Mixed visual reference frames: perceiving nonretino-centric visual quantities in a retino-centric frame

Abstract

It is a useful competence to see motion relative to the head or to the external world, although those quantities are not directly given on the retina. The same holds for judgement of the shape of an object. We argue that the required transformations can be, and are done independent of the associated direction transformations. This involves perceptual channels with retinal apertures but non-retinocentric motion-or shapesensitivity. In order to arrive at units that perform such a mixed transformation, the substructure of the retinotopic receptive field needs to be dynamically adjusted, using extra-retinal signals (or equivalent measures like vertical disparity). Here we show that detectors tuned to disparity-curvature X retinal-direction can extract (metric) object curvature from the retinal disparity field in one step. We point out the correspondence to a previously proposed model of heading detection, which contains detectors that become tuned to head-centric flow by dynamically changing their preferred structure of the flowfield in a retinal aperture, depending on the eye movement.

Direct extraction of curvature-based metric shape from stereo by view-modulated receptive fields

“…Acknowledgements Some of the results in this paper were announced in van den Berg et al (2005). The work was supported by a Human Frontier program grant to A.V.…”

Representation of Head-Centric Flow in the Human Motion Complex

“…This is remarkable because, for the rotating eye, the center of the radial flow on the retina no longer coincides with the heading direction (Gibson, 1966;Regan and Beverley, 1982;van den Berg and Beintema, 2000). Psychophysical studies indicate that humans cope with this rotation problem using visual and extra-retinal signals about the rotation of the eye (Warren and Hannon, 1988;Royden et al, 1994;van den Berg, 1996;Crowell et al, 1998;Lappe et al, 1999). Through the extra-retinal signal, the brain can compensate for this rotation and achieve a representation of flow relative to the head or body that allows for accurate heading judgments (Perrone, 1992;Beintema and van den Berg, 1998;Lappe, 1998;Zemel and Sejnowski, 1998;Hanada, 2005).…”

“…These parameters are the same for all dots. Unit vector d ជ i indicates the retinal direction from which each moving dot is seen by the eye, and scalar D i is its distance (for additional details, see van den Berg et al, 2001). In the control condition, the visual stimulus always consisted of a stationary random dot pattern.…”

“…Our fMRI study does not test a quantitative measure of this translational component. In general, the compensation for eye velocity can be done within a retino-centric receptive field (Bradley et al, 1996;Beintema and van den Berg, 1998;van den Berg et al, 2005). Monkey studies have investigated interactions between retinal motion and pursuit signals in the dorsal portion of the MST (Bradley et al, 1996;Lappe et al, 1996;Shenoy et al, 1999Shenoy et al, , 2002Page and Duffy, 1999;Churchland and Lisberger, 2005) and the lateral portion of the MST (Thier and Erickson, 1992;Ilg et al, 2004;Churchland and Lisberger, 2005).…”

“…This is remarkable because, for the rotating eye, the center of the radial flow on the retina no longer coincides with the heading direction (Gibson, 1966;Regan and Beverley, 1982;van den Berg and Beintema, 2000). Psychophysical studies indicate that humans cope with this rotation problem using visual and extra-retinal signals about the rotation of the eye (Warren and Hannon, 1988;Royden et al, 1994;van den Berg, 1996;Crowell et al, 1998;Lappe et al, 1999).…”