Kamermans M.,Netherlands Institute for Neuroscience |
Kamermans M.,University of Amsterdam |
Hawryshyn C.,Queen's University
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2011
In this review, we will discuss the recent literature on fish polarization vision and we will present a model on how the retina processes polarization signals. The model is based on a general retinalprocessing scheme and will be compared with the available electrophysiological data on polarization processing in the retina. The results of this model will help illustrate the functional significance of polarization vision for both feeding behaviour and navigation. First, we examine the linkage between structure and function in polarization vision in general. © 2011 The Royal Society.
Piwek L.,University of Glasgow |
McKay L.S.,Netherlands Institute for Neuroscience |
Pollick F.E.,University of Glasgow
Cognition | Year: 2014
The uncanny valley hypothesis states that the acceptability of an artificial character will not increase linearly in relation to its likeness to human form. Instead, after an initial rise in acceptability there will be a pronounced decrease when the character is similar, but not identical to human form (Mori, 1970/2012). Moreover, it has been claimed but never directly tested that movement would accentuate this dip and make moving characters less acceptable. We used a number of full-body animated computer characters along with a parametrically defined motion set to examine the effect of motion quality on the uncanny valley. We found that improving the motion quality systematically improved the acceptability of the characters. In particular, the character classified in the deepest location of the uncanny valley became more acceptable when it was animated. Our results showed that although an uncanny valley was found for static characters, the deepening of the valley with motion, originally predicted by Mori (1970/2012), was not obtained. © 2013 Elsevier B.V.
Nieuwenhuys R.,Netherlands Institute for Neuroscience
Frontiers in Neuroanatomy | Year: 2011
According to His (1891, 1893) the brainstem consists of two longitudinal zones, the dorsal alar plate (sensory in nature) and the ventral basal plate (motor in nature). Johnston and Herrick indicated that both plates can be subdivided into separate somatic and visceral zones, distinguishing somatosensory and viscerosensory zones within the alar plate, and visceromotor and somatomotor zones within the basal plate. To test the validity of this "four-functional-zones" concept, I developed a topological procedure, surveying the spatial relationships of the various cell masses in the brainstem in a single figure. Brainstems of 16 different anamniote species were analyzed, and revealed that the brainstems are clearly divisible into four morphological zones, which correspond largely with the functional zones of Johnston and Herrick. Exceptions include (1) the magnocellular vestibular nucleus situated in the viscerosensory zone; (2) the basal plate containing a number of evidently non-motor centers (superior and inferior olives). Nevertheless the functional zonal model has explanatory value. Thus, it is possible to interpret certain brain specializations related to particular behavioral profiles, as "local hypertrophies" of one or two functional columns. Recent developmental molecular studies on brains of birds and mammals confirmed the presence of longitudinal zones, and also showed molecularly defined transverse bands or neuromeres throughout development. The intersecting boundaries of the longitudinal zones and the transverse bands appeared to delimit radially arranged histogenetic domains. Because neuromeres have been observed in embryonic and larval stages of numerous anamniote species, it may be hypothesized that the brainstems of all vertebrates share a basic organizational plan, in which intersecting longitudinal and transverse zones form fundamental histogenetic and genoarchitectonic units. © 2011 Nieuwenhuys.
Keysers C.,Netherlands Institute for Neuroscience |
Gazzola V.,Netherlands Institute for Neuroscience
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2014
Spike-timing-dependent plasticity is considered the neurophysiological basis of Hebbian learning and has been shown to be sensitive to both contingency and contiguity between pre- and postsynaptic activity. Here, we will examine how applying this Hebbian learning rule to a system of interconnected neurons in the presence of direct or indirect re-afference (e.g. seeing/hearing one's own actions) predicts the emergence of mirror neurons with predictive properties. In this framework, we analyse how mirror neurons become a dynamic system that performs active inferences about the actions of others and allows joint actions despite sensorimotor delays. We explore how this system performs a projection of the self onto others, with egocentric biases to contribute to mind-reading. Finally, we argue that Hebbian learning predicts mirror-like neurons for sensations and emotions and review evidence for the presence of such vicarious activations outside the motor system.
