http://repub.eur.nl/res/aut/25145/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/34828/ 2012-04-20T00:00:00Z Artikel 7:677 lid 1 BW regelt het ontslag op staande voet (hierna: o.o.s.v.). Uit deze bepaling zijn drie voorwaarden af te leiden, waaraan zal moeten zijn voldaan wil het o.o.s.v. rechtsgeldig zijn gegeven. Zo moet er allereerst sprake zijn geweest van een dringende reden, moet er, in de tweede plaats een onverwijlde opzegging van de arbeidsovereenkomst hebben plaatsgevonden, terwijl, in de derde plaats, de dringende reden voor het o.o.s.v. gelijktijdig aan de werknemer moet zijn medegedeeld. In het hier te annoteren arrest staat de vraag centraal wanneer sprake is van een ‘dringende reden’. De literatuur spreekt in dit verband wel over de ‘objectiviteit’ (is er naar objectieve maatstaven sprake van een dringende reden?) en ‘subjectiviteit’ (is in dit concrete geval ook sprake van een dringende reden?, hetgeen onder meer kan blijken uit de onverwijldheid) van de dringende reden (zie C.J. Loonstra & W.A. Zondag, Arbeidsrechtelijke Themata, Den Haag: BJu 2010, p. 426). Het arrest handelt over het o.o.s.v. van een medewerker van de Bijenkorf die geweigerd was in het kader van een uitverkoopactie twee artikelen meer van de Bijenkorf af te nemen dan de vijf toegestane artikelen (tegen betaling van € 10), en vervolgens – daarbij een kennelijk wat minder door de Bijenkorf op prijs gestelde interpretatie gevende aan het begrip ‘Doldwaze Dagen’ – deze twee artikelen alsnog zelf (tegen betaling van € 0) afnam. http://repub.eur.nl/res/pub/34829/ 2012-04-20T00:00:00Z Artikel 7:677 lid 1 BW regelt het ontslag op staande voet (hierna: o.o.s.v.). Uit deze bepaling zijn drie voorwaarden af te leiden, waaraan zal moeten zijn voldaan wil het o.o.s.v. rechtsgeldig zijn gegeven. Zo moet er allereerst sprake zijn geweest van een dringende reden, moet er, in de tweede plaats een onverwijlde opzegging van de arbeidsovereenkomst hebben plaatsgevonden, terwijl, in de derde plaats, de dringende reden voor het o.o.s.v. gelijktijdig aan de werknemer moet zijn medegedeeld. In het hier te annoteren arrest staat de vraag centraal wanneer sprake is van een ‘dringende reden’. De literatuur spreekt in dit verband wel over de ‘objectiviteit’ (is er naar objectieve maatstaven sprake van een dringende reden?) en ‘subjectiviteit’ (is in dit concrete geval ook sprake van een dringende reden?, hetgeen onder meer kan blijken uit de onverwijldheid) van de dringende reden (zie C.J. Loonstra & W.A. Zondag, Arbeidsrechtelijke Themata, Den Haag: BJu 2010, p. 426). Het arrest handelt over het o.o.s.v. van een medewerker van de Bijenkorf die geweigerd was in het kader van een uitverkoopactie twee artikelen meer van de Bijenkorf af te nemen dan de vijf toegestane artikelen (tegen betaling van € 10), en vervolgens – daarbij een kennelijk wat minder door de Bijenkorf op prijs gestelde interpretatie gevende aan het begrip ‘Doldwaze Dagen’ – deze twee artikelen alsnog zelf (tegen betaling van € 0) afnam. http://repub.eur.nl/res/pub/34540/ 2011-12-01T00:00:00Z The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out salient features, integration with other senses, and adaptation of the whisker system to the general behavioral state of the animal. We present here an overview of the brain regions and their connections involved in the whisker system. We do not only describe the anatomy and functional roles of the cerebral cortex, but also those of subcortical structures like the striatum, superior colliculus, cerebellum, pontomedullary reticular formation, zona incerta, and anterior pretectal nucleus as well as those of level setting systems like the cholinergic, histaminergic, serotonergic, and noradrenergic pathways. We conclude by discussing how these brain regions may affect each other and how they together may control the precise timing of whisker movements and coordinate whisker perception. http://repub.eur.nl/res/pub/20700/ 2010-06-01T00:00:00Z Activity in cortical networks is heterogeneous, sparse and often precisely timed. The functional significance of sparseness and precise spike timing is debated, but our understanding of the developmental and synaptic mechanisms that shape neuronal discharge patterns has improved. Evidence for highly specialized, selective and abstract cortical response properties is accumulating. Singe-cell stimulation experiments demonstrate a high sensitivity of cortical networks to the action potentials of some, but not all, single neurons. It is unclear how this sensitivity of cortical networks to small perturbations comes about and whether it is a generic property of cortex. The unforeseen sensitivity to cortical spikes puts serious constraints on the nature of neural coding schemes. http://repub.eur.nl/res/pub/27497/ 2010-03-01T00:00:00Z In the mammalian brain, many thousands of single-neuron recording studies have been performed but less than 10 single-cell stimulation studies. This paucity of single-cell stimulation data reflects a lack of easily applicable single-cell stimulation techniques. We provide a detailed description of the procedures involved in nanostimulation, a single-cell stimulation method derived from the juxtacellular