To understand the principles of information processing in the brain, we depend on models with more than 10
5 neurons and 10
9 connections. These networks can be described as graphs of threshold elements that exchange point events over their connections.
From the computer science perspective, the key challenges are to represent the connections succinctly; to transmit events
and update neuron states efficiently; and to provide a comfortable user interface. We present here the neural simulation tool
NEST, a neuronal network simulator which addresses all these requirements. To simulate very large networks with acceptable
time and memory requirements, NEST uses a hybrid strategy, combining distributed simulation across cluster nodes (MPI) with
thread-based simulation on each computer. Benchmark simulations of a computationally hard biological neuronal network model
demonstrate that hybrid parallelization yields significant performance benefits on clusters of multi-core computers, compared
to purely MPI-based distributed simulation.