Acoustic Overexposure Increases the Expression of VGLUT-2 Mediated Projections from the Lateral Vestibular Nucleus to the Dorsal Cochlear Nucleus

The dorsal cochlear nucleus (DCN) is a first relay of the central auditory system as well as a site for integration of multimodal information. Vesicular glutamate transporters VGLUT-1 and VGLUT-2 selectively package glutamate into synaptic vesicles and are found to have different patterns of organization in the DCN. Whereas auditory nerve fibers predominantly co-label with VGLUT-1, somatosensory inputs predominantly co-label with VGLUT-2. Here, we used retrograde and anterograde transport of fluorescent conjugated dextran amine (DA) to demonstrate that the lateral vestibular nucleus (LVN) exhibits ipsilateral projections to both fusiform and deep layers of the rat DCN. Stimulating the LVN induced glutamatergic synaptic currents in fusiform cells and granule cell interneurones. We combined the dextran amine neuronal tracing method with immunohistochemistry and showed that labeled projections from the LVN are co-labeled with VGLUT-2 by contrast to VGLUT-1. Wistar rats were exposed to a loud single tone (15 kHz, 110 dB SPL) for 6 hours. Five days after acoustic overexposure, the level of expression of VGLUT-1 in the DCN was decreased whereas the level of expression of VGLUT-2 in the DCN was increased including terminals originating from the LVN. VGLUT-2 mediated projections from the LVN to the DCN are likely to play a role in the head position in response to sound. Amplification of VGLUT-2 expression after acoustic overexposure could be a compensatory mechanism from vestibular inputs in response to hearing loss and to a decrease of VGLUT-1 expression from auditory nerve fibers

Integration of vestibular and proprioceptive signals for spatial updating

Frissen I, Campos JL, Souman JL, Ernst MO. Integration of vestibular and proprioceptive signals for spatial updating. Experimental Brain Research. 2011;212(2):163-176.Spatial updating during self-motion typically involves the appropriate integration of both visual and non-visual cues, including vestibular and proprioceptive information. Here, we investigated how human observers combine these two non-visual cues during full-stride curvilinear walking. To obtain a continuous, real-time estimate of perceived position, observers were asked to continuously point toward a previously viewed target in the absence of vision. They did so while moving on a large circular treadmill under various movement conditions. Two conditions were designed to evaluate spatial updating when information was largely limited to either proprioceptive information (walking in place) or vestibular information (passive movement). A third condition evaluated updating when both sources of information were available (walking through space) and were either congruent or in conflict. During both the passive movement condition and while walking through space, the pattern of pointing behavior demonstrated evidence of accurate egocentric updating. In contrast, when walking in place, perceived self-motion was underestimated and participants always adjusted the pointer at a constant rate, irrespective of changes in the rate at which the participant moved relative to the target. The results are discussed in relation to the maximum likelihood estimation model of sensory integration. They show that when the two cues were congruent, estimates were combined, such that the variance of the adjustments was generally reduced. Results also suggest that when conflicts were introduced between the vestibular and proprioceptive cues, spatial updating was based on a weighted average of the two inputs

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