Three-dimensional antennal lobe atlas of male and female moths, Lobesia botrana (Lepidoptera: Tortricidae) and glomerular representation of plant volatiles in females

Abstract

Spatiotemporal odour coding is thought to be linked closely with the specific glomerular anatomy of the primary olfactory centre. In most insects the number of the glomeruli within the antennal lobe is limited to fewer than 100, allowing their individual identification. In the grapevine moth, Lobesia botrana, a map of the antennal lobe glomeruli was reconstructed three-dimensionally, by comparing three different brains in males and females. The map of the antennal lobe of females served then as a basis to identify glomeruli containing dendritic arborisations of 14 physiologically characterised projection neurons. Projection neurons responding to the same plant compound did not always arborise in the same glomerulus and some neurons arborising in the same glomerulus responded to different compounds. Different zones of target glomeruli were, however, identified when pooling all neurons responding to one of two different compounds respectively (α-farnesene and nonatriene). All identified glomeruli of specifically responding projection neurons were situated close to the anterior surface of the antennal lobe. One broadly responding projection neuron arborised in a more posteriorly situated glomerulus. A local interneuron responding to only one compound was arborising densely in a neighbouring glomerulus and had sparse branches in all other glomeruli. These results are discussed with respect to plant odour processing and structure-function relations in antennal lobe neurons. The 3D AL atlas will, in the future, also be used to obtain a better understanding of coding mechanisms of grapevine odours in this pest insect.

Calcium Current Diversity in Physiologically Different Local Interneuron Types of the Antennal Lobe

“…In parallel, we will present, as a reference, data from uniglomerular projection neurons (uPNs). Projection neurons generate Na ϩ -driven action potentials, and their morphology and response properties are well known in the cockroach (Burrows et al, 1982;Ernst and Boeckh, 1983;Boeckh and Ernst, 1987;Malun et al, 1993;Distler and Boeckh, 1997a) and other insects [Apis mellifera (Sun et al, 1997;Abel et al, 2001), Drosophila melanogaster (Wilson et al, 2004), Schistocerca americana (Wehr and Laurent, 1996;Stopfer and Laurent, 1999;Stopfer et al, 2003;Bazhenov et al, 2005;Broome et al, 2006), and different moths (Waldrop et al, 1987;Kanzaki et al, 1989;Hansson et al, 1994;Masante-Roca et al, 2005;Namiki et al, 2008)]. In the second part, we present a detailed analysis of the voltage-activated Ca 2ϩ currents in two physiologically different LN types and uPNs.…”

Chemosensory Selectivity of Output Neurons Innervating an Identified, Sexually Isomorphic Olfactory Glomerulus

“…Importantly, however, neither of these studies measured the doseresponse characteristics of the neurons. Recently, Masante-Roca et al (2005), based on findings in two animals, reported that PNs thought to arborize in the same glomerulus responded to different odor stimuli. Here, we found that G35-PNs could respond to other stimuli in addition to c3HA at high concentrations, but their specificity was higher at lower stimulus concentrations (Figs.…”

“…The glomeruli are organized chemotopically [i.e., each glomerulus is a functional unit dedicated to processing information about a particular odor compound or molecular attribute(s) of odor compounds] (for review, see Buck, 1996;Hildebrand and Shepherd, 1997). The mammalian OB includes Ͼ1000 glomeruli (Mombaerts et al, 1996), whereas the AL of most insects has only 40 -160 glomeruli, depending on the species (Flanagan and Mercer, 1989;Hildebrand, 1992, 2000;Berg et al, 2002;Masante-Roca et al, 2005). Thus, because of its numerical simplicity and the possibility of identifying glomeruli across individuals, the insect AL is an advantageous model for studies of glomerular function.…”

“…Thus, because of its numerical simplicity and the possibility of identifying glomeruli across individuals, the insect AL is an advantageous model for studies of glomerular function. As in other moths (Vickers et al, 1998;Berg et al, 2002;Masante-Roca et al, 2005), the AL of Manduca sexta (hereinafter referred to as Manduca) includes two olfactory subsystems. One, analogous to the "main" OB of vertebrates, has 60 sexually isomorphic glomeruli that process information about volatile compounds associated with food and possibly other odors.…”

The anatomical pathways for antennal sensory information in the central nervous system of the cricket, Gryllus bimaculatus

“…For example, male insects have sex specific glomeruli, the macroglomerular complex, which exclusively process information regarding sex pheromones released by conspecific females (cockroach: Burrows et al, 1982;moth: Christensen and Hildebrand, 1987;Kanzaki et al, 1989; fly: Kondoh, 2003;Stockinger et al, 2005). Further, in the moth, female specific glomeruli process odor information concerning host plants ( Masante-Roca et al, 2005;Skiri et al, 2005). On the other hand, like crickets some insects have no macroglomerulus (e.g.…”