Early associative learning enhances long-term memory retention in a social insect.

ARENAS, ANDRÉS; GIURFA, MARTIN; , FARINA WM; SANDOZ, JEAN CHRISTOPH

Copenhagen

Congreso; IUSSI 2010 Congress; 2010

IUSSI

The antennal lobe (AL), the first olfactory centre of the insect brain, is organized in glomeruli. These neuropiles are well-defined globular structures that encoded odor information in spatiotemporal patterns of activity. Whether and how such patterns are modified in the long term after an early olfactory experience (i.e. in the first days of adulthood) remains unknown. We used in vivo calcium imaging technique to measure the odor-evoked responses in the AL of 17-day-old honeybees which either experienced an odor associated with sucrose solution at the age of 5–8 days or were left untreated.  We found that precocious olfactory experiences associated to reward (i.e. 5–8 days after emergence) enhanced the activity and the number of activated glomeruli in the long-term, i.e. at the age of 17 days. Furthermore precocious learning seems to modify the spatial response of the patterns. Such effects were not limited to the experienced odor, but generalized to other perceptually similar odors. Behavioral experiments under the proboscis extension responses (PER) paradigm revealed a similar trend in which the increased responses to the experienced odor extended to perceptually similar odors in treated bees. Then we show that early olfactory conditioning during young adulthood affects neural activity in the honeybee AL on a long-term scale (9-12 days) in two different ways: i) increasing the general activity of the AL and ii) modifying the spatiotemporal response of the patterns. Those changes might underlie a long-term olfactory memory for the early-experienced odor.