There is no pattern of taste distribution that can be mapped. Yes some areas detect tastes at different thresholds so some areas are more sensitive and some less so. However every area of the tongue is capable of tasting all flavours.
I remember in school we were taught that the tongue has different areas for different tastes and also that electrons orbit a nucleus in a nice round fashion as planets orbit a sun. Both of these teachings of course are complete bollocks. They actually disproved that there are separate areas on...