Environment‐specific modulation of odorant representations in the honeybee brain

Abstract

Ca imaging techniques were applied to investigate the neuronal behavior of projection neurons in the honeybee antennal lobe (AL) to examine the effects of long-lasting adaptation on odorant coding. Responses to eight test odorants were measured before, during, and after an odor adaptation phase. Bees were exposed to the adapting odor for 30 min. Test odorant responses were only recorded from a sub-population of accessible glomeruli on the AL surface. Projection neurons, the output neurons of the antennal lobes, are projecting through the lateral, mediolateral, and medial AL tract to higher centers of the olfactory pathway. Due to our staining techniques, we primarily focused our study on projection neurons going through the lateral and medial tract. Test odorants comprised compounds with different functional groups (alcohol, aldehyde, ketone, and ester) representing floral and/or pheromone odorants. Strength and discriminability between combinatorial activity patterns induced by the test odorants were quantified. In two independent experiments, we investigated one group of animals adapted to a colony odor and another adapted to a synthetic odor. Within the experimental groups, we found test odorant responses either decreased or increased in AL projection neurons. Additionally, the discriminability between test odorant patterns became less distinct in the colony odor experiment and more distinct during adaptation in the synthetic mixture experiment. These results are interpreted as odor dependent adaptation effects, increasing or decreasing response strength and discriminability by altered neural coding mechanisms in the AL neuropile.

Morphofunctional experience-dependent plasticity in the honeybee brain

“…Recently, Chakroborty et al (2016) reported on changes in PN activity following 30 min adaptation of the olfactory system through exposure to complex mixtures. In our experiments, a long-duration preexposure was used to study the so-far-unaddressed issue of structural plasticity in relation to unrewarded odor exposure, which requires longer timescales.…”

Local deformation and stiffness distribution in fly wings

“…Eicosane melts at ∼37°C; well below maximum flight muscle temperature during flight in Calliphora (∼42°C, Stavenga et al, 1993). It is commonly used in insect research (Vallet et al, 1992; Szyszka et al, 2005; Haehnel et al, 2009; Yamagata et al, 2009; Chakroborty et al, 2016).…”

Olfactory coding in honeybees

“…1a). This allowed to complement the morphological atlas with the functional response properties of glomeruli in the honeybee antennal lobe (Galizia et al 1999b;Sachse et al 1999) (see also https ://neuro .uni-konst anz.de/honey beeAL atlas ), which has been used to investigate the principles of olfactory coding (Deisig et al 2006;Deisig et al 2010;Paoli et al 2016b;Paoli et al 2018;Sachse and Galizia 2003), the relationship between perceptual and chemical similarity of odorants (Carcaud et al 2012;Guerrieri et al 2005), as well as changes in olfactory representation upon learning (Chakroborty et al 2016;Chen et al 2015;Hourcade et al 2009;Rath et al 2011).…”