two distinct subdisorders, with very different intrinsic properties, where the common cellular phenotype is hyperexcitability. Their shared electrophysiological feature, a large fast AHP, suggests a possible expedited recovery of sodium channel inactivation, which allows BD neurons to sustain spiking activity. When looking for examples of fast or slow spiking neurons, it is useful to observe the other end of the spectrum as well. Down Syndrome neurons, which are hypoexcitable, have a very small amplitude of the fast AHP.56
