An Information Theoretic Approach to the Functional Classification of Neurons

A population of neurons typically exhibits a broad diversity of responses to sensory inputs. The intuitive notion of functional classification is that cells can be clustered so that most of the diversity is captured by the identity ofthe clusters rather than by individuals within clusters. We show how this intuition can be made precise using information theory, without anyneed to introduce a metric on the space of stimuli or responses. Applied to the retinal ganglion cells of the salamander, this approach recovers classicalresults, but also provides clear evidence for subclasses beyond those identified previously. Further, we find that each of the ganglion cellsis functionally unique, and that even within the same subclass only a few spikes are needed to reliably distinguish between cells.