Orientador: Carminda da Cruz Landim / Banca: Foued Salmen Espindola / Banca: Mario Sergio Palma / Banca: Klaus Hartmann Hartfelder / Banca: Maria Claudia Colla Ruvolo Takasusuki / Resumo: Apis mellifera é um organismo de grande interesse para estudos neurobiológicos, pois além de apresentar um cérebro estruturalmente simples, se comparado ao dos vertebrados, apresenta características próprias relacionadas ao comportamento social, com capacidade de memória e aprendizagem. As colônias destas abelhas são constituídas por machos e fêmeas, as fêmeas dividindo-se em duas castas, operárias e rainhas. Sabendo-se que as castas e os machos de A. mellifera apresentam morfologia, fisiologia e padrões comportamentais bastante distintos que, por sua vez, estão, em boa parte representados no polimorfismo cerebral, o presente trabalho visou desvendar como essas diferenças se estabelecem a partir do cérebro larval, basicamente igual para todos. Sendo A. mellifera uma espécie holometábola a transformação das estruturas larvais para as dos adultos ocorre durante a metamorfose, ou seja, durante a pupação. Para melhor compreensão, o estudo iniciou-se com a caracterização das diferenças morfológicas entre os cérebros de operárias, rainhas e machos recém emergidos. A partir da verificação de quais eram as estruturas que mais se diferenciavam entre as classes de indivíduos que compõem a colônia, foram escolhidas para ter sua diferenciação acompanhada os corpos pedunculados, os lobos ópticos e a "pars intercerebralis" no protocérebero e os lobos antenais no deutocérebro. Dessas estruturas foi feito um estudo comparativo entre operárias, rainhas e zangões usando preparações para microscopia de luz, mensurações da área ocupada por alguns de seus componentes, estudos estruturais de outros, bem como uma estimativa das taxas de multiplicação, e mortes celulares com técnicas citoquímicas e imunocitoquímicas. Esses estudos foram iniciados com larvas no último estágio larval... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Apis mellifera is an interesting model to neurobiological studies due to the simplicity of its brain commanding the complex behaviors demanded by the eusocial relationships and its capacity of learning and memorizing. The colonies of this bee consist of males and females. The females are differentiated in two castes: workers and queens. The castes and males from A. mellifera have distinct morphology, physiology and behavior correlated with their functions in the society and represented by some brain polymorphism. In this context the aim of the present study was clear up how the adult brain differences are established parting from the larval brain basicalIy equal to alI kinds of individuaIs. A. melliftra is a holometabolous insect and therefore, the change of the larval structures to the adult ones occurs during pupation or metamorphosis. In order to have a better vision of the differences found among the adult brains. was done a comparative morphological study of the brain from newly emerged workers, queens and males. The results showed that the brain structures more distinct among the individual classes were the mushroom bodies, optic lobes and "pars intercerebralis" from the protocerebrum and the antennal lobes from the deutocerebrum. Those were choose for have their differentiation accompanied during metamorphosis. Comparative studies of the structures among workers, queens and males were done using light and electronic microscopy, measuring the areas occupied from some of their components and estimative of the rates of mitosis and cell death using cytochemical and immuno-histochemical techniques. These studies started in the last larval instar and continued in pre-pupae, white, pink, brown, and black eyed pupae until black body pupae. Besides a search for differential protein expression among the individual classes whole brain was done... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2014-06-11T19:30:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-10Bitstream added on 2014-06-13T20:40:53Z : No. of bitstreams: 1 roat_tc_dr_rcla.pdf: 3118917 bytes, checksum: 7fa7780c7ad97251c717e1fa8f9219e5 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Apis mellifera é um organismo de grande interesse para estudos neurobiológicos, pois além de apresentar um cérebro estruturalmente simples, se comparado ao dos vertebrados, apresenta características próprias relacionadas ao comportamento social, com capacidade de memória e aprendizagem. As colônias destas abelhas são constituídas por machos e fêmeas, as fêmeas dividindo-se em duas castas, operárias e rainhas. Sabendo-se que as castas e os machos de A. mellifera apresentam morfologia, fisiologia e padrões comportamentais bastante distintos que, por sua vez, estão, em boa parte representados no polimorfismo cerebral, o presente trabalho visou desvendar como essas diferenças se estabelecem a partir do cérebro larval, basicamente igual para todos. Sendo A. mellifera uma espécie holometábola a transformação das estruturas larvais para as dos adultos ocorre durante a metamorfose, ou seja, durante a pupação. Para melhor