Acquisition and extended retention of a conditioned taste aversion in preweanling rats

The time course of memory decay for infant rats may shed light on the processes responsible for infantile amnesia. A taste aversion conditioning procedure appropriate for both neonatal and adult rats was employed in four experiments to investigate the ontogeny of extended retention. In Experiment 1, rats trained at 1, 10, 20, or 60 days of age were tested for retention of the taste aversion 25 days later. At testing, only those rats conditioned when 20 or 60 days old demonstrated significant taste aversions. Experiments 2 and 3 established that rats 14-15 days old and older were able to retain significant taste aversions following a 25-day retention interval. Younger rats did, however, acquire and retain the aversion for several days and showed a gradual retention loss over progressively longer retention intervals (Experiment 4). These findings suggest that preweanling rats demonstrate initial consolidation, storage, and retrieval of conditioned taste aversions. It is only after this initial period that retention deficits become evident.     

Role of the area postrema in three putative measures of motion sickness in the rat

After thermal cauterization of the area postrema in rats the absence of conditioned taste aversion to sucrose paired with lithium chloride (0.15 M, 3.3 ml/kg) was used as a pharmacologic/behavioral index of area postrema damage. In a subsequent experiment the effects of area postrema lesions on three measures proposed as species-relevant measures of motion sickness were studied, using off-vertical rotation at 150 degrees/s for either 30 or 90 min. Lesions of area postrema did not alter postrotational suppression of drinking or amount of defecation during motion. The initial acquisition of conditioned taste aversion to a novel cider vinegar solution paired with motion was not affected by lesioning of the area postrema, but these taste aversions extinguished more slowly in lesioned rats than in sham-operates or intact controls. Results are discussed in terms of proposed humoral factors which may induce motion sickness and in light of recent data on the role of the area postrema in similar measures in species possessing the complete emetic reflex.     

Potentiation of odor by taste in rats: tests of some nonassociative factors

The contribution of nonassociative neophobia and sensitization to the potentiation of odor by taste in rats was tested in three experiments. In Experiment 1, neophobia for almond odor (O), saccharin taste (T), and odor-taste compound (OT) cues was tested before and after noncontingent lithium chloride poisoning and compared with conditioned aversions produced by OT-LiCl temporal pairing. The OT compound potentiated unconditioned neophobia, but there was no evidence of poison-enhanced neophobia, disinhibition of neophobia, or sensitization by noncontingent LiCl; temporal pairing produced aversions for the compound and its elements. In Experiment 2, generalization to a novel odor was tested after O-LiCl or compound OT-LiCl pairing. The potentiated odor aversion did not generalize to the novel odor; it was specific to the odor paired with taste and LiCl. In Experiment 3, potentiation of the odor component by a discriminant or nondiscriminant taste component was tested. Potentiation was evident only when a novel discriminant taste was in compound with odor prior to LiCl poisoning. These studies support an associative "indexing" hypothesis of the potentiation effect in rats.     

Developmental flavor experience affects utilization of odor, not taste in toxiphobic conditioning

Feeding experiences were varied in developing rats and the effects upon flavor neophobia and lithium chloride-induced flavor aversions were observed. In Experiment 1, nursing experience of neonate rats was reduced by artificial feeding via intragastric cannula; the rats then were tested with apple juice paired with lithium chloride injection at weaning or maturity. Conditioned aversions were not affected, but neophobia to novel apple juice was attenuated in artificially-reared rats tested at maturity. In Experiment 2, rats received enriched feeding experience after weaning, which consisted of (a) obtaining many complex flavors, a few of which were paired with poisoning, effortlessly in the home cage, or (b) foraging for various foods on an elevated maze. No dramatic effects on neophobia or conditioned taste aversion for saccharin water were apparent. In Experiment 3, rats were given experience after weaning with vanilla-scented water either paired or unpaired with quinine water, and then tested with the odor of almond or that odor compounded with saccharin water for neophobia and lithium-induced aversions. Flavor-experienced rats exhibited more pronounced odor conditioning and more resistance to extinction of the odor aversion after both simple and compound conditioning. In contrast, saccharin taste aversions were relatively unchanged. Apparently, enriched feeding and drinking experience facilitates the utilization of odor more than taste cues.     

