Upon rereading Why Neurons Have Thousands Of Synapses I noticed a detail I must have overlooked before.
"There are three sources of input to the cell. The feedforward inputs (shown in green) which form synapses proximal to the soma, directly lead to action potentials."
I had the impression that a pyramidal neuron needed both feedforward and (feedback or context) excitation in order to fire an action potential. I thought this because only predicted (or depolarized) cells in a column are activated - so feedforward excitation is not enough. If feedforward excitation was enough to activate the soma then I guess all neurons in the column will activate, regardless of if they were already depolarized.
I feel I’m missing something here.
Playing with my new toy (nViz) - here is a visualization of what I mean. The left and right columns represent context and feedback neurons, while the bottom row represents feedforward inputs. The center neuron only activates when feedforward AND (context OR feedback) are provided. (segments have 70% threshold).