Experimental data show that biological synapses behave quite differently from the symbolic synapses in all common artificialneuralnetwork models. Biological synapses are dynamic, i.e., their "weight" changes on a short time scale by several hundred percent in dependence of the past input to the synapse. In this article we address the question how this inherent synaptic dynamics 							
						
							
					 															
					Wolfgang Maass, Eduardo D. Sontag