title: The looks of an odour--visualising neural odour response patterns in real time.
abstract: BACKGROUND
  Calcium imaging in insects reveals the neural response to odours, both at the receptor level on the antenna and in the antennal lobe, the first stage of olfactory information processing in the brain. Changes of intracellular calcium concentration in response to odour presentations can be observed by employing calcium-sensitive, fluorescent dyes. The response pattern across all recorded units is characteristic for the odour.
  
  
  METHODS
  Previously, extraction of odour response patterns from calcium imaging movies was performed offline, after the experiment. We developed software to extract and to visualise odour response patterns in real time. An adaptive algorithm in combination with an implementation for the graphics processing unit enables fast processing of movie streams. Relying on correlations between pixels in the temporal domain, the calcium imaging movie can be segmented into regions that correspond to the neural units.
  
  
  RESULTS
  We applied our software to calcium imaging data recorded from the antennal lobe of the honeybee Apis mellifera and from the antenna of the fruit fly Drosophila melanogaster. Evaluation on reference data showed results comparable to those obtained by previous offline methods while computation time was significantly lower. Demonstrating practical applicability, we employed the software in a real-time experiment, performing segmentation of glomeruli--the functional units of the honeybee antennal lobe--and visualisation of glomerular activity patterns.
  
  
  CONCLUSIONS
  Real-time visualisation of odour response patterns expands the experimental repertoire targeted at understanding information processing in the honeybee antennal lobe. In interactive experiments, glomeruli can be selected for manipulation based on their present or past activity, or based on their anatomical position. Apart from supporting neurobiology, the software allows for utilising the insect antenna as a chemosensor, e.g. to detect or to classify odours.
authors.forename: Martin
authors.initials: M
authors.lastname: Strauch
authors.forename: Clemens
authors.initials: C
authors.lastname: Müthing
authors.forename: Marc P
authors.initials: MP
authors.lastname: Broeg
authors.forename: Paul
authors.initials: P
authors.lastname: Szyszka
authors.forename: Daniel
authors.initials: D
authors.lastname: Münch
authors.forename: Thomas
authors.initials: T
authors.lastname: Laudes
authors.forename: Oliver
authors.initials: O
authors.lastname: Deussen
authors.forename: Cosmas Giovanni
authors.initials: CG
authors.lastname: Galizia
authors.forename: Dorit
authors.initials: D
authors.lastname: Merhof
mesh_terms: D000465:Algorithms; D000818:Animals; D057506:Arthropod Antennae / Q000502:physiology; D001516:Bees / Q000502:physiology; D001921:Brain / Q000502:physiology; D002118:Calcium / Q000737:chemistry; D004331:Drosophila melanogaster / Q000502:physiology; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry; D007090:Image Interpretation, Computer-Assisted; D059906:Neuroimaging / Q000379:methods*; D009474:Neurons / Q000502:physiology; D009812:Odorants; D055696:Olfactory Perception / Q000502:physiology*; D012984:Software
chemical_list: D005456:Fluorescent Dyes; D002118:Calcium