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Gary A. Banker coauthored work following the emergence of neuronal polarity in cultured hippocampal neurons. Sequential observations linked initially similar processes to distinct axon and dendrite outcomes. ^[ref] The culture model made cellular differentiation observable in the same cells through time, separating a developmental sequence from comparisons of unrelated endpoint images.

Neuronal polarity is the structural and molecular differentiation of a neuron into compartments such as an axon and dendrites. Different distributions of proteins, transport machinery and synapses support different roles in receiving and sending signals. This organization does not require every electrical event to travel in only one direction: action potentials can propagate back into dendrites.

In 1988, Carlos G. Dotti, Christopher A. Sullivan and Gary A. Banker followed individual embryonic rat hippocampus neurons in culture using repeated photography and time-lapse imaging. Several initially similar neurites preceded rapid growth of one future axon; staining for microtubule-associated protein 2 helped distinguish later dendrites. Following the same biological cells over time directly tested the developmental sequence, which a collection of mature shapes could only suggest.^[ref]