The complete connectome of a learning and memory centre in an insect brain

Associating stimuli with positive or negative reinforcement is essential for survival, but a complete wiring diagram of a higher-order circuit supporting associative memory has not been previously available. Here we reconstruct one such circuit at synaptic resolution, the Drosophila larval mushroom body. We find that most Kenyon cells integrate random combinations of inputs but that a subset receives stereotyped inputs from single projection neurons. This organization maximizes performance of a model output neuron on a stimulus discrimination task. We also report a novel canonical circuit in each mushroom body compartment with previously unidentified connections: reciprocal Kenyon cell to modulatory neuron connections, modulatory neuron to output neuron connections, and a surprisingly high number of recurrent connections between Kenyon cells. Stereotyped connections found between output neurons could enhance the selection of learned behaviours. The complete circuit map of the mushroom body should guide future functional studies of this learning and memory centre.

[1]  Thomas Preat,et al.  Two independent mushroom body output circuits retrieve the six discrete components of Drosophila aversive memory. , 2015, Cell reports.

[2]  Stephan Saalfeld,et al.  CATMAID: collaborative annotation toolkit for massive amounts of image data , 2009, Bioinform..

[3]  Raphael Cohn,et al.  Coordinated and Compartmentalized Neuromodulation Shapes Sensory Processing in Drosophila , 2015, Cell.

[4]  M. Bate,et al.  Embryonic development of identified neurons: origin and transformation of the H cell , 1981, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[5]  Andreas S. Thum,et al.  The Role of Dopamine in Drosophila Larval Classical Olfactory Conditioning , 2009, PloS one.

[6]  R. Menzel.  The honeybee as a model for understanding the basis of cognition , 2012, Nature Reviews Neuroscience.

[7]  Kei Ito,et al.  Embryonic and larval development of the Drosophila mushroom bodies: concentric layer subdivisions and the role of fasciclin II. , 2002, Development.

[8]  H. Sompolinsky,et al.  Sparseness and Expansion in Sensory Representations , 2014, Neuron.

[9]  Paul Szyszka,et al.  Converging Circuits Mediate Temperature and Shock Aversive Olfactory Conditioning in Drosophila , 2014, Current Biology.

[10]  Bertram Gerber,et al.  Adaptive Adjustment of the Generalization-Discrimination Balance in Larval Drosophila , 2010, Journal of neurogenetics.

[11]  Marta Zlatic,et al.  Organization of the Drosophila larval visual circuit , 2017 .

[12]  Matthias Landgraf,et al.  Even-Skipped+ Interneurons Are Core Components of a Sensorimotor Circuit that Maintains Left-Right Symmetric Muscle Contraction Amplitude , 2015, Neuron.

[13]  Anchi Cheng,et al.  Automated molecular microscopy: the new Leginon system. , 2005, Journal of structural biology.

[14]  G. Laurent,et al.  Normalization for Sparse Encoding of Odors by a Wide-Field Interneuron , 2011, Science.

[15]  Ronald L. Davis,et al.  Frontiers in Neural Circuits Neural Circuits , 2022 .

[16]  G. Laurent,et al.  Conditional modulation of spike-timing-dependent plasticity for olfactory learning , 2012, Nature.

[17]  A. Fiala,et al.  Punishment Prediction by Dopaminergic Neurons in Drosophila , 2005, Current Biology.

[18]  G. Rubin,et al.  The neuronal architecture of the mushroom body provides a logic for associative learning , 2014, eLife.

[19]  Robert A. A. Campbell,et al.  Cellular-Resolution Population Imaging Reveals Robust Sparse Coding in the Drosophila Mushroom Body , 2011, The Journal of Neuroscience.

[20]  L. Luo,et al.  Development of the Drosophila mushroom bodies: sequential generation of three distinct types of neurons from a neuroblast. , 1999, Development.

[21]  Scott Waddell,et al.  Olfactory learning skews mushroom body output pathways to steer behavioral choice in Drosophila , 2015, Current Opinion in Neurobiology.

[22]  Andrew C. Lin,et al.  Sparse, Decorrelated Odor Coding in the Mushroom Body Enhances Learned Odor Discrimination , 2014, Nature Neuroscience.

[23]  S. Farris.  Are mushroom bodies cerebellum-like structures? , 2011, Arthropod structure & development.

