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An exact mathematical description of computation with transient spatiotemporal dynamics in a complex-valued neural network (2311.16431v1)

Published 28 Nov 2023 in cs.NE

Abstract: We study a complex-valued neural network (cv-NN) with linear, time-delayed interactions. We report the cv-NN displays sophisticated spatiotemporal dynamics, including partially synchronized ``chimera'' states. We then use these spatiotemporal dynamics, in combination with a nonlinear readout, for computation. The cv-NN can instantiate dynamics-based logic gates, encode short-term memories, and mediate secure message passing through a combination of interactions and time delays. The computations in this system can be fully described in an exact, closed-form mathematical expression. Finally, using direct intracellular recordings of neurons in slices from neocortex, we demonstrate that computations in the cv-NN are decodable by living biological neurons. These results demonstrate that complex-valued linear systems can perform sophisticated computations, while also being exactly solvable. Taken together, these results open future avenues for design of highly adaptable, bio-hybrid computing systems that can interface seamlessly with other neural networks.

Summary

  • The paper introduces a complex-valued neural network that computes spatiotemporal dynamics in closed form with precise mathematical formulation.
  • It details how the network supports advanced computations such as memory encoding and complex logical operations via chimera states.
  • The approach enables secure message transmission and suggests potential for effective bi-directional interfacing with biological neurons.

Introduction

Neural networks serve as foundational components in many AI systems. A major research interest within this field is the design of neural networks that can process and store information in a manner that mirrors the dynamical properties of biological systems, such as the human brain. One key aspect of such biological processing is the generation of spatiotemporal dynamics - patterns of activity that unfold over space and time. Analyses of these dynamics typically involve nonlinear systems, which traditionally complicate the mathematical treatment, particularly with respect to understanding the exact dynamical trajectory that a network uses for computation.

Novelty in Computation

A paper focuses on a complex-valued neural network (cv-NN) featuring computations imbued with these spatiotemporal dynamics. The pioneering aspect of this paper is the introduction of a cv-NN where the linear interaction dynamics, when integrated with nonlinear readout (a process translating raw network activity into meaningful output), provide a comprehensive computational framework. This system is unique in that it can be encapsulated by a closed-form, exact mathematical expression. This precise formulation enables the cv-NN to generate rich dynamics, including patterns known as "chimera" states – typically seen in nonlinear systems - in a linear context. The work here details how the computations, such as complex logical operations and encoding of short-term memories, can be mathematically described and thus designed with a high degree of precision.

Capabilities and Applications

Not only does the cv-NN demonstrate the ability to perform computations and encode memories, but it also shows potential for secure message transmission. Utilizing spatiotemporal dynamics, messages can be transmitted securely in a process akin to symmetric-key encryption, where both the sender and receiver possess a shared secret key that allows only them to decipher the message. Additionally, one promising direction for this complex-valued network is its utility in interfacing with biological neurons. The researchers illustrate that computations from the cv-NN can be effectively decoded by living neurons, suggesting the basis for new modalities of neuron-computer interaction allowing bi-directional communication.

Conclusion and Implications

The discovery of a cv-NN capable of sophisticated, computable spatiotemporal dynamics widens the horizon for both AI and computational neuroscience. By achieving what has previously been exclusive to nonlinear systems within a linear framework, and being able to describe the process precisely through a mathematical expression, this approach presents an advancement in the development of adaptable, energy-efficient computing systems. With the potential to integrate seamlessly into biological neuronal frameworks and contribute to machine learning models, this new neural network platform establishes a novel benchmark for computation using transient dynamics in the field.