Cellular-Resolution Population Imaging Reveals Robust Sparse Coding in the Drosophila Mushroom Body

Honegger, K. S., Campbell, R. A. A., Turner, G. C. (2011) Cellular-Resolution Population Imaging Reveals Robust Sparse Coding in the Drosophila Mushroom Body. Journal of Neuroscience, 31 (33). pp. 11772-11785. ISSN 0270-6474

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URL: http://www.ncbi.nlm.nih.gov/pubmed/21849538
DOI: 10.1523/jneurosci.1099-11.2011

Abstract

Sensory stimuli are represented in the brain by the activity of populations of neurons. In most biological systems, studying population coding is challenging since only a tiny proportion of cells can be recorded simultaneously. Here we used two-photon imaging to record neural activity in the relatively simple Drosophila mushroom body (MB), an area involved in olfactory learning and memory. Using the highly sensitive calcium indicator GCaMP3, we simultaneously monitored the activity of >100 MB neurons in vivo (similar to 5% of the total population). The MB is thought to encode odors in sparse patterns of activity, but the code has yet to be explored either on a population level or with a wide variety of stimuli. We therefore imaged responses to odors chosen to evaluate the robustness of sparse representations. Different odors activated distinct patterns of MB neurons; however, we found no evidence for spatial organization of neurons by either response probability or odor tuning within the cell body layer. The degree of sparseness was consistent across a wide range of stimuli, from monomolecular odors to artificial blends and even complex natural smells. Sparseness was mainly invariant across concentrations, largely because of the influence of recent odor experience. Finally, in contrast to sensory processing in other systems, no response features distinguished natural stimuli from monomolecular odors. Our results indicate that the fundamental feature of odor processing in the MB is to create sparse stimulus representations in a format that facilitates arbitrary associations between odor and punishment or reward.

Item Type: Paper
Uncontrolled Keywords: short-term-memory olfactory representations antennal lobe odor representations receptor neurons neural activity gain-control fruit-flies intensity bodies
Subjects: organism description > animal > insect > Drosophila
organism description > animal behavior
organs, tissues, organelles, cell types and functions > organs types and functions > brain
organism description > animal behavior > forgetting
organism description > animal behavior > memory
organism description > plant > mushroom
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons

organism description > animal behavior > olfactory
CSHL Authors:
Communities: CSHL Post Doctoral Fellows
CSHL labs > Turner lab
Watson School > Publications
Depositing User: CSHL Librarian
Date Deposited: 26 Oct 2011 20:21
Last Modified: 22 Sep 2014 20:05
PMCID: PMC3180869
Related URLs:
URI: http://repository.cshl.edu/id/eprint/15647

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