Taste quality and extinction of a conditioned taste aversion in rats

Rats (Rattus norvegicus) that received a taste cue(saccharin, saline, quini ne, or sucrose) paired with a lithium chloride (LiCl) injection displayed a robust decrease in consumption of that taste, relative to controls that ha d the taste unpaired with LiCl. Consumption of the paired taste increased w ith each nonreinforced presentation (i.e., extinction). After asymptotic ex tinction, rats that had had a 0.1% saccharin cue paired with LiCl consumed less of the saccharin solution than did controls. A similar data pattern wa r; observed with a 10% sucrose solution. These results are consistent with the view that some aspect of the excitatory CS-US association remains after extinction. On the other hand, rats that had a bitter (0.005% or 0.001% qu inine) or salty (1% or 0.5% saline) solution paired with LiCl drank similar amounts of the fluid as controls after asymptotic extinction treatment. To gether, these experiments suggest that a taste that is either sweet or pref erred is required in order to demonstrate the chronic decrease in fluid con sumption after extinction treatment. The data suggest that the conditioning experience prevents the later development of a preference for the sweet ta ste, rather than there being a retained aversion that suppresses fluid cons umption.