"Bottleneck"

Definition in the field of engineering - from Wikipedia:

“In engineering, the "bottleneck" is a phenomenon by which the performance or capacity of an entire system is severely limited by a single component.

The term is metaphorically derived from the neck of a bottle, where the flow speed of the liquid is limited by its neck”

I have used the term to describe the surprising constraint between the richness of the world we live in, and our ability to learn about it.
I believe that this is a consequence of the perceptual/conceptual system within our brain, and not a single localised neuron or group of neurons. It seems likely that evolution would have "fixed" any local bottleneck.