memory place identity

School of Optometry, UC Berkeley

Wednesday, December 14 at 12:00

560 Evans

How is it that the eye can have an exquisite sense of motion even while the

retinal image of the stable world during fixation is in constant motion?

Several hypotheses have arisen: The "efference-copy" hypothesis holds that

efferent signals derived from the opto-motor control circuitry are used to

exactly offset the image instability induced by eye-motion[1]. The

"data-driven" hypothesis holds that image stabilization is computed from the

content of the images, deriving compensatory information from the

displacement of image features over time[2].  Or, we might just suppress the

lowest common motion of any visual scene[3]. In any case, the physiology

underlying this phenomenon remains largely unknown. Recent experiments from

our lab using an adaptive-optics-based eye tracker have revealed that the

percept of motion bears a different relationship to actual eye-motion than

any extant hypothesis predicts. We found that stimulus motions that have

directions which are consistent with eye-motion, but largely independent of

magnitude of that motion, produce the most stable percepts. These new

observations not only challenge all existing theories but, more importantly,

define a simpler path toward a physiological solution. 

1. Helmholtz,H. Helmholtz's Treatise on Physiological Optics. Optical

Society of America, Rochester (1924). 

2. Poletti,M., Listorti,C. & Rucci,M. Stability of the visual world during

eye drift. J. Neurosci. 30, 11143-11150 (2010). 

3. Murakami,I. & Cavanagh,P. A jitter after-effect reveals motion-based

stabilization of vision. Nature 395, 798-801 (1998).

---------------------------------------

Bruno A. Olshausen

Helen Wills Neuroscience Institute & School of Optometry Director, Redwood

Center for Theoretical Neuroscience UC Berkeley 575A Evans hall, MC 3198

Berkeley, CA 94720-3198

(510) 642-7250 / 2-7206 (fax)