Keysers C.,Netherlands Institute for Neuroscience |
Keysers C.,University of Groningen |
Gazzola V.,Netherlands Institute for Neuroscience |
Gazzola V.,University of Groningen
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2014
Spike-timing-dependent plasticity is considered the neurophysiological basis of Hebbian learning and has been shown to be sensitive to both contingency and contiguity between pre- and postsynaptic activity. Here, we will examine how applying this Hebbian learning rule to a system of interconnected neurons in the presence of direct or indirect re-afference (e.g. seeing/hearing one's own actions) predicts the emergence of mirror neurons with predictive properties. In this framework, we analyse how mirror neurons become a dynamic system that performs active inferences about the actions of others and allows joint actions despite sensorimotor delays. We explore how this system performs a projection of the self onto others, with egocentric biases to contribute to mind-reading. Finally, we argue that Hebbian learning predicts mirror-like neurons for sensations and emotions and review evidence for the presence of such vicarious activations outside the motor system. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Nieuwenhuys R.,Netherlands Institute for Neuroscience
Brain Structure and Function | Year: 2011
The Actinopterygii or ray-finned fishes comprise, in addition to the large superorder of teleosts, four other superorders, namely the cladistians, the chondrosteans, the ginglymodes, and the halecomorphs, each with a limited number of species. The telencephalon of actinopterygian fishes differs from that in all other vertebrates in that it consists of a pair of solid lobes. Lateral ventricles surrounded by nervous tissue are entirely lacking. At the end of the nineteenth century, the theory was advanced that the unusual configuration of the forebrain in actinopterygians results from an outward bending or eversion of its lateral walls. This theory was accepted by some authors, rejected or neglected by others, and modified by some other authors. The present paper is based on the data derived from the literature, complemented by new observations on a large collection of histological material comprising specimens of all five actinopterygian superorders. The paper consists of three parts. In the first, a survey of the development of the telencephalon in actinopterygian fishes is presented. The data collected show clearly that an outward bending or eversion of the pallial parts of the solid hemispheres is the principal morphogenetic event in all five actinopterygian superorders. In all of these superorders, except for the cladistians, eversion is coupled with a marked thickening of the pallial walls. In the second part, some aspects of the general morphology of the telencephalon in mature actinopterygians are highlighted. It is pointed out that (1) the degree of eversion varies considerably among the various actinopterygian groups; (2) eversion leads to the transformation of the telencephalic roof plate into a wide membrane or tela choroidea, which is bilaterally attached to the lateral or ventrolateral aspect of the solid hemispheres; (3) the lines of attachment or taeniae of the tela choroidea form the most important landmarks in the telencephalon of actinopterygians, indicating the sites where the greatly enlarged ventricular surface of the hemispheres ends and its reduced meningeal surface begins; (4) the meningeal surface of the telencephalon shows in most actinopterygians bilaterally a longitudinally oriented sulcus externus, the depth of which is generally positively correlated with the degree of eversion; (5) a distinct lateral olfactory tract, occupying a constant topological position close to the taenia, is present in all actinopterygians studied; and (6) this tract is not homologous to the tract of the same name in the evaginated and inverted forebrains of other groups of vertebrates. In the third and final section, the concept that the structural organization of the pallium in actinopterygians can be fully explained by a simple eversion of its walls, and the various theories, according to which the eversion is complicated by extensive shifts of its constituent cell groups, are discussed and evaluated. It is concluded that there are no reasons to doubt that the pallium of actinopterygian fishes is the product of a simple and complete eversion. © The Author(s) 2010.
