Made available in DSpace on 2016-02-26T14:53:08Z (GMT). No. of bitstreams: 1 ClaudiaBezerraSGoncalves.pdf: 706994 bytes, checksum: 7b1a77a7f4ff1c1b643ddf918c282667 (MD5) Previous issue date: 2007-02-28 / Most part of the external sensory receptaclles known are located in the antennal flagellate: sensilla placodea (olfactory discs, D.O.), basiconica, trichodea (cerdas), coeloconica, ampullaceae and campaniformia. The Apidae bees have been studied on diverse aspects, the external morphology, among which has call the attention for its importance is the bee antennae. The study of the antennae and their sensory olfactive structures has been done more frequently in highly social bees, such as Apina and Meliponina. The purpose of the paper was to analyze comparatively, at microscopic level, the size and the form of the antenna, the number and the distribution of the olfactory antennal structures or sensilla placodea in Euglossina and Meliponina bees with different social standards It was antennae from 10 males of Melipona favosa orbignyi and of Scaptotrigona depilis, 10 males of Eufriesea violaceae and of Exaerete smaragdina and 2 males of Exaerete dentata, totaling 62 bees analyzed for each species studied. For segment was counted the absolute number of the olfactory discs, it was measured diverse morphometric characters and obtained the following values AT (total area of the segment) aE (area with D.O), a (area with D.O.) and it was calculated the indices D.O./AT and D.O/aE. It was the Euglossina bees have more D.O., related to absolute numbers than the Meliponina. Among the Meliponina, the males and the workers the M. favosa orbignyi 5 have more absolute number of D.O., and comparing sex, the males have more D.O. than the females. As for the characters A (width of the segment) D and E (length of the segment), the Euglossina male show more value when compared to the workers and males of the Meliponina. As for the area of the antennal segment, Euglossina males present a total area AT much bigger than Meliponina. Among all the species analyzed, Euglossina show an area with olfactive structure (aE) and an area without theses D.O. (a) with similar sizes; while Meliponina, aE > a. Among the Meliponina, S. depilis have more discs (D.O./AT) with more concentration on the segment (D.O./aE) among the males, theses values are bigger than the females. The worker, M. favosa orbignyi, show theses indices much bigger than the males, indicating more quantity of D.O. with more concentration in the segment. Among all Euglossina, the males of Eufriesea violaceae have more D.O. than E. dentata and E. smaragdina (both with lower values than the Meliponina). Hence S. depilis, despite its smaller size, have the bigger number of D.O. than the Euglossina, Eufriesea violaceae have bigger number D.O. than the Exaerete (which are considered big bees and bigger than Eufriesea violaceae) / No flagelo antenal se encontra a maior parte de receptores sensoriais externos conhecidos: sensilla placodea (discos olfativos, D.O.), basiconica, trichodea (cerdas), coeloconica, ampullacea e campaniformia. Nas abelhas Apidae, têm sido estudadas sob os mais diversos aspectos, a morfologia externa, sendo que um dos caracteres que tem chamado a atenção pela sua importância é a antena das abelhas. O estudo das antenas e de suas estruturas sensoriais olfativas tem sido realizado com mais intensidade em abelhas altamente sociais, como nos Apina e Meliponina. O objetivo do trabalho foi analisar comparativamente, em nível de microscopia óptica, o tamanho e forma da antena, o número e a distribuição das estruturas olfativas antenais ou sensilla placodea em abelhas Euglossina e Meliponina com diferentes padrões sociais. Foram usadas antenas de 10 machos e 10 fêmeas de Melipona favosa orbignyi e de Scaptotrigona depilis; 10 machos de Eufriesea violaceae e de Exaerete smaragdina e, 2 machos de Exaerete dentata, totalizando 62 abelhas analisadas para cada espécie estudada. Para cada segmento foi contado o número absoluto de discos olfativos, foram medidos diversos caracteres morfométricos e obtidos os valores AT (área total do segmento), aE (área com D.O. ), a (área sem D.O.), e ainda, calculados os índices D.O./AT e D.O./aE. Verificou-se que as abelhas Euglossina têm mais D.O., em números absolutos, do que as Meliponina. Dentre os Meliponina, os machos e as operárias de M. favosa orbignyi tem maior número absoluto de D.O., e, na comparação entre os sexos, os machos possuem mais D.O. do que as fêmeas. 