Ralph L. Elkins

Individual Differences in Bait Shyness: Effects of Drug Dose and Measurement Technique

The conclusion that bait shyness in rats is characterized by a paucity of individual differences was reexamined through manipulation of toxic-dose magnitudes and measurement techniques. Individual differences in acquisition of a cyclophosophamide-induced aversion to saccharin flavored water were recorded even with relatively insensitive single-bottle measurement procedures. However, single-bottle extinction was quite rapid and dose independent. In contrast, sensitive 2-bottle measurement procedures revealed dose-dependent individual differences in both aversion acquisition and resistance to extinction. Results are discussed in relationship to aversion therapy treatment of alcholism.

Attenuation of drug-induced bait shyness to a palatable solution as an increasing function of its availability prior to conditioning.

Different groups of rats were familiarized with a saccharin solution for 1, 3, 10, or 20 days prior to conditioning. Saccharin ingestion was then followed by intraperitoneal cyclophosphamide injection. Control S s consumed saccharin as a novel flavor and were similarly injected with either cyclophosphamide or isotonic saline. As revealed by extended extinction tests, the strength of resultant saccharin aversions was inversely related to preconditioning saccharin familiarity. One day of saccharin preexposure failed to influence initial aversion magnitude, but resulted in an increased rate of extinction. Contrastingly, 20 days of flavor preexposure completely blocked aversion formation, while intermediate preexposures resulted in orderly and graded degrees of aversion attenuation.

Bait-shyness acquisition and resistance to extinction as functions of US exposure prior to conditioning

Cyclophosphamide-induced aversions to saccharin-flavored tap water were observed in normal control rats, in rats subjected to varying numbers of cyclophosphamide injections prior to conditioning, and in rats similarly subjected to preconditioning saline injections. Both initial magnitude and resistance to extinction of a conditioned flavor aversion were found to be inverse functions of preconditioning familiarity with drug-induced illness. Six preconditioning cyclophosphamide injections markedly reduced both initial aversion magnitude and resistance to extinction. In contrast, three such injections failed to affect initial aversion magnitude and resulted in a small acceleration of extinction rate, while one preconditioning cyclophosphamide injection produced no observable effects. These findings depict preconditioning familiarity with illness as one important variable modulating the strength of conditioned flavor aversions and emphasize the importance of viewing resistance to extinction as one indicator of aversion strength.

Rotation-induced taste aversions in strains of rats selectively bred for strong or weak acquisition of drug-induced taste aversions

Sprague-Dawley-derived rats have been selectively bred as strong or weak learners of a cyclophosphamide-induced saccharin aversion. Resultant aversion acquisition appears to be under strong genetic control, but specific mechanisms of strain differentiation remain to be determined. Current research involves possible generality of strain separation across different modes of aversion induction. Naive offspring of strong and weak-conditioner parents of the F-6 selected generation were used to pair the normal CS saccharin solution with two different magnitudes of an alternate mode of aversion induction, rotational stimulation. Six minutes of intermittent rotation produced no evidence of conditioned aversions within either strain, and equivalent results were obtained from weak conditioners exposed to 10 min of rotation. However, strong conditioners exposed to 10 min of rotation acquired significant aversions, thereby demonstrating that strain separation is not simply a function of differential sensitivity to cyclophosphamide, the US basis of genetic selection.

Aversion Therapy for Alcoholism: Chemical, Electrical, or Verbal Imaginary?

Aversion therapy approaches to alcoholism treatment and related experiments using nonhuman subjects have been critically reviewed. The traditional goal of such aversion therapy has been the induction of total abstinence through the development of conditioned aversions to alcoholic beverages. Toward this end, alcohol has been paired with a variety of aversive stimuli including chemically-induced illness, painful faradic stimulation, and drug-induced respiratory arrest. In addition to these abstinence-oriented efforts, recent innovations have rejected total abstinence as a necessary goal for all alcoholics and have attempted to convert alcoholics into controlled drinkers. The status of abstinence-oriented treatments will be summarized first and consideration will then be given to controlled drinking approaches.Historically, aversion therapy for alcoholism has emphasized the pairing of alcohol with chemically-induced nausea or emesis. Results of some such attempts were encouraging, but rigorous experimental ...

