Antennal lobes neurons

Figure 24.1 A surface reconstruction of a male antennal lobe of the moth Spodoptera littoralis. The brain was immunostained with synapsin antibody and optically sectioned using a confocal microscope. Stacks of images were integrated with the software Imaris 2,7 (Bitplane AG, Switzerland) on a Silicon Graphics workstation to obtain surface projections of the lobe. The macroglomerular complex (MGC) is located close to the entrance of the antennal nerve. M, medial D, dorsal (modified from Carlsson et at, 2002). B Synaptic organization of the major types of antennal lobe neurons. Sensory neurons (ORNs) make uniglomerular synapses both directly with projection neurons (PNs) and indirectly via local interneurons (LNs). In addition, local interneurons innervate several glomeruli and generally make inhibitory synapses. Cell bodies of PNs and LNs are located within the antennal lobe.

Figure 24.3 Temporal analysis of responses measured simultaneously in five different antennal lobe neurons in the moth Manduca sexta. The matrices show patterns of neural synchrony evoked by either of two pheromone components or a binary mixture at two concentrations. The number of synchronous events was averaged over 20 trials and calculated for 500 ms from stimulus onset. The gray scale ranges from 0 to 3.8 coincident spikes per stimulus. The horizontal displays below the matrices show the averaged spiking rate in each single neuron (gray scale ranges from 0 to 5.5 spikes per stimulus period). Neural synchrony was influenced not only by the odor quality but also by both stimulus intensity and blend interactions (redrawn from Christensen eta ., 2000).

Peele P, Ditzen M, Menzel R, Galizia CG (2006) Appetitive odor learning does not change olfactory coding in a subpopulation of honeybee antennal lobe neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol [A] 192 1083-1103... 

G. Laurent, Model of transient synchronization in the locust antennal lobe, Neuron 30... 

Recordings from antennal lobe neurons of Antherea sp. demonstrated that neurons responding to pheromones were located in the medial cluster, while no neurons studied in the lateral cluster responded to these compounds (Boeckh and Boeckh, 1979). Responses to pheromones were exclusively excitatory with a phasic-tonic pattern imposed upon a low resting activity (ca 1 imps" ). Responses were elicited exclusively by stimulation with sex pheromones on the ipsilateral antennae. All central neurons responding to pheromones were activated by both components of their respective pheromone blends in the two Antherea species. Only a quantitative difference in the effect on the neurons... 

Axons of antennal ORCs project through the antennal nerve to enter the brain at the level of the ipsilateral antennal lobe (AL) of the deutocerebrum (52). ORC axons project from the flagellum to targets in the AL, but axons from antennal mechanosensory neurons bypass the AL and project instead to an "antennal mechanosensory and motor center" in the deutocerebrum posteroventral (with respect to the body axis of the animal) to the AL (52, 58, 64). In moths and certain other insect groups, sex-pheromonal information is processed in a prominent male-specific neuropil structure in each AL called the macroglomerular complex (MGC) (16, 52, 64, 65). 

Fig-1 Schematic view of the overall olfactory processing in insects. Pheromones and other semiochemicals are detected by specialized sensilla on the antennae, where the chemical signal is transduced into nervous activity. The olfactory receptor neurons in the semiochemi-cal-detecting sensilla are connected directly to the antennal lobe. Here the semiochemical-derived electrical signals are processed and sent out (through projection neurons) to the protocerebrum. Olfactory information is then integrated with other stimulus modalities, a decision is made, and the motor system is told what to do... 

Axons originating in sensilla that are responsive to food odorants and those that originate in sex pheromone-responsive neurons terminate in different glomeruli, the first synaptic relay station within the antennal lobe (Boeckh and Ernst,... 

Christensen T. A. and Hildebrand J. G. (1987) Male-specific, sex pheromone-selective projection neurons in the antennal lobes of the modi Mundue a sexta. J. Comp. Physiol. [A] 160, 553-569. 

Distler P. G. and Boeckh J. (1997b) Synaptic connections between identified neuron types in the antennal lobe glomeruli of the cockroach, Periplaneta americana II. Local multiglomerular interneurons. J. Comp. Neurol. 383, 529-540. 

Matsumoto S. and Hildebrand J. (1981) Olfactory mechanisms in the moth Manduca sexta response characteristics and morphology of central neurons in the antennal lobes. Proc. R. Soc. London Ser. B 213, 249-277. 

Sun X. J., Tolbert L. P. and Hildebrand J. G. (1997) Synaptic organization of the uniglomerular projection neurons of the antennal lobe of the moth Manduca sexta a laser scanning confocal and electron microscopic study. J. Comp. Neurol. 379, 2-20. Takken W., van Loon J. J. A. and Adam W. (2001) Inhibition of host-seeking response and olfactory responsiveness in Anopheles gambiae following blood feeding. J. Insect. Physiol. 47, 303-310. 

Gao Q., Yuan B. and Chess A. (2000) Convergent projections of Drosophila olfactory neurons to specific glomeruli in the antennal lobe. Nat. Neurosci. 3, 780-785. 

Python F. and Stocker R. F. (2002) Adult-like complexity of the larval antennal lobe of D. melanogaster despite markedly low numbers of odorant receptor neurons. J. Comp. Neurol. 445, 374-387. 

Bhalerao S., Sen A., Stocker R. F. and Rodrigues V. (2003) Olfactory neurons expressing identified receptor genes project to subsets of glomeruli within the antennal lobe of Drosophila melanogaster, J. Neurobiol. 54, 577-592. 

Stocker R. F., Lienhard M. C., Borst A. and Fischbach K.-F. (1990) Neuronal architecture of the antennal lobe in Drosophila melanogaster. Cell Tissue Res. 262, 9-34. 

Figure 24.4 Gray-scaled signals of optical recordings of calcium activity from the antennal lobe of the moth Helicoverpa zea. A, B and C show thresholded (>50 percent of maximum) responses to the pheromone components Z11-16 Ald and Z9-16 Ald and a behavioral antagonist Z11-16 Ac, respectively. D A schematic figure of the organization of the macroglomerular complex in H. zea (from Vickers et al., 1998). The position of the glomeruli coincides with the foci of calcium responses, i.e. response to Z11-16 Ald takes place in the cumulus, Z9-16 Ald in the DM-P glomerulus and Z11-16 Ac in the DM-A glomerulus. These activity patterns corroborate the innervation patterns of functionally identified projection neurons (redrawn from Vickers et al., 1998).

Distler P. G., Bausenwein B. and Boeckh J. (1998) Localization of odor-induced neuronal activity in the antennal lobes of the blowfly Calliphora vicina a [3H] 2-deoxyglucose labeling study. Brain Res. 805, 263-266. 

Hansson B. S., Almaas T. J. and Anton S. (1995) Chemical communication in heliothine moths. V. Antennal lobe projection patterns of pheromone-detecting olfactory receptor neurons in the male Heliothis virescens (Lepidoptera Noctuidae). J. Comp. Physiol. A 177, 535-543. 

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