Joseph L. Demer

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Stability of images on the retina was determined in 14 normal humans in response to rotational and translational perturbations during self-generated pitch and yaw, standing, walking, and running on a treadmill. The effects on image stability of target distance, vision, and spectacle magnification were examined. During locomotion the horizontal and vertical(More)
PURPOSE Connective tissue structures constrain paths of the rectus extraocular muscles (EOMs), acting as pulleys and serving as functional EOM origins. This study was conducted to investigate the relationship of orbital and global EOM layers to pulleys and kinematic implications of this anatomy. METHODS High-resolution magnetic resonance imaging (MRI) was(More)
The vestibulo-ocular reflex (VOR) generates compensatory eye movements in response to angular and linear acceleration sensed by semicircular canals and otoliths respectively. Gaze stabilization demands that responses to linear acceleration be adjusted for viewing distance. This study in humans determined the transient dynamics of VOR initiation during(More)
 We employed binocular magnetic search coils to study the vestibulo-ocular reflex (VOR) and visually enhanced vestibulo-ocular reflex (VVOR) of 15 human subjects undergoing passive, whole-body rotations about a vertical (yaw) axis delivered as a series of pseudorandom transients and sinusoidal oscillations at frequencies from 0.8 to 2.0 Hz. Rotations were(More)
We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific beta-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis,(More)
The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with(More)
PURPOSE Magnetic resonance imaging (MRI) shows that the paths of recti extraocular muscle (EOM) bellies remain fixed in the orbit during large ocular rotations and across large surgical transpositions of their insertions. These findings imply that recti EOMs pass through pulleys coupled to the orbit and anterior to the muscle bellies, because the insertions(More)
1. The purpose of this study was to infer the properties of the mechanisms contributing to visual-vestibular interaction (VVI) of human beings during vertical motion. Predictable trains of single-frequency sinusoids; poorly predictable sums of sinusoidal harmonics; and unpredictable random impulses of passive, whole-body rotation about a horizontal,(More)
A method has been developed of clinically quantifying dynamic visual acuity (DVA), the acuity during imposed head motion in the pitch axis. In this method, visual acuity is measured using a computer-controlled projection system during vertical, sinusoidal relative motion either of the optotypes (the letters to be read) or of a servodriven swinging chair in(More)
PURPOSE Rectus extraocular muscles (EOMs) consist of orbital (OL) and global (GL) layers. This study enumerated the fibers in both layers along the length of each EOM. METHODS Four human (ages 17 months-93 years) and three monkey (ages 5-7 years) orbits were serially sectioned in the coronal plane and stained with Masson's trichrome. All fibers of the(More)