Neural networks distinguish between taste qualities based on receptor cellpopulation responses

Response features of taste receptor cell action potentials were examined us ing an artificial neural network to determine whether they contain informat ion about taste quality. Using the loose patch technique to record from ham ster taste buds in vivo we recorded population responses oi single fungifor m papillae to NaCl (100 mM), sucrose (200 mM) and the synthetic sweetener N C-00274-01 (NC-01) (200 muM). Features of each response describing both bur st and inter-burst characteristics were then presented to an artificial neu ral network for pairwise classification of taste stimuli. Responses to NaCl could be distinguished from those to both NC-01 and sucrose with accuracie s of up to 86%. In contrast, pairwise comparisons between sucrose and NC-01 were not successful, scoring at chance (50%). Also, comparisons between tw o different concentrations of NaCI, 0.01 and 0.005 M, scored at chance. Pai rwise comparisons using only those features that relate to the inter-burst behavior of the response (i.e. bursting rate) did not hinder the performanc e of the neural network as both sweeteners versus NaCI received scores of 7 5-85%. Comparisons using features corresponding to each individual burst sc ored poorly, receiving scores only slightly above chance. We then compared the sweeteners with varying concentrations of NaCI (0.1, 0.01, 0.005 and 0. 001 M) using only those features corresponding to bursting rate within a 1 s time window. The neural network was capable of distinguishing between NaC I and NC-01 at all concentrations tested; while comparisons between NaCI an d sucrose received high scores at all concentrations except 0.001 M. These results show that two different taste qualities can be distinguished from e ach other based solely on the bursting rates of action potentials in single taste buds and that this distinction is independent of stimulation intensi ty down to 0.001 M NaCI. These data suggest that action potentials in taste receptor cells may play a role in taste quality coding.