An appraisal of chemical aversion (emetic therapy) approaches to alcoholism treatment

More than 35,000 alcoholics have received chemical aversion (emetic therapy) in at least 75 settings worldwide since the 1930s. This consummatory aversion (CA) treatment, which pairs ethanol ingestion with emetically induced nausea, incorporates the highly efficient variety of learning known as taste aversion (TA) conditioning. The CA literature indicates that emetic therapy should induce conditioned alcohol aversions in many alcoholics. Such aversions have been widely reported by clinicians and have been confirmed by recent psychophysiological evidence. Long standing evidence of treatment effectiveness is found in the results of private hospitals which have consistently produced 1-yr abstinence rates approximating 60%. Diminished alcohol craving is a frequently reported benefit. Few experimental evaluations have been completed, as is generally the case for all alcoholism treatments, but those which used methodologically sound temporal parameters during conditioning have supported the clinical efficacy of emetic therapy. The clear need for more definitive research notwithstanding, there are compelling indications that emetic therapy is a useful component of multimodal treatment within certain alcoholic populations. However, its availability is severely limited. Many alcoholics could probably benefit from expanded treatment availability. The time is ripe for a reevaluation of resistances to the clinical use of emetic therapy alcoholism treatment.

Taste aversion and passive avoidance in rats with hippocampal lesions

Rats with near total hippocampal lesions were compared with cortical and normal control animals on taste aversion and passive avoidance conditioning. While the initial magnitude of the taste aversion induced through illness was not significantly affected by hippocampal ablation, the aversion did extinguish more rapidly in experimental animals. Locomotor passive avoidance was significantly impaired by the lesion.

Taste aversion proneness: A modulator of conditioned consummatory aversions in rats

Sprague-Dawley-derived rats were sequentially conditioned to avoid both anise- and saccharin-flavored solutions with counterbalanced orders of flavor exposures prior to cyclophosphamide-induced illness. The amounts of saccharin and anise solutions consumed during separate postconditioning single-bottle tests were correlated to determine if aversion strength was consistent across flavors. The saccharin-anise sequence revealed a positive and significant correlation, supporting the hypothesis that conditioned flavor aversions are modulated by some intrasubject factor or factors, a tendency designated as taste aversion proneness. However, a correlational coefficient of marginal significance was obtained from the anise-saccharin sequence, leaving unanswered questions concerning the salience and generality of taste aversion proneness. Despite this limitation, taste aversion proneness is viewed as having important applied implications for aversion therapy approaches to the treatment of human alcoholism.

Forgetting, preconditioning CS familiarization and taste aversion learning: An animal experiment with implications for alcoholism treatment ☆

Abstract The rapid taste aversion acquisition, which typically occurs in many species when ingestion of a novel flavor precedes gastrointestinal distress, is retarded by preconditioning familiarity with the CS flavor. This CS familiarity effect (CSFE) might contraindicate taste aversion approaches to alcoholism treatment since alcoholics are quite accustomed to the tastes of alcoholic beverages. However, many alcoholics do develop strong nausea—induced alcohol aversions under appropriate conditioning parameters. Additionally, the CSFE is attenuated in rats by repeated conditioning trials including discrimination training. The present animal experiment was conducted to determine if the CSFE could additionally be weakened by process of forgetting, i.e. by preconditioning withdrawal of a familiar flavor analogous to an alcoholics ‘drying out’ before psychotherapeutic intervention. Using saccharin as the CS flavor and cyclophosphamide as the conditioning agent, Sprague-Dawley derived rats acquired no aversions when conditioning was attempted immediately after flavor familiarization. However, significant and equivalent saccharin aversions were observed when conditioning was delayed for either 20 or 100 days after familiarization. These findings imply that the efficiency and cost effectiveness of taste aversion approaches to alcoholism treatment might be enhanced by a pretreatment period of abstinence from alcohol ingestion.

Differential olfactory bulb contributions to baitshyness and place avoidance learning.

Abstract Garcia and Ervin [14] hypothesized that neuroanatomically discrete associative mechanisms subserve illness-induced taste aversions and shock-motivated avoidance of telereceptive cues. Such neuroanatomical diversity implies that appropriately placed brain lesions might selectively influence one of these types of learning. While several limbic-system lesions can disrupt shock-motivated compartment avoidance (SMCA) without modifying illness-induced taste aversion (IITA) conditioning, the opposite pattern of selective interference has not been reported. The anterior tips of the olfactory bulbs of male albino rats were removed because neuroanatomical and behavioral data indicated that these lesions might disrupt IITA without influencing SMCA. Larger olfactory-bulb ablations approximating total bulbectomies were also studied for comparison purposes. Both total bulbectomies and anterior bulbectomies partially blocked IITA acquisition. Total bulbectomies also interfered with SMCA conditioning, but this learning was unimpaired by anterior bulbectomies. These anterior-bulbectomy results are consistent with the neuroanatomical-diversity hypothesis. Present findings are also discussed relative to the applied problem of selecting biologically appropriate noxious stimuli for aversion therapy approaches to alcoholism treatment.