3 Referente aos caracteres A (largura total do segmento) D e E ( relativos ao comprimento do segmento), os maiores valores são apresentados pelos machos Euglossina, quando comparados com operárias e machos de Meliponina. Quanto às áreas do segmento antenal, os machos Euglossina apresentam a área total AT muito maior do que em Meliponina. Dentre todas as espécies analisadas, os Euglossina mostram a área com estruturas olfativas (aE ) e a área sem esses D.O.(a) com tamanhos semelhantes; enquanto que nos Meliponina, aE > a. Dentre os Meliponina, S. depilis têm mais discos (D.O./AT), com maior concentração no segmento (D.O./aE) sendo que nos machos, esses valores são maiores do que nas fêmeas. As operárias M. favosa orbignyi mostram esses índices bem maiores do que nos machos, indicando maior quantidade de D.O., com maior concentração no segmento. Dentre todos os Euglossina, os machos de Eufriesea violaceae têm mais D.O. do que E. dentata e E. smaragdina (ambos com valores inferiores aos dos Meliponina). Portanto S. depilis, independente de seu tamanho menor, têm o maior número de discos olfativos; e dentre os Euglossina, Eufriesea violaceae têm maior número de D.O. do que as Exaerete (que são consideradas abelhas de grande porte, e maiores que Eufriesea violaceae)

Dans un monde dynamique la survie des animaux dépend de leur capacité à intégrer des signaux environnementaux afin d'adapter leur comportement à la survenue de conséquences positives (nourriture) ou négatives (dangers) c'est-à-dire de leurs capacités d’apprentissages associatifs appétitif et aversif. Pendant ce travail de thèse, nous nous sommes intéressés aux bases comportementales, moléculaires et génétiques de l'apprentissage aversif et aux relations existant entre apprentissages aversif et appétitif au sein d'un groupe social. L'abeille est un insecte eusocial qui constitue un modèle de choix pour cette étude grâce à l'existence des protocoles de conditionnement appétitif de la réponse d'extension du proboscis (REP) et de conditionnement aversif de la réponse d'extension du dard (RED). Jusqu'à présent, le renforcement utilisé dans le conditionnement aversif de la RED était un choc électrique. Ce stimulus traversant la majeure partie du corps de l'abeille, il est peu aisé d'étudier les structures responsables de sa détection. Dans un premier chapitre, nous avons donc testé l’effet d’une forte température (65°C) sur la RED. Nous montrons qu’une stimulation thermique au niveau des pièces buccales, des pattes ou des antennes induit une RED. De plus, les abeilles parviennent à associer une odeur à la présentation concomitante d'une forte température. Dans un deuxième chapitre, nous avons cartographié la sensibilité thermique du corps des abeilles en mesurant la RED. Ce travail a montré que la stimulation de presque toutes les parties du corps induit une RED. De plus, ces stimulations peuvent jouer le rôle de renforcement aversif lors d’un conditionnement olfactif de la RED. Nous nous sommes ensuite intéressés aux récepteurs périphériques potentiellement impliqués dans la détection des fortes températures, et en particulier à HsTRPA (Hymenoptera specific Transient Receptor Potential A). Nous montrons que l’injection d'inhibiteurs exogènes de HsTRPA réduit les RED à la température. Ces résultats suggèrent l’implication possible d’HsTRPA dans la détection de la température chez l’abeille. Dans un troisième chapitre, nous nous sommes intéressés aux relations existant entre les capacités d’apprentissages aversif et appétitif des abeilles. En nous appuyant sur le protocole aversif thermique, combiné au protocole de conditionnement de la REP existant, nous avons étudié la distribution des capacités hédoniques appétitive et aversive au sein d'une ruche. La reine étant fécondée par 15-20 mâles, la ruche est segmentée génétiquement en autant de lignées paternelles différentes. Nos données montrent que la sensibilité des individus aux renforcements aversif (chaleur) et appétitif (sucre) détermine leurs performances d'apprentissage au sein de chaque modalité hédonique. Nous montrons de plus l’existence d’un trade-off, sous déterminisme génotypique, entre les capacités cognitives appétitive et aversive au sein de la colonie. Le quatrième chapitre a étudié la plasticité comportementale induite par les deux types de conditionnement. La REP et la RED étant des réponses de type "tout ou rien", nous nous sommes demandé si les mouvements antennaires des abeilles pouvaient procurer une mesure fine et intégrer des apprentissages appétitif et aversif. Nous avons développé un système de capture vidéo enregistrant les mouvements antennaires à