title: Sparse odor representation and olfactory learning.
abstract: Sensory systems create neural representations of environmental stimuli and these representations can be associated with other stimuli through learning. Are spike patterns the neural representations that get directly associated with reinforcement during conditioning? In the moth Manduca sexta, we found that odor presentations that support associative conditioning elicited only one or two spikes on the odor's onset (and sometimes offset) in each of a small fraction of Kenyon cells. Using associative conditioning procedures that effectively induced learning and varying the timing of reinforcement relative to spiking in Kenyon cells, we found that odor-elicited spiking in these cells ended well before the reinforcement was delivered. Furthermore, increasing the temporal overlap between spiking in Kenyon cells and reinforcement presentation actually reduced the efficacy of learning. Thus, spikes in Kenyon cells do not constitute the odor representation that coincides with reinforcement, and Hebbian spike timing-dependent plasticity in Kenyon cells alone cannot underlie this learning.
authors.affiliation: National Institute of Child Health and Human Development, US National Institutes of Health, Building 35, Room 3A-102, Bethesda, Maryland 20982, USA.
authors.forename: Iori
authors.initials: I
authors.lastname: Ito
authors.forename: Rose Chik-Ying
authors.initials: RC
authors.lastname: Ong
authors.forename: Baranidharan
authors.initials: B
authors.lastname: Raman
authors.forename: Mark
authors.initials: M
authors.lastname: Stopfer
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal; D003214:Conditioning, Classical / Q000502:physiology*; D018402:Manduca; D024521:Mushroom Bodies / Q000166:cytology; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009812:Odorants; D009833:Olfactory Pathways / Q000502:physiology*; D012054:Reinforcement, Psychology; D012679:Sense Organs / Q000166:cytology; D012903:Smell / Q000502:physiology*; D013997:Time Factors
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