Related Experiment Video
Updated: Jul 13, 2026

Electrophysiological Methods for Measuring Photopigment Levels in Drosophila Photoreceptors
Published on: June 2, 2022
A functional circuitry for edge-induced brightness perception
Chou P Hung1, Benjamin M Ramsden, Anna Wang Roe
1Institute of Neuroscience and Brain Research Center, 155 Sec. 2 Li-Nong St., National Yang Ming University, Taipei 112, Taiwan.
Abstract:
The identification of visual contours and surfaces is central to visual scene segmentation. One view of image construction argues that object contours are first identified and then surfaces are filled in. Although there are psychophysical and single-unit data to suggest that the filling-in view is correct, the underlying circuitry is unknown. Here we examine specific spike-timing relationships between border and surface responses in cat visual cortical areas 17 and 18. With both real and illusory (Cornsweet) brightness contrast stimuli, we found a border-to-surface shift in the relative timing of spike activity. This shift was absent when borders were absent and could be reversed with relocation of the stimulus border, indicating that the direction of information flow is highly dependent on stimulus conditions. Furthermore, this effect was seen predominantly in 17-18, and not 17-17, interactions. These results demonstrate a border-to-surface mechanism at early stages of visual processing and emphasize the importance of interareal circuitry in vision.
Related Concept Videos
Anatomy of the Eyeball
Visual System
Once through the pupil, the light passes through the lens, a...
Vision
Photoreceptors and Visual Pathways
The Retina
Biasing of P-N Junction
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...