[24]  M. Bate,et al.  Embryonic development of identified neurons: segment-specific differences in the H cell homologues , 1981, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[25]  M. Heisenberg.  Mushroom body memoir: from maps to models , 2003, Nature Reviews Neuroscience.

[26]  Shamik Dasgupta,et al.  A Neural Circuit Mechanism Integrating Motivational State with Memory Expression in Drosophila , 2009, Cell.

[27]  Andreas S. Thum,et al.  Characterization of the octopaminergic and tyraminergic neurons in the central brain of Drosophila larvae , 2014, The Journal of comparative neurology.

[28]  Stephan Saalfeld,et al.  Quantitative neuroanatomy for connectomics in Drosophila , 2015 .

[29]  Bertram Gerber,et al.  Innate Attractiveness and Associative Learnability of Odors Can Be Dissociated in Larval Drosophila , 2011, Chemical senses.

[30]  Scott Waddell,et al.  Drosophila Learn Opposing Components of a Compound Food Stimulus , 2014, Current Biology.

[31]  J. Choe,et al.  Dopamine Signalling in Mushroom Bodies Regulates Temperature-Preference Behaviour in Drosophila , 2011, PLoS genetics.

[32]  Marta Zlatic,et al.  Four Individually Identified Paired Dopamine Neurons Signal Reward in Larval Drosophila , 2016, Current Biology.

[33]  Gerald M. Rubin,et al.  Heterosynaptic Plasticity Underlies Aversive Olfactory Learning in Drosophila , 2015, Neuron.

[34]  Rachel I. Wilson,et al.  Glutamate is an inhibitory neurotransmitter in the Drosophila olfactory system , 2013, Proceedings of the National Academy of Sciences.

[35]  Johannes E. Schindelin,et al.  TrakEM2 Software for Neural Circuit Reconstruction , 2012, PloS one.

[36]  Johannes Felsenberg,et al.  Activity of Defined Mushroom Body Output Neurons Underlies Learned Olfactory Behavior in Drosophila , 2015, Neuron.

[37]  Gregory S.X.E. Jefferis,et al.  Glomerular Maps without Cellular Redundancy at Successive Levels of the Drosophila Larval Olfactory Circuit , 2005, Current Biology.

[38]  Andrew C. Lin,et al.  Different Kenyon Cell Populations Drive Learned Approach and Avoidance in Drosophila , 2013, Neuron.

[39]  Louis K. Scheffer,et al.  A connectome of a learning and memory center in the adult Drosophila brain , 2017, eLife.

[40]  Kristin Branson,et al.  A multilevel multimodal circuit enhances action selection in Drosophila , 2015, Nature.

[41]  N. K. Tanaka,et al.  Stereotypic and random patterns of connectivity in the larval mushroom body calyx of Drosophila. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[42]  Marta Zlatic,et al.  Organization of the Drosophila larval visual circuit , 2017, bioRxiv.

[43]  Shilpy Sharma,et al.  An Optimized Method for Histological Detection of Dopaminergic Neurons in Drosophila melanogaster , 2008, The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society.

[44]  Casey M. Schneider-Mizell,et al.  Synaptic transmission parallels neuromodulation in a central food-intake circuit , 2016, bioRxiv.

[45]  Marc Gershow,et al.  Sensory determinants of behavioral dynamics in Drosophila thermotaxis , 2014, Proceedings of the National Academy of Sciences.

[46]  Haim Sompolinsky,et al.  Optimal Degrees of Synaptic Connectivity , 2017, Neuron.

[47]  Aljoscha Nern,et al.  Optimized tools for multicolor stochastic labeling reveal diverse stereotyped cell arrangements in the fly visual system , 2015, Proceedings of the National Academy of Sciences.

[48]  W. Schultz.  Neuronal Reward and Decision Signals: From Theories to Data. , 2015, Physiological reviews.

[49]  Casey M. Schneider-Mizell,et al.  Competitive Disinhibition Mediates Behavioral Choice and Sequences in Drosophila , 2016, Cell.

[50]  Omotara Ogundeyi,et al.  A GAL4 driver resource for developmental and behavioral studies on the larval CNS of Drosophila. , 2014, Cell reports.

[51]  Aravinthan D. T. Samuel,et al.  The wiring diagram of a glomerular olfactory system , 2016, bioRxiv.

[52]  Y. Hotta,et al.  Proliferation pattern of postembryonic neuroblasts in the brain of Drosophila melanogaster. , 1992, Developmental biology.

