PubMed · 9593258
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S D Wexner. 1998. Biofeedback for constipation?. https://doi.org/10.1007/bf02235284
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Autonomic evaluation using the heart rate spectrum is sensitive to changes in breathing parameters, but few studies using this technique have controlled both the rate and depth of breathing. Fewer still have also measured or controlled inspiration and expiration times, or end-tidal carbon dioxide. This study describes the development of a digital instrument that can be used to alter tidal volume, ventilation rate and the time of inspiration and expiration with paced breathing visual templates displayed on a computer monitor. The digital instrument runs during data acquisition and displays the ventilatory signal from the subject superimposed on the paced breathing templates. Thus, adjustment of ventilatory parameters is achieved by matching the actual breathing signal to the target template. By regulating the ventilation rate and the tidal volume, end-tidal carbon dioxide could be increased or decreased in small increments. This instrument provided ventilatory control to investigate the effects on the heart rate spectrum of breathing depth, ventilation rate, end-tidal carbon dioxide and the time of expiration.
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Head motion is a common cause of technical failure in functional magnetic resonance imaging. A simple visual alignment system has been developed to provide visual feedback to the subject about his or her head position. The subject is able to readjust his or her head position accurately during a study, should motion occur. This sighting system is incorporated into a visor that fits onto the commercial head coil. The accuracy of correcting head motion and activation maps obtained with this device are demonstrated. The cognitive workload of using the alignment system does not significantly alter the activation pattern associated with eye movement paradigms.