In this video around the 7 minute mark, Jeff is talking about Chandelier cells. These cells connect to the base of the axon and nobody knows what they do yet. Could these be to stop muscle movements during REM playback?
The input to the chandelier cells is exactly where you would expect to sample the fastest cells in mini-column temporal competition:
" Chandelier neurons synapse exclusively to the axon initial segment of pyramidal neurons, near the site where action potential is generated."
Look at the shape below, the blue dendrites sample axons in a small mini-column area and the red outputs shut down local activity - the perfect shape if it is the element that mediates the inter-column competition for temporal memory.
The output chemistry acts is to shut down local proximal dendrites, which is again what you want for temporal competition.
“GAT-1 is involved in the process of GABA reuptake into nerve terminals, thus helping to terminate its synaptic activity.”
Contrast that with nest basket cells which are better situated to mediate the sparsification activity emulated by k-winner in Numenta programs. They sample the lateral axonal projections and inhibit the cells in that general neighborhood; roughly a ring pattern around the active cell.