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On the Adversarial Robustness of Spiking Neural Networks Trained by Local Learning

Lin, Jiaqi, Sengupta, Abhronil

arXiv.org Artificial Intelligence

Recent research has shown the vulnerability of Spiking Neural Networks (SNNs) under adversarial examples that are nearly indistinguishable from clean data in the context of frame-based and event-based information. The majority of these studies are constrained in generating adversarial examples using Backpropagation Through Time (BPTT), a gradient-based method which lacks biological plausibility. In contrast, local learning methods, which relax many of BPTT's constraints, remain under-explored in the context of adversarial attacks. To address this problem, we examine adversarial robustness in SNNs through the framework of four types of training algorithms. We provide an in-depth analysis of the ineffectiveness of gradient-based adversarial attacks to generate adversarial instances in this scenario. To overcome these limitations, we introduce a hybrid adversarial attack paradigm that leverages the transferability of adversarial instances. The proposed hybrid approach demonstrates superior performance, outperforming existing adversarial attack methods. Furthermore, the generalizability of the method is assessed under multi-step adversarial attacks, adversarial attacks in black-box FGSM scenarios, and within the non-spiking domain.


Deep Learning without Weight Transport

Mohamed Akrout, Collin Wilson, Peter Humphreys, Timothy Lillicrap, Douglas B. Tweed

Neural Information Processing Systems

In a typical deep-learning network, some signals flow along a forward path through multiple layers of processing units from the input layer to the output, while other signals flow back from the output layer along a feedback path . Forward-path signals perform inference (e.g. they try to infer what objects are


Can Local Representation Alignment RNNs Solve Temporal Tasks?

Manchev, Nikolay, Garcia-Peraza-Herrera, Luis C.

arXiv.org Artificial Intelligence

Recurrent Neural Networks (RNNs) are commonly used for real-time processing, streaming data, and cases where the amount of training samples is limited. Backpropagation Through Time (BPTT) is the predominant algorithm for training RNNs; however, it is frequently criticized for being prone to exploding and vanishing gradients and being biologically implausible. In this paper, we present and evaluate a target propagation-based method for RNNs, which uses local updates and seeks to reduce the said instabilities. Having stable RNN models increases their practical use in a wide range of fields such as natural language processing, time-series forecasting, anomaly detection, control systems, and robotics. The proposed solution uses local representation alignment (LRA). We thoroughly analyze the performance of this method, experiment with normalization and different local error functions, and invalidate certain assumptions about the behavior of this type of learning. Namely, we demonstrate that despite the decomposition of the network into sub-graphs, the model still suffers from vanishing gradients. We also show that gradient clipping as proposed in LRA has little to no effect on network performance. This results in an LRA RNN model that is very difficult to train due to vanishing gradients. We address this by introducing gradient regularization in the direction of the update and demonstrate that this modification promotes gradient flow and meaningfully impacts convergence. We compare and discuss the performance of the algorithm, and we show that the regularized LRA RNN considerably outperforms the unregularized version on three landmark tasks: temporal order, 3-bit temporal order, and random permutation.


Training Large Neural Networks With Low-Dimensional Error Feedback

Hanut, Maher, Kadmon, Jonathan

arXiv.org Artificial Intelligence

Training deep neural networks typically relies on backpropagating high dimensional error signals a computationally intensive process with little evidence supporting its implementation in the brain. However, since most tasks involve low-dimensional outputs, we propose that low-dimensional error signals may suffice for effective learning. To test this hypothesis, we introduce a novel local learning rule based on Feedback Alignment that leverages indirect, low-dimensional error feedback to train large networks. Our method decouples the backward pass from the forward pass, enabling precise control over error signal dimensionality while maintaining high-dimensional representations. We begin with a detailed theoretical derivation for linear networks, which forms the foundation of our learning framework, and extend our approach to nonlinear, convolutional, and transformer architectures. Remarkably, we demonstrate that even minimal error dimensionality on the order of the task dimensionality can achieve performance matching that of traditional backpropagation. Furthermore, our rule enables efficient training of convolutional networks, which have previously been resistant to Feedback Alignment methods, with minimal error. This breakthrough not only paves the way toward more biologically accurate models of learning but also challenges the conventional reliance on high-dimensional gradient signals in neural network training. Our findings suggest that low-dimensional error signals can be as effective as high-dimensional ones, prompting a reevaluation of gradient-based learning in high-dimensional systems. Ultimately, our work offers a fresh perspective on neural network optimization and contributes to understanding learning mechanisms in both artificial and biological systems.


Reviews: Metalearned Neural Memory

Neural Information Processing Systems

UPDATED I think the authors for their rebuttal comments. All my concerns have been addressed (modulo seeing the extra results / error bars) so I am raising my score to 8. The idea of parameterising the memory as a neural network, and using ideas from metalearning to quickly train it to produce a specified output for new sequences, is very interesting and novel. The paper is overall well written, and I believe should be reproducable by those familiar with metalearning approaches. The justification for the model is interesting - essentially instead of writing some values to a fixed size memory, and then reads being limited to a convex combination of the written values, using a neural network allows potential benefits with compression, as well as generalisation, with constant space. Obviously the key issue with this is whether the memory function can be easily modified in one shot so that a new set of keys and values will be'read' approximately correctly.