Effects of timing of inspiratory occlusion on cerebral evoked potentials in humans

Abstract

Previous studies from these laboratories have shown that airway occlusion applied from the onset of inspiration or during midinspiration is associated with cerebral evoked potentials in human subjects. The hypothesis tested in the present study was that the more abrupt decrease in mouth pressure produced by midinspiratory occlusion will be associated with evoked potentials that have shorter peak latencies and greater peak amplitudes than those produced by occlusions from the onset of inspiration. The second objective of the present study was to determine whether there is bilateral projection of inputs from the respiratory system to the somatosensory cortex. Random presentation of 64 midinspiratory occlusions and 64 occlusions from the onset of inspiration was performed in eight subjects. The inspirations preceding the occlusions served as control. Evoked potentials were recorded from the scalp with electrode pairs Cz-C3 and Cz-C4. Reaction time to each type of occlusion was measured from the burst in electromyogram activity produced by contraction of the muscles encircling the eye. Each type of inspiratory occlusion was associated with evoked potentials that could be recorded bilaterally. The peak amplitudes of the evoked potentials recorded over the right cerebral hemisphere were significantly greater than those recorded from the left side. The peak amplitude was greater and the peak latency shorter for the evoked potentials produced by the midinspiratory occlusions. The results are consistent with the hypothesis that afferents mediating these potentials are stimulated by added loads to breathing and project bilaterally to the somatosensory cortex in humans.

An Adaptive Detector of Genioglossus EMG Reflex Using Berkner Transform for Time Latency Measurement in OSA Pathophysiological Studies

“…From (4) it is easy to demonstrate that (5) Owing to this, it is possible to follow an extremum from scale N to scale . In [19] we proposed a modified Berkner expansion with (6) so the recurrence relation (5) was also modified and led to (7)…”

“…Thus, the measurement of the genioglossus time latency reflex is of interest for understanding OSA pathophysiology. Previous studies have shown that respiratory-related cortical activity may be evoked by airway occlusion [4]- [6] or in response to small, brief negative pressure pulses [7]- [9]. Akay et al [10] have shown that the evoked response to pressure pulses applied at onset of inspiration is reduced in OSAS subjects.…”

Unaltered respiratory-related evoked potentials after acute diaphragm dysfunction in humans

“…The signal was sampled at a 1 kHz rate over a 0.5-500 Hz bandwidth. Respiratory-related potentials were evoked by mid-inspiratory occlusions [22]. To ensure immediate reproducibility of the signals, two separate averagings of 80 occluded breaths were systematically performed in each studied condition and the resulting traces superimposed.…”

Effects of upper airway anaesthesia on respiratory-related evoked potentials in humans

“…Sudden pressure changes within the airway appear particularly apt at evoking cortical responses. These can be induced by: 1) occlusion of the airway at the mouth at the beginning of inspiration [4] or during it [5]; 2) occlusion of the airway at the mouth during expiration [6]; 3) the sudden application of inspiratory resistances [7]; and 4) the application of negative pressure pulses to the airways during inspiration [8] or expiration [9].…”