compreensão, o estudo iniciou-se com a caracterização das diferenças morfológicas entre os cérebros de operárias, rainhas e machos recém emergidos. A partir da verificação de quais eram as estruturas que mais se diferenciavam entre as classes de indivíduos que compõem a colônia, foram escolhidas para ter sua diferenciação acompanhada os corpos pedunculados, os lobos ópticos e a pars intercerebralis no protocérebero e os lobos antenais no deutocérebro. Dessas estruturas foi feito um estudo comparativo entre operárias, rainhas e zangões usando preparações para microscopia de luz, mensurações da área ocupada por alguns de seus componentes, estudos estruturais de outros, bem como uma estimativa das taxas de multiplicação, e mortes celulares com técnicas citoquímicas e imunocitoquímicas. Esses estudos foram iniciados com larvas no último estágio larval... / Apis mellifera is an interesting model to neurobiological studies due to the simplicity of its brain commanding the complex behaviors demanded by the eusocial relationships and its capacity of learning and memorizing. The colonies of this bee consist of males and females. The females are differentiated in two castes: workers and queens. The castes and males from A. mellifera have distinct morphology, physiology and behavior correlated with their functions in the society and represented by some brain polymorphism. In this context the aim of the present study was clear up how the adult brain differences are established parting from the larval brain basicalIy equal to alI kinds of individuaIs. A. melliftra is a holometabolous insect and therefore, the change of the larval structures to the adult ones occurs during pupation or metamorphosis. In order to have a better vision of the differences found among the adult brains. was done a comparative morphological study of the brain from newly emerged workers, queens and males. The results showed that the brain structures more distinct among the individual classes were the mushroom bodies, optic lobes and pars intercerebralis from the protocerebrum and the antennal lobes from the deutocerebrum. Those were choose for have their differentiation accompanied during metamorphosis. Comparative studies of the structures among workers, queens and males were done using light and electronic microscopy, measuring the areas occupied from some of their components and estimative of the rates of mitosis and cell death using cytochemical and immuno-histochemical techniques. These studies started in the last larval instar and continued in pre-pupae, white, pink, brown, and black eyed pupae until black body pupae. Besides a search for differential protein expression among the individual classes whole brain was done... (Complete abstract click electronic access below)

The cockroach, with its large brain and physiological resilience, holds many advantages for the development of behavioral paradigms. The work presented here provides a foundation for, and describes the results of, the implementation of studies of neural correlates of learning and memory on restrained animals.Using the antennal projection response (APR) as an indicator of learning and retention, several learning paradigms have been developed. A visual-olfactory associative and a gustatory-olfactory aversive conditioning paradigm demonstrated a plastic behavior that could be driven in an intact and immobilized cockroach. Conditioning the APR to a visual cue paired with an olfactory cue characterized the role of unilateral and bilateral olfactory input in learning and memory. While unilateral olfactory input is sufficient to learn a visual-olfactory association, bilateral olfactory input is necessary for long-term retention of the association. This comparison identified a critical time period in which memory is consolidated. This time period was subsequently used to analyze gene expression during memory consolidation.The split-brain cockroach preparation was developed to investigate what parts of the brain are necessary and sufficient for learning and retention of a visual-olfactory association; this preparation was also used to examine learning-induced changes in test tissue versus control tissue provided by the same animal. Evidence suggests that half of a brain is sufficient for a visual-olfactory association to be established and sufficient for retention of that association between 12 and 24 hours. However, the entire brain is necessary for long-term memory to be established. Using the split-brain cockroach simultaneously as the control and the test subject, learning-induced alterations in the microglomerular synaptic complexes of the calyces were identified in the trained half, but not in the naïve half.Using the APR, spatial learning and memory was examined. Multiple representations of space were revealed in the brain of the cockroach. Cockroaches represent space in terms of an olfactory gradient map, as well as the visuospatial relationship between objects. When both representations of space can be utilized by the cockroach to localize a cue, the positional visual cue is the one that determines the behavioral response.

