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1.
Rats were successively exposed to three solutions with distinctively different flavors and then tested for both neophobia and propensity to form conditioned taste aversions to a fourth distinctively flavored solution. All permutations between the four solutions (salty, bitter, sweet, and sour) were examined. The prior exposures resulted in attenuation of neophobia to novel salty and sour solutions, but not to equally novel bitter or sweet solutions. These effects were found to depend upon thediversity of the prior ingestive events rather than upon either a single specific flavor experience or a summation of the reductions in generalized neophobia accrued by each substance separately; both of the latter findings are inconsistent with stimulus generalization being responsible for the observed attenuation of neophobia to salty and sour solutions following exposure to diverse different solutions. A further test of generalization between the salty and bitter solutions, consisting of associating one flavor with poison and extinguishing the avoidance response in half the animals prior to testing for generalization of conditioned taste aversion to the other flavor, also proved negative. Although these effects of exposure to flavors distinctly different from the test solution may be dependent upon solution concentrations, further research found that the same pretest exposures and same test concentrations failed to inhibit formation of conditioned taste aversions. A demonstration of “latent inhibition” attested to the sensitivity of our procedure to potential interference with acquisition of conditioned taste aversions. The results are considered in light of the relationship between neophobia and conditioned tasted aversions, the differential biological relevancy of specific tastes, and abstraction as a cognitive capability of rats. The possibility is raised that the defense against toxins is not the primary function of neophobia. 相似文献
2.
Three experiments were conducted to determine the effectiveness of intravenous (IV) flavor injections in the formation of conditioned taste aversions and in the attenuation of neophobia. In Experiment 1, two groups of rats were permitted to drink either a .1% saccharin solution or tap water followed immediately by IV injections of lithium chloride (LiCl), and two more groups were given IV injections of a 2% saccharin solution followed immediately by IV injections of either LiCl or distilled water. Injected flavor did not serve as an effective CS for the conditioning of an aversion to .1% saccharin. The second experiment employed a two-bottle procedure to detect attenuation of neophobia using the injected-flavor technique. It was found that, whether saccharin had been injected intravenously (2%), injected intraperitoneally (2% IP), or orally consumed (.1%), neophobia for .5% saccharin was attenuated equally relative to controls. CS-US intervals were manipulated in the final experiment such that IP injections of 2% saccharin solution were followed 0–480 min later by IP injections of LiCl. In this case, it was shown that injected flavor (2% saccharin) could act as an effective CS if the US was delayed (optimally about 120 min) and when the test solution was .1% saccharin. The delay gradient found in Experiment 3 was interpreted as a generalization gradient where optimum conditioning was displayed at the point where the concentration of saccharin circulating in the animal at the time of illness onset most closely matched the concentration of the test solution. 相似文献
3.
Hooded Lister rats exhibited less neophobia towards (i.e., drank more of) a novel fluid (3% lemon or 5% sucrose) on a 10-min test if given a 6-min exposure to that fluid 6 h earlier. Presentation of a distractor (1.26% coffee) immediately after preexposure to the test solution enhanced neophobia habituation to lemon (Experiment 1), but disrupted habituation to sucrose (Experiment 3). This bidirectional distractor effect was not due to distractor-induced change in the hedonic value of the preexposed test flavor (Experiment 4). Evidence was obtained (Experiment 5) indicating that the rat perceives lemon to be more similar to coffee than is sucrose. It is suggested that when test flavor and distractor are dissimilar, processing of the distractor denies the preexposed test flavor sufficient processing in STM to allow encoding of information about that flavor in LTM. Consequently, the rat responds to a subsequent presentation of the test flavor as it would to a novel stimulus. When test flavor and distractor are similar, however, the distractor elicits less processing in STM (cf. Wagner, 1976) and is therefore less able to disrupt STM processing of the preexposed test flavor. The resultant loss of neophobia to the test flavor resulting from encoding of information about that flavor in LTM may then be augmented by generalization of attenuated neophobia to the distractor. Consistent with this analysis, coffee was shown to suffer more proactive interference when preceded by lemon than when preceded by sucrose (Experiment 6). 相似文献
4.