Conditioned taste aversion in humans using motion-induced sickness as the US

The purpose of the experiment was to demonstrate conditioned taste aversion (CTA) and latent inhibition (LI) of CTA in humans using rotation-induced motion sickness as the unconditioned stimulus. To accomplish this, flavour familiarity (familiar vs unfamiliar) and rotation (rotation vs no rotation) were manipulated in a 2 X 2 factorial design. Subjects consumed either a familiarly flavoured carbonated beverage or a novel one after which half of each group was rotated or not rotated. Two hours later the subjects were re-presented with the flavoured drink that they had previously drunk. The groups receiving rotation consumed less of the drink that the non-rotated groups, thus demonstrating CTA. The rotated group pre-exposed to the novel flavoured drink consumed less than the rotated group pre-exposed to the familiar drink, thus demonstrating LI. The effectiveness of the rotation procedure in producing motion sickness was confirmed by self-reports of general feelings and by symptom rating scales. In addition, it was found that, at the time of consuming the test drink the rotation groups' motion-sickness symptom scores were reduced to the level of the nonrotated groups. Applications of these data to the prophylactic treatment of chemotherapy-induced food aversions were discussed.     

味觉厌恶性条件反射与条件反射性免疫抑制的研究

以环磷酰胺的注射为非条件刺激（ＵＣＳ）,糖精水的摄入为条件刺激（ＣＳ）,并以血白细胞和淋巴细胞数量及脾淋巴细胞的转化反应为免疫指标,糖精水的饮用量为行为指标,通过改变条件刺激与非条件刺激结合的次数来观察条件反射性厌恶行为与条件反射性免疫抑制的反应。结果表明不管是一次性的还是两次性的ＣＳ－ＵＣＳ结合训练都能使动物明显地建立起味觉厌恶性条件反射,然而条件反射性免疫抑制只在两次性ＣＳ－ＵＣＳ结合训练后才     

ACTH and ACTH4-10 modification of neophobia and taste aversion responses in the rat.

A series of experiments assessed the effects of ACTH and the ACTH analogue ACTH4-10 on drinking in conditioned taste aversion and neophobic situations. Both substances delayed the extinction of a conditioned taste aversion established by a single pairing of lithium chloride with milk (Experiment 1). However, in this situation, the ACTH parent peptide was more potent behaviorally. Administration of ACTH suppressed milk consumption in animals with no toxicosis experience (Experiment 2). This effect was apparently not due to the conditioning of a taste aversion (Experiment 3) with ACTH serving as a weak aversive unconditioned stimulus. Administration of exogenous ACTH (Experiment 4) or ACTH4-10 (Experiment 5) did not enhance neophobia; however, repeated injections of ACTH suppressed drinking. This ACTH suppression was related to the familiarity/novelty of the subtance being consumed. The neophobic response to milk eas no accompanied by pituitary-adrenal activation (Experiment 6). Both neophobic and conditioned taste aversion situation appear to be useful for assessing peptide effects on consummatory behavior.     