Reproductive division of labor is the most distinctive characteristic of the social Hymenoptera; some individuals reproduce and others forego their own reproduction to raise non-descendant offspring. In species where females are reproductively totipotent and lack morphologically distinct castes, there is potential for reproductive conflict because more than one female in a colony may attempt direct reproduction. I focused my dissertation research on a subtropical population of the primitively eusocial paper wasp, Mischocyttarus mexicanus, to investigate the initiation, establishment, and development of the colony before the emergence of adult offspring. Female M. mexicanus exhibit variation in behavior and task performance, and switch between reproductive and non-reproductive roles. These changes in behavior and reproduction may be influenced by social context. In three studies, I investigated the role of social context on reproduction, behavior, and brain structure. In the first study, I tested the role of body size, reproductive potential, and immediate egg-laying potential on the reproductive tactic employed by females. I found that large females either became solitary foundresses or became part of a group-initiated colony. In contrast, small females left their natal colony and pursued joining other colonies. This joiner tactic is unique to this population and has not been observed in temperate zone populations. I also found that subordinate females had the potential to lay eggs if given the opportunity. This suggests an incentive to remain in a colony for future opportunities of direct reproduction. In the second study, I investigated the effect of three variables on non-nestmate acceptance: non-nestmate age, stage of colony development, and non-nestmate aggressive behavior. I demonstrated that non-nestmate acceptance was context-dependent. Both non-nestmate age and stage of colony development had an effect on the proportion of accepted non-nestmates. Although, non-nestmate aggressive behavior did not affect non-nestmate acceptance, it did trigger an aggressive response from colony nestmates. In the third study, I assessed the relationship of Mushroom Bodies (MB) volume, the brain neuropils associated with learning and memory, to environmental conditions and social interactions. I compared MB volume of newly-established colonies initiated by solitary foundresses to groups of foundresses. In addition, I performed laboratory experiments to differentiate between the effect of environmental conditions and social interactions. I found a positive relationship between MB volume and environmental conditions including light intensity and foraging experience. In contrast to previous studies, I found no association between MB volume and social interactions. Ovary development was positively correlated with MB development. This result suggests that although reproductive dominance is established in newly-initiated colonies, social dominance may not yet be established. In summary, my studies found an effect of social context on behavior, adoption of reproductive tactics and brain structure in colonies of M. mexicanus during the offspring pre-emergence phase.

