Fixational instability and natural image statistics: Implications for early visual representations

Abstract

Under natural vicv-.Ting-conditions 1 srnall movements of the eye: head, and body prevent the maintenance of a, steady direction of gaze. It is known tlu.tt stinmli tend to fade when they are stabilized on the retina for scveraJ seconds. Hm:vever: it is undcar whether the physiological motion of the retinal image serves a visual purpose during the brief periods of natural visual fixation. Thb r:;tucly exrtmines the in1paet of Hxational instability on the statistics of the visua.1 input to the retina. and on the structure of neural activity in the crtrly visual system. We sho\\' that fixa.tiona.l im;tnbility introduees a cornponcmt in the retinal input signals that) in the presence of natural images, lacks spatiaJ correlations. This c:omponent strongly infl1.wncc;s neuraJ activity in a model of the LGN. It decorrdates cell responses even if the contrast sensitivity functions of simulated cells arc not perfc-;;ctly tuned to counter-balance the power-bsv spectrum of natura.l i1nagcs. A clecorrelation of neural activity at the early stages of the visual system has been proposed to be bendieial for discarding statistica.l redundancies in the input f:lignals. The results of this study suggest that fixa..tional instability rnight contribute to ef:lta.blbhing efficient representations of natural stimuli.

Internally Mediated Developmental Desynchronization of Neocortical Network Activity

“…Similarly, increasing sensory drive as the animal matures could also desynchronize neuronal activity, because uncorrelated peripheral inputs could serve to weaken or disorganize spontaneously correlated activity patterns (Rucci and Casile, 2005). Plucking of whiskers from early neonatal stages weakens the angular tuning of barrel cortical neurons (Simons and Land, 1987) without disrupting the cytoarchitectural and histochemical development of the barrel field (Simons and Land, 1987; Akhtar and Land, 1991; Fox, 1992).…”

EyeRIS: A general-purpose system for eye-movement-contingent display control

“…In addition to a general characterization of EyeRIS performance, this article has reported examples of experimental applications related to our own research on fixational instability (Rucci & Casile, 2005;Rucci & Desbordes, 2003). In this context, we have shown that EyeRIS produces image stabilization with quality comparable to that of a stimulus deflector coupled with a DPI eyetracker, a standard noninvasive method for eliminating retinal image motion.…”

The unsteady eye: an information-processing stage, not a bug

“…However, these pioneering experiments also suffered from a number of technological and methodological limitations, which cast serious doubts on extrapolating their conclusions to more natural viewing conditions [17, 21, 22]. Furthermore, the proposal of an involvement of fixational eye movements in spatial perception has recently found new support from multiples sources, including neurophysiological [16, 23, 24] and behavioral investigations [22, 25, 26], statistical examinations of retinal input signals [27, 28], and theoretical analyses of the impact of a continually moving retinal input on neural responses [15, 17, 18, 29, 30]. …”