c-Fos induction in response to saccharin after taste aversion learning depends on conditioning method

Increases in c-Fos-like immunoreactivity (FLI) in the intermediate nucleus of the solitary tract (iNTS) have been seen consistently as a correlate of the expression of a conditioned taste aversion (CTA) when conditioning occu rs using taste delivery through intraoral (I/O) infusions. The present stud y examined whether a similar FLI response would occur when conditioning was accomplished by presenting the taste solution in a bottle. I/O and bottle methods generated aversions that were comparable, when judged by the behavi oral response of solution rejection. However, elevations in FLI were seen o nly in animals conditioned with the I/O method. This finding adds to eviden ce that the neural pathways underlying CTA learning differ as a function of the type of conditioning method used. (C) 2000 Elsevier Science B.V. All r ights reserved.