  How does your brain decide what you will do next? Over the past few decades
compelling evidence has emerged that the basal ganglia, a collection of nuclei
in the fore- and mid-brain of all vertebrates, are vital to action selection.
Gurney, Prescott, and Redgrave published an influential computational account
of this idea in Biological Cybernetics in 2001. Here we take a look back at
this pair of papers, outlining the "GPR" model contained therein, the context
of that model's development, and the influence it has had over the past twenty
years. Tracing its lineage into models and theories still emerging now, we are
encouraged that the GPR model is that rare thing, a computational model of a
brain circuit whose advances were directly built on by others.
