Taste aversions conditioned by the aversiveness of insulin and formalin: Role of CS specificity.

Abstract

Experimenters in the past have reported that when insulin is used as the unconditioned stimulus (US), rats will learn an aversion to a sodium chloride but not a sucrose solution, whereas with formalin as the US, they will learn an aversion to a sucrose but not a saline solution. The present experiments failed to confirm these findings. Aversions to sucrose were conditioned with insulin and aversions to sodium chloride were conditioned with formalin. The use of a more concentrated sucrose solution in the present study may have been responsible for the successful sucrose-aversion conditioning with insulin. Although the source of the discrepancy in findings concerning aversion conditioning with formalin remains unclear, experiments ruled out numerous possibilities. These experiments also showed that sodium chloride aversion conditioning with formalin is a highly robust phenomenon that occurs with a variety of conditioned stimulus durations and formalin doses, with distributed and massed training, in male and female rats, and even if saline is not the only novel solution presented during conditioning. Furthermore, the aversion can be detected with both single-stimulus and choice test procedures.

Taste aversion and the generality of the laws of learning.

“…On the other hand, when sucrose is employed as the CS the opposite results are obtained. Domjan and Levy (1977) pointed out the possible evolutionary basis of this behavior: Animals low in blood sugar are unlikely to become ill while consuming sucrose, nor while con-suming saline when they are low in salt. In keeping with these findings, Frumkin (1975) was unable to train adrenalectomized (adrenalectomy causes a decrease in body sodium) rats to avoid sodium chloride or to train parathyroidectomized (parathyroidectomy causes a decrease in body calcium) rats to avoid calcium lactate.…”

Effects of CS amount on conditioned taste aversion at different CS-US intervals

“…The failure to find greater aversion with greater CS contact at the 30-min interval is not entirely unexpected, in that in some other experiments the phenomenon did not emerge or was found to be highly parameterdependent (cf. Barker, 1976;Domjan & Levy, 1977;Smith & Morris, 1963). Presumably, a different choice of CS and US intensity parameters (cf.…”

Food aversion learning based on voluntary running in non-deprived rats: a technique for establishing aversive conditioning with minimized discomfort

“…In the conventional CTA paradigm for laboratory rats, a target taste solution is paired with gastrointestinal discomfort induced by radiation exposure [29] or injection of emetic drugs such as lithium chloride [48] and cyclophosphamide [23]. Other effective procedures involve such things as high-speed rotation [31], high ambient room temperature [11], magnetic field [35], electric shock [39], tumor implantation [10], thiamine deficiency [64], histidine-free amino acid load [14], and injections of a variety of drugs such as apomorphine [72], ethanol [24], methyl mercury [16], insulin and formalin [22], psychoactive drugs [9], and so on (see Riley and Freeman [63] for a database). All of these treatments are coercive, and many of them are highly aversive for rats.…”