Transformation of Olfactory Representations in the Drosophila Antennal Lobe

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Transformation of Olfactory Representations in
the Drosophila Antennal Lobe

• Rachel I. Wilson, Glenn C. Turner, Gilles Laurent
• Science, January 16, 2004 303(5656) 366

Carrie Niziolek carrien 9.02 presentation draft
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Introduction

• How does olfaction work?

chemical input to sensory neurons (OSNs)

What is this transformation?
olfactory bulb / antennal lobe
odor representation in cortex
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Purpose of study

• To better understand the transforms of olfactory
  representations that occur in the antennal lobe,
  the layer between primary sensory neurons and
  cortex

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Methods

• Probe olfactory space with 33 odors and analyze
  responses
• Whole-cell patch-clamp recordings in Drosophila
  antennal lobe
• Odors were presented while recording from 43
  projection neurons (PNs) and the olfactory
  sensory neurons (OSNs) that innervate them

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Odor responses

• Most odors elicited responses from a large PN
  ensemble

• Each OSN expresses one type of odorant receptor,
  and OSNs with the same receptors target the same
  glomerulus
• Test PNs from different glomeruli

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Results

• Responses of PNs within a particular glomerulus
  are similar!
• Responses vary greatly across glomeruli.

Distribution of PNs based on tuning width
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Results, cont.

• PNs categorized Specialists respond to few or
  none of the odors tested generalists respond
  to many (broad tuning)
• PNs that responded strongly to some odors that
  elicited no response from the corresponding OSNs
• PNs and OSNs have different odor preferences,
  even when they converge on the same glomerulus
• PN responses thus shaped by inputs other than
  OSNs
• After first 100ms of response, PN and OSN
  decorrelated
• There is a nonlinear transformation of OSN inputs

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Conclusions

• PNs are more broadly tuned (showed less
  selectivity) than their OSN afferents
• PNs integrate information across channels
• Antennal lobe actively shapes olfactory
  responses, giving rise to PN tuning properties
• OSNs with the same receptors target the same
  glomerulus mapping of odor to glomerulus keeps
  odors separate in sensory space
• Glomeruli analogous to barrels in rat cortex