Following Di Paolo (2002b), we have implemented directional damping for the synapse efficacies. The synapse efficacies, which are variable due to STDP are limited to the interval [0,wmax], where wmax can be either positive or negative, and is a genetically determined maximum (in absolute value) efficacy. We thus have 0 < w/wmax < 1. "In interfacing a spiking neural controller with an embodied agent, a conversion of the analog input and output signal to binary spikes has to be performed. Following Di Paolo (2002b), the analog values of the sensor activations were converted to a spike train using a Poisson process with a firing rate proportional to the activation. The maximum firing rate of the input neurons was set to 100Hz." Di Paolo, E. A. (2002b) Spike timing dependent plasticity for evolved robots Adaptive Behavior 10, 243-263. Di Paolo, E. A. (2002a), Evolving spike-timing dependent plasticity for robot control EPSRC/BBSRC International Workshop: Biologically inspired Robotics, The Legacy of W. Grey Walter, WGWf2002. HP Labs, Bristol, 14 - 16 August 2002 . -------------------------------------------------------------------------------------------------- We have modeled STDP following the method of Song et al. (2000). Song, S., Miller, K. D. and Abbott, L. F. (2000) Competitive hebbian learning through spike-timing-dependent synaptic plasticity Nature Neuroscience 3, 919-926.