The cortex is a neural network of neural networks

Which means that each branch of a dendrite acts like a little nonlinear output device, summing up and outputting a local spike if that branch gets enough inputs at roughly the same time:
Deja vu. Now if we replace each little branch of dendrite with one of our little “neuron” devices, then a pyramidal neuron looks something like this:
Left: A single neuron has many dendritic branches (above and below its body). For example, with four inputs (Blue, Sea, Yellow, and Sun) and two branches acting as little non-linear devices, we can set up a pyramidal neuron to compute the “feature-binding” function: we can ask it to respond to Blue and Sea together, or respond to Yellow and Sun together, but not to respond otherwise — not even to Blue and Sun together or Yellow and Sea together.

Source: medium.com