Different neurons and glial cells in the Drosophila olfactory circuitry have distinct functions in olfaction. The mechanisms to generate most of diverse neurons and glial cells in the olfactory circuitry remain unclear due to the incomprehensive study of cell lineages. To facilitate the analyses of cell lineages and neural diversity, two independent binary transcription systems were introduced into Drosophila to drive two different transgenes in different cells. A technique called ‘dual-expression-control MARCM’ (mosaic analysis with a repressible cell marker) was created by incorporating a GAL80-suppresible transcription factor LexA::GAD (GAL4 activation domain) into the MARCM. This technique allows the induction of UAS- and lexAop- transgenes in different patterns among the GAL80-minus cells. Dual-expression-control MARCM with a ubiquitous driver tubP-LexA::GAD and various subtype-specific GAL4s which express in antennal lobe neurons (ALNs) allowed us to characterize diverse ALNs and their lineage relationships. Genetic studies showed that ALN cell fates are determined by spatial identities rooted in their precursor cells and temporal identities based on their birth timings within the lineage, and then finalized through cell-cell interactions mediated by Notch signaling. Glial cell lineage analyses by MARCM and dual-expression-control MARCM show that diverse post-embryonic born glial cells are lineage specified and independent of neuronal lineage. Specified glial lineages expand their glial population by symmetrical division and do not further diversify glial cells. Construction of a GAL4-insensitive transcription factor LexA::VP16 (VP16 acidic activation domain) allows the independent induction of lexAop transgenes in the entire mushroom body (MB) and labeling of individual MB neurons by MARCM in the same organism. A computer algorithm is developed to perform morphometric analysis to assist the study of MB neuron diversity.

A functional central nervous system (CNS) is composed of numerous types of neurons. Neurons are derived from a limited number of multipotent neural stem cells. Previous studies have suggested three major strategies nature uses to diversify neurons: lineage identity specification that gives an individual neural stem cell distinct identity based on its position in the developing CNS; temporal identity specification that gives neurons derived from a neural stem cell distinct identities based on their birth-order within the lineage; and binary cell fate specification that gives different identities to the two sister postmitotic neurons derived from the terminal division of a common precursor. Through the combination of the three strategies, almost unlimited neuron types can be generated. To understand neuronal diversification, we have to understand the underlying molecular mechanisms of each of the three strategies. The fruit fly Drosophila melanogaster, has been an excellent model for studying neuronal diversity, mainly due to its easily traceable nervous system and an impressive collection of genetic tools. Studies in fly have provided us fundamental insights into lineage identity, temporal identity, and binary cell fate specifications. Nevertheless, previous studies mostly centered on the embryonic ventral nerve cord (VNC) because of its simpler organization. Our understanding of the generation of neuronal diversity in the fly brain is still rudimentary. In this thesis work, I focused on the mushroom body (MB) and three antennal lobe neuronal lineages, studying their neuronal diversification during postembryonic brain development. In Chapter I, I reviewed the previous studies that have built our current understanding of the neuronal diversification. In Chapter II, I showed that MB temporal identity changes are instructed by environmental cues. In Chapter III, to search for the potential factors that mediate the environmental control of the MB temporal identity changes, I silenced each of the 18 nuclear receptors (NRs) in the fly genome using RNA interference. Although I did not identify any NR important for the regulation of MB temporal identities, I found that unfulfilled is required for regulating axon guidance and for the MB neurons to acquire all major subtype-specific identities. In Chapter IV, I demonstrated that the Notch pathway and its antagonist Numb mediate binary cell fate determination in the three classical antennal lobe neuronal lineages— anterodorsal projection neuron (adPN), lateral antennal lobe (lAL), and ventral projection neuron (vPN)—in a context-dependent manner. Finally, in Chapter V, I did detailed lineage analysis for the lAL lineage, and identified four classes of local interneurons (LNs) with multiple subtypes innervating only the AL, and 44 types projection neurons (PNs) contributing to olfactory, gustatory, and auditory neural circuits. The PNs and LNs were generated simultaneously but with different tempos of temporal identity specification. I also showed that in the lAL lineage the Notch pathway not only specifies binary cell fates, but is also involved in the temporal identity specification.

