Early Olfactory Experience modifies Neural Activity and shapes the primary olfactory center of an insect brain.

ANDRÉS ARENAS; M GIURFA; JC SANDOZ; JM DEVAUD; WM FARINA

Encuentro; 1st Latin American Meeting of Chemical Ecology; 2010

Early Olfactory Experience modifies Neural Activity and shapes the primary olfactory center of an insect brain Andrés Arenas1,2, Martín Giurfa3,4, Jean-Christophe Sandoz3,4, Jean-Marc Devaud3,4, Walter M. Farina1,2 E-mail: Walter@bg.fcen.uba.ar 1 Departamento de Biodiversidad y Biología Experimental, Grupo de Estudio de Insectos Sociales, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria (C1428EHA), Buenos Aires, Argentina. 2 IFIBYNE, CONICET, Grupo de Estudio de Insectos Sociales, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria (C1428EHA), Buenos Aires, Argentina. 3 Universite´ de Toulouse, UPS, Centre de Recherches sur la Cognition Animale, 118 route de Narbonne, F-31062 Toulouse Cedex 9,France. 4 CNRS, Centre de Recherches sur la Cognition Animale, 118 route de Narbonne, F-31062 Toulouse Cedex 9, France. The antennal lobe (AL), the first olfactory centre of an insect brain, is organized in glomeruli. These neuropiles are well-defined structures that encoded odor information in spatiotemporal patterns of activity. Whether and how such patterns are modified after an olfactory experience during early adulthood and their consequences at their long term scale remains unknown. We used in vivo calcium imaging technique to measure the odor-evoked responses in the AL of 17-day-old honeybees. These individuals experienced either a scented food at the age of 5-8 days after emergence or were left untreated.  Additionally, we evaluated whether early olfactory experiences could modify the shape of this primary processing center in the bee brain by measuring the glomerular volume in a confocal microscope. Physiological experiments showed that precocious olfactory experiences associated to reward enhanced the activity and the number of activated glomeruli in an adult bee while modify the spatial response of the patterns. Morphological experiments also revealed changes in the volume of specific glomeuruli of early-experienced bees. Interestingly, those glomeruli that most increased their size after the odor experience appeared as new recruited in odor-evoked patterns of activity suggesting a positive relationship between the functional and the structural properties of the AL. Long-lasting changes after the appetitive experience with odors may induce the reorganization of the neural networks in the AL of an adult insect, a fact that may result from the interaction between timing and nature of early sensory inputs [1, 2]. [1] Arenas A & Farina WF (2008) Age and rearing environment interact in the retention of early olfactory memories in honeybees. J. Comp. Physiol. A., 194, 629–640. [2] Arenas A, Fernández VM, Farina WM (2009) Associative Learning during Early Adulthood Enhances Later Memory Retention in Honeybees. PLoS ONE 4(12): e8046. doi:10.1371/ journal.pone.0008046. This study was supported by funds from a CNRS ⁄ CONICET cooperation grant. AA and WF thank CONICET, ANPCYT and the University of Buenos Aires for support this project. MG, J-MD and J-C S thank the CNRS and the University Paul Sabatier for support.