[53]  Scott Waddell,et al.  Sweet Taste and Nutrient Value Subdivide Rewarding Dopaminergic Neurons in Drosophila , 2015, Current Biology.

[54]  G. Technau,et al.  Origin of Drosophila mushroom body neuroblasts and generation of divergent embryonic lineages , 2012, Development.

[55]  A. Cardona,et al.  A circuit mechanism for the propagation of waves of muscle contraction in Drosophila , 2016, eLife.

[56]  Yoshinori Aso,et al.  Reward signal in a recurrent circuit drives appetitive long-term memory formation , 2015, eLife.

[57]  Ronald L. Davis,et al.  The GABAergic anterior paired lateral neuron suppresses and is suppressed by olfactory learning , 2008, Nature Neuroscience.

[58]  Johannes E. Schindelin,et al.  Fiji: an open-source platform for biological-image analysis , 2012, Nature Methods.

[59]  Johannes Felsenberg,et al.  Memory-Relevant Mushroom Body Output Synapses Are Cholinergic , 2016, Neuron.

[60]  G. Nagel,et al.  Light-Induced Activation of Distinct Modulatory Neurons Triggers Appetitive or Aversive Learning in Drosophila Larvae , 2006, Current Biology.

[61]  Yoshinori Aso,et al.  Dopaminergic neurons write and update memories with cell-type-specific rules , 2016, eLife.

[62]  Peter Levy,et al.  A Central Neural Pathway Controlling Odor Tracking in Drosophila , 2015, The Journal of Neuroscience.

[63]  Gerald M. Rubin,et al.  A Higher Brain Circuit for Immediate Integration of Conflicting Sensory Information in Drosophila , 2015, Current Biology.

[64]  Bertram Gerber,et al.  Maggot learning and Synapsin function , 2013, Journal of Experimental Biology.

[65]  Andreas S. Thum,et al.  Drosophila Larvae Establish Appetitive Olfactory Memories via Mushroom Body Neurons of Embryonic Origin , 2010, The Journal of Neuroscience.

[66]  S. Waddell.  Reinforcement signalling in Drosophila; dopamine does it all after all , 2013, Current Opinion in Neurobiology.

[67]  Kei Ito,et al.  A single GABAergic neuron mediates feedback of odor-evoked signals in the mushroom body of larval Drosophila , 2014, Front. Neural Circuits.

[68]  Jean-Loup Guillaume,et al.  Fast unfolding of communities in large networks , 2008, 0803.0476.

[69]  G. Rubin,et al.  Mushroom body output neurons encode valence and guide memory-based action selection in Drosophila , 2014, eLife.

[70]  Nils Otto,et al.  The Ol1mpiad: concordance of behavioural faculties of stage 1 and stage 3 Drosophila larvae , 2017, Journal of Experimental Biology.

[71]  Glenn C. Turner,et al.  Integration of the olfactory code across dendritic claws of single mushroom body neurons , 2013, Nature Neuroscience.

[72]  Gregory S.X.E. Jefferis,et al.  NBLAST: Rapid, Sensitive Comparison of Neuronal Structure and Construction of Neuron Family Databases , 2016, Neuron.

[73]  Aaron DiAntonio,et al.  Increased Expression of the Drosophila Vesicular Glutamate Transporter Leads to Excess Glutamate Release and a Compensatory Decrease in Quantal Content , 2004, The Journal of Neuroscience.

[74]  Oliver Barnstedt,et al.  Aversive Learning and Appetitive Motivation Toggle Feed-Forward Inhibition in the Drosophila Mushroom Body , 2016, Neuron.

[75]  Stefan R. Pulver,et al.  Selective Inhibition Mediates the Sequential Recruitment of Motor Pools , 2016, Neuron.

[76]  Vikram Chandra,et al.  Neural correlates of water reward in thirsty Drosophila , 2014, Nature Neuroscience.

[77]  L. Abbott,et al.  Random Convergence of Olfactory Inputs in the Drosophila Mushroom Body , 2013, Nature.

[78]  Gilles Laurent,et al.  Testing Odor Response Stereotypy in the Drosophila Mushroom Body , 2008, Neuron.

[79]  A. Cardona,et al.  Elastic volume reconstruction from series of ultra-thin microscopy sections , 2012, Nature Methods.

[80]  F. Schürmann,et al.  Fine structure of synaptic sites and circuits in mushroom bodies of insect brains. , 2016, Arthropod structure & development.