An FPGA-based coprocessor has been implemented which simulates the dynamics of a large recurrent neural network composed of binary neurons. The design has been used for unsupervised learning of receptive fields. Since the number of neurons to be simulated (>104) exceeds the available FPGA logic capacity for direct implementation, a set of streaming processors has been designed. Given the state- and activity vectors of the neurons at time t and a sparse connectivity matrix, these streaming processors calculate the state- and activity vectors for time t + 1. The operation implemented by the streaming processors can be understood as a generalized form of a sparse matrix vector product (SpMxV). The largest dataset, the sparse connectivity matrix, is stored and processed in a compressed format to better utilize the available memory bandwidth.
Algorithms for structured matrix-vector product of optimal bilinear complexity
