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1.
Jon L. Williams 《Learning & behavior》1987,15(3):333-341
In Experiment 1, rats received a session of 80 inescapable tail shocks or no shocks while restrained in a tube. During tests of conditioned defensive burying 24 h later, the bedding of the chamber contained odors from either stressed or nonstressed conspecific donor rats. Following a single prod shock, subjects that had had prior shocks or that were tested with the stress odors spent significantly less time burying the prod, made smaller piles of bedding, and displayed more freezing behavior. The combination of prior shock and stress odors during later testing enhanced these effects. In Experiment 2, a yoked group of rats that was given inescapable shocks, in contrast to a group that had wheel-turn escape training and one that was restrained but not shocked, later showed significantly less burying and more freezing when tested for defensive burying with stress odors present. In both experiments the duration of burying and the heights of piles were positively correlated, and both of these measures were negatively correlated with freezing. The demonstrated capacity of unconditioned stress odors to mediate different degrees of fear, depending upon the controllability of prior shock, is related to other studies of learned helplessness, and the predominance of freezing over burying is discussed in terms of various types of defensive strategies, stimulus-control processes, and the author’s stress-coping-fear-defense (SCFD) theory. 相似文献
2.
Two strains of rats (albino Wistar and hooded PVG/c) were exposed to a conditioned defensive burying paradigm that consisted of placing rats in a test chamber with bedding material on the floor, shocking them with a shock prod, and recording the time each rat spent in burying responses toward the prod. Various behaviors other than burying (freezing, grooming/paw licking) were observed by a time-sampling procedure during the control, conditioning, and extinction sessions, each of which was 15 min in duration. Wistar rats generally showed behavioral inhibition, as evidenced by less burying, lower exploratory and ambulatory behavior, and higher freezing behavior. PVG/c rats spent significantly more time engaged in burying and accumulated more bedding material in the conditioning session than did the Wistar rats. No significant differences between the two strains of rats were observed during the extinction session in terms of these measurements. The results indicate that Wistar rats have a greater tendency to freeze when coping with the noxious stimulus in a conditioned defensive burying paradigm, whereas the dominant coping style for PVG/c rats is defensive burying. 相似文献
3.
Rats shocked once by a stationary, wire-wrapped prod bury it if suitable materials are available. Does this conditioned defensive burying occur when rats have the opportunity to flee from the source of aversive stimulation, or is it limited to situations such as those in which it had previously been studied—those in which the relatively small test chamber confined each rat to the immediate vicinity of the prod? In the present experiments, the capacity of rats to flee from the shock prod was enhanced by increasing the floor dimensions of the test chamber up to 200X80 cm (Experiment 1) or by providing the rats with an opportunity to seek refuge in a separate, safe compartment (Experiment 2). Although both of these modifications to the usual conditioned-defensive-burying paradigm significantly reduced the duration of burying and the height of the accumulated mounds, burying remained well above control levels in all experimental conditions. 相似文献
4.
Rats shocked once by a stationary, wire-wrapped prod mounted on the wall of the test chamber incorporated sand, wooden blocks, or commercial bedding material on the floor of the chamber into a defensive response. They moved the available material toward and over the shock prod in all three conditions, adapting the response topography to the particular demands of the available material. In the sand and bedding conditions, the rats buried the prod by pushing and spraying piles of the material with snout and forepaws, whereas, in the blocks condition they picked up the blocks with their teeth and placed them individually around the prod. In Experiment 2, the rats buried the shock prod with blocks even when they had to first carry the blocks to the prod from the back of the chamber. Thus, conditioned defensive burying is not a simple, reflexive response to objects paired with a painful stimulus: it is a complex behavioral sequence that can vary as a function of the availability of burying materials. 相似文献
5.
