A Note

•  We, together with our sister lab at Charing Cross Hospital in London, published the first report showing which areas of the cerebral cortex are engaged in the perception of dyspnea (air hunger) using Positron Emission Tomography of radioactive water .   Studies of stroke patients and brain stimulation identified the cortical sites of other sensations (vision, hearing, touch, pain before the advent of functional brain imaging late in the 20th century,  functional brain imaging has provide more detail.  But, prior to our first study the site of dyspnea perception was completely unknown.  Our first study revealed significant activation of the right anterior insula.  This ancient region of the vertebrate brain also processes sensations such as pain, hunger, and thirst, which have been described by Denton as Primal Sensations. Banzett, Adams et al 2000

 We also published the first BOLD fMRI images of dyspnea.  Blood Oxygen Level Dependent functional Magnetic Resonance Imaging provides greater sensitivity and resolution than PET.  These studies showed Important activations in right and left  anterior insula, amygdala, cerebellum, and anterior cingulate.  The limbic and paralimbic areas activated show commonality with pain, thirst, and hunger.  (Evans et al 2002, Binks, Evans et al 2014 )

Our fMRI studies were also able to detect activation of the Amygdala.  This paralimbic structure has long been associated with fearful emotion.  Consistent with this, our work has shown that Air Hunger feels threatening and  evokes fear.  Prior to this date, brain imaging studies of somatic pain (eg, hot thermodes on the skin) had not detected amygdala activation.  Focal skin pain is unpleasant, but not  threatening.  In contrast, later studies of visceral pain showed amygdala activation.  Visceral pain does feel threatening and can evoke fear.   (Evans et al 2002)