Traditionally, in cognitive science there have been two proposed types of computation related to neural activity - digital and analog, with the vast majority of theoretical work incorporating a digital understanding of cognition. Computing systems which perform digital computation are functionally organized to execute operations on strings of digits with respect to the type and location of the digit on the string. It has been argued that neural spike train signaling implements some form of digital computation, since neural spikes may be considered as discrete units or digits, like 0 or 1 - the neuron either fires an action potential or it does not.