The degree of spatial and temporal contiguity between contact with a prod and shock was varied in three experiments to see how these factors contribute to defensive burying. In Experiment 1, rats shocked once through a grid floor while touching a prod buried the prod just as much as did rats shocked through the prod. Experiment 2 showed that rats either shocked through the floor more than 1 min after touching the prod or shocked in the absence of a prod did not bury the prod. Thus, close temporal contiguity between grid shock and prod contact appears necessary for burying. Nevertheless, grid-shocked rats do learn something different from prod-shocked rats, since they bury the prod less and the walls more than do prod-shocked rats when the position of the prod is changed in the test chamber (Experiment 3). 相似文献
6.
Genotypically based within-species differences in defensive burying were examined in 180 mice representing 15 inbred strains. Each mouse was tested twice in a cylindrical test chamber containing two similar prods. In the first test, one of the prods was electrified, whereas in the second test (24 h later), neither prod was. Although most strains selectively buried the shock prod in the first test (as determined by bedding-height-at-prod and position-of-highest-bedding-pile criteria), some strains did not discriminate between the shock and dummy prods and still others displayed little prod-directed bedding displacement at all (thereby resembling a heterogeneous nonshocked control group). In general, burying tended to be somewhat reduced in the second test, but strain differences in retention were observed. Factors contributory to the observed differences among strains and the need for multiple measures of burying are discussed. Collectively, these findings indicate that intraspecific genetic variation, acting at multiple burying-relevant behavioral levels, can be an important determinant of the expression of the defensive-burying response in mice. 相似文献
7.
Natural sources of aversive stimuli are frequently well-defined material objects that are present both before and after the aversive event. In the present experiment, rats acquired information about such a source after the aversive event and used this information to guide their subsequent defensive reactions to it. The rats were shocked by one of two possible sources, either a black or a striped prod, mounted on opposite end walls of the test chamber. Immediately following the shock, the houselights were momentarily extinguished and the patterns on the two prods were automatically switched for subjects in the experimental condition or left unchanged for subjects in the control condition. The rats were left in the chamber for another 5 min with the patterns in their new positions before being removed for 2 min while the two prods were mounted on the side walls. During the ensuing test of conditioned defensive burying, the rats in the control condition directed the majority of their burying behavior at the prod exhibiting the pattern displayed by the shock source prior to and during the shock administration. In contrast, the rats in the experimental group buried the prod exhibiting the pattern displayed by the shock source during the postshock period more than they did the prod displaying the pattern present on the shock source prior to and during the shock administration. 相似文献
8.
Genotypic and environmental contributions to the defensive burying response were examined by testing four sublines of two inbred strains of mice in test chambers of three different lengths. Burying was found to be dependent on both the particular subline tested and the length of the test chamber employed. For two sublines, specific increases in the length of the test chamber resulted in the complete abolition of defensive burying. A third subline never displayed defensive burying, and the fourth buried in all three chamber-length conditions. Sex differences in burying were never observed. Rather than being viewed as a species-specific defensive reaction, it was proposed that defensive burying should more appropriately be viewed as a genotypically dependent response, the expression of which is contingent on the specific environmental context in which an aversive stimulus is encountered. Apparent conflicts in the defensive-burying literature were reconciled in accordance with this interpretation. 相似文献
9.
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
10.
Heidar A. Modaresi 《Learning & behavior》1982,10(1):97-102
Experiment 1 investigated the proposition that rats cover the source of aversive stimulation with the bedding material available to them and sought to determine whether familiarization with this material would affect burying. The results indicated that rats are no more likely to cover an aversive object than they are not to cover it, although they collect a considerable amount of bedding material in the area surrounding the aversive object. Experiment 2 demonstrated that the rat’s defensive “burying” toward an aversive object is affected by the subject’s predisposition to displace material toward the front side of the apparatus. Some theoretical complexities involved in considering the act of “burying” toward an aversive object as a defensive behavior are discussed. 相似文献
11.
