The organization of extrinsic neurons and their implications in the functional roles of the mushroom bodies in Drosophila melanogaster Meigen.

By Kei Ito, Kazumi Suzuki, Patricia Estes, Mani Ramaswami, Daisuke S Yamamoto, N. Strausfeld. 1998

Although the importance of the Drosophila mushroom body in olfactory learning and memory has been stressed, virtually nothing is known about the brain regions to which it is connected. Using Golgi and GAL4-UAS techniques, we performed the first systematic attempt to reveal the anatomy of its extrinsic neurons. A novel presynaptic reporter construct, UAS-neuronal synaptobrevin-green fluorescent protein (n-syb-GFP), was used to reveal the direction of information in the GAL4-labeled neurons. Our results showed that the main target of the output neurons from the mushroom body lobes is the anterior part of the inferior medial, superior medial, and superior lateral protocerebrum. The lobes also receive afferents from these neuropils. The lack of major output projections directly to the deutocerebrum's premotor pathways discourages the view that the role of the mushroom body may be that of an immediate modifier of behavior. Our data, as well as a critical evaluation of the literature, suggest that the mushroom body may not by itself be a "center" for learning and memory, but that it can equally be considered as a preprocessor of olfactory signals en route to "higher" protocerebral regions.

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Citations in the corpus

Coordinated and Compartmentalized Neuromodulation Shapes Sensory Processing in Drosophila (2015, neutral): “, 2014), MZ19-Gal4 (Ito et al., 1998), VGlut-Gal4, UAS-DopR2-RNAi (TRiP.”
The neuronal architecture of the mushroom body provides a logic for associative learning (2014, background): “The MBONs and DANs send their processes to stereotyped locations, defining spatially restricted ‘subdomains’ in each lobe (Ito et al., 1998; Tanaka et al., 2008; Mao and Davis, 2009; Pech et al., 2013).”
Dopamine Is Required for Learning and Forgetting in Drosophila (2012, neutral): “, 2009), MZ604-gal4 (Ito et al., 1998; Tanaka et al., 2008), and NP7135-gal4 (Tanaka et al.”
The Mushroom Body of Adult Drosophila Characterized by GAL4 Drivers (2009, background): “The lobes of the MB are considered as the main output site of Kenyon cells, but also receive many inputs from extrinsic neurons (Ito et al., 1998; Tanaka et al., 2008; Johard et al., 2008).”
Origins of Cell-Type-Specific Olfactory Processing in the Drosophila Mushroom Body Circuit. (2017, unknown): “…(attP2) (von Philipsborn et al., 2011); VT43924-Gal4 (attP2) and APL-Gal4 (VT43924-Gal4 (attP2), UAS-Gal4) (Wu et al., 2013); Mz19-Gal4 (Ito et al., 1998; Tanaka et al., 2004), OK107-Gal4 (Connolly et al., 1996), UAS-ReaChR::Citrine (attP40) (Inagaki et al., 2014), UAS-mCD8::GFP…”
Organization of antennal lobe‐associated neurons in adult Drosophila melanogaster brain (2012, background): “Using the fluorescent marker that is predominantly transported to the presynaptic sites, e.g., neuronal synaptobrevin::GFP (n-syb::GFP), it is possible to suggest the direction of information in the labeled neurons (Ito et al., 1998; Otsuna and Ito, 2006).”
Heterosynaptic plasticity underlies aversive olfactory learning in Drosophila (2015, unknown): “The dendrites of eachMBON type occupy a specific subregion of theMB lobes (Aso et al., 2014a; Ito et al., 1998; Tanaka et al., 2008).”
Imaging a Population Code for Odor Identity in the Drosophila Mushroom Body (2013, background): “Our approach to reading neural activity is biologically plausible because neurons downstream of KCs have extensive dendritic arbors (Ito et al., 1998; Tanaka et al., 2008) and likely pool from at least this number of inputs.”
Two pairs of mushroom body efferent neurons are required for appetitive long-term memory retrieval in Drosophila. (2013, background): “When the conditioned odor is perceived, potentiation of these synapses would result in an increased response in MB-V3 neurons, which in turn could alter olfactory information to subsequent brain structures (Ito et al., 1998).”
Evolution of insect mushroom bodies: old clues, new insights (2005, background): “The primary calyces of Periplaneta and Drosophila mushroom bodies also show extensive innervation by large GABAergic cells with dendrites in other regions of the protocerebrum, rather than the lobes (Ito et al., 1998; Yamazaki et al., 1998; Strausfeld and Li, 1999a; Strausfeld et al., 2003).”
A map of olfactory representation in the Drosophila mushroom body. (2007, unknown): “Presumably, information processed in different MB lobes is then delivered by their output neurons to distinct brain regions, including inferior medial, superior medial, and superior lateral protocerebrum (Ito et al., 1998).”
An olfactory sensory map in the fly brain. (2000, background): “Axons vesicles in nerve terminals, allows the visualization of in the Antennal Lobe terminal axonal projections (Ito et al., 1998; Estes et al., These experiments”