Interhemispheric transfer time asymmetry of visual information depends on eye dominance: an electrophysiological study

International audienceThe interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual information is believed to be faster from the right to the left hemisphere in right-handers. Such an asymmetry is considered as a relevant fact in the context of the lateralization of the human brain. We show here using current source density (CSD) analyses of visually evoked potential (VEP) that, in right-handers and, to a lesser extent in left-handers, this asymmetry is in fact dependent on the sighting eye dominance, the tendency we have to prefer one eye for monocular tasks. Indeed, in right-handers, a faster interhemispheric transfer of visual information from the right to left hemisphere was observed only in participants with a right dominant eye (DE). Right-handers with a left DE showed the opposite pattern, with a faster transfer from the left to the right hemisphere. In left-handers, albeit a smaller number of participants has been tested and hence confirmation is required, only those with a right DE showed an asymmetrical interhemispheric transfer with a faster transfer from the right to the left hemisphere. As a whole these results demonstrate that eye dominance is a fundamental determinant of asymmetries in interhemispheric transfer of visual information and suggest that it is an important factor of brain lateralization

Improved resolution and signal-to-noise ratio in laser-ultrasonics by SAFT processing.

Laser-ultrasonics is an emerging nondestructive technique using lasers for the generation and detection of ultrasound which presents numerous advantages for industrial inspection. In this paper, the problem of detection by laser-ultrasonics of small defects within a material is addressed. Experimental results obtained with laser-ultrasonics are processed using the Synthetic Aperture Focusing Technique (SAFT), yielding improved flaw detectability and spatial resolution. Experiments have been performed on an aluminum sample with a contoured back surface and two flat-bottom holes. Practical interest of coupling SAFT to laser-ultrasonics is also discussed

Improvement of sensitivity of acousto-optical imaging using a powerful long pulse laser

Peer reviewed: YesNRC publication: Ye

Ultrasound-modulated optical imaging using a powerful long pulse laser

Peer reviewed: YesNRC publication: Ye

Acousto-optical imaging using a powerful long pulse laser

Peer reviewed: YesNRC publication: Ye

Ultrasound-modulated optical imaging using a confocal Fabry-Perot interferometer and a powerful long pulse laser

Ultrasound-modulated optical imaging combines the good spatial resolution of ultrasonic waves (mm scale) and the spectroscopic properties of light to detect optically absorbing objects inside thick (cm scale) highly scattering media. Light propagating in a scattering medium can interact with an ultrasonic wave thereby being tagged by a frequency shift equal to the ultrasound frequency or its harmonics. In this paper, a confocal Fabry-Perot interferometer(CFPI) is used as a tunable spectral filter to detect selectively the ultrasound-tagged photons. The CFPI allows obtaining high spectral resolution (MHz scale) while maintaining a high light gathering power when compared to other spectroscopic devices of comparable resolution. The contrast between the tagged photons and the untagged photons can be further enhanced by cascading CFPI. Moreover, the fast response of the CFPI allows performing measurements within the speckle decorrelation time typically encountered in biomedical applications. In this paper, the use of a single-frequency laser emitting powerful optical pulses allows illuminating the scattering medium only during the transit time of the probing ultrasonic pulses. Consequently, the acoustic and the optical power are both concentrated in time to enhance the signal-to-noise ratio of the tehcnique while remaining below the biomedical safety limits. The detection of optically absorbing objects (mm size) inside 30- and 60-mm thick scattering media is presented.L\u2019imagerie optique modul\ue9e aux ultrasons combine la bonne r\ue9solution spatiale des ondes ultrasoniques (\ue0 l\u2019\ue9chelle du mm) et les propri\ue9t\ue9s spectroscopiques de la lumi\ue8re pour d\ue9tecter des objets optiquement absorbants \ue0 l\u2019int\ue9rieur de milieux \ue9pais (\ue0 l\u2019\ue9chelle du cm) \ue0 forte diffusion. La propagation de la lumi\ue8re dans un milieu diffusant peut interagir avec une onde ultrasonique, \ue9tant ainsi marqu\ue9e par un d\ue9calage de fr\ue9quence \ue9gal \ue0 la fr\ue9quence des ultrasons ou de leurs harmoniques. Pour le pr\ue9sent travail, on a utilis\ue9 un interf\ue9rom\ue8tre confocal de Fabry-Perot (ICFP) comme filtre spectral r\ue9glable pour d\ue9tecter s\ue9lectivement les photons marqu\ue9s par les ultrasons. L\u2019ICFP permet d\u2019obtenir une r\ue9solution spectrale \ue9lev\ue9e (\ue0 l\u2019\ue9chelle du MHz) tout en maintenant un pouvoir de convergence de la lumi\ue8re \ue9lev\ue9 comparativement \ue0 d\u2019autres dispositifs spectroscopiques ayant une r\ue9solution comparable. Le contraste entre les photons marqu\ue9s et les photons non marqu\ue9s peut \ueatre am\ue9lior\ue9 par des ICFP en cascade. De plus, la r\ue9ponse rapide de l\u2019ICFP permet de r\ue9aliser des mesures pendant le temps de d\ue9corr\ue9lation du speckle observ\ue9 typiquement dans des applications biom\ue9dicales. L\u2019utilisation d\u2019un laser \ue0 fr\ue9quence unique \ue9mettant des impulsions optiques puissantes permet d\u2019illuminer le milieu diffusant uniquement pendant le temps de transit des impulsions ultrasoniques de d\ue9tection. En cons\ue9quence, la puissance optique et la puissance acoustique sont toutes deux concentr\ue9es dans le temps afin d\u2019am\ue9liorer le rapport signal/bruit de la technique, tout en restant sous les limites de s\ue9curit\ue9 pour des applications biom\ue9dicales. On pr\ue9sente la d\ue9tection d\u2019objets optiquement absorbants (taille de l\u2019ordre du mm) \ue0 l\u2019int\ue9rieur de milieux diffusants de 30 et 60 mm d\u2019\ue9paisseur.Peer reviewed: YesNRC publication: Ye

Acceptability of insect ingredients by innovative student chefs : an exploratory study

Background: In Western societies, the acceptability of entomophagy is low despite the sustainable and nutritional benefits of insects. It is recognized that insect meals incorporated in into familiar foods increases willingness to eat insects. Chefs can offer positive culinary insect-based experiences to their customers which can then contribute to increasing the acceptability of entomophagy by consumers. However, little is known about chefs' perceptions of the use of insect-based ingredients. Objective: The aim of this study was to explore the reasons why innovative student chefs are willing (or not) to incorporate mealworms meals into their dishes. Methodology: Semi-structured interviews were conducted with 7 innovative student chefs at the Institut de tourisme et d'hôtellerie du Québec (ITHQ). Thematic analysis based on a priori Rogers' Diffusion of Innovation Theory was conducted using transcript verbatim. Results: Most participants had a past consumption experience with entomophagy and all of them had a positive attitude toward this practice. The main perceived disadvantages of mealworm meal was the texture (granular and uneven), the odor as well as the low acceptability by consumers. Despite that, student chefs were generally willing to use insect-based ingredients, but they thought that transparency and more opportunities for consumers to try good insect-based dishes are keys to enhancing the acceptability of insect consumption. Conclusion: Understanding perceptions of innovative chefs about the use of insect-based ingredients can help to promote their use in gastronomy and ultimately improve their acceptability by consumers

Nondestructive Structure Characterization by Laser-Ultrasonics

Peer reviewed: YesNRC publication: Ye