Neural pattern discrimination.

~ (Received 8 July 1969, and in revised form 10 November 1969) lI, Some possible neural mechanisms of pattern discrimination are discussed, leading to neural networks which can discriminate any number of essentially arbitrarily complicated space-time patterns and activate cells which can then learn and perform any number of essentially arbitrarily complicated space-time patterns in response to the proper input pattern. Among the topics that arise in this discussion are: use of non-recurrent inhibitory interneurons for temporal or spatial discrimination tasks which recurrent inhibitory interneurons cannot carry out; mechanisms of temporal generalization whereby the same cells control performance of a given act at variable speeds; a tendency for cells furthest from the sensory periphery to have the most specific response modes and the least ability to follow sensory intensities (e.g. on-off and bimodal responses are common); uses of non-recurrent on-off fields whose signals arrive in waves forming "interference patterns", with the net effect of rapidly choosing at most one behavioral mode from any number of competitive modes, or of non-specifically arousing or suppressing cells which can sample and learn ongoing internal patterns; uses of specific vs. nonspecific inhibitory interneurons, axon hillock inhibition, presynaptic inhibition, equal smoothing of excitatory and inhibitory signals, possible production of both excitatory and inhibitory transmitter in a single synaptic knob, blockade of postsynaptic potential response, logarithmic transduction of inputs to spiking frequencies, or saturation of cell body response in non-recurrent on-off fields for purposes of pattern discrimination.