Hyperacuity and the estimated positional accuracy of a theoretical simple cell

Receiver operating characteristic (ROC) analysis was used to estimate positional discrimination thresholds for a theoretical simple cell by assuming Poisson distribution of the response, average response strength, and an optimal spatial frequency of 16.0 cyc/deg. These thresholds were compared to the positional difference required to generate a response change of one action potential. This comparison indicated that the inability to alter the response by less than one spike may be limiting positional accuracy. Taking account of this limitation, displacement thresholds were, depending on parameters, estimated to be as small as, or smaller than, the lowest psychophysical thresholds of about 2 sec of arc. This suggests that it may be possible to account for even the lowest human hyperacuity thresholds in terms of single cortical neurons.