Methods and apparatus are provided for implementing structural plasticity in an artificial nervous system. One example method for altering a structure of an artificial nervous system generally includes determining a synapse in the artificial nervous system for reassignment, determining a first artificial neuron and a second artificial neuron for connecting via the synapse, and reassigning the synapse to connect the first artificial neuron with the second artificial neuron. Another example method for operating an artificial nervous system, generally includes determining a synapse in the artificial nervous system for assignment; determining a first artificial neuron and a second artificial neuron for connecting via the synapse, wherein at least one of the synapse or the first and second artificial neurons are determined randomly or pseudo-randomly; and assigning the synapse to connect the first artificial neuron with the second artificial neuron.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method for operating an artificial nervous system, comprising: determining a synapse in the artificial nervous system for reassignment; determining a first artificial neuron and a second artificial neuron for connecting via the synapse; and reassigning the synapse to connect the first artificial neuron with the second artificial neuron. 2. The method of claim 1, wherein determining the synapse comprises randomly or pseudo-randomly determining the synapse for reassignment. 3. The method of claim 1, wherein determining the synapse for reassignment comprises determining that a weight associated with the synapse is 0 or near 0. 4. The method of claim 1, wherein determining the synapse for reassignment comprises determining that a weight associated with the synapse is below a threshold. 5. The method of claim 1, wherein determining the synapse for reassignment comprises determining that a difference between a first spike time of a post-synaptic artificial neuron connected with the synapse and a second spike time input to the synapse is above a threshold. 6. The method of claim 1, wherein determining the first and second artificial neurons comprises selecting two artificial neurons whose future relative spike timing is likely to potentiate. 7. The method of claim 1, wherein determining the first and second artificial neurons is based at least in part on a relative spike timing between the first and second artificial neurons. 8. The method of claim 7, wherein determining the first and second artificial neurons is based at least in part on the relative spike timing between the first and second artificial neurons and on spike-timing dependent plasticity (STDP). 9. The method of claim 8, wherein a search window for determining the relative spike timing corresponds to an STDP window. 10. The method of claim 9, wherein determining the first and second artificial neurons comprises: accumulating energy of the first artificial neuron over the search window; applying a delay to an STDP function; and convolving the accumulated energy and the delayed STDP function. 11. The method of claim 10, wherein accumulating the energy of the first artificial neuron comprises calculating a spike count or a probability density function for the first artificial neuron. 12. The method of claim 9, wherein the STDP window is based on at least one of a post-synaptic trigger or a pre-synaptic trigger. 13. The method of claim 7, wherein determining the first and second artificial neurons is based at least in part on the relative spike timing between the first and second artificial neurons and on an order of spikes. 14. The method of claim 1, wherein determining the first and second artificial neurons comprises randomly or pseudo-randomly determining the first and second artificial neurons. 15. The method of claim 1, wherein reassigning the synapse comprises applying a non-zero weight to the synapse. 16. The method of claim 1, wherein the second artificial neuron comprises a null neuron, such that reassigning the synapse renders the synapse ineffectual. 17. An apparatus for operating an artificial nervous system, comprising: a processing system configured to: determine a synapse in the artificial nervous system for reassignment; determine a first artificial neuron and a second artificial neuron for connecting via the synapse; and reassign the synapse to connect the first artificial neuron with the second artificial neuron; and a memory coupled to the processing system. 18. The apparatus of claim 17, wherein the processing system is configured to determine the synapse by randomly or pseudo-randomly determining the synapse for reassignment. 19. The apparatus of claim 17, wherein the processing system is configured to determine the synapse for reassignment by determining that a weight associated with the synapse is 0 or near 0. 20. The apparatus of claim 17, wherein the processing system is configured to determine the synapse for reassignment by determining that a weight associated with the synapse is below a threshold. 21. The apparatus of claim 17, wherein the processing system is configured to determine the synapse for reassignment by determining that a difference between a first spike time of a post-synaptic artificial neuron connected with the synapse and a second spike time input to the synapse is above a threshold. 