The focus of a radial optic flow is a valid visual cue used to perceive and control the heading direction of animals. Gaze patterns in response to the focus of radial optic flow were measured in human infants (N = 100, 4-18 months) and in adults (N = 20) using an eye-tracking technique. Overall, although the adults showed an advantage in detecting the focus of an expansion flow (representing fo...

Optokinetic eye movements stabilize vision in response to large–field visual motion. We have studied oculomotor behavior of rhesus monkeys that viewed large optic flow stimuli. These stimuli present radial motion that is normally experienced during forward self–movement. In previous work (Lappe et al., 1998) we have described that such radial optic flow stimuli also elicit optokinetic responses...

This study concerns the retinotopic organization of the ganglion cell fibres in the visual system of the frog Xenopus laevis. HRP was used to trace the pathways taken by fibres from discrete retinal positions as they pass from the retina, along the optic nerve and into the chiasma. The ganglion cell fibres in the retina are arranged in fascicles which correspond with their circumferential posit...

Both electro-physiological and psychophysical studies point to the existence of detectors specialised for the analysis of optic flow. However, it is unclear whether these detectors are tuned to specific 'cardinal directions' (such as radial and circular motion), or whether they respond equally to all directions of optic-flow motion, including intermediate spiral motions. Here summation and mask...

When illusory self-motion is induced in a stationary observer by optic flow, the perceived distance traveled is generally overestimated relative to the distance of a remembered target (Redlick, Harris, & Jenkin, 2001): subjects feel they have gone further than the simulated distance and indicate that they have arrived at a target's previously seen location too early. In this article we assess h...

Earlier studies of neurons in the anterior region of the superior temporal polysensory area (STPa) have demonstrated selectivity for visual motion using stimuli contaminated by nonmotion cues, including texture, luminance, and form. The present experiments investigated the motion selectivity of neurons in STPa in the absence of form cues using random dot optic flow displays. The responses of ne...

STUDY DESIGN A prospective audit. OBJECTIVE To establish the efficacy of lumbar medial branch neurotomy under optimum conditions. SUMMARY OF BACKGROUND DATA Previous reports of the efficacy of lumbar medial branch neurotomy have been confounded by poor patient selection, inaccurate surgical technique, and inadequate assessment of outcome. METHODS Fifteen patients with chronic low back pai...