Abstract
Visual perception begins by dissecting the retinal image into millions of small patches for local analyses by local receptive fields. However, image structures extend well beyond these receptive fields and so further processes must be involved in sewing the image fragments back together to derive representations of higher order (more global) structures. To investigate the integration process, we also need to understand the opposite process of suppression. To investigate both processes together, we measured triplets of dipper functions for targets and pedestals involving interdigitated stimulus pairs (A, B). Previous work has shown that summation and suppression operate over the full contrast range for the domains of ocularity and space. Here, we extend that work to include orientation and time domains. Temporal stimuli were 15-Hz counter-phase sine-wave gratings, where A and B were the positive and negative phases of the oscillation, respectively. For orientation, we used orthogonally oriented contrast patches (A, B) whose sum was an isotropic difference of Gaussians. Results from all four domains could be understood within a common framework in which summation operates separately within the numerator and denominator of a contrast gain control equation. This simple arrangement of summation and counter-suppression achieves integration of various stimulus attributes without distorting the underlying contrast code.
Highlights
It is well established that higher order vision involves substantial neuronal convergence from the preliminary analyses by tiny receptive fields to more global analyses that are selective for either larger or more complex structures, or both
Recent work in our laboratory has begun to address this at threshold in the spatial domain using spatially modulated carriers (e.g. “Battenbergs:” Meese, 2010; and “Swiss cheese:” Meese & Baker, 2011a; Meese & Summers, 2007, 2009), stimuli that were designed to encourage the observer to integrate over a fixed neuronal manifold while the experimenter varied the extent of the target
The results from the single increment (A) on dual pedestal (AB) show that the benefit is preserved along the entire dipper function—it only appears to be lost in the A on A versus AB on AB comparisons because the signal benefit is offset by counter-suppression from the extra pedestal component (Meese et al, 2006)
Summary
It is well established that higher order vision involves substantial neuronal convergence from the preliminary analyses by tiny receptive fields to more global analyses that are selective for either larger or more complex structures, or both. “Battenbergs:” Meese, 2010; and “Swiss cheese:” Meese & Baker, 2011a; Meese & Summers, 2007, 2009), stimuli that were designed to encourage the observer to integrate over a fixed neuronal manifold while the experimenter varied the extent of the target. The aim of this approach was to clamp the level of internal noise so as to achieve a clean measure of the integration process.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
