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Yeon Jin Kim, Edward A. Essock; Anisotropic Gain Control Pools Are Tuned In Temporal Frequency As Well As Spatial Frequency And Orientation. Journal of Vision 2010;10(7):1253. doi: 10.1167/10.7.1253.
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© ARVO (1962-2015); The Authors (2016-present)
Masking of a grating by broadband content is greatest for the horizontal orientation and least for oblique orientations (Essock, Haun and Kim, JOV, 2009; Kim, Haun and Essock, VSS, 2007). Thus when viewing oriented content in a natural scene (or other broadband images), oblique content is seen best and horizontal is seen least well (the “horizontal effect” e.g., Essock et al, VisResearch, 2003). We have suggested that his horizontal effect is due to anisotropic suppression that is observed when enough contextual spatial content is present to create a significant response in a gain control pool, thus revealing the anisotropy. Previously we have shown that the anisotropic gain control pools are local (i.e., “tuned”) in spatial frequency and orientation. Here we compare these pools (suppression magnitude and anisotropy magnitude) for narrowband tests across the spatio-temporal surface with either spatially or temporally broadband masks. Results show: (1) a horizontal effect anisotropy at all spatio-temporal conditions tested, (2) the magnitude of suppression and of the horizontal effect anisotropy are greatest at middle values (2cpd/10Hz for spatially broadband masks, and 4cpd/.5Hz for spatially broadband masks), and (3) the anisotropic gain control pools are local in not only spatial frequency but also in temporal frequency. This tuning in temporal frequency is in contrast to prior temporal masking studies that show only 2 (or 3) tuned channels when narrow-band masks are used. This suggests that a lower-level suppression exists, that is anisotropic, and becomes significant when driven by many spatial components (i.e., content broadband in spatial, temporal and/or orientation) but is apparently not revealed by a single (narrowband) mask as in prior studies.
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