La mouche Drosophila melanogaster est un modèle de choix dans l’étude des grandes fonctions neurophysiologiques notamment en raison de la disponibilité d’une importante variété d’outils disponibles (approches génétiques, pharmacologiques et comportementales). Le cerveau de la mouche, malgré sa simplicité apparente, est capable de traiter des fonctions complexes d’intégration des différents paramètres environnementaux nécessaires à sa survie. Dans le cerveau drosophile, les corps pédonculés (CP) sont des structures impliquées dans de nombreuses fonctions neurophysiologiques de premier plan telles que l'apprentissage et la mémoire olfactive, la régulation de l’activité locomotrice, l'orientation spatiale, la régulation du sommeil ou encore la prise de décision. Il a été montré par des approches associant essentiellement observations comportementales et outils génétiques que la voie de signalisation de l'AMPc joue un rôle crucial dans la réalisation des fonctions diverses des CP. Les cellules de Kenyon (CK) qui sont les cellules intrinsèques des CP, reçoivent principalement des afférences du système olfactif par l’intermédiaire des neurones de projections (PN) en provenance des lobes antennaires et des afférences neuromodulatrices (dopaminergiques et octopaminergiques). Les synapses entres PN et CK se font sur un mode cholinergique grâce à des récepteurs canaux à l’acétylcholine de type nicotinique (nAchR). Nous avons utilisé une technique récente d’imagerie calcique par bioluminescence utilisant une protéine recombinante, la GFP-Aequorine. Cette technique nous a permis de suivre l’activité cellulaire calcique consécutive à l’application de nicotine, un agoniste des nAchR. Grâce à l’observation de ces réponses suite à une combinaison d’approches génétiques corroborée par des approches pharmacologiques, nous avons pu mettre en évidence une modulation complexe et régionalisée de la réponse calcique dans les CP par l’AMPc et d’autres différents partenaires tels que des canaux K+ et Ca2+. Dans un premier temps, nous avons démonté l’existence d’une modulation directe de l’intensité de la réponse par l’AMPc. Nous avons également montré, pour la première fois, que des réponses Ca2+ « spontanées » peuvent être directement inductibles par augmentation de l’AMPc. Nous avons mis en évidence l’existence d’un nouveau partenaire de la modulation de la réponse des CP indépendant de la PKA : les CNG (Cyclic Nucleotides Gated Channels) dont le rôle n’avait jusqu’ici jamais été démontré dans les corps pédonculés. Enfin nous avons pu observer une régionalisation de la régulation de l’activité Ca2+ des CP par l’AMPc. Dans un deuxième temps nous nous somme intéressé aux principales conductances calciques et potassiques. Nous avons mis en évidence que différents canaux calciques voltages dépendants (VGCC) sont impliqués de façon régionalisée et séquentielle dans la formation de la réponse calcique. Il a pu également être démontré que le signal est modulé de façon différentielle dans les calices et les lobes par l’AMPc à travers différents canaux potassiques. Enfin des protocoles originaux ont été développés, tels que la micro application de drogue ou l’électrostimulation permettant d’étudier la neuromodulation dans les CP, à réutiliser pour des travaux ultérieurs du laboratoire. Ce travail est une première étape dans la compréhension des voies de signalisations et des mécanismes intracellulaires impliqués dans l’apprentissage et la mémoire olfactive. / In Drosophila, the Mushroom-Bodies (MBs) are implicated in multiple functions, as olfactory learning and memory, locomotor activity, spatial orientation, sleep, decision making, and up to now but indirectly, in various addiction. Notably, the MBs, which express the nAchR, receive their main inputs from the cholinergic olfactory pathways, through the Projections Neurons (PNs). In this thesis we characterized, at the cellular and molecular levels, the nicotine effect on the Kenyon cells (KCs: the intrinsic neurons) of the Mushroom-Bodies. We used the in-Vivo brain imaging approach, based on the Ca2+-Sensitive bioluminescent probe (GFP-Aequorin), to characterize the nicotinic induced Ca2+-Response on the KCs of the MBs. More specifically we