Self M.W.,Netherlands Institute for Neuroscience
Current biology : CB | Year: 2013
What roles do the different cortical layers play in visual processing? We recorded simultaneously from all layers of the primary visual cortex while monkeys performed a figure-ground segregation task. This task can be divided into different subprocesses that are thought to engage feedforward, horizontal, and feedback processes at different time points. These different connection types have different patterns of laminar terminations in V1 and can therefore be distinguished with laminar recordings. We found that the visual response started 40 ms after stimulus presentation in layers 4 and 6, which are targets of feedforward connections from the lateral geniculate nucleus and distribute activity to the other layers. Boundary detection started shortly after the visual response. In this phase, boundaries of the figure induced synaptic currents and stronger neuronal responses in upper layer 4 and the superficial layers ~70 ms after stimulus onset, consistent with the hypothesis that they are detected by horizontal connections. In the next phase, ~30 ms later, synaptic inputs arrived in layers 1, 2, and 5 that receive feedback from higher visual areas, which caused the filling in of the representation of the entire figure with enhanced neuronal activity. The present results reveal unique contributions of the different cortical layers to the formation of a visual percept. This new blueprint of laminar processing may generalize to other tasks and to other areas of the cerebral cortex, where the layers are likely to have roles similar to those in area V1. Copyright © 2013 Elsevier Ltd. All rights reserved.
Marcotte L.,University of Pennsylvania |
Aronica E.,Netherlands Institute for Neuroscience |
Aronica E.,University of Amsterdam |
Baybis M.,University of Pennsylvania |
Crino P.B.,University of Pennsylvania
Acta Neuropathologica | Year: 2012
Tubers are cerebral cortical developmental malformations associated with epilepsy and autism in tuberous sclerosis complex (TSC). The disparity between tuber number and severity of neurological impairment often observed in TSC led us to hypothesize that microscopic structural abnormalities distinct from tubers may occur in TSC. Serial frontal to occipital lobe sections were prepared from five postmortem TSC brain specimens. Sections were probed with cresyl violet stain or NeuN antibodies to define cytoarchitectural abnormalities and phospho-S6 (Ser235/236) antibodies to define mammalian target of rapamycin complex 1 (mTORC1) pathway activation. Tubers identified in all specimens (mean, 5 tubers per brain specimen) were defined by abnormal cortical lamination, dysmorphic neurons, and giant cells (GCs) and exhibited robust phospho-S6 immunolabeling. Histopathological analysis of non-tuber cortices demonstrated that 32% of the sections exhibited microscopic cytoarchitectural alterations, whereas 68% of the sections did not. Four types of morphological abnormalities were defined including: (1) focal dyslamination, (2) heterotopic neurons, (3) small collections of giant cells (GCs) and neurons we termed "microtubers", (4) isolated GCs we termed "sentinel" cells. When compared with control cortex, phospho-S6 labeling was enhanced in microtubers and sentinel cells and in some but not all areas of dyslamination. There are microscopic cytoarchitectural abnormalities identified in postmortem TSC brain specimens that are distinct from tubers. mTORC1 cascade activation in these areas supports a widespread effect of TSC1 or TSC2 mutations on brain development. Tubers may represent the most dramatic developmental abnormality in TSC; however, more regionally pervasive yet subtle abnormalities may contribute to neurological disability in TSC. © Springer-Verlag 2012.
Ahmadlou M.,Netherlands Institute for Neuroscience |
Adeli A.,Ohio State University |
Bajo R.,Complutense University of Madrid |
Adeli H.,Ohio State University
Clinical Neurophysiology | Year: 2014
Objectives: The objective is to study the changes of brain activity in patients with mild cognitive impairment (MCI). Using magneto-encephalogram (MEG) signals, the authors investigate differences of complexity of functional connectivity network between MCI and normal elderly subjects during a working memory task. Methods: MEGs are obtained from 18 right handed patients with MCI and 19 age-matched elderly participants without cognitive impairment used as the control group. The brain networks' complexities are measured by Graph Index Complexity (Cr) and Efficiency Complexity (Ce). Results: The results obtained by both measurements show complexity of functional networks involved in the working memory function in MCI subjects is reduced at alpha and theta bands compared with subjects with control subjects, and at the theta band this reduction is more pronounced in the whole brain and intra left hemisphere. Conclusions: Ce would be a better measurement for showing the global differences between normal and MCI brains compared with Cr. Significance: The high accuracy of the classification shows Ce at theta band can be used as an index for assessing deficits associated with working memory, a good biomarker for diagnosis of MCI. © 2013 International Federation of Clinical Neurophysiology.
