Institution
University of Fribourg
Education•Fribourg, Freiburg, Switzerland•
About: University of Fribourg is a education organization based out in Fribourg, Freiburg, Switzerland. It is known for research contribution in the topics: Population & Context (language use). The organization has 6040 authors who have published 14975 publications receiving 542500 citations. The organization is also known as: UNIFR & Universität Freiburg.
Papers published on a yearly basis
Papers
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TL;DR: Neurons in the orbitofrontal cortex of monkeys process the motivational value of rewarding outcomes of voluntary action, mainly irrespective of the spatial and visual features of reward-predicting stimuli and behavioural reactions.
Abstract: The orbital part of prefrontal cortex appears to be crucially involved in the motivational control of goal-directed behaviour. Patients with lesions of orbitofrontal cortex show impairments in making decisions about the expected outcome of actions. Monkeys with orbitofrontal lesions respond abnormally to changes in reward expectations and show altered reward preferences. As rewards constitute basic goals of behaviour, we investigated here how neurons in the orbitofrontal cortex of monkeys process information about liquid and food rewards in a typical frontal task, spatial delayed responding. The activity of orbitofrontal neurons increases in response to reward-predicting signals, during the expectation of rewards, and after the receipt of rewards. Neurons discriminate between different rewards, mainly irrespective of the spatial and visual features of reward-predicting stimuli and behavioural reactions. Most reward discriminations reflect the animals' relative preference among the available rewards, as expressed by their choice behaviour, rather than physical reward properties. Thus, neurons in the orbitofrontal cortex appear to process the motivational value of rewarding outcomes of voluntary action.
1,309 citations
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University of Oldenburg1, University of Vienna2, Zoological Society of London3, University College London4, International Union for Conservation of Nature and Natural Resources5, Lincoln University (New Zealand)6, Leibniz Association7, Free University of Berlin8, University of Auckland9, Charles University in Prague10, Stellenbosch University11, Academy of Sciences of the Czech Republic12, National and Kapodistrian University of Athens13, University of Fribourg14, University of Sassari15, University of Porto16, Sapienza University of Rome17, Durham University18, University of Konstanz19, University of Concepción20, Charles Darwin Foundation21, CABI22, University of Göttingen23, Helmholtz Centre for Environmental Research - UFZ24, Martin Luther University of Halle-Wittenberg25, United States Forest Service26, Bielefeld University27, Botanical Society of Britain and Ireland28, Environment Agency29, National Museum of Natural History30, Institut national de la recherche agronomique31, University of Silesia in Katowice32
TL;DR: In this paper, the authors used a database of 45,813 first records of 16,926 established alien species and showed that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970-2014).
Abstract: Although research on human-mediated exchanges of species has substantially intensified during the last centuries, we know surprisingly little about temporal dynamics of alien species accumulations across regions and taxa. Using a novel database of 45,813 first records of 16,926 established alien species, we show that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970-2014). Inter-continental and inter-taxonomic variation can be largely attributed to the diaspora of European settlers in the nineteenth century and to the acceleration in trade in the twentieth century. For all taxonomic groups, the increase in numbers of alien species does not show any sign of saturation and most taxa even show increases in the rate of first records over time. This highlights that past efforts to mitigate invasions have not been effective enough to keep up with increasing globalization.
1,301 citations
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TL;DR: In this paper, the authors empirically investigate a simple framework of link prediction on the basis of node similarity and propose a new similarity measure, motivated by the resource allocation process taking place on networks, which can remarkably enhance the prediction accuracy.
Abstract: Missing link prediction in networks is of both theoretical interest and practical significance in modern science. In this paper, we empirically investigate a simple framework of link prediction on the basis of node similarity. We compare nine well-known local similarity measures on six real networks. The results indicate that the simplest measure, namely Common Neighbours, has the best overall performance, and the Adamic-Adar index performs second best. A new similarity measure, motivated by the resource allocation process taking place on networks, is proposed and shown to have higher prediction accuracy than common neighbours. It is found that many links are assigned the same scores if only the information of the nearest neighbours is used. We therefore design another new measure exploiting information on the next nearest neighbours, which can remarkably enhance the prediction accuracy.
1,284 citations
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TL;DR: Recent neurophysiological studies in primates that have revealed that neurons in a limited number of brain structures carry specific signals about past and future rewards provide the first step towards an understanding of how rewards influence behaviour before they are received.
Abstract: The fundamental biological importance of rewards has created an increasing interest in the neuronal processing of reward information. The suggestion that the mechanisms underlying drug addiction might involve natural reward systems has also stimulated interest. This article focuses on recent neurophysiological studies in primates that have revealed that neurons in a limited number of brain structures carry specific signals about past and future rewards. This research provides the first step towards an understanding of how rewards influence behaviour before they are received and how the brain might use reward information to control learning and goal-directed behaviour.
1,282 citations
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TL;DR: Dopamine neurons respond phasically to alerting external stimuli with behavioral significance whose detection is crucial for learning and performing delayed response tasks.
Abstract: The present investigation had two aims: (1) to study responses of dopamine neurons to stimuli with attentional and motivational significance during several steps of learning a behavioral task, and (2) to study the activity of dopamine neurons during the performance of cognitive tasks known to be impaired after lesions of these neurons Monkeys that had previously learned a simple reaction time task were trained to perform a spatial delayed response task via two intermediate tasks During the learning of each new task, a total of 25% of 76 dopamine neurons showed phasic responses to the delivery of primary liquid reward, whereas only 9% of 163 neurons responded to this event once task performance was established This produced an average population response during but not after learning of each task Reward responses during learning were significantly more numerous and pronounced in area A10, as compared to areas A8 and A9 Dopamine neurons also showed phasic responses to the two conditioned stimuli These were the instruction cue, which was the first stimulus in each trial and indicated the target of the upcoming arm movement (58% of 76 neurons during and 44% of 163 neurons after learning), and the trigger stimulus, which was a conditioned incentive stimulus predicting reward and eliciting a saccadic eye movement and an arm reaching movement (38% of neurons during and 40% after learning) None of the dopamine neurons showed sustained activity in the delay between the instruction and trigger stimuli that would resemble the activity of neurons in dopamine terminal areas, such as the striatum and frontal cortex Thus, dopamine neurons respond phasically to alerting external stimuli with behavioral significance whose detection is crucial for learning and performing delayed response tasks The lack of sustained activity suggests that dopamine neurons do not encode representational processes, such as working memory, expectation of external stimuli or reward, or preparation of movement Rather, dopamine neurons are involved with transient changes of impulse activity in basic attentional and motivational processes underlying learning and cognitive behavior
1,276 citations
Authors
Showing all 6204 results
Name | H-index | Papers | Citations |
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Jens Nielsen | 149 | 1752 | 104005 |
Sw. Banerjee | 146 | 1906 | 124364 |
Hans Peter Beck | 143 | 1134 | 91858 |
Patrice Nordmann | 127 | 790 | 67031 |
Abraham Z. Snyder | 125 | 329 | 91997 |
Csaba Szabó | 123 | 958 | 61791 |
Robert Edwards | 121 | 775 | 74552 |
Laurent Poirel | 117 | 621 | 53680 |
Thomas Münzel | 116 | 1055 | 57716 |
David G. Amaral | 112 | 302 | 49094 |
F. Blanc | 107 | 1514 | 58418 |
Markus Stoffel | 102 | 620 | 50796 |
Vincenzo Balzani | 101 | 476 | 45722 |
Enrico Bertini | 99 | 865 | 38167 |
Sandeep Kumar | 94 | 1563 | 38652 |