L. J. G. T. van Hemmen

Learn More
A correlation-based ~‘‘Hebbian’’! learning rule at a spike level with millisecond resolution is formulated, mathematically analyzed, and compared with learning in a firing-rate description. The relative timing of presynaptic and postsynaptic spikes influences synaptic weights via an asymmetric ‘‘learning window.’’ A differential equation for the learning(More)
Over a broad parameter regime, spike-time dependent learning leads to an intrinsic stabilization of the mean firing rate of the postsynaptic neuron. Subtractive normalization of the synaptic weights (summed over all presynaptic inputs converging on a postsynaptic neuron) follows if, in addition, the mean input rates are identical at all synapses and(More)
Computational tasks, such as object recognition and sound localization, rely on specific, highly organized neuronal structures in the brain. A representation of this kind of network organization is the neuronal map, where neighboring neurons are sensitive to external stimuli that possess some similarity.1, 2 To achieve this, the pairwise connections between(More)
Poster presentation The sand scorpion Paruroctonus mesaensis is able to determine the distance to its prey [1]. Experimental data shows that a sand scorpion, which has a diameter of 5 cm, can accurately determine distances up to 15 cm with an error of about 1 cm. For distances exceeding 15 cm, a scorpion must only move approximately 10 centimeters towards(More)
Life and career (by Boele Braaksma) Erik Thomas studied mathematics at the University of Paris, where in 1969 he obtained his PhD on the thesis L’intégration par rapport à une mesure de Radon vectorielle published in Annales de l’Institut Fourier [1]. His advisor was Laurent Schwartz, a Fields medalist, whose best known achievement is the foundation of the(More)
We present an exact solution for the time-dependent Stokes problem of an infinite cylinder of radius r = a in a fluid with harmonic boundary conditions at infinity. This is a 3-dimensional problem but, because of translational invariance along the axis of the cylinder it effectively reduces to a 2-dimensional one. The Stokes problem being a linear reduction(More)
  • 1