Hooded rats and golden hamsters were shocked by one of two prods in a chamber with a sawdust-covered floor. Rats buried the prod through which they had been shocked, but hamsters displayed no burying behavior. Hamsters may not have buried the prod because they could not perform the required motor pattern. However, hamsters can carry and pile food pellets. Therefore, in a second experiment, rats and hamsters were shocked in a chamber with wooden blocks on the floor. Rats piled blocks around the prod through which they had been shocked, but hamsters did not. The third experiment established that, like rats, hamsters can associate a prod with shock in one trial, since they showed differential avoidance of a prod through which they had been shocked. Since hamsters are nonsocial and rats are social, these results are consistent with suggestions that burying sources of aversive stimulation evolved as an altruistic behavior. 相似文献
12.
In Experiment 1, male rats were exposed to either aggressive (i.e., alpha) or nonaggressive conspecific colonies and tested 24 h later, with or without alpha odors, for freezing behavior and burying of a wall prod that had been the source of a brief electric shock. The results indicated that prior defeat experience and the presence of alpha odors alone during testing had no significant effects, but the combination of prior defeat and alpha-odor testing significantly decreased burying and increased freezing behavior. In Experiment 2, we examined the effects of noncontact exposure to a cat, as a predatory Stressor, during subsequent prod-shock tests involving the presence or absence of cat odors. Exposure to a cat failed to disrupt later prod burying and did not produce freezing. However, the presence of cat odors during testing significantly reduced the amount of defensive burying,without resulting in an increment in freezing. In Experiment 3, rats were given 1, 5, or 30 inescapable preshocks in the presence of either cat odors or a hedonically neutral citronella odor and were tested 24 h later for prod burying and freezing with or without these odors. Both the cat and the citronella odors resulted in a significant reduction in burying and an increase in freezing for rats given 5 and 30 preshocks and tested in the presence of these respective conditioned odors. For the groups that were given 5 preshocks, preshock and later testing in the presence of cat odors resulted in significantly less prod burying and more freezing than for rats that were preshocked and tested in the presence of citronella. The findings of these three ethoexperimental studies are discussed in terms of the learned-helplessness theory, the stress-coping-fear-defense (SCFD) theory, and the concept of selective CS-US associability. 相似文献
13.
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
14.
Stephen F. Davis Scott A. Moore Cynthia L. Cowen Debra K. Thurston John C. Maggio 《Learning & behavior》1982,10(4):516-520
Attempts to establish the generality of the defensive-burying response have proved quite successful with several strains of albino and hooded rats and with mice. However, three previous attempts to demonstrate this behavior in gerbils have been completely unsuccessful. Three additional defensive-burying experiments employing gerbils as subjects are reported. Defensive burying did not occur when testing took place in a rectangular chamber (Experiments 1 and 3), but did occur when a circular chamber was employed (Experiments 2 and 3). Hence, the geometric shape of the test chamber appears to be a crucial factor in determining the elicitation of this behavior in gerbils. Furthermore, the overall topography of the gerbil defensive-burying response was found to be different from that of previously examined species. 相似文献
15.
Three experiments investigated the influence that various stress-controllability manipulations had on the defensive behaviors of rats when they were subsequently tested as intruders in previously established, aggressive colonies of conspecifics. In Experiment 1, naive subjects that had received a session of 80 shocks in a tube showed an enhanced series of defensive responses and received more bites than did a group of restrained nonshocked rats as colony intruders 24 h later. These two measures were also found to be positively correlated within each group. In Experiment 2, a group that was given 80 yoked inescapable shocks, in contrast to a group that had wheel-turn escape training and a restrained nonshocked control group, displayed more defeat and was bitten more frequently when tested as intruders on the following day. In Experiment 3, 60 trials of wheel-turn escape training were given 4 h prior to (i.e., immunization) or after (i.e., therapy) a session of 60 inescapable tube shocks. During resident-intruder testing 24 h later, both of these groups showed less defeat and received fewer bites than did an inescapably preshocked group but did not differ from a restrained nonshocked control group. These findings clearly indicate that stress controllability alters species-typical defensive responses, and their implications concerning other learned helplessness effects and interpretations are discussed. 相似文献
16.
