Piryankova I.V.,Max Planck Institute for Biological Cybernetics |
Piryankova I.V.,Center for Integrative Neuroscience |
De La Rosa S.,Max Planck Institute for Biological Cybernetics |
Kloos U.,Reutlingen University |
And 3 more authors.
Displays | Year: 2013
Many scientists have demonstrated that compared to the real world egocentric distances in head-mounted display virtual environments are underestimated. However, distance perception in large screen immersive displays has received less attention. We investigate egocentric distance perception in a virtual office room projected using a semi-spherical, a Max Planck Institute CyberMotion Simulator cabin and a flat large screen immersive display. The goal of our research is to systematically investigate distance perception in large screen immersive displays with commonly used technical specifications. We specifically investigate the role of distance to the target, stereoscopic projection and motion parallax on distance perception. We use verbal reports and blind walking as response measures for the real world experiment. Due to the limited space in the three large screen immersive displays we use only verbal reports as the response measure for the experiments in the virtual environment. Our results show an overall underestimation of distance perception in the large screen immersive displays, while verbal estimates of distances are nearly veridical in the real world. We find that even when providing motion parallax and stereoscopic depth cues to the observer in the flat large screen immersive display, participants estimate the distances to be smaller than intended. Although stereo cues in the flat large screen immersive display do increase distance estimates for the nearest distance, the impact of the stereoscopic depth cues is not enough to result in veridical distance perception. Further, we demonstrate that the distance to the target significantly influences the percent error of verbal estimates in both the real and virtual world. The impact of the distance to the target on the distance judgments is the same in the real world and in two of the used large screen displays, namely, the MPI CyberMotion Simulator cabin and the flat displays. However, in the semi-spherical display we observe a significantly different influence of distance to the target on verbal estimates of egocentric distances. Finally, we discuss potential reasons for our results. Based on the findings from our research we give general suggestions that could serve as methods for improving the LSIDs in terms of the accuracy of depth perception and suggest methods to compensate for the underestimation of verbal distance estimates in large screen immersive displays. © 2013 Elsevier B.V. All rights reserved.
Synofzik M.,University of Tubingen |
Synofzik M.,German Center for Neurodegenerative Diseases |
Ilg W.,Hertie Institute for Clinical Brain Research |
Ilg W.,Center for Integrative Neuroscience
BioMed Research International | Year: 2014
The cerebellum is essentially involved in movement control and plays a critical role in motor learning. It has remained controversial whether patients with degenerative cerebellar disease benefit from high-intensity coordinative training. Moreover, it remains unclear by which training methods and mechanisms these patients might improve their motor performance. Here, we review evidence from different high-intensity training studies in patients with degenerative spinocerebellar disease. These studies demonstrate that high-intensity coordinative training might lead to a significant benefit in patients with degenerative ataxia. This training might be based either on physiotherapy or on whole-body controlled videogames ("exergames"). The benefit shown in these studies is equal to regaining one or more years of natural disease progression. In addition, first case studies indicate that even subjects with advanced neurodegeneration might benefit from such training programs. For both types of training, the observed clinical improvements are paralleled by recoveries in ataxia-specific dysfunctions (e.g., multijoint coordination and dynamic stability). Importantly, for both types of training, the retention of the effects seems to depend on the frequency and continuity of training. Based on these studies, we here present preliminary recommendations for clinical practice, and articulate open questions that might guide future studies on neurorehabilitation in degenerative spinocerebellar disease. © 2014 Matthis Synofzik and Winfried Ilg.
Zuccotti A.,University of Tubingen |
Zuccotti A.,University of Heidelberg |
Lee S.C.,University of Tubingen |
Campanelli D.,University of Tubingen |
And 12 more authors.
Frontiers in Molecular Neuroscience | Year: 2013
Voltage-gated L-type Ca2+ channels (L-VGCCs) like CaV1.2 are assumed to play a crucial role for controlling release of trophic peptides including brain-derived neurotrophic factor (BDNF). In the inner ear of the adult mouse, beside the well described L-VGCC CaV1.3, also CaV1.2 is expressed. Due to lethality of constitutive CaV1.2 KO mice, the function of this ion channel as well as its putative relationship to BDNF in the auditory system is entirely elusive. We recently described that BDNF plays a differential role for inner hair cell (IHC) vesicles release in normal and traumatized condition. To elucidate a presumptive role of CaV1.2 during this process, two tissue-specific conditional mouse lines were generated. To distinguish the impact of CaV1.2 on the cochlea from that on feedback loops from higher auditory centers CaV1.2 was deleted, in one mouse line, under the Pax2 promoter (CaV1.2Pax2) leading to a deletion in the spiral ganglion neurons (SGN), dorsal cochlear nucleus (DCN), and inferior colliculus (IC). In the second mouse line, the Egr2 promoter was used for deleting CaV1.2 (CaV1.2Egr2) in auditory brainstem nuclei. In both mouse lines normal hearing threshold and equal number of IHC release sites were observed. We found a slight reduction of auditory brainstem response (ABR) wave I amplitudes in the CaV1.2Pax2 mice but not in the CaV1.2Egr2 mice. After noise exposure, CaV1.2Pax2 mice had less pronounced hearing loss that correlated with maintenance of ribbons in IHCs and less reduced activity in auditory nerve fibers, as well as in higher brain centers at supra-threshold sound stimulation. As reduced cochlear BDNF mRNA levels were found in CaV1.2Pax2 mice, we suggest that a CaV1.2 dependent step may participate in triggering part of the beneficial and deteriorating effects of cochlear BDNF in intact systems and during noise exposure through a pathway that is independent of Cav1.2 function in efferent circuits. © 2013 Zuccotti, Lee, Campanelli, Singer, Satheesh, Patriarchi, Geisler, Köpschall, Rohbock, Nothwang, Hu, Hell, Schimmang, Rüttiger and Knipper.
Rosendal F.,Aarhus University Hospital |
Chakravarty M.M.,Center for Integrative Neuroscience |
Chakravarty M.M.,Aarhus University Hospital |
Sunde N.,Aarhus University Hospital |
And 6 more authors.
Stereotactic and Functional Neurosurgery | Year: 2010
The intercommissural line joining the anterior and posterior commissures defines stereotactic coordinate systems used in functional neurosurgical procedures. Such coordinate systems are generally accepted in humans and nonhuman primate experimental settings and provide high stereotactic precision and reproducibility. The ethical concern surrounding the use of nonhuman primates has motivated and helped popularize the use of the Göttingen minipig as an alternative experimental model for experimental functional neurosurgery. We investigated the position and variability of the intercommissural line in the minipig brain using in vivo MRI. From these data, standard coordinates for the minipig basal ganglia were estimated. We found the variability of the intercommissural line to be small in the Göttingen minipig and the variability of the basal ganglia structures to the mid-commissural point to be minor. © 2010 S. Karger AG, Basel.
Theis L.,Center for Integrative Neuroscience |
Hoffman M.D.,Adobe Research
32nd International Conference on Machine Learning, ICML 2015 | Year: 2015
Stochastic variational inference allows for fast posterior inference in complex Bayesian models. However, the algorithm is prone to local optima which can make the quality of the posterior approximation sensitive to the choice of hyperparameters and initialization. We address this problem by replacing the natural gradient step of stochastic varitional inference with a trust-region update. We show that this leads to generally better results and reduced sensitivity to hyperparameters. We also describe a new strategy for variational inference on streaming data and show that here our trust-region method is crucial for getting good performance. © Copyright 2015 by International Machine Learning Society (IMLS). All rights reserved.