The effect of a retention interval on latent inhibition was studied in three experiments by using rats and the conditioned taste-aversion procedure. In Experiment 1, we demonstrated an apparent loss of latent inhibition (i.e., a strengthening of the aversion) in preexposed subjects that experienced a retention interval of 12 days between conditioning and the test. In Experiment 2, we found no effect of this retention interval on the habituation of neophobia produced by the phase of exposure to the flavor. In Experiment 3, we showed that interposing a retention interval between preexposure and conditioning produced effects exactly comparable to those seen in Experiment 1. The implications of these results for rival theories of latent inhibition, as an acquisition deficit or as a case of interference at retrieval, are discussed. 相似文献
5.
M. A. Ungless 《Learning & behavior》1998,26(1):15-19
Following brief pairing of an odor with a feeding experience (food-attraction conditioning), snails will lower their tentacles when subsequently presented with that odor alone. Three experiments investigated the possible behavioral mechanism mediating food-attraction conditioning in the snailHelix aspersa. It is suggested that food-attraction conditioning is an example of Pavlovian conditioning. In this case, the odor (conditioned stimulus) is paired with oral stimulation (unconditioned stimulus), which elicits lowering of the tentacles (unconditioned response). Following conditioning, the odor comes to elicit lowering of the tentacles (conditioned response). Experiment 1 ruled out nonassociative effects, such as habituation and sensitization, using an unpaired control group. Experiment 2 provided further evidence against a role for habituation of neophobia, through the demonstration of extinction following conditioning. In Experiment 3, an omission procedure was used to rule out the possible role of instrumental contingencies. 相似文献
6.
Rick Richardson Tania Q. Duffield Glynis K. Bailey R. Frederick Westbrook 《Learning & behavior》1999,27(4):399-415
Rats were shocked in the black but not the white compartment of a shuttlebox and then exposed to the black compartment in the absence of the shock unconditioned stimulus (US) to extinguish fear responses (passive avoidance). In five experiments, rats were then shocked in a reinstatement context (distinctively different from the shuttlebox) to determine the conditions that reinstate extinguished fear responding to the black compartment. Rats shocked immediately upon exposure to the reinstatement chamber failed to show either reinstatement of avoidance of the black compartment or fear responses (freezing) when tested in the reinstatement chamber. In contrast, rats shocked 30 sec after exposure to the reinstatement chamber exhibited both reinstatement of avoidance of the black compartment and freezing responses in the reinstatement chamber (Experiment 1). Rats shocked after 30 sec of exposure to the reinstatement chamber but then exposed to that chamber in the absence of shock failed to exhibit reinstatement of the avoidance response and did not freeze when tested in the reinstatement chamber (Experiment 2). Rats exposed to a signaled shock in the reinstatement chamber and then exposed to that chamber in the absence of shock also failed to exhibit reinstatement of the avoidance response (Experiment 5). These rats showed fear responses to the signal but not to the reinstatement chamber. Finally, rats exposed for some time (20 min) to the reinstatement chamber before shock exhibited reinstatement of the avoidance response but failed to freeze when tested in the reinstatement chamber (Experiments 3 and 4). These results are discussed in terms of the contextual conditioning (Bouton, 1994) and the US representation (Rescorla, 1979) accounts of postextinction reinstatement. 相似文献
7.
In two experiments, rats (n = 228) received pretraining access to a distinctive novel flavor (saline) followed by aversion conditioning to a different novel conditioned stimulus (CS) (saccharin). Then the rats were tested for aversion to the CS (saccharin) or for conditioning-enhanced neophobia to a third novel flavor (casein hydrolysate). Pretraining access to a distinctive novel flavor that differed from the CS reliably reduced the magnitude of conditioning-enhanced neophobia to casein, but did not reliably affect conditioned aversion effects to the CS. Pretraining access to the CS reduced aversion effects to the CS and reduced postconditioning neophobia to casein to the performance level shown by ingestion-toxin controls. Results were consistent with the view (Braveman & Jarvis, 1978) that conditioned aversion and neophobia may be independent phenomena with separable underlying mechanisms. 相似文献
8.
