Figure 6 shows a sample gold dendrite grown by electrodeposition
(actual size, about 1 mm) from a 54% nitric acid solution to which gold
chloride was added. When such a dendrite is attached to a piece of
iron (both submerged), activation of the excitable element produces a
field in such a direction as to promote further growth of the dendritic
structure. Thus, if gold chloride is added to the solution used in
the elementary interaction cells described above, all input influence
“weights” tend to increase with use and, hence, produce a plasticity of
function.