Investigations into the neurophysiological basis of respiratory perception in humans using transient inspiratory occlusions

In humans breathing is an essential behaviour for life. It is recognized that humans and animals can perceive or sense their breathing, although the actual cortical and sub cortical structures by which this occurs remains unknown. The processing of sensations presumably arise from afferent information originating from mechanoreceptors within the muscles of the upper and lower airways, lungs and chest wall. This information is integrated by the central nervous system, which leads to a perception of respiratory sensations at th~ cortex, although the specific contnbutions of these sources remain unknown. In addition, distressing respiratory sensations such as breathlessness (dyspnoea) . and hyperinflation occur in individuals exhibiting pulmonary disease, such as asthma and chronic obstructive pulmonary disease (COPD). In response to these sensations, individuals can also voluntarily or behaviourally adjust their breathing. Hence, the aim of this thesis was to investigate: (i) the modulation of respiratory related sensory activity measured from the cortex in humans, using electroencephalography in response to applications of transient inspiratory occlusions (TIas) during hyperinflation, voluntary breathing and in tracheostomy patients' who lack an upper airway and (ii) the cortical and subcortical structures mediating the response to the TIO by using functional magnetic resonance imaging (fMRI). The results of these studies show that (i) voluntary breathing modulates respiratory perception, whereas perception is unaffected in tracheostomy patients and in hyperinflated states in response to TIas; and (ii) TIas can also generate cortical and sub cortical activity specifically activating sensory - motor structures including the, primary motor cortex, primary somatosensory cortex, supplementary motor area, inferior parietal areas, thalamus and cerebellum. In conclusion, respiratory perception (i) is altered by voluntary breathing; (ii) is unaffected .in hyperinflated and tracheostomized states; and (iii) can be investigated . using fMRl through the application of TIOs.EThOS - Electronic Theses Online ServiceGBUnited Kingdo