Neurophysiology of geniculate ganglion (facial nerve) taste systems: species comparisons

On the basis of various measures taken from geniculate ganglion taste neurons in four species, it was concluded that within each species the neurons could be subdivided into distinct functional groups. In this report, the neural groups of different species were directly compared. Units from all four species were studied with a common test series of solutions in addition to other stimuli. Since these stimuli were presented at the same concentrations to all species, direct quantitative comparisons across species were possible for a wide range of chemical compounds. In addition, the neural groups were compared with respect to spontaneous and evoked activity measures, latency to electrical stimulation, and receptive field characteristics. These neurophysiological data suggest a basic model of four distinct subgroups: acid units, salt units, amino acid units, and X units.