Neurons learn by predicting future activity

• Published in: Nature machine intelligence Vol. 4; no. 1; pp. 62 - 72
• Main Authors: Luczak, Artur, McNaughton, Bruce L., Kubo, Yoshimasa
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2022; Nature Publishing Group
• Subjects: 631/114/116/2396; 631/378/1595/2618; Algorithms; Artificial neural networks; Back propagation; Brain; Engineering; Equilibrium; Learning; Neurons
• ISSN: 2522-5839; 2522-5839
• DOI: 10.1038/s42256-021-00430-y

Understanding how the brain learns may lead to machines with human-like intellectual capacities. It was previously proposed that the brain may operate on the principle of predictive coding. However, it is still not well understood how a predictive system could be implemented in the brain. Here we demonstrate that the ability of a single neuron to predict its future activity may provide an effective learning mechanism. Interestingly, this predictive learning rule can be derived from a metabolic principle, whereby neurons need to minimize their own synaptic activity (cost) while maximizing their impact on local blood supply by recruiting other neurons. We show how this mathematically derived learning rule can provide a theoretical connection between diverse types of brain-inspired algorithm, thus offering a step towards the development of a general theory of neuronal learning. We tested this predictive learning rule in neural network simulations and in data recorded from awake animals. Our results also suggest that spontaneous brain activity provides ‘training data’ for neurons to learn to predict cortical dynamics. Thus, the ability of a single neuron to minimize surprise—that is, the difference between actual and expected activity—could be an important missing element to understand computation in the brain. In artificial neural networks, a typical neuron generally performs a simple summation of inputs. Using computational and electrophysiological data, the authors show that a single neuron predicts its future activity. Neurons that predict their own future responses are a potential mechanism for learning in the brain and neural networks.