Numenta idealizes pyramidal cells as working a certain way, and replaces the action of the inhibitory inter-neurons with a simple k-means function. While this is certainly good enough to demonstrate the basic HTM model, it ignores the many “other” cell types that populate the cortex.
A few minutes reviewing the literature on cell types in the cortex should show you that there are a zoo of different cell types with very different morphology and neurotransmitter profiles.
and
https://www.nature.com/articles/s41586-020-2907-3
and
https://www.researchgate.net/figure/Historical-milestones-in-cortical-cell-type-classification-Morphological_fig1_335713782
One of the ignored types is metabotropic, that have actions measured in seconds or even minutes. This is certainly a good candidate for communications through time.