The present research examined the temporal distribution of responding in a lick suppression paradigm. In Experiment 1, rats were trained with either a 30- or a 120-s conditioned stimulus (CS), which was followed either by a footshock (unconditioned
stimulus [US]) or nothing. Licking during the CS was suppressed only in the former condition. Suppression was more pronounced
early in the CS. In Experiment 2, rats were exposed to two 30-s or two 120-s CSs, with delivery of the shock being contingent on CS1 for half of the animals
and on CS2 for the other half. For both the paired and the unpaired conditions, suppression at the beginning of CS1 was observed
for all the groups. By discounting the possibility of generalization between CS1 and CS2, it appears that this initial suppression
was not a conditioned response to the CS, but an unconditioned one due to mere exposure to the shock US. 相似文献
9.
Four experiments examined the effects of separate presentations of shock on conditioned suppression of instrumental responding evoked by a CS previously paired with shock. Experiment 1 showed that conditioned suppression of responding resulting from noise-shock pairings increased as a function of time after the initial noise-shock pairings. However, it also showed that this time-dependent increase in conditioned suppression of responding could be attenuated by presentations of light-shock pairings immediately prior to the test of the noise CS. Experiment 2 showed that this attenuation effect can be produced by presentations of either light-shock pairings or shock alone. Experiment 3 showed that the magnitude of this attenuation effect was directly related to the temporal proximity of the light-shock pairings to the test of the noise CS. Experiment 4 showed that the magnitude of this attenuation effect was inversely related to the intensity of separate shock presentations. 相似文献
10.
Robert J. Robbins 《Learning & behavior》1980,8(4):534-542
An investigation was made of the occurrence of learned and nonlearned aversions in the acquisition of illness-induced taste aversions in mice of the genusPeromyscus. It was determined: (1) that illness following the ingestion of a novel flavor both produced aversions specific to that flavor and also enhanced neophobia directed toward novel flavors in general; (2) that the specific aversion and the enhanced neophobia appeared to be mediated by independent processes, with no indication that the enhanced neophobia was dependent upon the integrity of the specific aversion; and (3) that illness following the ingestion of familiar water produced enhanced neophobia, which did not appear to be mediated by an aversion to water. It was noted that the results were fundamentally in agreement with those previously obtained with laboratory rats, except that a demonstration of the independence between the two types of aversions has not yet been reported in those animals. 相似文献
11.
Thirsty Sprague-Dawley rats drank flavored water in a wind tunnel prior to lithium-induced toxicosis. Flavors were presented for 5 min; 30 min later a toxin, lithium chloride, was injected. After the rats had recovered, subsequent aversions to the taste and the odor were assessed separately. In Experiment 1, extensive preexposure to the taste component of the flavor attenuated neophobia to the flavor and the subsequent taste aversion. However, the subsequent odor aversion was unaffected. Experiment 2 partially replicated the results of Experiment 1 and showed that, in a situation in which only taste-potentiated odor aversions are usually found, nonpotentiated aversions were evident. Experiment 3 found that, in addition to attenuating taste aversions, taste preexposure enhances the capacity of rats to learn nonpotentiated odor aversions. The results are interpreted with a neural-based model of conditioned flavor aversions. 相似文献
12.
