Local online learning in recurrent networks with random feedback
Abstract
Recurrent neural networks (RNNs) enable the production and processing of time-dependent signals such as those involved in movement and working memory. Classic gradient-based algorithms for training RNNs have been available for decades, but are inconsistent with biological features of the brain, such as causality and locality. We derive an approximation to gradient-based learning that comports with these constraints by requiring synaptic weight updates to depend only on local information about pre- and postsynaptic activities, in addition to a random feedback projection of the RNN output error. In addition to providing mathematical arguments for the effectiveness of the new learning rule, we show through simulations that it can be used to train an RNN to perform a variety of tasks. Finally, to overcome the difficulty of training over very large numbers of timesteps, we propose an augmented circuit architecture that allows the RNN to concatenate short-duration patterns into longer sequences.
Data availability
Code implementing the RFLO learning algorithm for the example shown in Figure 2 has been included as a source code file accompanying this manuscript.
Article and author information
Author details
Funding
National Institutes of Health (DP5 OD019897)
- James M Murray
National Science Foundation (DBI-1707398)
- James M Murray
Gatsby Charitable Foundation
- James M Murray
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Peter Latham, University College London, United Kingdom
Version history
- Received: November 1, 2018
- Accepted: May 23, 2019
- Accepted Manuscript published: May 24, 2019 (version 1)
- Accepted Manuscript updated: May 31, 2019 (version 2)
- Version of Record published: June 12, 2019 (version 3)
Copyright
© 2019, Murray
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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