When1: 1959
Who: Jerome Y. Lettvin [Lettvin, Jerome Y.]
What: biologist
Where: USA
works\ What the Frog's Eye Tells the Frog's Brain [1959: with Maturana, McCulloch, and Pitts]
Detail: He lived 1920 to ?. Axons from frog retinal ganglion cells have four groups that respond differently to different stimuli and that end in four distinct optic-tectum layers, all with same topographic map. Frog is normally motionless, so detectors detect environment changes.
Sustained contrast detectors make immediate and prolonged signals when object edge, either lighter or darker than background, moves into receptive field and stops.
Net convexity detectors make immediate and temporary signals when large dark-object small or convex edges pass through visual field. Smooth movement has less effect than jerky movement.
Moving-edge detectors respond to edges moving through receptive field. Net dimming detectors make immediate and prolonged signals with sudden illumination reduction. Frogs can recognize prey and enemy categories.
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Date Modified: 2022.0224