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1.
The effects of age on the forgetting of stimulus attributes in a differential fear-conditioning paradigm were examined with
18- and 70-day-old rats tested in either the original conditions or shifted stimulating conditions at one of three retention
intervals (1, 48, and 120 h). Adults displayed significant shifts at each retention interval, with those tested in the original
context displaying greater fear than those tested in the shifted conditions. By contrast, by 48 h the 18-day-olds had forgotten
the specific attributes of the training situation and began treating the two stimulating conditions as functionally equivalent
(Experiment 1). In Experiment 2, we tracked the ontogenetic emergence of adult-like memory for stimulus attributes and found
a dramatic increase in memory capability by 25 days of age. Experiment 3 illustrated that the forgotten memory attributes
of infants may be retrieved by administering a 90-sec cuing treatment 10 min prior to the 48-h test. Implications for the
phenomenon of infantile amnesia are discussed. 相似文献
2.
Three experiments assessed the conditions that potentiate effects of an electroconvulsive shock (ECS) administered 24 h after avoidance training. Stimuli present immediately prior to the ECS were systematically varied. In Experiment 1, which employed a passive avoidance task, the primary determinant of whether the ECS disrupted retention was whether the situational cues present at the time of ECS delivery were those associated with the initial training experience: ECS disrupted performance only when it was administered in the original training apparatus, regardless of whether or not a footshock was presented immediately prior to ECS. In Experiment 2, which employed an active, shuttlebox avoidance task, both the situational cues from the training apparatus and a footshock were necessary to potentiate the disruptive effects of the ECS. Experiment 3 revealed that ECS effects on performance of the active avoidance task can also be potentiated by a combination of apparatus cues and the warning signal used in initial training. These results are interpreted as indicating that informational functions of stimuli present when an ECS is administered are important determinants of the effects of the ECS. 相似文献
3.
The specificity of memory retrieval by 3-month-old infants was examined in 3 experiments. All infants were trained in the mobile conjugate reinforcement paradigm to kick their feet to produce movement in an overhead crib mobile and were tested 2 weeks later. 24 hours prior to the test, subjects received a 3-min reminder treatment. The results of Experiment 1 demonstrated that only the moving training mobile alleviated forgetting after the 2-week retention interval; forgetting was not alleviated by exposure to the stationary training mobile or to the mobile stands and ribbon alone. The results of Experiments 2 and 3 demonstrated that, once retrieved, the reactivated memory was highly specific to the conditions of original training. Furthermore, the memory attributes that were the last to be forgotten (e.g., the general or global features) were the first to be retrieved following the reminder treatment. Conversely, those memory attributes that were forgotten first (e.g., the specific or local details) were the last to be retrieved. These findings have important implications for infant memory retrieval, reminiscence, and infantile amnesia. 相似文献
4.
In 3 experiments, 6-month-old infants learned to move a mobile by kicking and were tested 1 to 21 days later for retention of the newly acquired memory as a function of the training and testing contexts. In Experiment 1, decreasing the relative distinctiveness of the training and testing context did not impair retrieval of the newly acquired memory. In Experiment 2, however, testing in a different context completely eliminated retention after delays of 1 and 3 days, when retention was otherwise perfect; after progressively longer delays, retention improved paradoxically. The familiarity or novelty of the test context was not a factor in the failure of infants to recognize the mobile in the altered context after 1 day. In Experiment 3, the effect of an altered context was assessed in a reactivation paradigm. After the training memory was forgotten, infants were presented with the original mobile as a reminder and were tested for retention of the training memory 1 day later. When either the reminding context or the testing context was different, they exhibited no retention. These findings reveal that memory retrieval at 6 months is highly specific to the setting in which the memory is acquired. We propose that infants learn what specific events are associated with what specific places prior to the age when they can locomote independently and acquire a spatiotemporal map of the relations between those places. 相似文献
5.
