SPATIAL INTERACTIONS IN HUMAN VISION - FROM NEAR TO FAR VIA EXPERIENCE-DEPENDENT CASCADES OF CONNECTIONS

Perceptual learning has been shown to affect early visual processes. H ere, we show that learning induces an increase in the spatial range of lateral interactions. Using a lateral masking/facilitation paradigm a nd bandpass-localized stimuli, we measured the interaction range befor e and after extensive training on a threshold detection task. For naiv e observers, target threshold was found to be facilitated by mask pres ence at distances up to six times the target period. However, practice had the effect of increasing the facilitation range by at least a fac tor of three. We suggest that the induced longer-range facilitation is a result of internal response transmission via a cascade of local con nections. The data presented also show that this chain can be broken. These results suggest a plasticity in early vision governed by Hebbian -like rules.