Large-Scale Simulation Using Parallel GENESIS

PGENESIS is a parallel form of GENESIS that enables simulation of very large models. Simulation models are critical for integration of behavioral data with anatomical and physiological data. Although explanations of behavioral data are possible without resort to neural simulation models (Chomsky 1957, e.g.), those integrative accounts that make contact with the anatomical and physiological data require large-scale simulation models at the neural level. The scale of the models required can be seen in theories about the function of the hippocampus in learning and memory (McClelland and Goddard 1996, Levy 1996). These theories assert that statistical properties of firing rates, synaptic transmission efficiencies, and connection structures are crucial in explaining information processing in the hippocampus. The validity of these statistical properties is conditioned on sufficient sample sizes that cannot hold if the model scales down the real system by more than one or two orders of magnitude. Even scaling down by two orders of magnitude leaves us with very large models that, as we shall see, go beyond the capabilities of existing simulation environments.