haute vitesse. Nous montrons que les abeilles modifient leur réponse antennaire à une odeur après un apprentissage appétitif mais pas après un apprentissage aversif. Durant ce travail de thèse, nous avons ainsi développé deux nouveaux protocoles comportementaux en contention, et avons procuré de nouvelles données sur l’apprentissage aversif chez l’abeille. Nous avons observé un trade-off au sein de la ruche entre les capacités hédoniques appétitive et aversive, sous déterminisme génétique. De telles spécialisations cognitives pourraient jouer un rôle prépondérant dans l'évolution des groupes sociaux. / In a dynamic world, animals constantly face environmental changes that may affect them (Alock, 1997). Their survival depends on their ability to integrate this information in order to adapt their behaviors to subsequent positive or negative outcomes, in other words to their appetitive and aversive learning abilities. This thesis investigates the behavioral, molecular and genetic basis of aversive learning and its putative relationship with appetitive learning in a social group. The honeybee is a social insect which constitutes a profitable model for this study thanks to appetitive conditioning of the proboscis extension response (PER) and aversive conditioning of the sting extension response (SER) protocols that have been developed. To date, aversive conditioning of the SER has involved the use of electric shocks as a negative reinforcement. However, this stimulus is ecologically irrelevant for honeybees and electric currents pass through almost every part of the bee’s body making it difficult to study the dedicated structures and sensory pathways responsible for its detection. In the first chapter, we assessed the impact of high temperatures on SER, a stimulus that is also highly aversive. We showed that a SER may be triggered by heat stimulation of mouthparts, forelegs and antennae. In addition, we demonstrated that honeybees are able to associate an odor with high temperatures, resulting in the odor alone triggering the SER after conditioning. In the second chapter, we mapped the heat sensitivity of the bee’s body recording SER subsequent to heat stimulation. This work revealed that heat stimulation of almost every body structures (beside the wings and the tip of the abdomen) induces a SER. Furthermore, these stimulations may act as aversive reinforcement during an olfactory conditioning of the SER. We then focused on putative peripheral receptors involved in high temperature detection, specifically focusing on HsTRPA (Hymenoptra specific Transient Receptor Potential). Using a neuropharmalogical approach, we showed that HsTRPA exogenous inhibitor injections decrease SER triggered by high temperatures yet have no impact on sucrose PER. These results suggest a putative involvement of HsTRPA in the detection of high temperatures in honeybees. In the third chapter, we investigated the relationship between appetitive and aversive learning. By combining thermal aversive conditioning with the PER conditioning protocol, we studied the distribution of hedonic learning abilities in the hive. Since the queen mates with 15-20 males, the hive is, thus, genetically segmented in as many different patrilines. Our data shows that individual sensitivity to aversive (heat) and appetitive reinforcement varies among workers and determines their learning success in each hedonic modality. In addition, we observed that the better an individual (and therefore a patriline) is at appetitive learning, the less successful it will be in aversive learning, and vice versa. The forth chapter focused on the behavioral plasticity induced by the two types of conditioning. PER and SER are binary responses in an “all or nothing” fashion and subtle behavioral variations are difficult to observe. We therefore investigated if honeybee antennal movements may yield a finer measurement to integrate appetitive and aversive learning. We developed a motion capture system that records antennal movements at high speed. We showed that honeybees modify their antennal response to an odor previously associated with sucrose reward however thermal aversive conditioning did not induce any antennal movement modifications. During this PhD work, we developed two new behavioral assays in harnessed individuals, furthering our understanding on aversive learning in the honeybee. Within the hive, we observed a trade-off between appetitive and aversive hedonic learning, which was genetically influenced. Such cognitive specialization could play a key role in social evolution.

