From 2007.igem.org

.:: An Engineer's View on Biological Learning ::.

An equivalent system behavior can be realized using [http://en.wikipedia.org/wiki/Flip-flop_%28electronics%29 flip-flops], implemented by [http://en.wikipedia.org/wiki/Logic_gate logical gates]. As described in the model, a toggle switch is used to implement the memory or learning behavior of the system, supplemented by a discriminator between same or different input.

In terms of flip-flops, the toggle switch can be implemented by JK flip-flop. This bistable

A	B	A AND B	A NAND B
0	0	0	1
0	1	0	1
1	0	0	1
1	1	0	0