searched the role of different partners involved in the cAMP pathway, in order to understand their roles in the different components of the response and in its modulation. First using both genetics and pharmacological approaches to interfere with different components of the cAMP signaling pathway, we first show that the Ca2+-Response is proportional to the levels of cAMP. Second, we reveal that an acute change in cAMP levels is sufficient to trigger a Ca2+-Response. Third, genetic manipulation of protein kinase A (PKA), a direct effector of cAMP, suggests that cAMP also has a PKA-Independent effect through the cyclic nucleotide-Gated Ca2+-Channel (CNG). Finally, the disruption of calmodulin, one of the main regulators of the rutabaga adenylate cyclase (AC), yields different effects between the calyx/cell-Bodies and the lobes, suggesting a differential and regionalized regulation of ACSecond we exploited both genetic approaches to interfere with different types of Ca2+- and K+-Channels, first we show that the disruption of the VGCC, as cacophony, Dmcα1d and Dmcα1g lead to a striking decrease of the Ca2+-Response both in the CCB and the lobes. Moreover, for two of them, cacophony and Dmcα1d, the duration of the response is importantly increased. Second, the disruption of the fast inactivating K+-Currents, as shaker (sh), shaker-Like (shal) and slowpoke (slo) reveal that the knocked-Down of shal and slo lead to a striking decrease of the Ca2+-Response, while the knocked-Down of sh has only a mild effect. Interestingly, the stimulation of the adenylate cyclase (AC) by the forskolin with the various K+-Channels disruption show an antagonist effect of the cAMP in the CCB between sh (inhibitory) and slow (excitatory) while AC simulation mediate excitatory effects in the ML though both shal and sh. Finally, the knock-Down of the two slow inactivating K+-Currents as shaker w (shaw) and shaker b (shab) also yields to a strong decrease of the Ca2+-Response In conclusion, our results provide new insights into the complexity of the Ca2+-Response in the MBs and are a first step toward deciphering the roles of the VGCC and K+-Channels in the multiples roles of the MBs. Finaly we developed several original protocols to explore the role of the neuromodulation on the KC.This work constitutes an important step toward a better understanding of the pathway required in learning and memory.

Understanding how memory is formed requires looking beyond the genes involved to the neural circuitry and temporal aspects of memory. In this dissertation I have focused my investigation on Dorsal Paired Medial (DPM) neurons, two modulatory neurons essential for memory in Drosophila. DPM neurons highly express the amnesiac (amn) gene, which encodes for a putative pre-pro-neuropeptide. amn function in DPM neurons is required for memory. Here I provide evidence that DPM neurons are cholinergic and that acetylcholine (ACh) and AMN act as co-transmitters essential for DPM function. In order to investigate the temporal requirements of DPM output I blocked transmitter release during discrete intervals in the memory process using shibirets1 and tested flies for shock and sugar-reinforced memory. These experiments demonstrated that stable memory requires persistent transmitter release from DPM neurons. Furthermore these results suggest AMN and DPM neurons act as general stabilizers of mushroom body dependent memory. To further investigate the neural circuitry underlying DPM function I disrupted DPM projections onto the mushroom body lobes by ectopically expressing DScam17-2::GFP in DPM neurons. Flies with DPM neurons that predominantly project to the mushroom body α´/β´ lobes exhibit normal memory, and blocking transmitter release from the mushroom body prime lobes neurons themselves abolishes memory indicating DPM neuron-mushroom body α´/β´ neuron interaction that are critical for memory. Taken together, the experimental evidence presented here are used to provide a rudimentary model of the neural circuitry involved in memory stability, where DPM neurons form a recurrent feedback loop with the mushroom body α´/β´ lobe neurons and act to stabilize odorspecific conditioned memories at Kenyon cell synapses.

