Activation of respiratory afferents by resistive loaded breathing modifiessomatosensory evoked potentials to median nerve stimulation in humans

The cortical projections of respiratory afferents (vagus and respiratory mu scle nerves) are well documented in humans. It is also shown that their act ivation during loaded breathing modifies the perception of tactile sensatio n as well as the motor drive to skeletal muscles. The effects of expiratory or inspiratory loaded breathing on somatosensory evoked potentials (SEPs) elicited by median nerve stimulation were studied in eight healthy subjects . No significant changes occurred in latencies of N20, N30 and P40 througho ut the expiratory loading period, except for a significant lengthening in P 1 latency compared with unloaded breathing. However, inspiratory loading in duced a significant increase in peak latency of N20, N30 and P40 components . We suggest that projections of inspiratory afferents from the diaphragm a nd the intercostal muscles, activated by inspiratory loading, could be resp onsible for the lengthened latency of median nerve SEP components. Thus, re spiratory afferents very likely interact with pathways of the somatosensory system. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.