The nature of anisotropy in gain control pools.

Abstract

ACKNOWLEDGMENTSSo many people impacted this work that I can not begin to thank them all. But, Iwould like to particularly thank my mentor Dr. Edward A. Essock for his careful guidance, thoughtful patience, and support as well as for offering me the opportunity to engage in graduate study. I would also like to thank the rest of my committee members: , 2003). It is thought that anisotropic suppression reflects a gain control mechanism whose output is intented to equalize the neural response to the orientation content biases in natural scenes.Here we further investigate the dependence of this gain control anisotropy on temporal and spatial frequency by measuring tuning properties of these pools.Experiment 1 evaluates (1) the shape and the peak suppression of temporal frequency tuning functions for grating targets at 10 fixed spatio-temporal combinations by varying the temporal frequency of the lifbroadband masks, and (2) whether the observed suppression show the horizontal effect. Experiment 2 evaluates the same properties for spatial frequency tuning. iv The results showed that multiple local gain control pools across the spatiotemporal locations are tuned in temporal frequency and spatial frequency, and all of these pools are stronger at horizontal. Surprisingly, results showed that multiple temporallytuned pools are revealed with a broadband mask, whereas prior studies using very narrowband masks have shown only 2 (or 3) temporally-tuned channels (e.g.,