ÐA method is developed to analyze the accuracy of the relative head-to-object position and orientation (pose) in augmented reality systems with head-mounted displays. From probabilistic estimates of the errors in optical tracking sensors, the uncertainty in head-to-object pose can be computed in the form of a covariance matrix. The positional uncertainty can be visualized as a 3D ellipsoid. One...

Radial head fractures are fairly common, occurring in 17-44% of all elbow injuries. Mason Type 2 fractures may be fixed using mini fragment screws, this fixation often needing augmentation with a plate to make the construct rotationally stable. However, the drill holes needed to fix the plate to the radial head, carry the risk of inflicting more injury to the fractured fragments. In our case, t...

We have investigated the relationships among the firing frequency B(t) of inhibitory burst neurons (IBNs) and the metrics and dynamics of the eye, head, and gaze (eye + head) movements generated during voluntary combined eye-head gaze shifts in monkey. The same IBNs were characterized during head-fixed saccades in our first of three companion papers. In head-free gaze shifts, the number of spik...

OBJECTIVE We examined the eye movement response patterns of a group of patients with bilateral vestibular loss (BVL) during suppression head impulse testing. Some showed a new saccadic strategy that may have potential for explaining how patients use saccades to recover from vestibular loss. METHODS Eight patients with severe BVL [vestibulo-ocular reflex (VOR) gains less than 0.35 and absent o...

2 Previous studies suggest that stimulation of lateral intraparietal cortex (LIP) evokes saccadic eye movements towards eye-fixed or head-fixed goals, whereas most single-unit studies suggest that LIP uses an eye-fixed frame with eye position modulations. The goal of our study was to determine the reference frame for gaze shifts evoked during LIP stimulation in head-unrestrained monkeys. Two ma...

introduction: in iran, thousands of young individuals become victims of head injury annually. head injury can damage neuronal cells which may in turn complicate the recovery of the patients. also, the increase of iron in cerebrospinal fluid (csf) following head injury may contribute to the hypoxic-ischemia brain damage by catalyzing the formation of free radicals (harber-weiss rection). the obj...

When a human subject is oscillated about the nasooccipital axis and fixes upon targets along the horizontal head-fixed meridian, angular eye velocity includes a vertical component that increases with the horizontal eccentricity of the line-of-sight. This vertical eye movement component is necessary to prevent retinal slip. We asked whether fixation on a near head-fixed target during the same to...

Vestibular responses play an important role in maintaining gaze and posture stability during rotational motion. Previous studies suggest that these responses are state dependent, their expression varying with the environmental and locomotor conditions of the animal. In this study, we simulated an ethologically relevant state in the laboratory to study state-dependent vestibular responses in bir...

24 25 Vestibular responses play an important role in maintaining gaze and posture stability 26 during rotational motion. Previous studies suggest that these responses are state-dependent, their 27 expression varying with the environmental and locomotor conditions of the animal. In this 28 study, we simulated an ethologically relevant state in the lab in order to study state-dependent 29 vestibu...

The vestibulo-ocular reflex (VOR) generated by voluntary head movements keyed to a tone varying sinusoidally in pitch was studied in 13 men. Modulation of pitch at frequencies ranging from 0.1-5.0 Hz yielded systematic variation in head movement frequencies, although above 2 Hz head frequencies fell below requested frequencies. Three conditions of visual stimulation were used. When an Earth-fix...