The neuronal architecture of the mushroom body provides a logic for associative learning

Elife. 2014 Dec 23:3:e04577. doi: 10.7554/eLife.04577.


We identified the neurons comprising the Drosophila mushroom body (MB), an associative center in invertebrate brains, and provide a comprehensive map describing their potential connections. Each of the 21 MB output neuron (MBON) types elaborates segregated dendritic arbors along the parallel axons of ∼2000 Kenyon cells, forming 15 compartments that collectively tile the MB lobes. MBON axons project to five discrete neuropils outside of the MB and three MBON types form a feedforward network in the lobes. Each of the 20 dopaminergic neuron (DAN) types projects axons to one, or at most two, of the MBON compartments. Convergence of DAN axons on compartmentalized Kenyon cell-MBON synapses creates a highly ordered unit that can support learning to impose valence on sensory representations. The elucidation of the complement of neurons of the MB provides a comprehensive anatomical substrate from which one can infer a functional logic of associative olfactory learning and memory.

Keywords: D. melanogaster; associative memory; dopamine; mushroom body; neuronal circuits; neuroscience; olfactory learning; plasticity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Association Learning*
  • Brain / anatomy & histology
  • Brain / physiology
  • Cell Compartmentation
  • Cell Shape
  • Dendrites / metabolism
  • Dopaminergic Neurons / cytology
  • Dopaminergic Neurons / metabolism
  • Drosophila melanogaster / cytology*
  • Drosophila melanogaster / physiology*
  • Green Fluorescent Proteins / metabolism
  • Logic*
  • Models, Neurological
  • Mushroom Bodies / cytology*
  • Mushroom Bodies / innervation*
  • Neurotransmitter Agents / metabolism
  • Olfactory Pathways / anatomy & histology
  • Olfactory Pathways / physiology
  • Sensory Receptor Cells / physiology*
  • Smell / physiology


  • Neurotransmitter Agents
  • Green Fluorescent Proteins