Joseph R. Troisi Philip J. Bersh Michael F. Stromberg Benjamin C. Mauro Wayne G. Whitehouse 《Learning & behavior》1991,19(1):88-94
Two experiments investigated the effectiveness of multiple (five) sessions of signaled eseapable-shock pretraining in preventing (immunizing against) the shack-escape impairment produced by an equal number of sessions of signaled inescapable shock. In Experiment 1, rats were exposed to 50 pairings per session of a white-noise stimulus with escapable shock during the immunization phase. Subsequently, they were exposed to 50 pairings per session of a different (houselight) stimulus with inescapable shock. Shock-escape performance in a shuttlebox test with constant illumination revealed no evidence of immunization relative to the performance of rats given five prior sessions of light-signaled inescapable shock only. Experiment 2 was identical in all respects to Experiment 1, except that both the escapable- and the inescapable-shock phases for animals in the immunization treatment group involved the same stimulus (houseüght) as a shock signal. Under these circumstances, the prior escapable-shock training significantly reduced the shuttle-box escape deficit engendered by chronic exposure to signaled inescapable shock; performance in the shuttle-box was not reliably different from that of rats exposed to signaled escapable shock alone. These findings suggest that, under chronic conditions, the development of stimulus control using Pavlovian conditioning procedures may serve to modulate the normally prophylactic influence on later shock-escape acquisition of serial exposure to escapable and inescapable shocks. 相似文献
13.
Rats shifted from 32% sucrose to 4% sucrose lick less than rats that experience oniy the 4% solution. Previous experiments have found this negative contrast effect to be reduced (“disinhibited”) by the addition of a novel tone in the postshift period. In Experiment 1 of this paper, the negative contrast effect was enhanced when a novel flavor was added to the sucrose solution in the postshift period. In Experiments 2–4, changes in the ambient context, even changes sufficient to produce disruptions in licking, did not alter the degree of negative contrast. Tiese results suggest that (1) rats compare rewards across substantially different contexts, (2) contrast may serve to enhance taste neophobia, and (3) a disinhibitory effect may be confined to the presentation of punctate, nontaste, novel stimuli within a familiar context. 相似文献
14.
Rats injected with lithium chloride after ingesting familiar food pellets presented in textured metal sleeves learned aversions to the sleeved food. In a choice between sleeved and unsleeved food, the aversions were evident following conditioning with toxicosis delayed as long as 120 min after exposure to the sleeved food (Experiment 1). Texture-specific aversions resulted from procedures in which rats were exposed to food in both rough- and smooth-textured sleeves but were injected with lithium only in conjunction with one of the textures (Experiments 2–4). This differential aversion learning occurred when lithium treatment was delayed 30 min after exposure to the sleeved food (Experiments 3 and 4) and was equally evident in rats conditioned and tested in total darkness or in normal room-level illumination (Experiment 4). However, differential texture aversion learning was not observed with 90- or 300-min delayed toxicosis (Experiment 3). The present experiments highlight the importance of tactile cues in the poison-avoidance learning of species that handle their food during the course of ingestion. 相似文献
15.
Pentobarbital is self-administered by rats but has also been reported to produce a conditioned place aversion. Since the self-administration and place preference paradigms both are considered to assess drug reward, we further examined the hedonic properties of pentobarbital, using place conditioning. In Experiment 1, a dose of 15 mg/kg (intraperitoneal) of pentobarbital produced a conditioned place aversion after 4 conditioning trials of various durations (5, 15, 30, or 60 min). Since rats are typically drug experienced in the self-administration paradigm, in Experiments 2 and 3, we examined the effect of drug history on pentobarbital-induced place conditioning. Although preexposure to pentobarbital attenuated the place aversion, it never resulted in a place preference. As has been reported with alcohol, pentobarbital is hedonically aversive in rats, when novel. 相似文献
16.
Whereas rats exposed to a series of progressively decreasing shock durations show deficits in shuttle-escape performance 24 h later, the same number and intensity of shocks in the reverse (increasing) order of durations does not produce the “learned helplessness” effect (Balleine & Job, 1991). We conducted two experiments to establish the generality of this shock-duration order effect on other measures of distress and helplessness in rats. In Experiment 1, rats exposed to decreasing durations of inescapable shock showed reduced consumption of quinine-adulterated water (finickiness), whereas increasing durations produced no finickiness. By contrast, increasing shock durations produced greater conditioned fear to the shock context than did decreasing shock durations in Experiment 2. The differential effects of shock-duration order on finickiness and fear are explicated in terms of the specificity of fear conditioning during exposure to increasing versus decreasing series of shock duration orders. 相似文献
17.