In Experiment 1, it was shown that generalization testing following successive discrimination training between two closely spaced wavelengths results in a sharp gradient with a peak of responding shifted from S+ so as to be further removed from S?. Testing after a 24-h delay resulted in a flatter gradient with greater peak (and area) shift. A 5-min pretest exposure to S+, reinforced or unreinforced, or to S? (unreinforced) reinstated immediate test performance; free reinforcement with no discriminative stimulus present had no such effect. Experiment 2 replicated the flattening of generalization gradients and enhanced peak shift in delayed testing. Free feeding in a pretest treatment with a distinctive food uniquely associated with the wavelength discrimination problem failed to reinstate immediate test performance. Experiment 3 tested the hypothesis that free feeding failed as a reactivation treatment because it did not engender keypecking. Subjects were trained to peck a vertical line stimulus before being given wavelength discrimination training. Again, the enhanced peak shift and greater flattening with delayed wavelength generalization testing was found. A pretest exposure to the vertical line stimulus elicited pecking but had no effect on subsequent wavelength generalization. Thus, only a reactivation treatment that included one of the discrimination training stimuli was effective in producing delayed test performance comparable to that obtained in an immediate test. 相似文献
6.
In 2 experiments we asked whether training in multiple contexts could eliminate context-dependent memory retrieval at 6 months as it does for adults. We found that 24-hour retention was disrupted when infants were trained in one context and tested in another but not when they were trained in multiple contexts prior to testing in a novel context (Experiment 1). After a long delay, however, training in multiple contexts did not facilitate memory retrieval in a novel context: An otherwise effective retrieval cue (the training mobile) did not alleviate forgetting 3 weeks later when it was presented in a novel context (Experiment 2). These findings demonstrate that multiple learning contexts can override the debilitating effects of an altered context on memory retrieval at 6 months, but only over the short term. The resistance of older memories to retrieval in novel contexts after long periods of disuse may be adaptive, insuring that potentially inappropriate or irrelevant memories will not be expressed. 相似文献
7.
Two experiments were run in order to investigate the influence of external contextual cues on the interaction between two conflicting memories. Rats were trained, in the same apparatus, on a passive-avoidance task and, 10 min later, on an active-avoidance task, then submitted to a 24-h delayed test (without reinforcement). When contextual cues remained unchanged throughout these three phases, the animals exhibited proactive interference, as shown by longer response latencies than those of control animals that had learned only the active-avoidance task (Experiment 1). When training contexts were made slightly different from one task to the other (by the presence of a continuous tone during either the first or the second task), the animals behaved at subsequent testing in accordance with the response contingencies present in the context exactly similar to the test context; this control of behavior by testing context was demonstrated both when the tone was absent (Experiments 1 and 2) and present (Experiment 2) at testing. A cuing procedure—a 90-sec exposure to the tone in the experimental room 5 min prior to testing—led the animals to behave in accordance with the response previously acquired in the presence of the tone (Experiments 1 and 2), exactly in the same way as animals tested in the presence of the tone (Experiment 2). The same cuing treatment was ineffective when administered 1 h before testing (Experiment 2). These results are interpreted in terms of a dual function of contextual cues at the time of retrieval: the general contextual information present during testing or during pretest cuing is assumed to induce concurrent reactivation of both memories. Consequently, the experimentally manipulated contextual cue (the tone) would have a discriminative function, leading the animals to choose between the two equally available representations. 相似文献
8.
We examined the causal role of decreased food intake in the body weight pattern observed after exposure to intermittent footshock. In Experiment 1, relative to controls, shocked animals decreased food intake and lost weight in the 24-h test. An unshocked group whose food intake was yoked to the shocked group (food-yoked group) for the poststress period revealed that food intake was a sufficient cause of the body weight loss. In Experiment 2, after the first 24 h, the shock group recovered food intake and body weight gain but did not compensate for the initial losses. Body weights of food-yoked animals again indicated that food intake was a sufficient cause of these effects. The lowered body weight of shocked animals at the end of testing was due to a transient hypoingestion and a failure to subsequently show a compensatory hyperingestion. Dess’s (1991) regulatory shift hypothesis is refined in the light of these findings. 相似文献
9.
