Things I had to look up

Simple and complex V1 cells

There are two distinct classes of cells in the primary visual cortex (V1): simple cells and complex cells. One defining feature of complex cells is their spatial phase invariance; they respond strongly to oriented grating stimuli with a preferred orientation but with a wide range of spatial phases.
See https://en.wikipedia.org/wiki/Complex_cell
Apparently, there is a heirarchy between these simple cnd complex cells (which makes sense) and this heirarchy can be used to compare neurons using granger causlity in V1. See https://www.mdpi.com/1422-0067/24/9/8229.

Predictive coding

The concept that the brain predicts sensory input based on past experience. See https://en.wikipedia.org/wiki/Predictive_coding