It has been suggested that afferents from intercostal muscles may play a role in the genesis of dyspnea. In this study, lower intercostal muscles were tapped or vibrated to induce a reflex, evoked potentials, and sensation. The tapping stimulus induced H reflex in the same muscle with a latency of 12 msec. Also the same stimulus induced evoked potentials in the cerebral cortex (N1: 19.8 +/- 1.2 msec). This suggests projection of the intercostal muscle spindle afferents to the cerebral cortex. 100 Hz vibration induced a later component, presumably an event-related potential, at 250 msec after the onset of both the inspiratory and expiratory phase. Thus, it may be possible that intercostal muscle spindle afferents project to the cerebral cortex and play a role in respiratory sensation. It has been suggested that dyspnea is reduced by increasing inspiratory and expiratory intercostal muscle spindle afferents during the inspiratory and expiratory phases, respectively. Thus, stretching the inspiratory and expiratory intercostal muscles during the respective muscular contraction phase may be effective in reducing dyspnea.