The acquisition of taste aversions in humans with eating and drinking disorders

A written questionnaire or interview concerned with acquisition of illness-induced (taste) aversions to foods and drinks was given to three groups of people with eating and drinking disorders. These groups consisted of 101 male and 1 female hospitalized alcoholics, 8 male and 8 female college-student heavy consumers of alcohol and 18 females with anorexia nervosa and/or bulimia. In most respects taste-aversion acquisition in these three groups was similar to taste-aversion acquisition in a general college-student population previously studied by Logue, Ophir and Strauss (1981), and to taste-aversion acquisition in other species. In all three groups the aversions were more likely to be reported as having been formed through forward rather than simultaneous or backward conditioning, and long-delay learning was frequent. The aversions usually formed to the tastes rather than to the appearance or other aspects of the foods and drinks. Extinction appeared more effective in decreasing the aversions than did forgetting. While the illness responsible for the aversions forming was usually attributed to the subsequently aversive food or drink, in at least one third of the cases subjects reported that something else might have caused their illness. Aversions were more likely to have formed to relatively less familiar and less preferred foods and drinks. However, the hospitalized alcoholics reported fewer aversions, less generalization of aversions, and stronger nausea as the cause of the aversions than did Logue et al.'s (1981) subjects. About 15% of these subjects reported taste aversions to alcoholic beverages. The college-student heavy consumers of alcohol reported no generalization of their taste aversions, but in other respects were similar to Logue et al.'s subjects. Thirty-one percent of these subjects reported taste aversions to alcoholic beverages. The anorexic and bulimic subjects were also similar to Logue et al.'s subjects with the exception that they, like the hospitalized alcoholics, reported stronger nausea as the cause of the aversions. These data may help to understand and treat people with eating and drinking disorders     

Flavor preexposures in a conditioned taste aversion situation: a dissociation of behavioral and endocrine effects in rats

A series of experiments examined the effects of flavor preexposures on pituitary-adrenal/behavior relations in a conditioned taste aversion paradigm. It was found that reexposure to a novel milk solution paired earlier with lithium chloride (LiCl) elicited conditioned activation of the pituitary-adrenal system (Experiment 1). The unconditioned response to LiCl (measured by changes in plasma levels of corticosterone) did not vary as a function of prior (2 and 5 vs. 10) exposures to the milk solution (Experiment 2). Increased familiarity with the substance (resulting from 10 prior exposures) rendered the conditioning of a taste aversion to this substance less effective. Further, reexposure to this familiar substance after its pairing with LiCl was not accompanied by the characteristic conditioned pituitary-adrenal activation (Experiment 3). By titrating the number of conditioned stimulus (CS) preexposures (Experiment 4) it was found that within the range of preexposures manipulated (5-10), subjects exhibited (a) a coupling of behavioral and pituitary-adrenocortical responses when the conditioned taste aversion to the milk solution was paralleled by elevated plasma corticosterone (5-6 preexposures), (b) a coupling of these two response systems when flavor consumption was accompanied by suppressed plasma titers of corticoids (9-10 preexposures), or (c) a dissociation of the two system when the conditioned taste aversion was not accompanied by conditioned adrenocortical activity (7-8 preexposures). These data are discussed in terms of a dissociation in the effects of CS preexposures on conditioned adrenocortical and behavioral response systems.     

The influence of flavor preexposure and test interval on conditioned taste aversions in the rat

The effects of flavor preexposure and test interval on conditioned taste aversions were examined in four experiments. In the first three experiments, prior experience with a flavor different from that used as a conditioned-stimulus (CS) produced attenuated aversions when testing occurred after a 1-day interval but not after a 21-day interval. Preexposure to the same stimulus used as a CS produced attenuated aversions at both 1- and 21-day intervals. In Experiment 4, a delay interval between flavor preexposure and conditioning eliminated the attenuating effect of preexposure, but only when different stimuli were used for preexposure and conditioning. These data could not be easily accounted for by contemporary interpretations of preexposure as an event that interferes with subsequent acquisition of a conditioned aversion. An alternative retrieval interference hypothesis was outlined.     

Time of day-dependent latent inhibition of conditioned taste aversions in rats

We have determined that the temporal context of drinking can modulate latent inhibition of learned saline aversions in Wistar rats by changing the time of day of drinking of the preexposure and conditioning phases. Latent inhibition was absent in the group preexposed and conditioned to saline at different times of the day, but not in the group that was preexposed and conditioned at the same time of day. The results confirm a previous report that the time of day can modulate taste aversion learning independently of other environmental cues. It is proposed that the features and duration of the habituation training to the temporal contexts used may be critical for time-dependent latent inhibition to appear.     

Susceptibility to motion sickness induced by optokinetic rotation and self-rotation by walking around a vertical pole.

