Visual orientation behaviour of flies after selective laser beam ablation of interneurones

Abstract

The use of a laser microbeam has allowed us to ablate specific small groups of cells deep in the larval brain of the housefly Musca domestica, without damage to overlying tissues. The ablation results in various specific alterations in brain structure and behaviour of adult flies. In the experiments described here, a set of large horizontal and vertical neurones on one side of the adult optic lobes was ablated. These neurones are known to be directionally motion sensitive and are thought to play an essential part in visual orientation of the fly^1–8. However, visually guided orientation behaviour towards single objects by flies lacking the large horizontal and vertical neurones on one side was not significantly different from the behaviour of normal flies, although the response to moving gratings was reduced on the ablated side. Therefore we suggest that other sets of nerve cells are involved in the information processing of single moving objects, whereas the horizontal and vertical cells seem to be implicated in ordinary optomotor flight stabilization.