Royal Netherlands Academy for Arts and science

Amsterdam, Netherlands

Royal Netherlands Academy for Arts and science

Amsterdam, Netherlands

Time filter

Source Type

Ghazaleh N.,Ecole Polytechnique Federale de Lausanne | Ghazaleh N.,University of Geneva | Zwaag W.V.D.,Royal Netherlands Academy for Arts and science | Zwaag W.V.D.,Biomedical Imaging Center | And 6 more authors.
Brain Topography | Year: 2017

Animal models of hearing loss and tinnitus observe pathological neural activity in the tonotopic frequency maps of the primary auditory cortex. Here, we applied ultra high-field fMRI at 7 T to test whether human patients with unilateral hearing loss and tinnitus also show altered functional activity in the primary auditory cortex. The high spatial resolution afforded by 7 T imaging allowed tonotopic mapping of primary auditory cortex on an individual subject basis. Eleven patients with unilateral hearing loss and tinnitus were compared to normal-hearing controls. Patients showed an over-representation and hyperactivity in a region of the cortical map corresponding to low frequencies sounds, irrespective of the hearing loss and tinnitus range, which in most cases affected higher frequencies. This finding of hyperactivity in low frequency map regions, irrespective of hearing loss range, is consistent with some previous studies in animal models and corroborates a previous study of human tinnitus. Thus these findings contribute to accumulating evidence that gross cortical tonotopic map reorganization is not a causal factor of tinnitus. © 2017 Springer Science+Business Media New York


Cui F.,University of Groningen | Cui F.,Royal Netherlands Academy for Arts and science | Arnstein D.,University of Groningen | Arnstein D.,University of Tübingen | And 6 more authors.
PLoS ONE | Year: 2014

Some theories of motor control suggest efference-copies of motor commands reach somatosensory cortices. Here we used functional magnetic resonance imaging to test these models. We varied the amount of efference-copy signal by making participants squeeze a soft material either actively or passively. We found electromyographical recordings, an efference-copy proxy, to predict activity in primary somatosensory regions, in particular Brodmann Area (BA) 2. Partial correlation analyses confirmed that brain activity in cortical structures associated with motor control (premotor and supplementary motor cortices, the parietal area PF and the cerebellum) predicts brain activity in BA2 without being entirely mediated by activity in early somatosensory (BA3b) cortex. Our study therefore provides valuable empirical evidence for efference-copy models of motor control, and shows that signals in BA2 can indeed reflect an input from motor cortices and suggests that we should interpret activations in BA2 as evidence for somatosensory-motor rather than somatosensory coding alone. © 2014 Cui et al.


PubMed | University of Groningen and Royal Netherlands Academy for Arts and science
Type: | Journal: NeuroImage | Year: 2015

Here we examine whether brain responses to dynamic facial expressions of pain are influenced by our responsibility for the observed pain. Participants played a flanker task with a confederate. Whenever either erred, the confederate was seen to receive a noxious shock. Using functional magnetic resonance imaging, we found that regions of the functionally localized pain-matrix of the participants (the anterior insula in particular) were activated most strongly when seeing the confederate receive a noxious shock when only the participant had erred (and hence had full responsibility). When both or only the confederate had erred (i.e. participants shared or no responsibility), significantly weaker vicarious pain-matrix activations were measured.


Kruijt B.,Royal Netherlands Academy for Arts and science | van den Berg T.J.T.P.,Royal Netherlands Academy for Arts and science
PLoS ONE | Year: 2012

This study optically determines whether the amount of light scatter due to laser-induced damage to the intraocular lens (IOL) is significant in relation to normal straylight values in the human eye. Two IOLs with laser-induced damage were extracted from two donor eyes. Each IOL had 15 pits and/or cracks. The surface area of each pit was measured using a microscope. For 6 pits per intraocular lens the point spread function (PSF) in terms of straylight was measured and the total straylight for all 15 pits was estimated. The damage in the IOLs was scored as mild/moderate. The total damaged surface areas, for a 3.5 mm pupil, in the two IOLs were 0.13% (0.0127 mm 2) and 0.66% (0.064 mm 2), respectively. The angular dependence of the straylight caused by the damage was similar to that of the normal PSF. The total average contribution to straylight was log(s) = -0.82 and -0.42, much less than the straylight value of the normal eye. The straylight due to normal levels of laser induced damage of the IOL is much lower than normal straylight values found clinically for the normal eye and may therefore be considered not significant. © 2012 Kruijt, van den Berg.