Christopher L. Cunningham Dobrina M. Okorn Christine E. Howard 《Learning & behavior》1997,25(1):31-42
DBA/2J mice were exposed to a distinctive floor stimulus (CS+) and ethanol (2 g/kg) in a place conditioning paradigm. A different floor stimulus (CS?) was presented with saline. Mice injected just before or 30 min before CS exposure (Groups 0, ?30) showed conditioned place preference, whereas mice injected right after exposure to the CS (Group 5) displayed place aversion (Experiment 1). None of the other groups (?120, ?60, 15, 60) showed place conditioning. Handling and saline injection given just before or after CS exposure were unable to produce place conditioning (Experiment 2). However, there was a positive relationship between ethanol concentration (10% vs. 20%) and test performance, suggesting that peritoneal irritation influences place conditioning (Experiment 3). Overall, these findings support the suggestion that intraperitoneal injection of ethanol produces an initial short-duration aversive effect that is followed by a longer lasting positive motivational effect. 相似文献
18.
In Experiments 1 and 2, rats were exposed to two compound flavors, AX and BX, containing one flavor in common (X). Following this exposure phase, an aversion was conditioned to A in the experimental group by pairing its consumption with an injection of lithium, while a control group drank A without being poisoned. The effect of this treatment was to establish B as a conditioned inhibitor. In Experiment 1, experimental animals were slower than controls to condition an aversion to B when its consumption was paired with lithium (a retardation test of conditioned inhibition). In Experiment 2, B alleviated the suppression of intake of another flavor previously paired with lithium (a summation test). Experiments 3 and 4 established that these effects depended upon prolonged prior exposure to AX and BX. 相似文献
19.
In Experiment 1, four groups of male rats were given a session as an intruder in either aggressive (i.e., alpha) or nonaggressive colonies of conspecifics and later received either a 2-h exposure to the odors of the alpha colonies or an exposure-control session with the odors of a nonalpha colony. Two additional groups of rats that had been attacked and defeated by alpha residents were later given a 12-h exposure session with alpha-colony odors or nonaipha-control odors. Twenty-four h after the colony-intruder session, all subjects were given a single 6.5-mA shock from a prod with alpha-colony odors present in the bedding of the test chamber. Attacked rats that had been given exposure-control sessions showed significantly less prod burying and greater freezing than nondefeated subjects. This implies that the alpha-colony odors elicited conditioned fear. In contrast, the attacked subjects that had been given a pretest exposure session with alpha-colony odors showed significantly more prod burying and significantly less freezing. This suggests that the alpha-odor exposure resulted in the extinction of fear to these odors. Furthermore, the 12-h exposure to alpha-colony odors was found to be more effective in reducing fear-mediated responses than was the 2-h exposure. In Experiment 2, three groups of rats were exposed to a cat while they were in a protective cage; later they were given a 12-h exposure session with cat odors, a 12-h exposure-control session with no cat odors, or no exposure treatment. Compared with the two control groups, the subjects that were exposed to cat odors showed less freezing during subsequent prod-shock tests in the presence of cat odors, but they did not show prod burying. The reported changes in fear-mediated reactions to the odors of conspecifics and a predator are discussed in terms of both associative and nonassociative processes. 相似文献
20.
The effect of food deprivation level at the time of initial exposure to a subsequent food reinforcer was investigated in two experiments. In Experiment 1, deprivation at the time of initial exposure influenced the subsequent acquisition and extinction of an instrumental response. In Experiment 2, the residual deprivation effect associated with a reduction in deprivation level occurred only when rats initially experienced the reinforcer at a high, as compared with a low, deprivation level. Results were discussed in terms of the assumption that the limits of incentive generated by a reinforcer are influenced by the deprivation state at the time of first exposure to that reinforcer. 相似文献