Simple striate neurons in the cat. I. Comparison of responses to moving and stationary stimuli

Abstract

1. Peristimulus time (PST) histograms of simple striate responses to static presentations of narrow bright and dark bars in an array of receptive-field (RF) positions have demonstrated one to four response regions with distinct response properties. 2. There is a high degree of correlation of these responses with PST histograms of responses to the same stimuli moving smoothly ("dynamic" stimuli) in a direction perpendicular to the long axis of the RF. 3. Trailing responses to smoothly moving bar stimuli usually occur as the stimulus leaves an apparently inhibitory (for that stimulus) RF region. 4. Spatially leading responses to smoothly moving stimuli occur just as a bar stimulus enters an excitatory RF region, and may be based on certain gradient-detecting properties of neurons. 5. Close agreement in peak firing rates and in positions of responses for statically and dynamically elicited responses in units that are not strongly directionally selective suggests the possibility that in most respects smooth movement responses may be the sequential linear superposition of static responses. A quantitative superposition of static responses from two units supports this conclusion. 6. The dependence on a steady background for sustained responses to static presentation of dark bars illustrates the significance of steady illumination in the RF and raises questions about the efficacy of using edge stimuli as elemental visual probes.