31 subjects viewed an optokinetic rotating drum for 12 min. in one session and self-rotated by walking quickly around a vertical pole with eyes closed while alternately flexing and extending the neck in another session. The self-rotation session contained 6 trials (3 clockwise and 3 counterclockwise rotations). Each trial contained 20 cycles of self-rotations. Self-reported ratings of nausea and symptoms of motion sickness were obtained for each session. The subjects developed symptoms of nausea, sweating, dizziness, headache, drowsiness, and changes in salivation in both drum rotation and self-rotation sessions. However, the subjects reported higher ratings of nausea in the session of optokinetic rotation than in the session of self-rotation around a vertical pole. These results indicated that both optokinetic rotation and self-rotation with eyes closed while alternately flexing and extending the neck are effective means of inducing nausea and motion sickness.     

Is blockade of conditioned flavor aversions by chlorpheniramine the result of state dependency?

Conditioned flavor aversions induced by pairing flavored fluids with ionizing irradiation, lithium chloride, estrogen, or centrifugal rotation have been blocked by prior administration of chlorpheniramine. The blockade may be due to state dependency. This possibility was evaluated in the present experiment, which assigned female Long-Evans rats to a factorial combination of chlorpheniramine (20 mg/kg) vs saline during training, centrifugal rotation (150 rpm for 15 min) vs none as an UCS, and chlorpheniramine vs saline in testing. Rats conditioned with saline and rotation showed strong aversions when tested with either same or chlorpheniramine. Rats conditioned with chlorpheniramine and rotation showed no change during conditioning; when tested with saline they showed no aversion, and when tested with chlorpheniramine they showed no change from conditioning. Rats conditioned with either chlorpheniramine or saline and no rotation showed high fluid intake when tested with saline and reduced fluid intake when tested with chlorpheniramine. The results were interpreted as offering little support for state dependency.     

The acquisition of taste aversions in humans

A written questionnaire or an interview was given to 517 undergraduates concerning their acquisition of illness-induced (taste) aversions to foods and drinks. The subjects reported 415 aversions, with 65% of the subjects reporting at least one aversion. The aversions were more likely to be reported as having been formed through forward rather than simultaneous or backward conditioning, and long-delay learning was frequent. The aversions usually formed to the taste of the foods, rather than the appearance or other aspects of the foods. Extinction appeared more effective in decreasing the aversions than did forgetting. The illness responsible for the aversion's forming was usually attributed to the subsequently aversive food, but for 21% of the reported aversions subjects were sure that something else had caused their illness. Aversions were more likely to have formed to relatively less familiar and less preferred foods. Aversions were also more likely to form between the ages of 13 and 20. Generalization of the aversions to similar foods occurred in 29% of the cases. Approximately one fourth of the aversions were to alcoholic beverages. Finally, instances of aversions forming without food or drink consumption and instances of observational learning were reported. The data were quite similar to laboratory taste aversion data collected using other species and can help in optimizing taste aversion treatments of eating and drinking disorders. Taste aversions among humans are frequent and strong.     

A comparison of two methods of measuring conditioned taste aversions

Two methods of measuring conditioned taste aversions were compared. Following adaptation to a daily 10-min water drinking schedule, rats were made ill with an injection of cyclophosphamide after presentation of a novel-tasting fluid. Three days after this treatment, Ss were tested by (1) measuring the amount of the novel fluid consumed on the continuing 10-min access schedule or (2) measuring their preference between plain water and the novel fluid. When the drinking behavior of the conditioned animals was compared with that of appropriate controls, the preference method proved to be the more sensitive.     

