reference for nonsymmetric interconnection networks

[Gune Yen]

Hi,
  Synthesis techniques for associative memories via artificial feedback
  neural networks have been studied for many years. Among them, I am
  very interested in any design method results in neural networks with
  non-symmetric interconnecting structure. Obviously, the requirement
  to have symmetric interconnection weights will pose difficulties in
  implementation and may result in spurious states as well. 

  I am aware of the work given below:
    A. Lapedes and R. Farber, "A Self-Optimizing Nonsymmetrical Neural
    Net for Content Addressable Memory and Pattern Recognition", Physica
    22D, 1986, pp. 247-259.

    J. A. Farrell and A. N. Michel, "Analysis and Synthesis Techniques
    for Hopfield Type Synchronous Discrete Neural Networks with
    Application to Associative Memory", IEEE Transactions on Circuits
    and Systems, Vol. 37, No. 11, November 1990, pp. 1356-1366.

  Could anyone who familiar in this type of problem provide any
  references and comments in terms of 
    symmetric/non-symmetric interconnection weights,
    with/without self-feedback term,
    difficulties in analog/digital implementation,
    and etc.

  Thank you very much.

Gary at gyen at steinbeck.helios.nd.edu
University of Notre Dame