The research topic of this group is the regulation of cellular and network excitability in the central nervous system (CNS). The program is part of the general theme on nervous plasticity and it participates in the Graduate School for Neurosciences Amsterdam (ONWA). Within the central theme, we concentrate on the regulation of neuronal excitability, in particular in relation to ion channels and intracellular calcium regulation. This research line investigates the development of various types of calcium channels, their distribution over different neuronal compartments, and their relative abundance in cell groups within well defined local neuronal circuits. A second research line at the cellular level relates calcium influx to energy-driven calcium efflux and calcium buffer capacity. Here we combine electrophysiological and optical techniques in order to obtain the spatio-temporal characteristics of calcium concentration in morphologically defined neuron types. At the level of the local neuronal network the emphasis is on understanding how the particular properties of individual cell groups contribute to the overall transfer of the local neuronal network and how specific synaptic connections can be modified to adapt local circuitry according to needs. Computational modeling at the cellular and network level is essential to put results and hypotheses in perspective.