The effects of a flavour - toxicosis pairing upon long-delay, flavour aversion learning

Mackintosh (1973) has suggested that rats readily associate flavours with illnesses in cue-to-consequence studies because they have already learned that changes in internal states are unrelated to changes in external stimuli. An implication of this suggestion is that learned predispositions may also subserve the ability of rats to form long-delay, flavour-illness associations. Six experiments tested this idea by examining the strengths of aversions in a delayed flavour-toxicosis paradigm after exposure to a paired or unpaired relation between another flavour and toxicosis. Exposure to a paired relation enhanced the strengths of subsequently established flavour aversions (Experiment I). The enhanced aversions were associative in origin (Experiment II), observed with delays of 3 h and 1·5 h in, respectively, a forward (Experiment III) and backward (Experiment IV) delayed conditioning paradigm and with a 10-day interval between the flavour-toxin pairing and the delayed paradigm (Experiment V). The enhanced aversions, however, were removed by the extinction of the original flavour aversion prior to the delayed flavour-toxin pairing (Experiment VI). The results supported the idea that the ability of the rat to form long-delay, flavour-illness associations reflects an associative history involving flavours and internal changes and were discussed in terms of Mackintosh's (1975) theory of the mechanism underlying stimulus selection. The effects of a flavour-toxicosis pairing upon long-delay, flavour aversion learning.     

Classical conditioning in the leechMacrobdella Ditetra as a function of CS and UCS intensity

Classical conditioning in the leech was obtained using two levels of shock as the UCS, two levels of light as the CS; for each condition there was a CS-UCS paired and unpaired group. Analysis showed significant effects of pairing and a UCS intensity by trials interaction during acquisition. Spontaneous recovery was evident during the second day of extinction.     

Selective associations in one-day-old rats: taste-toxicosis and texture-shock aversion learning

One-day-old rats learned aversions to a novel taste paired with lithium-induced distress and to a tactile stimulus paired with brief electric shocks. However, aversions did not develop when taste was paired with shock or when the tactile stimulus was paired with lithium treatment. The aversions occurred only when lithium treatment immediately followed taste exposure and when shock was concurrent with exposure to the tactile stimulus. These findings indicate that selective associations in aversion learning are mediated by innate mechanisms that govern conditioning in the absence of extensive ontogenetic experience. The present research also shows that selective associations are sufficient for the occurrence of long-delay learning.     

Taste reactivity and consumption measures in the assessment of overshadowing: Modulation of aversive,but not ingestive,reactivity

Three dependent measures—a taste reactivity test, a two-bottle preference test, and a one-bottle extinction test—were used to investigate the conditioning effects of pairing a taste/taste compound with LiCl-induced illness in rats. Avoidance of saccharin consumption in the one-bottle test was attenuated if saccharin and denatonium were paired during illness training (overshadowing). Also, saccharin was found to be more palatable if paired with denatonium during training as reflected by aversive (but not ingestive) taste reactivity measures. It is argued that overshadowing was reflected mainly by a modulation of aversive taste reactivity behavior with little influence on ingestive taste reactivity. The results are discussed in terms of current palatability issues, and it is suggested that applying taste reactivity tests to phenomena associated with taste avoidance learning (e.g., overshadowing or potentiation) may further our understanding of the mechanisms that guide such learning.     

条件反射性免疫抑制激活过程中下丘脑核团c-fos的表达

利用经典条件反射性免疫抑制的动物模型,以糖精水为条件刺激（CS）,免疫抑制剂-环磷酰胺为非条件刺激 （UCS）,观测两次CS-UCS结合训练后,再次条件刺激诱发条件反射性免疫抑制作用的动态改变,获得条件反射性免疫抑制和味觉厌恶性条件反射各自保持的情况,并在此基础上,采用c-fos免疫组化技术, 进一步观察再次条件刺激诱发条件反射性免疫抑制反应时大鼠下丘脑各核团内FOS蛋白的表达情况。结果表明,条件反射性免疫抑制作用在训练后第5天较强,第30天基本消失,而味觉厌恶性条件反射始终稳定保持到第30天。进一步研究显示出,下丘脑室旁核FOS蛋白表达在第5天非常密集,而第30天几乎没有表达,与细胞免疫功能改变在时程和趋势上具有一致性。通过FOS蛋白表达时程差异比较,提示下丘脑室旁核可能是CNS内介导CS诱导的免疫抑制效应的重要核团。