fNIRS analysis of rostral prefrontal cortex activity and perception of inspiratory loads.

It is well-established that the brainstem is responsible for the automatic control of breathing, however, cortical areas control perception and conscious breathing. This study investigated activity in the prefrontal cortex (PFC) during breathing difficulty using functional near-infrared spectroscopy (fNIRS). It was hypothesized that extrinsic inspiratory loads will elicit regional changes in PFC activity and increased perception ratings, as a function of load magnitude and type. Participants were exposed to varying magnitudes of resistive (R) and pressure threshold (PT) inspiratory loads to increase breathing effort. Perception ratings of breathing effort and load magnitude were positively correlated (p < 0.05). PT loads were rated more effortful than R loads (p < 0.05). Differences in perceived effort were a function of inspiratory pressure-time-product (PTP) and inspiratory work of breathing (WoB). PFC activity increased with the largest PT load (p < 0.01), suggesting that the PFC is involved in processing respiratory stimuli. The results support the hypothesis that the PFC is an element of the neural network mediating effortful breathing perception.