Memories of a fruitfly

Abstract

Despite its tiny size, the fruitfly brain is staggeringly intricate. So teasing apart how it remembers things — even a simple line pattern — is a daunting task. Progress is being made, thanks to genetic innovations. Like humans, Drosophila fruit flies recognize and remember visual landmarks, and they recognize patterns (such as vertical or oblique bars) independently of where they are projected on the retina at first encounter. In an experiment using genetic manipulation and a fruit-fly flight simulator, the nerve cells required for these feats of visual memory have been identified for the first time in an insect. Two groups of about 20 neurons are found in two narrow strata in the ‘fan-shaped body’, the largest component of the central complex that is characteristic of the arthropod brain. The main role of the central complex was thought to be to integrate information in the two brain hemispheres; this new study is the first to attribute well defined behavioural functions to this brain region.