At the first time step:
ai = (max - a i) neti - decay (ai - rest)
= (1 - 0) Ii
So a1 = I1 and a2 = I2
At the second timestep:
net1 = I1 - a2 = I1 - I2 and net2 = I2 - a1 = I2 - I1
So: a1 = (1 - I1)(I1 - I2) and
a2 = I2 (I2 - I1)
Because 1 - I1 and I2 are positive and I1 > I2: a1 > 0 and
a2 < 0. So a1 grows while a2 dies.