A series of four experiments investigated a number of parameters reported to produce “helplessness” in rats. Consistent differences in escape behavior were not found between inescapably shocked and restrained rats when a FR 1 shuttling response was used. Escape latencies also did not differ between groups when a reduced shock intensity was employed during escape training in FR 2 procedure or when an increased FR 3 response was employed during escape training. Findings are discussed in terms of the robustness of the failure-to-escape phenomenon from which “helplessness” in the rat is inferred. 相似文献
17.
John M. Pearce 《Learning & behavior》1978,6(3):341-345
Three experiments examined the relationship between shock magnitude and the rate of acquisition of a passive avoidance response. Experiment 1 indicated that the use of a relatively large magnitude of shock can disrupt learning to remain on a platform in the center of an open field to avoid shock. The inferior learning of the group trained with high shock was replicated in Experiment 2, which also demonstrated that avoidance learning can occur rapidly with this level of shock if the platform is located in the corner of the apparatus. To explain this, it was proposed that thigmotactic behavior is responsible for the disruption in avoidance behavior when training is conducted in the center with high-magnitude shock. Finally, Experiment 3, essentially a replication of Experiment 1 except that the platform was placed in the corner of the test compartment, demonstrated a direct relationship between shock magnitude and passive avoidance learning. The results are seen as being consistent with accounts which maintain that avoidance learning can be influenced by the occurrence of species-specific defense reactions. 相似文献
18.
Bruce L. Brown Nancy S. Hemmes Soledad Cabeza De Vaca Concettina Pagano 《Learning & behavior》1993,21(4):360-368
In two experiments, pigeons were exposed to an autoshaping procedure in which a keylight was followed by food under delay or trace conditions, while measures were taken of keypecking and time spent near the key. In Experiment 1, the birds in the trace group spent less time near the key than did the delay birds. Moreover, the trace birds exhibited a pattern of withdrawal from the key during the trial. In Experiment 2, visual observations of the birds’ location and latencies to eat both indicated that the trace birds’ withdrawal from the conditioned stimulus was accompanied by goal tracking. The difference in performance between the delay and trace conditions was taken as evidence that a trace stimulus may exert control over behavior as an occasion setter. 相似文献
19.
V. Csányi 《Learning & behavior》1986,14(1):101-109
The possible role of eyespot patterns in predator recognition by paradise fish was examined using a passive avoidance conditioning technique with various dummies or live goldfish. It was found that a low-intensity shock, although clearly uncomfortable, elicited exploratory behavior in the fish and that observable learning did not occur. However, if the paradise fish was shocked in the presence of a live goldfish or various fish dummies, exploration diminished and avoidance learning was detected. This was characterized by a considerable increase in latency to enter the shocked compartment. The most effective dummies were those with two laterally arranged eye-like spots. The possible role of species-specific key stimuli in avoidance learning and organizing defensive behavior of the paradise fish is discussed. 相似文献
20.
John E. Kelsey 《Learning & behavior》1977,5(1):83-92
Male rats which had received approximately 21 min of pulsed, inescapable tail shock during a 6-h session in a wheel-turn chamber were markedly deficient in acquisition of an FR 2 crossing escape response in a shuttlebox when first tested 22 or 70 h later (Experiments 1 and 2). Rats which had received identical amounts and patterns of escapable/avoidable shock, however, were not deficient (Experiment 1). Preventing wheel-turn responses during the inescapable shocks prevented the occurrence of the subsequent escape deficit, whereas reducing the feedback provided for the first crossing response of the FR 2 requirement enhanced the deficit (Experiment 3). These data can be best explained by the learned helplessness hypothesis and indicate that the types of responses available and made during the inescapable shocks are more important than previously indicated. 相似文献