The freshwater prawn, Macrobrachium rosenbergii (de Man, 1879) is an important aquaculture species but one that has the disadvantage of heterogeneous individual growth (HIG) according to different morphotypes. Chemical cues, especially, pheromones, are one of the most important communication types between individual prawns, along with visual and tactile methods. Testing pheromones, whilst restricting other cues, may therefore lead to a better understanding of the influence of these communicatory compounds on the prawn reproductive process. The three principle objectives of this study were therefore: 1) To examine the effect of moult stage and morphotype on pheromone-induced sexual behaviour 2) To examine the role of pheromone / urine concentrations on sexual attraction behaviour 3) To describe the functional morphology of the antennal gland and examine its possible role in pheromone production and release. Identical bioassay tanks were designed and constructed to study the reproductive behaviour of prawns. Experiments were set up to examine responses to pheromone release by live prawns over 30 minutes and behavioural response observations were made with the aid of a Closed-Circuit Videotape System (CCVS). Results were statistically analysed using a repeated measures general linear model (GLM). Three trials were designed to test the effect of moult stage of both males and females and male morphotypes on sexual attraction behavioural responses. Twelve prawns were used for each trial and each prawn was used five times (1 no-pheromone control and 4 for experimental tests). The first trial studied the effect of female moult stages (pre-, inter and newly-moulted) on sexual attraction behaviour of blue claw (BC) male. Results of this trial showed that newly-moulted females spent significantly (p<0.05) less time approaching the BC male than the pre- and inter-moult females. The second trial studied the effect of male moult stage (pre-, inter and newly-moulted) on sexual attraction to receptive females. Results showed that the time taken by the inter-moult males was (p<0.05) less than the pre- and newly-moulted males in approaching the newly-moulted female. The third trial tested the effect of male morphotypes (small male, SM, orange claw, OC and dominant blue claw, BC) on sexual attraction behaviour towards newly-moulted females. Results showed that the BC male was significantly more attractive (p<0.05) than other morphotypes to newly-moulted females and that the OC male was the least attractive. The role of moulting stage for both male and female prawns on reproductive response behaviour was investigated. Because BC males responded significantly faster towards newly-moulted female more than to either pre-or inter-moult females, results of the first trial suggest that BC males are able to use different chemical cues to gather information about a conspecific’s gender and can differentiate female’s moult stages. Since BC males responded significantly faster towards newly-moulted females more than to either pre-or inter-moult females, this suggests that females at this particular stage released a distinct sexual pheromone or concentration of pheromone that differed from those pheromones released by both pre- and inter-moult females. In contrast, newly-moulted females prefer the inter-moult BC males which indicate that females have an ability to distinguish the moult status of BC males. Furthermore, it indicates that pheromone characteristics change with the moult status of BC males. Also, newly-moulted females are most likely to be avoiding the potential costs of mate guarding with soft shell BC males. Results obtained from the third trial suggested that a newly-moulted female can discriminate male morphotypes (SM, OC and BC) from their pheromone cues. This indicates that male morphotypes release pheromones which differ from each other in some way. Newly-moulted females responded positively to both SM and BC males with different levels of attraction with the greatest attraction to BC males to BC males suggesting that pheromone released from the BC male may carry information relating to dominance status. Urine is believed to be one of the main carriers of pheromone and is usually released from the antennal gland. Different urine concentrations (0.1, 1.0, 2.0, 3.0, 5.0 and 10µl l-1) of collected urine from BC males were used to test the sexual attraction behaviour of receptive newly-moulted females. Also, the attractant capability of fresh urine following exposure to different temperature regimes (cooled at 4ºC, frozen at -70ºC and heated at 70ºC) was tested. Since newly-moulted female M. rosenbergii were attracted to BC male urine, this indicates the existence of sex pheromone in the fresh urine. Also, it was found that the sexual response of females to fresh urine of BC males was directly proportional to urine concentration with faster responses observed with increasing urine concentrations. At the three fresh urine concentrations 0.1 µl l-1, 1.0 µl l-1 and 2.0 µl l-1, statistical analysis indicated no significant difference (p>0.05) between these three concentrations while a significant (P<0.05) response was to concentrations more than 3.0 µl l-1. This may indicate that these three concentrations were not sufficient to elicit attraction behaviour in newly-moulted females. A concentration of 3.0 µl l-1 of fresh urine is suggested to be a sufficient concentration to elicit a significant sexual attraction under laboratory conditions. Response of newly-moulted female prawns to the various temperature treatments tested declined in response to nominally increasingly degradative treatments. Also, statistical analysis showed that temperature treatment and concentration added both had a significant effect on the response of females. The greatest degradation of urine attractiveness was found with the 70ºC heat treatment. It can be concluded that the pheromone components of prawn urine are friable when exposed to high temperatures. Using light and transmission electron microscopes, ultrastructural observation of the antennal gland (AG) of M. rosenbergii suggests that it has four distinct regions, the coelomosac, the nephridial tubules, the labyrinth and the bladder. Morphological and functional descriptions of each of these regions were compared with those of other aquatic Crustacea.

