Design and Analysis of a Reconfigurable Hierarchical Temporal Memory Architecture

Self-learning hardware systems, with high-degree of plasticity, are critical in performing spatio-temporal tasks in next-generation computing systems. To this end, hierarchical temporal memory (HTM) offers time-based online-learning algorithms that store and recall temporal and spatial patterns. In this work, a reconfigurable and scalable HTM architecture is designed with unique pooling realizations. Virtual synapse design is proposed to address the dynamic interconnections occurring in the learning process. The architecture is interweaved with parallel cells and columns that enable high processing speed for the cortical learning algorithm. HTM has two core operations, spatial and temporal pooling. These operations are verified for two different datasets: MNIST and European number plate font. The spatial pooling operation is independently verified for classification with and without the presence of noise. The temporal pooling is verified for simple prediction. The spatial pooler architecture is ported onto an Altera cyclone II fabric and the entire architecture is synthesized for Xilinx Virtex IV. The results show that ≈ 91% classification accuracy is achieved with MNIST database and ≈ 90% accuracy for the European number plate font numbers with the presence of Gaussian and Salt & Pepper noise. For the prediction, first and second order predictions are observed for a 5-number long sequence generated from European number plate font and ≈ 95% accuracy is obtained. Moreover, the proposed hardware architecture offers 3902X speedup over the software realization. These results indicate that the proposed architecture can serve as a core to build the HTM in hardware and eventually as a standalone self-learning hardware system.