Chorda tympani transection and selective desalivation differentially disrupt two-lever salt discrimination performance in rats.

Water-restricted rats were trained to press 1 of 2 levers if a sampled stimulus was NaCl and the other lever if the stimulus was KCl (0.05, 0.1, or 0.2 M). Responses were reinforced with water. After training, the average rate of correct responses was 90%. Performance was unchanged following sham surgery. Chorda tympani (CT) transection reduced average discrimination performance to 67.7% correct, and extirpation of the sublingual and submaxillary salivary glands reduced average performance to 80% correct. Although selective desalivation moderately reduced discriminability, a disrupted salivary environment does not explain the effects of CT transection. More likely, the discrimination deficit in CT-transected rats reflects a loss of critical taste input conveyed by the CT about salts.