Abstract

Spatial vision in adults is thought to be mediated by multiple bandpass spatial frequency-tuned (SF-tuned) channels with inhibitory interactions. Existing preferential looking data imply that young infants lack these channels (Banks, Stephens, & Hartmann, 1985), instead, processing spatial information with multiple lowpass channels, or a single "channel". Further, questions have been raised as to whether inhibitory systems are in place to mediate spatial vision in the infant (e.g. Morrone & Burr, 1986). Previously, we have used a SF adaptation paradigm (Blakemore & Campbell, 1969) combined with visual evoked potentials (VEPs) to demonstrate the bandpass and inhibitory nature of SF channels in adults (Suter, Armstrong, Suter, & Powers, 1991). SF adaptation decreased VEP amplitude in a bandpass manner near the adapting SF, and increased VEP responding at SFs removed from the adapting SF. Increased contrast sensitivity thresholds, reduced cortical response, and reduction of VEP amplitude after adaptation may be due to neuronal fatigue or adjustment of a local contrast gain mechanism within the adapted channel (Ohzawa, Sclar, & Freeman 1985). Following adaptation, lower contrast sensitivity thresholds at SFs removed from the adapting SF have been explained by release of inhibition on neighboring channels when SF adaptation reduced responding of the adapted channel (De Valois, 1977). The research summarized here uses the VEP with the SF adaptation paradigm to demonstrate the existence of multiple, bandpass, co-inhibitory SF-tuned channels in 3, 6, and 12 week-old infants.

© 1993 Optical Society of America