Nonassociative plasticity alters competitive interactions among mixture components in early olfactory processing

LOCATELLI F; VILLARREAL, F.; MEZZINOGLU K; HUERTA R.; GALIZIA G; SMITH B

Huerta Grande, Cordoba

Congreso; II REUNION CONJUNTA DE NEUROCIENCIAS; 2010

Sociedad Argentina de Neurociencias

Nonassociative plasticity alters competitive interactions among mixture components in early olfactory processing Fernando F Locatelli[1],[2], Francis Villareal1, Kerem Mezzinoglu[3], Ramon Huerta3, Giovanni Galizia[4], and Brian H. Smith1 Nonassociative plasticity modifies olfactory processing both in the mammalian olfactory bulb and in the insect antennal lobe, but mechanisms and effects of the changes are not well understood. Using calcium imaging in the honey bee AL, we show that stimulation with a binary odor mixture (A+X) sets up a spatiotemporal activity pattern that is intermediate to the patterns for the two pure components. Unreinforced exposure to one component (A) shifts the pattern to the mixture such that it becomes less similar to the pattern for A and more like the pattern for X. These results suggest that nonassociative plasticity modifies the neural network in the AL in a way that affects local, competitive interactions among mixture components. We also tested in behavioral analyses that unreinforced exposure of A causes the mixture A+X to become perceptually more similar to X. We then use a computational model to evaluate the most likely targets for modification of the network. We show that hebbian modification of synapses from inhibitory local interneurons to projection neurons most reliably produces the observed shift in the transient for the mixture. These results are consistent with a model in which plasticity in the AL acts to filter out irrelevant cues in complex olfactory stimuli. [1] School of Life Sciences, Arizona State University, P.O. Box 874501, Tempe, AZ 85287. Address correspondence to B.H.S. (brian.h.smith@asu.edu). [2] Present address: Laboratorio de Neurobiología de la Memoria, Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IFIByNE (UBA CONICET), Ciudad Universitaria,1428EHA Buenos Aires, Argentina. [3] Biocircuits Institute, University of California, San Diego, La Jolla, CA 92093-0328. [4] University of Konstanz, Department of Biology, D-78457 Konstanz, Germany (galizia@uni-konstanz.de)