Abstract: In this experiment, conditioned taste aversion (CTA) was established by intraoral infusion of either 0.1% saccharin (Sac) or 0.2 mol/L sucrose (Suc) paired with intraperitoneal injection of 0.15 mol/L LiCl, the rats showed similar aversion for both Sac and Suc. Then the rats were trained to discriminate Sac and Suc with differential conditioning paradigm that one taste stimulus combined with LiCl (Sac+ or Suc+) but the other not (Sac- or Suc-), the rats showed aversion for Sac+ or Suc+, and preference for Sac- or Suc-. The distribution of Fos-like immunoreactive (FLI) neurons induced by intraoral infusion of either Sac or Suc in subdivisions of PBN was observed. It showed that different stimuli had no influence in dorsal lateral subnucleus (dls) and ventral lateral subnucleus (vls) on c-fos expression; And FLI neurons induced by Suc were more than that induced by Sac in internal lateral subnucleus (ils) and external medial subnucleus (ems), but in external lateral subnucleus (els), the number of FLI neurons induced by Sac were more than that induced by Suc; Furthermore, hedonic stimulus (Sac- and Suc-) induced higher c-fos expression in ils, cms and central lateral subnucleus (cls), and aversive stimulus (Sac+ and Suc+) induced higher c-fos expression in ems. The effects of quality and hedonics of taste stimuli were separate in ils and cms, and they were interactional in els and ems. These results suggested that there were regions where related to taste discrimination and reward value in PBN, the two regions were partly overlapped, and ems and els might have an important role in integrating the information of taste quality and reward value

Key words: conditioned taste aversion, differential, c-fos, parabrachial nucleus