In this paper we review space flight experiments performed by our laboratory. Rhesus monkeys were tested before and after 12 days in orbit on COSMOS flights 2044 (1989) and 2229 (1992-1993). There was a long-lasting decrease in post-flight ocular counter-rolling (70%) and vergence (50%) during off-vertical axis rotation. In one animal, the orientation of optokinetic after-nystagmus shifted by 2...

When two dissimilar stimuli are presented to the eyes, perception alternates between multiple interpretations, a phenomenon dubbed binocular rivalry. Numerous recent imaging studies have attempted to unveil neural substrates underlying multistable perception. However, these studies had a conceptual constraint: access to observers' perceptual state relied on their introspection and active report...

Our perception does not provide us with an exact imprint of the outside world, but is continuously adapted to our internal expectations, task sets, and behavioral goals. Although effects of reward-or value in general-on perception therefore seem likely, how valuation modulates perception and how such modulation relates to attention is largely unknown. We probed effects of reward on perception b...

BACKGROUND To find out the smallest stimulus size still able to elicit optokinetic nystagmus (OKN). To discuss the differences in the generation of OKN between normals and patients with tunnel vision. METHODS AND PATIENTS OKN was elicited monocularly with black and white stripes of 2 degrees moving on a screen temporally-to-nasally or nasally-to-temporally at velocities of 15, 30, 45, and 60 ...

PURPOSE To investigate the efficacy of a computerized optokinetic nystagmus (OKN) test in evaluating the objective distance visual acuity and to determine the correlation between subjective and objective visual acuities. METHODS This prospective, noninterventional study included 83 eyes of 83 volunteers. Objective visual acuity was defined as the smallest size stripe that evoked the OKN respo...

Patients with unilateral spatial neglect are impaired in directing focal attention toward the contralesional side of space. Provision of static spatial cues on the neglected side has previously been shown to help overcome this deficit. Common movement of visual stimuli may also guide the allocation of spatial attention, although such effects have not been examined in patients with unilateral sp...

Perceptual stability requires the integration of information across eye movements. We first tested the hypothesis that motion signals are integrated by neurons whose receptive fields (RFs) do not move with the eye but stay fixed in the world. Specifically, we measured the RF properties of neurons in the middle temporal area (MT) of macaques (Macaca mulatta) during the slow phase of optokinetic ...

Extra-retinal information about eye velocity is thought to play an important role in compensating the retinal motion experienced during an eye movement. Evidently this compensation process is prone to error, since stimulus properties such as contrast and spatial frequency have marked effect on perceived motion with respect to the head. Here we investigate the suggestion, that 'optokinetic poten...

The mechanisms underlying visual perceptual stability are usually investigated using voluntary eye movements. In such studies, errors in perceptual stability during saccades and pursuit are commonly interpreted as mismatches between actual eye position and eye-position signals in the brain. The generality of this interpretation could in principle be tested by investigating spatial localization ...

During optokinetic nystagmus (OKN) the mean eye position of gaze (the beating field) shifts in the direction of the fast phases. The function of this shift may be to re-orient the eyes in the direction of self-motion which optic flow implies (in-coming field). This idea leads to the hypothesis that visual attention may be directed toward the In-coming field. In Experiment 1, subjects detected a...