Made available in DSpace on 2015-03-26T13:30:42Z (GMT). No. of bitstreams: 1 texto completo.pdf: 851127 bytes, checksum: ecfdf02c9cd43f58963fe56b126f4b98 (MD5) Previous issue date: 2012-07-19 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The eusocial stingless bee Melipona quadrifasciata anthidioides belongs to the Meliponini, a tribe that comprises important pollinators of tropical and subtropical plants. Within a typical eusocial colony there are drones and females that include different casts, i.e. workers and queen(s). In this species, the caste differentiation can be influenced by the Juvenile Hormone (JH). When JH is topically applied in last instar male larvae, they originate individuals with queen s phenotype in which the male-like reproductive system persists. Take into account that different individuals play different roles in the colony, it is reasonable to assume that they can be distinguished by their sensorial organs. Sensilla are basic integumental unit that are important for the insect thermo, mechanical, higro, CO2 and chemical perceptions. In addition, these sensory structures may be distinguished by their morphologies and functions. The objective of this study was to compare the antennal sensilla of individuals of different sexes and castes, including queen-like males of M. quadrifasciata anthidioides, showing for the first time details of their antennal topographies. Images of antenna dorsal surfaces were taken with the scanning electron microscope. Different types of antennal sensilla can be classified as follows: trichoid (ST, subtypes I to VII), placoid, basiconic, coeloconic and ampullacea. The the ST I and placoid sensilla were the most abundant sensillum types found in all individuals, even more in males. On the other hand, basiconic sensilla were only found in females, i.e. in workers and queens. The ST II is the third most abundant type of sensilla found in M. quadrifasciata anthidioides and the ST III and IV occurred only in the first flagellomere, being the first one bigger in females in comparison to males and the second one capable of separating the castes according to their types and length, though their numbers are not different. Moreover, the ST V and VI and the ampullacea types occurred only at the antenna s tip, with ST V being lower in number and smaller. ST VI is also larger in queens, separating them from other individuals, and greater in females. On the other hand, the other sensillae were seen along all antennas surface. The chaetic sensillum had apical pore and this pore was only found in females. Despite queen-like males had queen s phenotype, according to the Morisita similarity index, they resembled more the males, especially 2n ones, regarding the antenna phenotype and the composition of their sensilla. Generally speaking, irrespective of gender and cast, individuals of the stingless bee M. quadrifasciata anthidioides have similar sensillum types. However, they differed significantly in respect to the sensilla number and length and these differences were discussed here according to the gender and cast of this species. / A abelha sem ferrão Melipona quadrifasciata anthidioides é conhecida popularmente como mandaçaia e pertence à tribo Meliponini que inclui importantes insetos eusociais polinizadores de espécies de plantas tropicais e subtropicais. Em um ninho típico de abelhas sociais há indivíduos de diferentes sexos e castas. Esses são compostos pelos zangões e pelas castas femininas que incluem as operárias e a(s) rainha(s). Entretanto, quando o hormônio juvenil (HJ) é aplicado topicamente em larvas de machos, eles desenvolvem fenótipo da rainha. Entretanto, esses rainhóides ainda retêm o sistema reprodutivo masculino. Considerando que os indivíduos de diferentes castas e sexos desempenham papéis diferentes no ninho, podemos afirmar que os seus órgãos sensoriais como, por exemplo, as sensilas antenais também o sejam. Essas estruturas sensoriais podem ser diferenciadas tanto pela sua morfologia quanto pela função que desempenham como, por exemplo, a quimio- e mecanorrecepção. O objetivo deste trabalho foi estudar comparativamente as sensilas antenais de indivíduos de diferentes sexos e castas, incluindo os machos 2n e rainhóides, de M. quadrifasciata anthidioides, através de imagens da superfície dorsal das antenas, que foram feitas ao microscópio eletrônico de varredura. As diferentes sensilas antenais foram identificadas como sendo: sensilas tricóides (ST, dos subtipos I ao VI), placóides, basicônicas, céticas, celocônicas e ampuláceas. As sensilas basicônicas possuem um poro apical e são exclusivas das fêmeas (rainhas e operárias). As ST I e as placóides são as mais abundantes em todos os indivíduos, sendo encontradas em maior quantidade nos machos. Já as sensilas basicônicas possuem um poro apical e são