Authors: Aashman Mehta, AbdelQader AlKilany, Dan F. M. Goodman, Giacomo Indiveri, Melika Payvand
Organizations: Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland · University of California, Los Angeles, CA, USA · Imperial College London, London, UK
Gating mechanisms allow a fixed neural network to adapt its computation to the current input by dynamically modulating its effective parameters. In the brain, neuromodulation uses this principle to move neural circuits between dynamical regimes, and deep learning exploits input-dependent gating, e.g., in gated recurrent networks and self-attention. Input-dependent modulation has also recently been shown to improve spiking neural networks, with particularly strong benefits in small, parameter-limited ones. This makes neuromodulation especially promising for neuromorphic processors at the edge, where area, memory and energy budgets constrain network size, while circuit physics limits parameter precision. Here we demonstrate input-dependent, within-trial neuromodulation of a spiking recurrent neural network on a mixed-signal neuromorphic processor. An off-chip modulator reads the on-chip network's input and activity and adjusts its population-level gains while the chip's analog circuits compute with the physics of the silicon. Neuromodulation raises binary spoken-digit classification accuracy by +17.3±10.4 percentage points, tested across five hardware network instantiations.
Figures & tables
Fig. 3 : Chip-in-the-loop modulation on DYNAP-SE (5 RNNs; excitatory and inhibitory gains of the E neurons on chip and somatic gain for off-chip readout neurons rewritten every 40 ms; 213 test trials); ( ) What is fixed, trained and modulated; ( ) Test accuracy of each RNN without and with modulation, the modulator trained with the activity-gated estimated gradient; ( ) Change in test accuracy over the unmodulated baseline for the modulated network and Controls A–C, mean ± SD over RNNs.
Modification
Tests whether improvement requires
A
Retrain readout only (fresh optimizer, same epochs)
Modulation beyond extra readout training
B
Gains held at the mean of the modulated validation run
Dynamic gains rather than a better operating point
C
Another trial’s gain trajectory played through the reservoir
Dependence of the gains on the current input
TABLE I : Controls used in the hardware experiments.
Although deep learning-based methods can achieve high accuracy in automatic modulation recognition (AMR) tasks, their high computational cost makes it difficult to strike a balance between accuracy and power consumption, thereby limiting their application on resource-constrained platforms. Neuromorphic architectures that perform spike-driven inference with modest energy budgets have recently been explored for vision and timeseries tasks. Motivated by these works, we propose EMRFormer, a novel end-to-end spiking nerural network (SNN) architecture that applies spike-driven transformer to the constraints of neuromorphic hardware for AMR. The model incorporates an adaptive spike encoder and Integer Leaky Integrate-and-Fire neurons to mitigate the degradation of effective information and enhance SNN representational capacity. By integrating spike-separable Convolution Neural Networks (SSCNN) into Spike-Driven Transformers (SpikeFormer), EMRFormer effectively extracts multi-scale temporal features from the raw IQ waveforms. We validate our approach across various mainstream datasets, the experimental results show that EMRFormer achieves state-of-the-art interms of accuracy, outperforming all the baselines. Furthermore, the model maintains strong performance in low signal-to-noise(SNR) environments and reduces theoretical energy consumption by over 90%. Finally, we evaluate our model on a KA200 neuromorphic chip. The results show that our model achieves up to 5 times reduction in power compared to running on a 3090 GPU or an Orin NX. This work demonstrates a promising pathway for AMR on resource-constrained devices.
Xiaohu Li, Chongxiao Qu, Caiyong Lin +2
China Nanhu Academy of Electronics and Information Technology, Jiaxing, China · University of Electronic Science and Technology of China, Chengdu, China
We propose a scalable neuromorphic architecture based on spiking dynamics emerging from the autonomous time-continuous evolution of clockless (asynchronous) digital circuits. Implemented on commercially available field-programmable gate arrays (FPGAs), our system implements networks of interacting Boolean spiking neurons with configurable excitatory and inhibitory synaptic weights. A complete processing pipeline enables efficient handling of spike-encoded data for solving machine-learning tasks. We demonstrate competitive performance for an audio classification task with spike-based encoding and high-speed processing. Power consumption is significantly lower than traditional digital implementations; this makes our approach an efficient alternative that bridges the gap to dedicated analog neuromorphic systems without the need for specialized hardware design. More generally, our approach establishes clockless digital hardware as a viable platform for neuromorphic computing. It paves the way for reconfigurable chips to be turned into energy-efficient quasi-analog neuromorphic processors.
Eric Oliveira Gomes, Damien Rontani
LMOPS UR4423 Laboratory, CentraleSup´elec and Universit´e de Lorraine, Metz F-57070, France
On-chip learning is key to scalable and adaptive neuromorphic systems, yet existing training methods are either difficult to implement in hardware or overly restrictive. However, recent studies show that feedback-control optimizers can enable expressive, on-chip training of neuromorphic devices. In this work, we present a proof-of-concept implementation of such feedback-control optimizers on a mixed-signal neuromorphic processor. We assess the proposed approach in an In-The-Loop(ITL) training setup on both a binary classification task and the nonlinear Yin-Yang problem, demonstrating on-chip training that matches the performance of numerical simulations and gradient-based baselines. Our results highlight the feasibility of feedback-driven, online learning under realistic mixed-signal constraints, and represent a co-design approach toward embedding such rules directly in silicon for autonomous and adaptive neuromorphic computing.
Jonathan Haag, Christian Metzner, Dmitrii Zendrikov +4
Institute of Neuroinformatics, University of Zürich and ETH Zürich, Zürich, Switzerland · AI Center, ETH, Zürich, Switzerland · Digital Society Initiative, University of Zurich, Switzerland