Comprehensive classification of the auditory sensory projections in the brain of the fruit fly Drosophila melanogaster

Azusa Kamikouchi, Takashi Shimada, Kei Ito

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154 Citations (Scopus)


We established a comprehensive projection map of the auditory receptor cells (Johnston's organ neurons: JONs) from the antennae to the primary auditory center of the Drosophila brain. We found 477 ± 24 cell bodies of JONs, which are arranged like a "bottomless bowl" within the auditory organ. The target of the JONs in the brain comprises five spatially segregated zones, each of which is contributed by bundles of JON axons that gradually branch out from the antennal nerve. Four zones are confined in the antennal mechanosensory and motor center, whereas one zone further extends over parts of the ventrolateral protocerebrum and the subesophageal ganglion. Single-cell labeling with the FLP-out technique revealed that most JONs innervate only a single zone, indicating that JONs can be categorized into five groups according to their target zones. Within each zone, JONs innervate various combinations of subareas. We classified these five zones into 19 subareas according to the branching patterns and terminal distributions of single JON axons. The groups of JONs that innervate particular zones or subareas of the primary auditory center have their cell bodies in characteristic locations of the Johnston's organ in the antenna, e.g., in concentric rings or in paired clusters. Such structural organization suggests that each JON group, and hence each zone of the primary auditory center, might sense different aspects of sensory signals.

Original languageEnglish
Pages (from-to)317-356
Number of pages40
JournalJournal of Comparative Neurology
Issue number3
Publication statusPublished - 2006 Nov 20
Externally publishedYes


  • Auditory system
  • Drosophila
  • GAL4 enhancer trap
  • Insect
  • Johnston's organ
  • Projection target

ASJC Scopus subject areas

  • Neuroscience(all)


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