Optimization methods for improved efficiency and performance of Deep Q-Networks upon conversion to neuromorphic population platforms

Deep Spiking Neural Networks (SNNs) with event-driven dynamics become increasingly popular in many challenging Machine Learning applications, based on their cheap and efficient computations. The discontinuity of the SNN dynamics, however, leads to problems in the learning process, resulting in performance loss, as the dominant gradient-based training approaches are not easily adaptable to the discontinuous SNN activation domain. One promising approach develops SNNs by converting trained Deep Neural Networks to SNNs, which has been very successful in classification applications. Recently, the scope of the conversion studies has been extended to Deep Q-Networks (DQNs), and highly competitive performance has been achieved on many challenging Atari games. The present work provides a comprehensive description of the DQN to SNN conversion algorithm and evaluates the causes of the potential performance loss during the conversion process. We analyze three key factors which allow practical implementations without loss of generality for a large class of highly demanding Q-learning problems, including robust conversion rate, threshold percentile, and simulation time. Our results are not only competitive to DQN in terms of performance but also highly efficient, which is extremely beneficial upon implementations on neuromorphic platforms.