Abstract

The Echo State Network (ESN) framework is an efficient recurrent neural network paradigm of importance for both neuroscience and machine learning. It is quick and efficient to train, and also has been suggested as a possible model of brain function. It is not fully known how network structure influences ESN functionality, dynamics, and robustness. We used biological networks to study this, compared with randomly initialised ESNs. In both biological and artificial neural network contexts, neurons and clusters demonstrate functional specificity. We asked if synapse-resolution connectome-based ESNs demonstrate functional specificity/generality at the neural level. We used the larval Drosophila melanogaster connectome, which exhibits a hierarchical modular structure according to type, class, and function. We built connectome-based ESNs from this and compared neural specificity metrics between connectome and equivalent random networks across tasks in memory, decision-making, and time-series prediction. Connectome ESNs contain smaller subsets of task-selective neurons, while random networks exhibit more distributed, “general” groups. We tested the interpretation of these metrics by systematically pruning nodes based on their measure of engagement, finding that connectome ESNs maintain performance more robustly across pruning. Finally, we investigated structural features of the networks, uncovering correlations between task-relevance and characteristics such as recurrence, node degree, and biological cell-type annotations. We find that correlations are consistent across connectome and conventional ESNs, but that connectome ESNs exhibit stronger correlations. These findings indicate that biologically-inspired connectivity can enable sparsely selective and compact neural networks, which may reduce energy consumption and optimise robustness. The approaches and metrics used in this research may suggest a way to initialise better performing, more efficient and robust ESNs, as well as provide insight into individual node feature importance in biological networks.