Understanding the mechanisms of memory is vital in making sense of the continuity of the self, our experience of time and of the relation between mind and body. The invertebrate Drosophila melanogaster offers us an opportunity to study and comprehend the overwhelming complexity of memory on a smaller scale. The work presented here investigates the neural circuitry in the fly brain required for olfactory memory processing. Our observation that Dorsal Paired Medial (DPM) neurons, which project only to mushroom body (MB) neurons, are required during memory storage but not for acquisition or retrieval, led us to revisit the role of MB neurons in memory processing. We show that neurotransmission from the α'β' subset of MB neurons is required to acquire and stabilize aversive and appetitive odor memory but is dispensable during memory retrieval. In contrast neurotransmission from MB αβ neurons is only required for memory retrieval. These data suggest a dynamic requirement for the different subsets of MB neurons in memory and are consistent with the notion that recurrent activity in a MB α'β' neuron-DPM neuron loop is required to consolidate memories formed in the MB αβ neurons. Furthermore, we show that a single two-minute training session pairing odor with an ethologically relevant sugar reinforcement forms long-term appetitive memory that lasts for days. This robust, stable LTM is protein-synthesis-, Creb- and radish-dependent and relies on the activity in the DPM neuron and mushroom body α'β' neuron circuit during the first hour after training and mushroom body αβ neuron output during retrieval. Lastly, experiments feeding and/or starving flies after training reveals a critical motivational drive that enables memory retrieval. Neural correlates of motivational states are poorly understood, but using our assay we found a neural mechanism that accounts for this motivation-state-dependence. We demonstrate a role for the Neuropeptide F (dNPF) circuitry, which led to the identification of six dopaminergic MB-MP neurons that innervate the mushroom bodies as being critical for appetitive memory performance. Directly blocking the MB-MP neurons releases memory performance in fed flies whereas stimulating them suppresses memory performance in hungry flies. These studies provide us with an enhanced knowledge of systems level memory processing in Drosophila.

In the Drosophila brain, memories are processed and stored in two mirrorsymmetrical structures composed of approximately 5,000 neurons called Mushroom Bodies (MB). Depending on their axonal extensions, neurons in the MB can be further classified into three different subgroups: αβ, α’β’ and γ. In addition to the morphological differences between these groups of neurons, there is evidence of functional differences too. For example, it has been previously shown that while neurotransmission from α’β’ neurons is required for consolidation of olfactory memory, output from αβ neurons is required for its later retrieval. To gain insight into the functional properties of these discrete neurons we analyzed whether they were different at the level of gene expression. We generated an intersectional genetic approach to exclusively label each population of neurons and permit their purification. Comparing expression profiles, revealed a large number of potentially interesting molecular differences between the populations. We focused on the finding that the MB αβ neurons, which are the presumed storage site for transcription-dependent long-term memory, express high levels of mRNA for transposable elements and histones suggesting that these neurons likely possess unique genomic characteristics. For decades, transposable elements (TE) were considered to be merely “selfish” DNA elements inserted at random in the genome and that they their sole function was to self-replicate. However, new studies have started to arise that indicate TE contribute more than just “junk” DNA to the genome. Although it is widely believed that mobilization of TE destabilize the genome by insertional mutagenesis, deletions and rearrangements of genes, some rearrangements might be advantageous for the organism. TE mobilization has recently been documented to occur in some somatic cells, including in neuronal precursor cells (NPCs). Moreover, mobilization in NPCs seems to favor insertions within neuronal expressed genes and in one case the insertion elevated the expression. During the last decade, the discovery of the small RNA pathways that suppress the expression and mobilization of TE throughout the animal have helped to uncover new functions that TE play. In this work, we demonstrate that proteins of the PIWI-associated RNA pathway that control TE expression in the germline are also required to suppress TE expression in the adult fly brain. Moreover, we find that they are differentially expressed in subsets of MB neurons, being under represented in the αβ neurons. This finding suggests that the αβ neurons tolerate TE mobilization. Lastly, we demonstrate by sequencing αβ neuron DNA that TE are mobile and we identify >200 de novo insertions into neurally expressed genes. We conclude that this TE generated mosaicism, likely contributes a new level of neuronal diversity making, in theory, each αβ neuron genetically different. In principle the stochastic nature of this process could also render every fly an individual.