Figure 3.

Functional groups of geniculate ganglion (GG) neuron receptive fields. Three types of GG receptive fields are shown in boxes that include extracellular recordings from single GG cells, mapping of individual FP in the receptive field by electrical stimulation, and drawing of FP in the receptive field on a tongue diagram. A. GG responses to several chemicals and to cold water (4°C) in a chemical/thermal receptive field of 7 FP. There were no responses to tactile stimuli. B. GG responses to lingual stimulation with cold water. There were no responses to a mixture of chemical or taste stimuli, or to tactile stroking. The field has 2 FP. Surrounding FP do not respond to stimulation. C. GG responses to lingual tactile stroking only, not to lingual stimulation with a mixture of chemicals or to cold water (4°C). The field has 3 FP. In general, GG receptive fields for responses to temperature and tactile stimuli are smaller than those for chemicals. (Data from Ref. 26).