Neurophysiological Evaluation of Orientation and Spatial Frequency Discrimination

Citation Info

Bradley, A., Skottun, B.C., Ohzawa, I., Sclar, G., and Freeman, R.D. (1985)
Neurophysiological evaluation of the differential response model for orientation and spatial frequency discrimination.
J. Opt. Soc. Am. A 2: 1607-1610.
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Recent models have attempted to reconcile low psychophysical orientation and spatial-frequency discrimination thresholds with relatively broad orientation and spatial-frequency tuning of cortical neurons. These models have relied on the ability of the neurons to convert small stimulus changes into reliable response changes. We have examined this ability in a sample of neurons from the cat's striate cortex. We present here data from two cells that reliably signaled the smallest orientation and spatial-frequency differences. Using receiver operating characteristic analysis, we find that these cells could reliably signal orientation differences of 1.84 deg and spatial-frequency differences of 0.073 octave. We compare these single-cell results to cat and human behavioral discrimination thresholds.