Mapping the brainstem terminations of tracheal and laryngeal afferent fibers using neurovirulent viruses. The schematic diagram shows herpes simplex 1 strain H129 tracing of tracheal vagal sensory neurons in rodents involved in sensing airway irritations. Note that afferents terminate in both the nucleus of the solitary tract (nTS) and the paratrigeminal nucleus (Pa5). The photomicrograph above shows an example of nTS and Pa5 terminations traced from the airways using a recombinant HSV1 H129 expressing a red fluorescent protein. See text and references [37, 38] for further details.