Vision affects mushroom bodies and central complex in Drosophila melanogaster.

Abstract

The brain of Drosophila is structurally altered by sensory stimuli that the flies receive during their adult life. Size and fiber number of the mushroom bodies, central complex, and optic lobes are influenced by social, spatial, or olfactory cues. Recently, the optic lobes have been shown to depend on the light regime that flies experience. Structural plasticity in the brain is thought to be a correlate of functional adaptations and long-term memory. We therefore extend our investigation of volume changes to the calyces of the mushroom bodies and the central complex. We show that rearing flies in constant light for 4 days increases the volume of both structures by up to 15% compared to rearing them in total darkness. Much of this difference develops during the first day. The effect of light is not hormonally mediated, as monocularly deprived flies develop a smaller ipsilateral calyx. Mutant analysis suggests that light generates its effects through known visual pathways. In contrast to the optic lobes, in the calyx and central complex structural changes can be linked to cAMP signaling, as in the mutants dunce z and amnesiac 1 no volume differences are observed. Surprisingly, the mutant rutabaga ~ shows a prominent light-dependent volume increase in the calyx and central complex, dissociating structural from behavioral plasticity. In complete darkness wild-type flies grow larger calyces under crowded conditions in their normal culture vials than if kept in small groups on fresh food. This stimulating effect of crowding is not 1Corresponding author. observed in any of the cAMP mutants, including rutabaga 1.

Self-organization in the olfactory system: one shot odor recognition in insects

“…There is some evidence that the MB is a multi-modal integration region combining, apart from olfactory inputs, also visual [2,8] and possibly other information. The system investigated in this paper does not depend on the type and source of information projected to the MB.…”

Visual Input Regulates Circuit Configuration in Courtship Conditioning of Drosophila melanogaster

“…In any case, these studies present a picture of the mushroom bodies as an important integration site only for olfactory behaviors. It is clear that the mushroom bodies receive information from visual pathways (Barth and Heisenberg 1997) but this information is apparently not used for modulation of courtship behavior. An additional fallout of these experiments and experiments in which CaMKII is inhibited globally (Joiner and Griffith 1997) is that memory formed using visual information is biochemically distinct from that formed when only chemosensory input is used.…”

The Steroid Hormone 20-Hydroxyecdysone Enhances Neurite Growth ofDrosophilaMushroom Body Neurons Isolated during Metamorphosis

“…As in other insects , the MBs of adult Drosophila are essential components of the neural pathway that mediates associative learning (Heisenberg et al, 1985;de Belle and Heisenberg, 1994; Connolly et al, 1996). E xperience-dependent neuroanatomical plasticity in the MBs has also been demonstrated during adult life (Technau, 1984;Balling et al, 1987;Heisenberg et al, 1995;Barth and Heisenberg, 1997). Therefore, studying Kenyon cell development during the pupal period, when adult M B organization is initially established, should contribute to understanding the mechanisms that generate the neuronal architecture required for learning and memory.…”