labeling technique. Nanostimulation is easy to apply and can be directed to a wide variety of identifiable neurons in anesthetized and awake animals. We describe the recording approach and the parameters of the electric configuration underlying nanostimulation. We use glass pipettes with a DC resistance of 4-7 MΩ. Obtaining the juxtacellular configuration requires a close contact between pipette tip and neuron and is associated with a several-fold increase in resistance to values ≥20 MΩ. The recorded action potential (AP) amplitude grows to ≥2 mV, and neurons can be activated with currents in the nanoampere range-hence the term nanostimulation. While exact AP timing has not been achieved, AP frequency and AP number can be parametrically controlled. We demonstrate that nanostimulation can also be used to selectively inhibit sensory responses in identifiable neurons. Nanostimulation is biophysically similar to electroporation, and based on this assumption, we argue that nanostimulation operates on membranes in the micrometer area directly below the pipette tip, where membrane pores are induced by high transmembrane voltage. There is strong evidence to suggest that nanostimulation selectively activates single neurons and that the evoked effects are cell-specific. Nanostimulation therefore holds great potential for elucidating how single neurons contribute to behavior. http://repub.eur.nl/res/pub/29466/ 2008-11-19T00:00:00Z In mammals, most sensory information passes through the thalamus before reaching cortex. In the rat whisker system, each macrovibrissa is represented by ∼250 neurons in the ventral posterior medial nucleus (VPM) of the thalamus and ∼10,000 neurons in a cortical barrel column. Here we quantify the sensory impact of individual thalamic neurons in the rat VPM. We first trained animals to report microstimulation of VPM. All animals learned to report microstimulation currents of 2-5 μA. We then evoked action potentials (APs) in single thalamic neurons close to the microstimulation site using juxtacellular stimulation, adding on average 17.8 APs to 2.6 spontaneous APs during 200 ms current applications. A population analysis revealed that animals responded equally often in single-cell stimulation trials as in catch trials without stimulation, suggesting that APs of single thalamic cells in VPM lead to either no or only a very weak perceptual effect. These results are surprising given the relatively small number of VPM neurons and our previous observations that single neurons in other parts of the vibrissal system do have an impact on perception or motor output. Our findings therefore suggest that neural representations in whisker thalamus are more distributed than in other whisker-related structures. Copyright http://repub.eur.nl/res/pub/30169/ 2008-07-01T00:00:00Z It is unclear how the complex spatiotemporal organization of ongoing cortical neuronal activity recorded in anesthetized animals relates to the awake animal. We therefore used two-photon population calcium imaging in awake and subsequently anesthetized rats to follow action potential firing in populations of neurons across brain states, and examined how single neurons contributed to population activity. Firing rates and spike bursting in awake rats were higher, and pair-wise correlations were lower, compared with anesthetized rats. Anesthesia modulated population-wide synchronization and the relationship between firing rate and correlation. Overall, brain activity during wakefulness cannot be inferred using anesthesia. http://repub.eur.nl/res/pub/28940/ 2008-01-03T00:00:00Z Understanding how neural activity in sensory cortices relates to perception is a central theme of neuroscience. Action potentials of sensory cortical neurons can be strongly correlated to properties of sensory stimuli and reflect the subjective judgements of an individual about stimuli. Microstimulation experiments have established a direct link from sensory activity to behaviour, suggesting that small neuronal populations can influence sensory decisions. However, microstimulation does not allow identification and quantification of the stimulated cellular elements. The sensory impact of individual cortical neurons therefore remains unknown. Here we show that stimulation of single neurons in somatosensory cortex affects behavioural responses in a detection task. We trained rats to respond to microstimulation of barrel cortex at low current intensities. We then initiated short trains of action potentials in single neurons by juxtacellular stimulation. Animals responded significantly more often in single-cell stimulation trials than in catch trials without stimulation. Stimulation effects varied greatly between cells, and on average in 5% of trials a response was induced. Whereas stimulation of putative excitatory neurons led to weak biases towards responding, stimulation of putative inhibitory neurons led to more variable and stronger sensory effects. Reaction times for single-cell stimulation were long and variable. Our results demonstrate that single neuron activity can cause a change in the animal's detection behaviour, suggesting a much sparser cortical code for sensations than previously anticipated.