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Gibert G.,French Institute of Health and Medical Research | Gibert G.,Stem Cell and Brain Research Institute | Gibert G.,University of Lyon | Gibert G.,University of Western Sydney | And 9 more authors.
European Signal Processing Conference | Year: 2012

Virtual humans have become part of our everyday life (movies, internet, and computer games). Even though they are more and more realistic, their speech capabilities are, most of the time, limited and not coherent and/or not synchronous with the corresponding acoustic signal. We describe a method to convert a virtual human avatar (animated through key frames and interpolation) into a more naturalistic talking head. Speech-capabilities were added to the avatar using real speech production data. Electromagnetic articulography (EMA) data provided lip, jaw and tongue trajectories of a speaker involved in face to face communication. An articulatory model driving jaw, lip and tongue movements was built. Constraining the key frame values, a corresponding high definition tongue articulatory model was developed. The resulting avatar was able to produce visible and partly occluded facial speech movements coherent and synchronous with the acoustic signal. © 2012 EURASIP. Source


Gibert G.,French Institute of Health and Medical Research | Gibert G.,Stem Cell and Brain Research Institute | Gibert G.,University of Lyon | Gibert G.,University of Western Sydney | And 2 more authors.
Speech Communication | Year: 2013

Several puppetry techniques have been recently proposed to transfer emotional facial expressions to an avatar from a user's video. Whereas generation of facial expressions may not be sensitive to small tracking errors, generation of speech-related facial movements would be severely impaired. Since incongruent facial movements can drastically influence speech perception, we proposed a more effective method to transfer speech-related facial movements from a user to an avatar. After a facial tracking phase, speech articulatory parameters (controlling the jaw and the lips) were determined from the set of landmark positions. Two additional processes calculated the articulatory parameters which controlled the eyelids and the tongue from the 2D Discrete Cosine Transform coefficients of the eyes and inner mouth images. A speech in noise perception experiment was conducted on 25 participants to evaluate the system. Increase in intelligibility was shown for the avatar and human auditory-visual conditions compared to the avatar and human auditory-only conditions, respectively. Depending on the vocalic context, the results of the avatar auditory-visual presentation were different: all the consonants were better perceived in /a/ vocalic context compared to /i/ and /u/ because of the lack of depth information retrieved from video. This method could be used to accurately animate avatars for hearing impaired people using information technologies and telecommunication. © 2012 Elsevier B.V. All rights reserved. Source


Mottet B.,Joseph Fourier University | Mottet B.,University Hospital | Chiquet C.,Joseph Fourier University | Chiquet C.,University Hospital | And 6 more authors.
Investigative Ophthalmology and Visual Science | Year: 2012

Purpose. We evaluated the supine 24-hour IOP rhythm reproducibility over 6 weeks in healthy humans. Methods. Six healthy young male subjects underwent six 24-hour sessions of IOP measurements over a 6-week period. Subjects were housed in a sleep laboratory in a constant controlled supine position and in a strictly controlled environment. IOP was measured hourly using a pneumatonometer. A nonlinear least-squares dual harmonic regression analysis was used to model the 24-hour IOP rhythm. The intra- and intersubject variability of acrophase, bathyphase, amplitude, and IOP values were evaluated. Results. A significant nyctohemeral IOP rhythm was noted in 30 of 36 (83%) sessions. Mean nocturnal IOP was significantly higher than diurnal IOP (20.1 ± 0.2 mm Hg [SD] vs. 18.8 ± 0.1 mm Hg, P < 0.001) in all subjects. Amplitudes were not statistically different among subjects (P = 0.52). In contrast, acrophase and bathyphase were statistically different (P < 0.05). Intrasubject homogeneity of distribution over time of the acrophase and bathyphase was significant in 3 of 6 and 4 of 6 subjects, respectively. Intraclass correlation coefficients of midline estimating statistic of rhythm (MESOR) and IOP values at 2:00, 3:00, 4:00, 10:00, and 11:00 AM, and 2:00 PM showed fair to good agreement among sessions. Conclusions. In a constant supine position, all subjects exhibited a nyctohemeral IOP rhythm present at an average rate of 80% of all sessions. With the currently available methods of tonometry, intrasubject reproducibility of rhythmic parameters and IOP values is limited. IOP values in the morning and IOP MESOR were the most reproducible parameters among the six visits. © 2012 The Association for Research in Vision and Ophthalmology, Inc. Source


O'Reilly J.X.,University of Oxford | Croxson P.L.,Mount Sinai School of Medicine | Jbabdi S.,University of Oxford | Sallet J.,University of Oxford | And 8 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

In the absence of external stimuli or task demands, correlations in spontaneous brain activity (functional connectivity) reflect patterns of anatomical connectivity. Hence, resting-state functional connectivity has been used as a proxy measure for structural connectivity and as a biomarker for brain changes in disease. To relate changes in functional connectivity to physiological changes in the brain, it is important to understand how correlations in functional connectivity depend on the physical integrity of brain tissue. The causal nature of this relationship has been called into question by patient data suggesting that decreased structural connectivity does not necessarily lead to decreased functional connectivity. Here we provide evidence for a causal but complex relationship between structural connectivity and functional connectivity: we tested interhemispheric functional connectivity before and after corpus callosum section in rhesus monkeys. We found that forebrain commissurotomy severely reduced interhemispheric functional connectivity, but surprisingly, this effect was greatly mitigated if the anterior commissure was left intact. Furthermore, intact structural connections increased their functional connectivity in line with the hypothesis that the inputs to each node are normalized. We conclude that functional connectivity is likely driven by corticocortical white matter connections but with complex network interactions such that a near-normal pattern of functional connectivity can be maintained by just a few indirect structural connections. These surprising results highlight the importance of network-level interactions in functional connectivity and may cast light on various paradoxical findings concerning changes in functional connectivity in disease states. Source


Gerardin P.,Stem Cell and Brain Research Institute | Gerardin P.,University of Lyon | Nicolas J.,University of Lyon | Farne A.,University of Lyon | Pelisson D.,University of Lyon
Investigative Ophthalmology and Visual Science | Year: 2015

PURPOSE. Visual exploration relies on saccadic eye movements and attention processes. Saccadic adaptation mechanisms, which calibrate the oculo motor commands to continuously maintain the accuracy of saccades, have been suggested to act at downstream (motor) andupstream (visuoattentional) levels of visuo motor transformation. Conversely, whether attention can directly affect saccadic adaptation remains unknown. To answer this question, we manipulated the level of attention engaged in a visual discrimination task performed during saccadic adaptation. METHODS. Participants performed low or high attention demanding orientation discrimination tasks on largely or faintly oriented Gabor patches, respectively, which served as targets for reactive saccades. Gabor patches systematically jumped backward during eye motion to elicit an adaptive shortening of saccades, and replaced 50 msec later (100 msec in two subjects) by a mask. Subjects judged whether Gabors’ orientation was “nearly horizontal” versus “nearly vertical” (low attention demanding) or “slightly left” versus “slightly right” (high attention demanding), or made no discrimination (control task). RESULTS. We found that the build-up and the retention of adaptation of reactive saccades were larger in the “high attention demanding” condition than in the “low attention demanding” and the no-discrimination control conditions. CONCLUSIONS. These results indicate that increasing the level of attention to the perceptual processing of otherwise identical targets boosts saccadic adaptation, and suggest that saccadic adaptation mechanisms and attentional load effects may functionally share common neural substrates. © 2015 The Association for Research in Vision and Ophthalmology, Inc. Source

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