Neuroimaging of cerebral activations and deactivations associated with hypercapnia and hunger for air

摘要

There are defined medullary, mesencephalic, hypothalamic, and tha- lamic functions in regulation of respiration, but knowledge of cortical control and the elements subserving the consciousness of breathless- ness and air hunger is limited. In nine young adults, air hunger was produced acutely by CO_2 inhalation. Comparisons were made with inhalation of a N_2/O_2 gas mixture with the same apparatus, and also with paced breathing, and with eyes closed rest. A network of activations in pons, midbrain (mesencephalic tegmentum, parabra- chial nucleus. and periaqueductal gray), hypothalamus, limbic and paralimbic areas (amygdala and periamygdalar region) cingulate, parahippocampal and fusiform gyrus, and anterior insula were seen along with caudate nuclei and pulvinar activations. Strong deadiva- tions were seen in dorsal cingulate, posterior cingulate, and prefron- tal cortex. The Striking response of limbic and paralimbic regions points to these Structures having a singular role in the affective sequelae entrained by disturbance of basic respiratory control whereby a process of which we are normally unaware becomes a salient element of consciousness. These activations and deactivations include phylogenetically ancient areas of allocortex and transitional cortex that together with the amygdalar/periamygdalar region may subserve functions of emotional representation and regulation of breathing.