Analysis of a spatial orientation memory in Drosophila

Abstract

Flexible goal-driven orientation requires that the position of a target be stored, especially in case the target moves out of sight. The capability to retain, recall and integrate such positional information into guiding behaviour has been summarized under the term spatial working memory. This kind of memory contains specific details of the presence that are not necessarily part of a long-term memory. Neurophysiological studies in primates indicate that sustained activity of neurons encodes the sensory information even though the object is no longer present. Furthermore they suggest that dopamine transmits the respective input to the prefrontal cortex, and simultaneous suppression by GABA spatially restricts this neuronal activity. Here we show that Drosophila melanogaster possesses a similar spatial memory during locomotion. Using a new detour setup, we show that flies can remember the position of an object for several seconds after it has been removed from their environment. In this setup, flies are temporarily lured away from the direction towards their hidden target, yet they are thereafter able to aim for their former target. Furthermore, we find that the GABAergic (stainable with antibodies against GABA) ring neurons of the ellipsoid body in the central brain are necessary and their plasticity is sufficient for a functional spatial orientation memory in flies. We also find that the protein kinase S6KII (ignorant) is required in a distinct subset of ring neurons to display this memory. Conditional expression of S6KII in these neurons only in adults can restore the loss of the orientation memory of the ignorant mutant. The S6KII signalling pathway therefore seems to be acutely required in the ring neurons for spatial orientation memory in flies.

Oviposition preference for and positional avoidance of acetic acid provide a model for competing behavioral drives in Drosophila

“…Meanwhile, the EB (likely the R1 and R4 ring neurons) plays a role in the olfactory-based positional repulsion to AA. Our data are consistent with studies showing the EB plays a role in olfactory-related tasks (30,31) and spatial memory (32).…”

Linking the Input to the Output: New Sets of Neurons Complement the Polarization Vision Network in the Locust Central Complex

“…In locusts, stationary flight is correlated with dramatic activity changes in neurons of the central complex and LAL (Homberg, 1994). In Drosophila, learning of visual objects and landmark parameters is associated with neurons of the central complex (Liu et al, 2006;Neuser et al, 2008). These findings suggest considerable learning-and behavior-dependent (Pfeiffer et al, 2005).…”

What insects can tell us about the origins of consciousness

“…In Drosophila, neural activity within the CX encodes the fly's heading relative to visual landmarks in the environment and presumably enables the fly to maintain a course relative to those landmarks (83). The CX is also vital for flies to learn spatial tasks (84,85).…”