Rxivist logo

Modulatory ( e.g. dopaminergic) neurons provide 'teaching signals' that drive associative learning across the animal kingdom, but the circuit mechanisms by which these signals are computed are still unclear. To provide a basis for understanding the circuit implementation of learning algorithms, we generated a synaptic-resolution connectivity map of the circuits upstream of all modulatory neurons in an associative learning center, the mushroom body (MB) of the Drosophila larva. We discovered afferent pathways from sensory neurons and a large number of one-step and two-step feedback pathways originating from MB output neurons. We also found a surprising density of cross-compartment feedback pathways that link distinct memory systems ( e.g. aversive and appetitive). This architecture suggests that the MB functions as an interconnected ensemble during learning and that any previously formed memories of a stimulus can potentially regulate future learning about that stimulus. We functionally confirmed some of the structural pathways and found that some modulatory neurons compare inhibitory input from their own compartment and excitatory input from compartments of opposite valence, potentially enabling them to more accurately compute predicted values of stimuli. We developed a model of the circuit constrained by the connectome and functional data and used it to explore the computational advantages offered by the newly discovered feedback motifs. The model shows that the observed feedback pathways increase the network′s performance on complex learning tasks. It also shows that cross-compartment connections support the computation of predicted values and improve performance on higher-order learning tasks. Our study provides the most detailed view to date of a brain circuit that computes teaching signals and provides insights into the architectural motifs that support reinforcement learning in a biological system.

Download data

  • Downloaded 1,953 times
  • Download rankings, all-time:
    • Site-wide: 4,311 out of 100,737
    • In neuroscience: 609 out of 17,945
  • Year to date:
    • Site-wide: 8,112 out of 100,737
  • Since beginning of last month:
    • Site-wide: None out of 100,737

Altmetric data


Downloads over time

Distribution of downloads per paper, site-wide


PanLingua

Sign up for the Rxivist weekly newsletter! (Click here for more details.)


News

  • 20 Oct 2020: Support for sorting preprints using Twitter activity has been removed, at least temporarily, until a new source of social media activity data becomes available.
  • 18 Dec 2019: We're pleased to announce PanLingua, a new tool that enables you to search for machine-translated bioRxiv preprints using more than 100 different languages.
  • 21 May 2019: PLOS Biology has published a community page about Rxivist.org and its design.
  • 10 May 2019: The paper analyzing the Rxivist dataset has been published at eLife.
  • 1 Mar 2019: We now have summary statistics about bioRxiv downloads and submissions.
  • 8 Feb 2019: Data from Altmetric is now available on the Rxivist details page for every preprint. Look for the "donut" under the download metrics.
  • 30 Jan 2019: preLights has featured the Rxivist preprint and written about our findings.
  • 22 Jan 2019: Nature just published an article about Rxivist and our data.
  • 13 Jan 2019: The Rxivist preprint is live!