1. Animation of Function of Hebbian learning circuit Chrisantha Fernando et al 2008

2. Only w 1, the unconditional stimulus weight exists at rest. It is constitutively expressed.

3. However, alone it cannot produce output P (green). For this one must insert some transcription factors.

4. By depressing r 1 by putting in stimulus u 1 we can activate the promotor of p. Before p decays, it feeds back on w 1

5. Imagine that instead we had put in u 2. No p would be Produced because there is no w 2.

6. Now imagine putting u 1 and u 2 in at the same time. u 1 will produce p, which will then allow u 2 to produce w 2.

7. Once w 2 has been produced, we can see that u 2 alone is sufficient to produce p, see next slide.