Published: 2014-09-03

Spared Ability to Perceive Direction of Locomotor Heading and Scene-Relative Object Movement Despite Inability to Perceive Relative Motion

Lucia Maria Vaina, Ferdinando Buonanno, Simon K. Rushton

(Brain and Vision Research Laboratory, Boston University, Boston, USA)

Med Sci Monit 2014; 20:1563-1571

DOI: 10.12659/MSM.892199

Background: All contemporary models of perception of locomotor heading from optic flow (the characteristic patterns of retinal motion that result from self-movement) begin with relative motion. Therefore it would be expected that an impairment on perception of relative motion should impact on the ability to judge heading and other 3D motion tasks.
Material and Methods: We report two patients with occipital lobe lesions whom we tested on a battery of motion tasks. Patients were impaired on all tests that involved relative motion in plane (motion discontinuity, form from differences in motion direction or speed). Despite this they retained the ability to judge their direction of heading relative to a target. A potential confound is that observers can derive information about heading from scale changes bypassing the need to use optic flow. Therefore we ran further experiments in which we isolated optic flow and scale change.
Results: Patients’ performance was in normal ranges on both tests. The finding that ability to perceive heading can be retained despite an impairment on ability to judge relative motion questions the assumption that heading perception proceeds from initial processing of relative motion. Furthermore, on a collision detection task, SS and SR’s performance was significantly better for simulated forward movement of the observer in the 3D scene, than for the static observer. This suggests that in spite of severe deficits on relative motion in the frontoparlel (xy) plane, information from self-motion helped identification objects moving along an intercept 3D relative motion trajectory.
Conclusions: This re... read more

Keywords: Motion Perception, Stroke, Vision Disorders

Published: 2014-09-02

Multi-Slice Computed Tomography 5-Minute Delayed Scan is Superior to Immediate Scan after Contrast Media ...

Dailun Hou, Huifang Qu, Xu Zhang, Ning Li, Cheng Liu, Xiangxing Ma

Med Sci Monit 2014; 20:1556-1562

DOI: 10.12659/MSM.890719

Published: 2014-09-01

Association Between GSTM1 Null Genotype and Coronary Artery Disease Risk: A Meta-Analysis

Mei Yang, Jing Zhao, Lin Xing, Li Shi

Med Sci Monit 2014; 20:1550-1555

DOI: 10.12659/MSM.890876