Neural Ensemble Codes in Drosophila Olfaction
Our research program aims to understand how neural ensembles represent and process information. Information is inevitably tied to a physical carrier - a pencil mark on paper, a charge on a capacitor, an action potential or synaptic event in a nervous system. Any information processing operation, be it a measurement or a computation, transforms one such representation into another, according to a set of rules embodied in the physical properties of the system.
While these rules are fairly well understood for single neurons encoding simple stimulus features, neural representations of complex stimuli, their inter-relations, and their behavioral significance remain largely mysterious. It is presumed that these representations are distributed over neural ensembles - groups of neurons in transient functional linkage - and written in a code that involves the spatial locations of active cells or synapses and the times at which activity occurs. Due to a paucity of experimental approaches, however, even seemingly elementary facts about ensemble codes are unknown: the sizes of ensembles and their dynamics, the nature of the functional linkage among ensemble members, or the features which demarcate co-active ensembles.