HTM theory clearly articulates the biological existence and computational utility of apical connections, yet these are absent from the nupic core - both absent from the core Temporal Memory, and (I believe) absent from the way the network API implements links. I have found in the numenta research code two temporal memory algorithms with apical inputs: this one, and this one. But I cannot find:
- any projects/examples using these (or other) apical TMs
- any “research code” which extends the network API to cater for apical connections.
I am also not sure whether the description of the use of apical connections in a sequence memory in Figure 4 of the numenta paper “Why Neurons Have Thousands of Synapses, a Theory of Sequence Memory in Neocortex” corresponds with either of the apical TMs provided in the numenta research code repository?
Given the obvious importance of apical connections to HTM I am confused as to why code implementing apical connections does not seem to be used much, or discussed much in the HTM forum - am I missing something?