Contribution of supraglottal mechanoreceptor afferents to respiratory-related evoked potentials in humans

We used the global field power (GFP) to estimate the magnitude and timing o f activation of the somatosensory cortex by respiratory mechanoreceptor aff erents in normal humans in response to brief, negative oral pressure pulses applied at the onset of inspiration. We compared responses before (test) a nd after insertion of a laryngeal mask airway (LMA) that prevented supraglo ttal airway receptors from sensing the applied stimulus. Evoked potential r esponses without supraglottic stimulation were smaller, with delayed or mis sing features, than those with all receptors stimulated. Supraglottic recep tors contribute about one-half of the GFP summed over the 100 ms poststimul us, and subglottal receptors, including those in the larynx, provide a GFP response similar to 38% above baseline. The most obvious difference between test and LMA responses occurred at 55 ms on average, when the LMA GFP lack ed activation features seen in the test condition. We conclude that mechano receptors above the larynx are responsible for a major portion of the midla tency afferent information arriving at the somatosensory cortex in response to applied pressure pulses.