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Although the supplementary eye field (SEF) has been implicated in the control of head movements associated with gaze shifts, there is no direct evidence that SEF plays a role in the generation of head movements independent of gaze. If the SEF does, varying the duration of stimulation should selectively alter the head-movement kinematics during the(More)
The countermanding saccade task has been used in many studies to investigate the neural mechanisms that underlie the decision to execute or restrain rapid eye movements. In this task, the presentation of a saccade target is sometimes followed by the appearance of a stop cue that indicates that the subject should cancel the planned movement. Performance has(More)
When humans or monkeys are asked to make saccades to visual targets accompanied by one or more distractors, the two dimensional trajectory of the saccade will sometimes display significant curvature. Port and Wurtz used dual electrode recordings to show that this phenomenon is associated with activity at more than one site in superior colliculus (SC). The(More)
Because of limitations in the oculomotor range, many gaze shifts must be accomplished using coordinated movements of the eyes and head. Stimulation and recording data have implicated the primate superior colliculus (SC) in the control of these gaze shifts. The precise role of this structure in head movement control, however, is not known. The present study(More)
The use of absorbable orthopedic implants has increased substantially during the last decade. Currently, most of them are fabricated from poly-L-lactide (PLLA), its co-polymers, or mixtures with other constituents. In vivo, PLLA persists for years after its surgical role has ended, which is confirmed by a long-term histological study of PLLA implanted in(More)
It has long been believed that the superior colliculus (SC) is involved in the production of saccades but plays no role in the generation of vergence eye movements. However, results from several recent studies suggest that it may be worthwhile to examine the role of the SC in saccade-vergence interactions. Specifically, the available literature suggests two(More)
One important behavioral role for head movements is to assist in the redirection of gaze. However, primates also frequently make head movements that do not involve changes in the line of sight. Virtually nothing is known about the neural basis of these head-only movements. In the present study, single-unit extracellular activity was recorded from the(More)
  • M Walton
  • 1999
Anterior cruciate ligament replacement was performed on 71 sheep to compare graft security using a titanium or an absorbable polyglyconate interference screw (Acufex, Mansfield, MA) to hold the bone-patellar tendon-bone autograft. Early self mobilization was followed later by retrieval of most specimens up to 12 weeks. No grafts failed in vivo or migrated(More)
  • M Walton
  • 1991
The rate at which absorbable sutures lose their mechanical strength in a slow healing wound is clinically important, particularly because the factors inhibiting normal healing are not always apparent at the time of closure. Sutures of chromic catgut and two monofilament absorbable synthetic suture materials (polydioxanone and polyglyconate) were used to(More)
STUDY DESIGN Experimental study performed using an animal model. OBJECTIVES To determine if EMG responses generated by the electrical stimulation of thoracolumbar pedicle screws could be used to predict the screw position. SUMMARY OF BACKGROUND DATA Evoked EMG has been used successfully to predict pedicle screw position in the lumbar spine. No data have(More)