Neurogenesis Drives Stimulus Decorrelation in a Model of the Olfactory Bulb

The reshaping and decorrelation of similar activity patterns by neuronal networks can enhance their discriminability, storage, and retrieval. How can such networks learn to decorrelate new complex patterns, as they arise in the olfactory system? Using a computational network model for the dominant neural populations of the olfactory bulb we show that fundamental aspects of the adult neurogenesis observed in the olfactory bulb -- the persistent addition of new inhibitory granule cells to the network, their activity-dependent survival, and the reciprocal character of their synapses with the principal mitral cells -- are sufficient to restructure the network and to alter its encoding of odor stimuli adaptively so as to reduce the correlations between the bulbar representations of similar stimuli. The decorrelation is quite robust with respect to various types of perturbations of the reciprocity. The model parsimoniously captures the experimentally observed role of neurogenesis in perceptual learning and the enhanced response of young granule cells to novel stimuli. Moreover, it makes specific predictions for the type of odor enrichment that should be effective in enhancing the ability of animals to discriminate similar odor mixtures

Influence of Dynamic Field of View Restrictions on Rotation Gain Perception in Virtual Environments

International audienceThe perception of rotation gain, defined as a modification of the virtual rotation with respect to the real rotation, has been widely studied to determine detection thresholds and widely applied to redirected navigation techniques. In contrast, Field of View (FoV) restrictions have been explored in virtual reality as a mitigation strategy for motion sickness, although they can alter user's perception and navigation performance in virtual environments. This paper explores whether the use of dynamic FoV manipulations, referred also as vignetting, could alter the perception of rotation gains during virtual rotations in virtual environments (VEs). We conducted a study to estimate and compare perceptual thresholds of rotation gains while varying the vignetting type (no vignetting, horizontal and global vignetting) and the vignetting effect (luminance or blur). 24 Participants performed 60 or 90 degrees virtual rotations in a virtual forest, with different rotation gains applied. Participants have to choose whether or not the virtual rotation was greater than the physical one. Results showed that the point of subjective equality was different across the vignetting types, but not across the vignetting effect or the turns. Subjective questionnaires indicated that vignetting seems less comfortable than the baseline condition to perform the task. We discuss the applications of such results to improve the design of vignetting for redirection techniques

Los espacios eróticos en Prosas profanas de Rubén Darío

Esta ponencia se propone estudiar algunos de los espacios presentes en Prosas profanas de Rubén Darío. A partir de las apreciaciones propuestas por Claude Calame en Eros en la Antigua Grecia quien distingue los espacios de la pólis desde lo femenino y desde lo masculino. Estos últimos, están integrados en la ciudad y son propios de Eros y los primeros están en los prados, confundidos con jardines, llenos de flores, ámbitos donde comienzan los juegos eróticos para pasar a los jardines de Afrodita en los que se da la transición de la adolescencia a la madurez sexual (Calame, 2002, p. 160). Así también, en la poesía del nicaragüense los espacios, como los jardines versallescos, palacios o salones, son los que albergan al erotismo y a las figuras femeninas que analizamos detenidamente en consonancia con la tradición clásica. La Belleza sobrenatural de las diosas grecorromanas y la belleza femenina en general van a conducir y traducir a la poesía misma y a eso apunta nuestro trabajo. Veremos así, cómo la elección de Eros en vez de Venus o al revés nos marcan el camino para una lectura de la concepción erótica del poeta, un itinerario hacia la consumación del amor o hacia la conquista y los juegos del deseo