des variables temporelles, cinématiques et dynamiques relatives au mouvement d'écriture. Ce chapitre expose les problématiques relatives à l'utilisation des tablettes et décrit la manière d'acquérir et d'analyser l'ensemble des variables de l'écriture manuscrite grâce à un logiciel gratuit et en libre accès que nous avons développé

Quantification of Pulmonary Fibrosis in a Bleomycin Mouse Model Using Automated Histological Image Analysis.

Current literature on pulmonary fibrosis induced in animal models highlights the need of an accurate, reliable and reproducible histological quantitative analysis. One of the major limits of histological scoring concerns the fact that it is observer-dependent and consequently subject to variability, which may preclude comparative studies between different laboratories. To achieve a reliable and observer-independent quantification of lung fibrosis we developed an automated software histological image analysis performed from digital image of entire lung sections. This automated analysis was compared to standard evaluation methods with regard to its validation as an end-point measure of fibrosis. Lung fibrosis was induced in mice by intratracheal administration of bleomycin (BLM) at 0.25, 0.5, 0.75 and 1 mg/kg. A detailed characterization of BLM-induced fibrosis was performed 14 days after BLM administration using lung function testing, micro-computed tomography and Ashcroft scoring analysis. Quantification of fibrosis by automated analysis was assessed based on pulmonary tissue density measured from thousands of micro-tiles processed from digital images of entire lung sections. Prior to analysis, large bronchi and vessels were manually excluded from the original images. Measurement of fibrosis has been expressed by two indexes: the mean pulmonary tissue density and the high pulmonary tissue density frequency. We showed that tissue density indexes gave access to a very accurate and reliable quantification of morphological changes induced by BLM even for the lowest concentration used (0.25 mg/kg). A reconstructed 2D-image of the entire lung section at high resolution (3.6 μm/pixel) has been performed from tissue density values allowing the visualization of their distribution throughout fibrotic and non-fibrotic regions. A significant correlation (p<0.0001) was found between automated analysis and the above standard evaluation methods. This correlation establishes automated analysis as a novel end-point measure of BLM-induced lung fibrosis in mice, which will be very valuable for future preclinical drug explorations

Representative images of original and 2D-reconstructed lung sections for the quantification and the mapping of pulmonary tissue density by means of digital automatic analysis.

<p>Masson trichrome-stained images (A, E) and their respective 2D-reconstructed images (C, G) correspond to a lung section from saline control (A, C) and BLM-treated (0.75 mg/kg) lungs (E, G). Panels B, D, F, H show details from their original stained (B, F) and 2D-reconstructed (D, H) images at higher magnification. Lung tissue density was determined from thousands of micro-tiles crisscrossing entire lung sections. For mapping thousands tissue density values throughout lung section density values were graded in 20 classes of increasing values (I) and pseudocolours were assigned from blue (low density values) to yellow (high density values) according to their classification. Note that high density values (yellow) were restricted in alveolar parenchyma of BLM-treated lung (G, H) and located in fibrotic lesions evidenced in the respective original stained image (E, F). The frequency of tissue density (I) was determined from the classification of the whole unitary density values obtained in each lung section (A, E). HDFm index corresponds to the sum of the frequencies of the highest tissue density (classes 12 to 20) expressed in fibrotic foci. The mean tissue density (Dm) (J) was evaluated for each lung section from thousands of micro-tiles. Scale bars: 1 mm (A, C, E, G), 100 μm (B, D, F, H).</p

Distribution of tissue density frequency and determination of high tissue density frequency (HDFm) in saline control and bleomycin (BLM)-treated lungs.

<p>Lung tissue density was determined from several thousands of micro-tiles covering the whole lung sections of saline control (n = 6) and BLM-treated (n = 12/dosing group) mice. A: Tissue density values were graded in 20 classes of increasing values (mean ± s.e.m) and their frequency per class was expressed in percent (compared to the total number of density values). B: BLM administration induced a dose-dependent increase of HDFm which corresponded to the sum of the percentage of tissue densities from class 12 to 20. ****p<0.0001 was considered statistically significant in comparison to the non BLM-treated control group.</p