22. The apparatus of claim 17, wherein determining the first and second artificial neurons comprises selecting two artificial neurons whose future relative spike timing is likely to potentiate. 23. The apparatus of claim 17, wherein the processing system is configured to determine the first and second artificial neurons based at least in part on a relative spike timing between the first and second artificial neurons. 24. The apparatus of claim 23, wherein the processing system is configured to determine the first and second artificial neurons based at least in part on the relative spike timing between the first and second artificial neurons and on spike-timing dependent plasticity (STDP). 25. The apparatus of claim 24, wherein a search window for determining the relative spike timing corresponds to an STDP window. 26. The apparatus of claim 25, wherein the processing system is configured to determine the first and second artificial neurons by: accumulating energy of the first artificial neuron over the search window; applying a delay to an STDP function; and convolving the accumulated energy and the delayed STDP function. 27. The apparatus of claim 26, wherein accumulating the energy of the first artificial neuron comprises calculating a spike count or a probability density function for the first artificial neuron. 28. The apparatus of claim 25, wherein the STDP window is based on at least one of a post-synaptic trigger or a pre-synaptic trigger. 29. The apparatus of claim 23, wherein the processing system is configured to determine the first and second artificial neurons based at least in part on the relative spike timing between the first and second artificial neurons and on an order of spikes. 30. The apparatus of claim 17, wherein the processing system is configured to determine the first and second artificial neurons by randomly or pseudo-randomly determining the first and second artificial neurons. 31. The apparatus of claim 17, wherein the processing system is configured to reassign the synapse by applying a non-zero weight to the synapse. 32. The apparatus of claim 17, wherein the second artificial neuron comprises a null neuron, such that reassigning the synapse renders the synapse ineffectual. 33. An apparatus for operating an artificial nervous system, comprising: means for determining a synapse in the artificial nervous system for reassignment; means for determining a first artificial neuron and a second artificial neuron for connecting via the synapse; and means for reassigning the synapse to connect the first artificial neuron with the second artificial neuron. 34. A computer program product for operating an artificial nervous system, comprising a computer-readable medium having instructions executable to: determine a synapse in the artificial nervous system for reassignment; determine a first artificial neuron and a second artificial neuron for connecting via the synapse; and reassign the synapse to connect the first artificial neuron with the second artificial neuron. 35. A method for operating an artificial nervous system, comprising: determining a synapse in the artificial nervous system for assignment; determining a first artificial neuron and a second artificial neuron for connecting via the synapse, wherein at least one of the synapse or the first and second artificial neurons are determined randomly or pseudo-randomly; and assigning the synapse to connect the first artificial neuron with the second artificial neuron. 36. The method of claim 35, wherein assigning the synapse comprises applying a substantial weight to the synapse. 37. The method of claim 35, wherein assigning the synapse comprises initially assigning the synapse. 38. An apparatus for operating an artificial nervous system, comprising: a processing system configured to: determine a synapse in the artificial nervous system for assignment; determine a first artificial neuron and a second artificial neuron for connecting via the synapse, wherein at least one of the synapse or the first and second artificial neurons are determined randomly or pseudo-randomly; and assign the synapse to connect the first artificial neuron with the second artificial neuron; and a memory coupled to the processing system. 39. The apparatus of claim 38, wherein the processing system is configured to assign the synapse by applying a substantial weight to the synapse. 40. The apparatus of claim 38, wherein the processing system is configured to assign the synapse by reassigning the synapse. 41. An apparatus for operating an artificial nervous system, comprising: means for determining a synapse in the artificial nervous system for assignment; means for determining a first artificial neuron and a second artificial neuron for connecting via the synapse, wherein at least one of the synapse or the first and second artificial neurons are determined randomly or pseudo-randomly; and means for assigning the synapse to connect the first artificial neuron with the second artificial neuron. 42. A computer program product for operating an artificial nervous system, comprising a computer-readable medium having instructions executable to: determine a synapse in the artificial nervous system for assignment; determine a first artificial neuron and a second artificial neuron for connecting via the synapse, wherein at least one of the synapse or the first and second artificial neurons are determined randomly or pseudo-randomly; and assign the synapse to connect the first artificial neuron with the second artificial neuron.