Conditioned flavor aversion

The best investigated odor-taste interactions occur in conditioned flavor aversions. Tastes that precede a delayed food-related illness are often avoided after only one experience. Odors are not avoided under similar conditions. However, if taste and odor are presented together before the malaise, animals will avoid odor when encountered later by itself. Taste affects odor, but not vice versa. If only the taste intensity is increased, both taste and odor aversion increase. Conversely, if only the odor stimulus is increased, only the odor aversion increases (Garcia etal, 1986). 

Garda, J., Holder, M. D., and Yirmiya, R. (1986). Taste and odor interactions in conditioned flavor aversions. Appetite 7,259. 

Other animal studies have shown that acute and subacute exposure to GB can result in neurobehavioral changes in the test animals. Single intramuscular (i.m.) injections of 6 pg GB/kg to marmosets resulted in adverse behavioral effects when the animals were tested for hand-eye coordination, but no adverse effects were seen in a visual discrimation test (Wolthuis 1992). A dose of 3 pg/ kg had no adverse effects on behavior, and hand-eye coordination was improved in three of six animals (Wolthuis 1992). An intraperitoneal (i.p.) dose of 50 pg GB/kg resulted in decreases in rearing and grooming behavior and locomotive activity in male Wistar rats (Nieminen et al. 1990). A subcutaneous (s.c.) injection of 61 pg GB/kg increased spontaneous motor activity in male Sprague-Dawley rats a dose of 71 pg/kg produced conditioned flavor aversions 84 and 115 pg/kg caused significant decreases in spontaneous locomotive activity and... 

Provenza, F.D., E.A. Burritt, T.P. Clausen, J.P. Bryant, P.B. Reichardt R.A. Distel. 1990. Conditioned flavor aversion a mechanism for goats to avoid condensed tannins in black brush. Am. Nat. 136 810-828. 

Nishida N, Farmer JD, Kodavanti PRS, et al. 1997. Effects of acute and repeated exposures to Aroclor 1254 in adult rats Motor activity and flavor aversion conditioning. Fundam Appl Toxicol 40 68-74. 

Specific hungers (except for sodium himger, 21, 72) are thus viewed as arising from a conditioned food aversion process, that is, the pairing of characteristics of food (usually taste or flavor for mammals) with illness (73). The discovery of conditioned food aversions has been an important breakthrough for the understanding of diet selection by wild animals, for providing... 

Little, E. E., 1977, Conditioned aversion to amino acid flavors in the catfish, Ictalurus punctatus. Physiol. Behav., 19 743. 

Food preferences also can be learned, and, like learned aversions, conditioned preferences can be used to evaluate chemosensory abilities. Typically, preferences are induced by pairing the ingestion of a novel flavor with calories (Bolles et al. 1981 Messier White 1984 Booth 1985 Mehiel Bolles 1984, 1988 Simbayi et al. 1985), recovery from nutritional deficiency (Garcia et al. 1967 Zahorik et al. 1974), and recovery from malaise (Green Garcia 1971 Zahorik 1977 Sherman et al. 1983). The novel flavor is subsequently preferred, as are other flavors that subjects perceive as similar to the conditioned stimulus. However,... 

The approach to developing improved bird repellents can proceed along these same lines. There are numerous seeds, berries, and plants that birds normally avoid. Part of this avoidance could be due to conditioned aversion (89) or to aversive taste (93). Regardless of the physiological and behavioral mechanisms involved in the repellent effects, I believe the trend toward exploitation of natural food items as a source for developing more attractive or repellent animal food flavors will continue. 

---