Membrane Potentials and Spike Trains
Since, between biological neurons, information is exchanged via so-called spikes (or action potentials), their temporal patterns of occurance is the main feature to be reproduced correctly by every kind of spiking neuron model.
- A so-called rasterplot of spike times as measured at 24 different neuron circuits in the FACETS hardware. The time scale is already converted to simulated biological real time, i.e. the real experiment duration was 200 usec (with a speedup factor of 50.000).
Still, these spike times are determined by the course of the neurons' membrane potentials, and thus the voltage traces emulated by the electronic circuits on the FACETS hardware also have to be included into any calibration flow. As a reference for correct analog behavior, the software simulator NEST with the same underlying neuron model as for the hardware is used.
- Top: The course of a membrane potential under synaptic stimulation over time, recorded at a neuron circuit in the FACETS hardware. Bottom: The membrane potential as calculated by a numerical software simulation for a corresponding model neuron under the same input as the hardware neuron above. Note the different time scales!
Publications
A Software Framework for Tuning the Dynamics of Neuromorphic Silicon Towards Biology
Daniel Bruederle, Andreas Gruebl, Karlheinz Meier, Eilif Mueller, and Johannes Schemmel
Springer LNCS 4507
Proceedings of the 2007 International Work Conference on Artificial Neural Networks, San Sebastián, Spain
pp. 479 - 486