Johnson D.G.,University of Virginia | Noorman M.,Royal Netherlands Academy for Arts and science
2014 IEEE International Symposium on Ethics in Science, Technology and Engineering, ETHICS 2014 | Year: 2014

A survey of popular, technical and scholarly literature suggests that autonomous artificial agents will populate the future. Although some visions may seem fanciful, autonomous artificial agents are being designed, built, and deployed in a wide range of sectors. The specter of future artificial agents - with more learning capacity and more autonomy - raises important questions about responsibility. Can anyone (any humans) be responsible for the behavior of entities that learn as they go and operate autonomously? This paper takes as its starting place that humans are and always should be held responsible for the behavior of machines, even machines that learn and operate autonomously. In order to prevent evolution to a future in which no humans are thought to be responsible for the behavior of artificial agents, four principles are proposed, principles that should be kept in mind as artificial agents are developed. © 2014 IEEE.


Kruijt B.,Royal Netherlands Academy for Arts and science | Van Den Berg T.J.,Royal Netherlands Academy for Arts and science
Current Eye Research | Year: 2012

Purpose: To investigate whether light scattering of posterior capsule opacifications (PCOs) changes after fixation with paraformaldehyde (PFA). Methods: The intraocular lens with the lens capsule were extracted from pseudophakic donor eyes. Images of the extracted sample were acquired pre and post PFA-fixation using a dark field microscope. Light scatter intensity was measured for different regions pre and post fixation. Results: The regression lines between the light intensities measured pre and post fixation for the three color channels showed the same slope of 0.96. Also the correlation coefficients were the same for the three color channels, namely 0.97. Conclusions: Scattering intensities of PCO tissue pre and post fixation are quantitatively similar. The effects of fixation on the optical properties of PCO can be considered small. © 2012 Informa Healthcare USA, Inc.


Kruijt B.,Royal Netherlands Academy for Arts and science | Franssen L.,Royal Netherlands Academy for Arts and science | Prick L.J.J.M.,Academic Medical Center and Oculenti | Van Vliet J.M.J.,Academic Medical Center and Oculenti | Van Den Berg T.J.T.P.,Royal Netherlands Academy for Arts and science
Optometry and Vision Science | Year: 2011

Purpose. Albinism is an inherited disorder that affects the melanin biosynthesis pathway, which results in reduced or absent pigment formation. This may lead to increased light transmission through the iris and more reflected light from the fundus. Both these effects contribute to the occurrence of ocular straylight. One aim of this study is to determine whether and how increased iris transmission and fundus reflection in subjects with albinism contributes to the occurrence of ocular straylight. The other aim is to determine the effect that an iris print-contact lens (CL) could have in terms of reducing the occurrence of ocular straylight. Methods. Ocular straylight was quantified by means of the straylight parameter s and measured as a function of angle and wavelength in 17 subjects with different types of albinism, none of whom wore an iris print-CL. The measurements were then repeated with the subjects wearing an iris print-CL to reduce the iris transmission component and thus the occurrence of ocular straylight. The contributions of transmission and reflectance components were estimated for each individual. Results. Straylight level increase varied from normal (s ≈9) to severe (8x). In 15 cases, the reflectance component contributed s >3 to up to s = 17. In eight cases, the transmission component contributed s >3 to up to s = 101. A significant reduction in straylight was observed using an iris print-CL in six subjects with elevated straylight values. In the other 11 subjects with albinism, the iris print-CL had no significant effect on straylight because of the low values of the transmission component. Conclusions. This study gives insight into the effects of transmission and reflectance on the total measured straylight occurrence in subjects with albinism. Subjects experiencing increased ocular straylight values may benefit significantly from wearing iris print-CLs because transmission of light through the natural iris may cause a significant increase in straylight. © 2011 American Academy of Optometry.


PubMed | Royal Netherlands Academy for Arts and science
Type: Journal Article | Journal: Current eye research | Year: 2012

To investigate whether light scattering of posterior capsule opacifications (PCOs) changes after fixation with paraformaldehyde (PFA).The intraocular lens with the lens capsule were extracted from pseudophakic donor eyes. Images of the extracted sample were acquired pre and post PFA-fixation using a dark field microscope. Light scatter intensity was measured for different regions pre and post fixation.The regression lines between the light intensities measured pre and post fixation for the three color channels showed the same slope of 0.96. Also the correlation coefficients were the same for the three color channels, namely 0.97.Scattering intensities of PCO tissue pre and post fixation are quantitatively similar. The effects of fixation on the optical properties of PCO can be considered small.

Loading Royal Netherlands Academy for Arts and science collaborators
Loading Royal Netherlands Academy for Arts and science collaborators