Cited by 4Reinforcement Learning in RoboticsNeurobiology and Insect Physiology ResearchNeural dynamics and brain function

Learning with sparse reward in a gap junction network inspired by the insect mushroom body

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Wei, Tianqi, Guo, Qinghai, Webb, Barbara·2024·PLOS Computational Biology

Abstract

Animals can learn in real-life scenarios where rewards are often only available when a goal is achieved. This ‘distal’ or ‘sparse’ reward problem remains a challenge for conventional reinforcement learning algorithms. Here we investigate an algorithm for learning in such scenarios, inspired by the possibility that axo-axonal gap junction connections, observed in neural circuits with parallel fibres such as the insect mushroom body, could form a resistive network. In such a network, an active node represents the task state, connections between nodes represent state transitions and their connection to actions, and current flow to a target state can guide decision making. Building on evidence that gap junction weights are adaptive, we propose that experience of a task can modulate the connections to form a graph encoding the task structure. We demonstrate that the approach can be used for efficient reinforcement learning under sparse rewards, and discuss whether it is plausible as an account of the insect mushroom body.

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Crossref · 10.1371/journal.pcbi.1012086

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  • The bee faces a classic problem of sparse reward: successful foraging only pays off upon return to the hive, so proper behaviour must be shaped in the absence of immediate reward.

    “The bee also faces a classic problem of sparse reward [23]: successful foraging only pays off upon return to the hive, which means that proper behaviour must be shaped in the absence of immediate reward.”

    From Phenomenal interface theory: a model for basal consciousness (2025) · cites this paper as [23]

    The Introduction (page not provided) describes sparse reward as learning appropriate actions when only the final goal state provides reinforcement, and says insects appear capable of doing so. It does not say that a bee’s foraging reward arrives only upon return to the hive; that specific account is unsupported by our copy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • Experience-dependent modulation of gap junctions connecting the neurons of the mushroom bodies could support the mapping of states to outcomes such that a sequence of actions can be learned when the reward is obtained only on completion of the sequence.

    “Experience-dependent modulation of gap junctions connecting the neurons of the mushroom bodies could support the mapping of states to outcomes such that a sequence of actions can be learned when the reward is obtained only on completion of the sequence [23].”

    From Phenomenal interface theory: a model for basal consciousness (2025) · cites this paper as [23]

  • The mushroom bodies could have the capacity to solve the sparse reward problem.

    “More recent work [23] exploring the theoretical capacities of gap junctions in the mushroom body network suggests the mushroom bodies could have the capacity to solve the so-called ‘sparse reward’ problem”

    From Phenomenal interface theory: a model for basal consciousness (2025) · cites this paper as [23]

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Research works printed but not linked: 7

  1. [25]Pathak D, Agrawal P, Efros AA, Darrell T. Curiosity-driven exploration by self-supervised prediction. In: International Conference on Machine Learning; 2017. p. 2778– 2787.
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Authors
Wei, T., Guo, Q., & Webb, B.
Affiliations
  • Sun Yat-sen University (CN)
  • Huawei Technologies (China) (CN)
  • University of Edinburgh (GB)
Corresponding author
  • Wei, Tianqi
  • Guo, Qinghai
  • Webb, Barbara
Venue
PLOS Computational Biology
Published
2024-05-23
Volume
20
Issue
5
Pages
e1012086
ISSN
  • 1553-734X (ISSN-L)
  • 1553-7358
OpenAlex
W4398258546
Cited by
4
References
70
Citations by year
2026: 1 · 2025: 2 · 2024: 1
FWCI
0.59
Type
journal article
Language
en
Open access
Locations
  • PLoS Computational Biology (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • Edinburgh Research Explorer (University of Edinburgh) (submittedVersion, cc-by)
Funders
Huawei Technologies (YBN2020045132)
Topics
  • Physical Sciences › Computer Science › Artificial Intelligence › Reinforcement Learning in Robotics
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neurobiology and Insect Physiology Research
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neural dynamics and brain function
Keywords
reinforcement learning, gap junctions, parallel fibers, electric current, decision-making
MeSH terms
Algorithms, Animals, Insecta, Learning, Models, Neurological, Nerve Net, Reward, Gap Junctions, Computational Biology, Mushroom Bodies

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