  Protein and lipid nanodomains are prevalent on the surface of mammalian
cells. In particular, it has been recently recognized that ion channels
assemble into surface nanoclusters in the soma of cultured neurons. However,
the interactions of these molecules with surface nanodomains display a
considerable degree of heterogeneity. Here, we investigate this heterogeneity
and develop statistical tools based on the recurrence of individual
trajectories to identify subpopulations within ion channels in the neuronal
surface. We specifically study the dynamics of the K$^+$ channel Kv1.4 and the
Na$^+$ channel Nav1.6 on the surface of cultured hippocampal neurons at the
single-molecule level. We find that both these molecules are expressed in two
different forms with distinct kinetics with regards to surface interactions,
emphasizing the complex proteomic landscape of the neuronal surface. Further,
the tools presented in this work provide new methods for the analysis of
membrane nanodomains, transient confinement, and identification of populations
within single-particle trajectories.