exclusivas das fêmeas (rainhas e operárias). As ST II são o terceiro tipo de sensilas mais abundante em M. quadrifasciata anthidioides e as ST III e IV ocorrem apenas no primeiro flagelômero, sendo o primeiro tipo de sensila maior nas fêmeas que nos machos e o segundo tipo capaz de separar as castas femininas quanto ao seu comprimento, mas não diferem à quantidade. Por outro lado, as ST V e VI e ampuláceas ocorrem apenas na extremidade do último flagelômero antenal, com ST V sendo menor nos machos de M. quadrifasciata anthidioides tanto em quantidade quanto em comprimento, mas sendo úteis ainda para a distinção das castas femininas. As ST VI são mais compridas nas rainhas, separando-as dos demais indivíduos, e maiores nas fêmeas. Apesar dos rainhóides se assemelharem às rainhas quanto à morfologia externa, uma análise utilizando o índice de similaridade de Morisita mostrou que eles se assemelham mais aos machos, principalmente os 2n, quanto às suas antenas e a composição das sensilas, colocando-os em um grupo separado das fêmeas. Embora de maneira geral os mesmos tipos de sensilas tenham sido encontrados nas diferentes classes de indivíduos de M. quadrifasciata anthidioides, diferenças significativas foram observadas no número e no comprimento dos morfotipos das mesmas. Essas diferenças foram discutidas de acordo com a função do sexo e das castas dessa espécie.

In dieser Arbeit werden zwei wesentliche neue Ergebnisse vorgestellt. Das erste bezieht sich auf die olfaktorische Kodierung und das zweite auf das sensorische Gedaechtnis. Beide Phaenomene werden am Beispiel des Gehirns der Honigbiene untersucht. In Bezug auf die olfaktorische Kodierung zeige ich, dass die neuronale Dynamik waehrend der Stimulation im Antennallobus duftspezifische Trajektorien beschreibt, die in duftspezifischen Attraktoren enden. Das Zeitinterval, in dem diese Attraktoren erreicht werden, betraegt unabhaengig von der Identitaet und der Konzentration des Duftes ungefaehr 800 ms. Darueber hinaus zeige ich, dass Support-Vektor Maschinen, und insbesondere Perzeptronen, ein realistisches und biologisches Model der Wechselwirkung zwischen dem Antennallobus (dem kodierenden Netwerk) und dem Pilzkoerper (dem dekodierenden Netzwerk) darstellen. Dieses Model kann sowohl Reaktionszeiten von ca. 300 ms als auch die Invarianz der Duftwahrnehmung gegenueber der Duftkonzentration erklaeren. In Bezug auf das sensorische Gedaechtnis zeige ich, dass eine einzige Stimulation ohne Belohnung dem Hebbschen Postulat folgend Veraenderungen der paarweisen Korrelationen zwischen Glomeruli induziert. Ich zeige, dass diese Veranderungen der Korrelationen bei 2/3 der Bienen ausreichen, um den letzten Stimulus zu bestimmen. In der zweiten Minute nach der Stimulation ist eine erfolgreiche Bestimmung des Stimulus nur bei 1/3 der Bienen moeglich. Eine Hauptkomponentenanalyse der spontanen Aktivitaet laesst erkennen, dass das dominante Muster des Netzwerks waehrend der spontanen Aktivitaet nach, aber nicht vor der Stimulation das duftinduzierte Aktivitaetsmuster bei 2/3 der Bienen nachbildet. Man kann deshalb die duftinduzierten (Veraenderungen der) Korrelationen als Spuren eines Kurzzeitgedaechtnisses bzw. als Hebbsche "Reverberationen" betrachtet werden. / Two major novel results are reported in this work. The first concerns olfactory coding and the second concerns sensory memory. Both phenomena are investigated in the brain of the honeybee as a model system. Considering olfactory coding I demonstrate that the neural dynamics in the antennal lobe describe odor-specific trajectories during stimulation that converge to odor-specific attractors. The time interval to reach these attractors is, regardless of odor identity and concentration, approximately 800 ms. I show that support-vector machines and, in particular perceptrons provide a realistic and biological model of the interaction between the antennal lobe (coding network) and the mushroom body (decoding network). This model can also account for reaction-times of about 300 ms and for concentration invariance of odor perception. Regarding sensory memory I show that a single stimulation without reward induces changes of pairwise correlation between glomeruli in a Hebbian-like manner. I demonstrate that those changes of correlation suffice to retrieve the last stimulus presented in 2/3 of the bees studied. Succesful retrieval decays to 1/3 of the bees within the second minute after stimulation. In addition, a principal-component analysis of the spontaneous activity reveals that the dominant pattern of the network during the spontaneous activity after, but not before stimulation, reproduces the odor-induced activity pattern in 2/3 of the bees studied. One can therefore consider the odor-induced (changes of) correlation as traces of a short-term memory or as Hebbian reverberations.

