A bio-inspired bistable recurrent cell allows for long-lasting memory

TL;DR

This paper introduces a biologically-inspired bistable recurrent cell for RNNs, enabling long-lasting memory at the cellular level, and enhances biological plausibility by linking it with neuromodulation and standard GRU cells.

Contribution

The paper proposes a novel bistable recurrent cell inspired by biological neurons, improving long-term memory in RNNs using only cellular connections.

Findings

Significantly improves RNN performance on long-memory time-series tasks.

Demonstrates durable memory retention through cellular bistability.

Links the bistable cell to GRU via neuromodulation, enhancing biological plausibility.

Abstract

Recurrent neural networks (RNNs) provide state-of-the-art performances in a wide variety of tasks that require memory. These performances can often be achieved thanks to gated recurrent cells such as gated recurrent units (GRU) and long short-term memory (LSTM). Standard gated cells share a layer internal state to store information at the network level, and long term memory is shaped by network-wide recurrent connection weights. Biological neurons on the other hand are capable of holding information at the cellular level for an arbitrary long amount of time through a process called bistability. Through bistability, cells can stabilize to different stable states depending on their own past state and inputs, which permits the durable storing of past information in neuron state. In this work, we take inspiration from biological neuron bistability to embed RNNs with long-lasting memory at the cellular level. This leads to the introduction of a new bistable biologically-inspired recurrent cell that is shown to strongly improves RNN performance on time-series which require very long memory, despite using only cellular connections (all recurrent connections are from neurons to themselves, i.e. a neuron state is not influenced by the state of other neurons). Furthermore, equipping this cell with recurrent neuromodulation permits to link them to standard GRU cells, taking a step towards the biological plausibility of GRU.