News Article | February 25, 2017
Attitudes about marijuana seem to be changing and diversifying in Latin America. Throughout the 20th century its consumption was associated with criminal behavior. But over the last decade the drug's image has improved in some countries. A new survey reveals that in some Latin countries more than 40 percent of the population is in favor of legalizing marijuana, although in other countries favor remains low. “Until now, the scientific literature showed that Latin America had a consistent position on decriminalization,” says lead author Andrés Mendiburo Seguel, a sociologist at the University of Santiago, Chile. “Our work points out that there are differences of opinion that could influence future public policies adopted in the region.” The survey was conducted by Mendiburo Seguel and researchers at Andrés Bello National University of Chile and the University of London, and was published in the International Journal of Drug Policy. The researchers interviewed 8,952 adults in large cities in nine Latin American countries: Argentina, Uruguay, Chile, Bolivia, Mexico, Peru, Costa Rica, Colombia and El Salvador. More than 40 percent of the populations of Chile, Colombia, Uruguay and Mexico are in favor of legalizing marijuana whereas in El Salvador and Bolivia that number did not exceed 10 percent. The survey also assessed the acceptance of recreational marijuana use, with favorable responses in Uruguay (68 percent), Mexico (57 percent) and Costa Rica (55 percent). Less support for such use was reported in Peru (44 percent), El Salvador (31 percent) and Bolivia (30 percent). In all countries acceptance of medicinal marijuana use, either to treat pain or epilepsy, was greater than for recreational use. “There is a correlation between the countries that most disagree with the legalization of marijuana and their level of human development. The most conservative, such as Bolivia, Peru and El Salvador have a lower level of development. They are also countries where illegal drug trafficking is a big problem. The more liberal nations, such as Uruguay and Chile, reached a better level,” according to the researchers. Yet, this is not the only possible interpretation, says Ricardo Pautassi, a researcher at the Mercedes and Martin Ferreyra Institute for Medical Research, CONICET, in Argentina, who did not participate in the survey. “The differences of opinion have to do with which public policies are being carried out in their countries. The human development index has some correlation with income, which promotes access to marijuana use. This in turn tends to facilitate positive views toward legalization for recreational and therapeutic use.” Indeed, all nine nations have enacted laws that make it a crime to produce and distribute drugs, but laws around consumption vary widely. In Bolivia, Colombia and El Salvador, for example, using marijuana is still a criminal offense. Argentina’s Supreme Court decided in 2009 that the punishment for marijuana possession without distribution to third parties was unconstitutional. In Mexico consumption of small amounts was decriminalized whereas in Uruguay personal consumption was never a crime, although in 2013 the country passed a law allowing the production and sale of marijuana in amounts regulated by the state. “We have registered 5,864 people growing cannabis, and 33 clubs with up to 45 members who are also involved in the cultivation, processing and distribution,” says Héctor Suárez, head of the Uruguayan Drug Observatory. “You can’t advertise the product but it will be sold in pharmacies in the coming months. In this way social and sanitary support is given to people with problematic consumption, while illegal drug trafficking is avoided,” he adds. Chile is debating the decriminalization of pot for recreational use, and in 2014 a pilot project for cultivating and distributing marijuana for medicinal purposes was authorized. Last December Colombia passed a law enabling marijuana for medicinal use. Peru has authorized up to eight grams of marijuana for personal use. In Costa Rica the use and possession of drugs for personal use is not considered a crime but it is not yet clear whether growing the plant for personal use is accepted. The questionnaire also measured risk perception. On average, except in Bolivia, El Salvador and Peru, most people believe tobacco and alcohol are more harmful than marijuana. “The overall assessment is correct based on studies conducted in the U.K. While it is not harmless, marijuana causes less harm and involves less risk of dependence than alcohol, tobacco and drugs such as benzodiazepines (which are prescribed as sedatives), cocaine and heroin," says Enzo Tagliazucchi, an addiction researcher at the Netherlands Institute for Neuroscience.