Chez les abeilles domestiques, les neurones à récepteurs olfactifs hébergés dans les antennes sont des neurones sensoriels primaires responsables de la détection des odeurs et des phéromones. L'information olfactive est ensuite acheminée par les nerfs antennaires jusqu'aux lobes antennaires qui constituent le premier étage d'intégration de l'information olfactive. Les abeilles butineuses sont exposées aux insecticides, notamment ceux de la classe des pyréthrinoïdes, qui sont utilisés pour la protection des plantes et la lutte contre les insectes considérés comme étant nuisibles.Nous avons caractérisé l'effet des pyréthrinoïdes sur les canaux sodiques activés par le potentiel (responsables des potentiels d'action) dans les deux premiers étages du système olfactif de l'abeille. Nos enregistrements électrophysiologiques en mode potentiel imposé dans les neurones à récepteurs olfactifs mis en culture révèlent que l'effet des pyréthrinoïdes de type I et II (notamment la tétraméthrine et la deltaméthrine) est amplifié par une intensification de l'activité électrique neuronale. Cette amplification survient notamment via le démasquage de canaux sodiques silencieux que nous avons également mis en évidence avec la toxine d'anémone de mer ATX-II. Le niveau maximal de canaux sodiques modifiés est atteint en quelques centaines de millisecondes. Dans les neurones centraux des lobes antennaires, cette amplification apparait très limitée voire absente avec les pyréthrinoïdes mais elle peut toutefois survenir en présence de l'alcaloïde végétal vératridine. Par ailleurs, dans ces neurones centraux, les pyréthrinoïdes semblent être à l’origine d’une accélération de l'inactivation lente des canaux sodiques auparavant décrite en présence de certains anesthésiques locaux. Les modifications différentielles observées dans les neurones périphériques et centraux pourraient être responsables des effets délétères des pyréthrinoïdes sur les capacités de perception, d'orientation et d'apprentissage de l'abeille domestique. / In domestic honeybees, the olfactory receptor neurons localized in the antennae are primary sensory neurons responsible for the detection of odor and pheromone compounds. The olfactory information is further conveyed to the antennal lobes by the antennal nerves. The antennal lobes are the first stage of integration of the olfactory information. Forager bees are exposed to insecticides, especially pyrethroids that are used for plant protection and eradication of pests.In the honeybee olfactory pathway, we investigated the effects of pyrethroids on the voltage-gated sodium channels (which underlie action potentials). Our patch-clamp recordings in the antennal olfactory receptor neurons maintained in cell culture reveal that the effects of type I and type II pyrethroids (e.g. tetramethrin and deltamethrin) are increased by an augmentation of neuronal electrical activity. The amplification of the effects of pyrethroids occurs as a result of the unmasking of silent sodium channels that we have also shown evidence for, with sea anemone toxin ATX-II. The maximal sodium channels modification takes place within few hundreds of milliseconds. In the central antennal lobe neurons, that amplification is rather limited or absent with pyrethroids but the plant alkaloid veratridine is able to induce such an amplification. Furthermore, in the latter cell type, pyrethroids cause an acceleration of the sodium channels slow inactivation. Such an effect has been previously reported for some local anesthetics. The differential actions of pyrethroids that we have observed in the peripheral and central neurons may be responsible for the impairment of learning performance, perception and disorientation exhibited by pyrethroid-exposed honeybees.