196 research outputs found
Direct Learning-Based Deep Spiking Neural Networks: A Review
The spiking neural network (SNN), as a promising brain-inspired computational
model with binary spike information transmission mechanism, rich
spatially-temporal dynamics, and event-driven characteristics, has received
extensive attention. However, its intricately discontinuous spike mechanism
brings difficulty to the optimization of the deep SNN. Since the surrogate
gradient method can greatly mitigate the optimization difficulty and shows
great potential in directly training deep SNNs, a variety of direct
learning-based deep SNN works have been proposed and achieved satisfying
progress in recent years. In this paper, we present a comprehensive survey of
these direct learning-based deep SNN works, mainly categorized into accuracy
improvement methods, efficiency improvement methods, and temporal dynamics
utilization methods. In addition, we also divide these categorizations into
finer granularities further to better organize and introduce them. Finally, the
challenges and trends that may be faced in future research are prospected.Comment: Accepted by Frontiers in Neuroscienc
Embedding Physics to Learn Spatiotemporal Dynamics from Sparse Data
Modeling nonlinear spatiotemporal dynamical systems has primarily relied on
partial differential equations (PDEs) that are typically derived from first
principles. However, the explicit formulation of PDEs for many underexplored
processes, such as climate systems, biochemical reaction and epidemiology,
remains uncertain or partially unknown, where very sparse measurement data is
yet available. To tackle this challenge, we propose a novel deep learning
architecture that forcibly embedded known physics knowledge in a
residual-recurrent -block network, to facilitate the learning of the
spatiotemporal dynamics in a data-driven manner. The coercive embedding
mechanism of physics, fundamentally different from physics-informed neural
networks based on loss penalty, ensures the network to rigorously obey given
physics. Numerical experiments demonstrate that the resulting learning paradigm
that embeds physics possesses remarkable accuracy, robustness, interpretability
and generalizability for learning spatiotemporal dynamics.Comment: 18 pages. arXiv admin note: substantial text overlap with
arXiv:2105.0055
Deep Learning Models of Learning in the Brain
This thesis considers deep learning theories of brain function, and in particular biologically plausible deep learning. The idea is to treat a standard deep network as a high-level model of a neural circuit (e.g., the visual stream), adding biological constraints to some clearly artificial features. Two big questions are possible. First, how to train deep networks in a biologically realistic manner? The standard approach, supervised training via backpropagation, needs overly complicated machinery for backpropagation and precise labels (that are somewhat scarce in the real world). The first result in this thesis approaches the first problem, backpropagation, by avoiding it completely. A layer-wise objective is proposed, which results in local, Hebbian weight updates that use a global error signal. The second result approaches the need for precise labels. It is focused on a principled approach to self-supervised learning, framing the problem as dependence maximisation using kernel methods. Although this is a deep learning study, it is relevant to neuroscience: self-supervised learning appears to be a suitable learning paradigm for the brain as it only requires binary (same source or not) teaching signals for pairs of inputs. Second, how realistic is the architecture itself? For instance, most well-performing networks have some form of weight sharing - having the same weights for different neurons at all times. Convolutional networks share filter weights among neurons, and transformers do so for matrix-matrix products. While the operation is biologically implausible, the third result of this thesis shows that it can be successfully approximated with a separate phase of weight-sharing-inducing Hebbian learning
New deep learning approaches to domain adaptation and their applications in 3D hand pose estimation
This study investigates several methods for using artificial intelligence to give machines the ability to see. It introduced several methods for image recognition that are more accurate and efficient compared to the existing approaches
Neuromorphic Online Learning for Spatiotemporal Patterns with a Forward-only Timeline
Spiking neural networks (SNNs) are bio-plausible computing models with high
energy efficiency. The temporal dynamics of neurons and synapses enable them to
detect temporal patterns and generate sequences. While Backpropagation Through
Time (BPTT) is traditionally used to train SNNs, it is not suitable for online
learning of embedded applications due to its high computation and memory cost
as well as extended latency. Previous works have proposed online learning
algorithms, but they often utilize highly simplified spiking neuron models
without synaptic dynamics and reset feedback, resulting in subpar performance.
In this work, we present Spatiotemporal Online Learning for Synaptic Adaptation
(SOLSA), specifically designed for online learning of SNNs composed of Leaky
Integrate and Fire (LIF) neurons with exponentially decayed synapses and soft
reset. The algorithm not only learns the synaptic weight but also adapts the
temporal filters associated to the synapses. Compared to the BPTT algorithm,
SOLSA has much lower memory requirement and achieves a more balanced temporal
workload distribution. Moreover, SOLSA incorporates enhancement techniques such
as scheduled weight update, early stop training and adaptive synapse filter,
which speed up the convergence and enhance the learning performance. When
compared to other non-BPTT based SNN learning, SOLSA demonstrates an average
learning accuracy improvement of 14.2%. Furthermore, compared to BPTT, SOLSA
achieves a 5% higher average learning accuracy with a 72% reduction in memory
cost.Comment: 9 pages,8 figure
Brain-Inspired Computing
This open access book constitutes revised selected papers from the 4th International Workshop on Brain-Inspired Computing, BrainComp 2019, held in Cetraro, Italy, in July 2019. The 11 papers presented in this volume were carefully reviewed and selected for inclusion in this book. They deal with research on brain atlasing, multi-scale models and simulation, HPC and data infra-structures for neuroscience as well as artificial and natural neural architectures
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