I am afraid I forgot an important reference in my earlier
post regarding the derivation of the sigmoid nonlinearity
in Freeman's work. Another reference is:
Eeckman,F.H. and Freeman, W.J. (1991) "Asymmetric sigmoid
nonlinearity in the rat olfactory system," Brain Research
557, 13-21.
Leslie Kay
lmk2 at garnet.berkeley.edu