Two experiments were conducted using rats to determine whether extinction is susceptible to a traditional amnestic agent (i.e., hypothermia) and to examine whether amnesia for extinction follows the same characteristics as those that occur with original memories. In Experiment 1, rats received hypothermia immediately, 60 min, or 120 min after extinction. When tested, the subjects cooled shortly after extinction showed little memory of the extinction training. This amnesia for extinction disappeared with longer postextinction delays, demonstrating a temporal gradient. Experiment 2 replicated the basic finding and demonstrated that an amnestic-extinguished memory could be recovered by reexposing the subjects to the amnestic agent and that the recovered extinction memory did not persist. These findings provide more evidence that extinction is a form of new learning and are consistent with retrograde amnesia research for original memories showing a temporal gradient and alleviation of retrograde amnesia by reexposure to the amnestic agent. 相似文献
10.
In Experiment 1, six groups of pigeons (n=8) were tested for wavelength generalization either immediately or 24 h after learning a successive discrimination, with 550 nm reinforced and a black vertical line extinguished. The groups differed in the stimulus present during single stimulus pretraining, which was 550 nm (pretrain S+), the vertical Une (pretrain S?), or a neutral dim white light (pretrain Sn), respectively. The three immediate generalization gradients were steep and indistinguishable, reflecting only the immediately preceding discrimination training condition. The three delay gradients were flatter, with the flattening particularly marked in the pretrain S? group. This was interpreted as proactive interference (PI) resulting from the memory that both the 550-nm and the line stimuli had previously been reinforced. In Experiment 2, two (TD) groups of pigeons (n=16) were given single stimulus training with a 555-nm keylight followed by eight sessions of discrimination training with two line angles, then one session of non-differential (ND) training with the same two lines, and then a wavelength generalization test either immediately or after a 24-h delay. Two other (hold) groups (n=16) received similar training, except for the TD Une angle training sessions, in these hold groups, the wavelength gradient was flatter in a delayed test; in the TD groups it was steeper, indicating PI from the prior TD training. These two experiments suggest that the “attentional sets,” which purportedly result from TD and ND training, may fruitfully be viewed as target memories subject to the principles of interference theory. 相似文献
11.
Prior cuing treatments intended to alleviate the forgetting of a conditioned avexsion-to an odor were tested with 18-day-old rats. Previous experiments had shown that when such pups were conditioned with the use of a CS?/CS+ procedure, pretest presentation of the CS? or US, but not the CS+, alleviated the forgetting otherwise seen after a 3-h retention interval. In Experiment 1, it was determined that the forgetting was not alleviated if the GS? was either preceded or followed by presentation of the CS+, despite the fact that the CS?/CS+ ordering mimicked that of original conditioning. Experiment 2 was an examination of the balance of extinction and reactivation effects caused by presenting the CS+ for varying durations following the 3-h retention interval. The forgetting over this interval was alleviated if the CS+ was presented for 5 or 15 sec, but not 30 sec. With an increase in duration of exposure from 15 to 30 sec, the consequences of the CS+ as a prior cuing treatment apparently shifted from reactivation to extinction. Experiment 3 was a test of the interaction between the consequences of different lengths of CS+ exposure and the effectiveness of adding CS? to the CS+ as a reactivation treatment. The varied effectiveness of reactivation treatments is discussed interms of a change in stimulus conditions from training to reactivation. 相似文献
12.
Marcia L. Spetch 《Learning & behavior》1990,18(3):332-340
In Experiments 1 and 2, pigeons’ spatial working memory in an open-field setting was examined under conditions that differed in terms of working-memory load (number of sites visited prior to a retention test) at various delays between initial choices and the retention test. In Experiment 1, pigeons were tested under two conditions of memory load (three or five sites visited prior to the delay) and two delay intervals (15 and 60 min). Accuracy declined as a function of delay but was not affected significantly by memory load. In Experiment 2A, pigeons were tested under three conditions of memory load (two, four, or six sites visited prior to the delay). In separate phases, the delay was 2, 15, and 60 min. Accuracy was not affected by memory load in any of these phases. In Experiment 2B, three conditions of memory load (two, four, or six sites visited prior to the delay) were tested at two delays (2 and 60 min) within a test phase. Accuracy declined with increasing delay, but memory load again had no significant effects. These results are inconsistent with previous suggestions that pigeons’ retention of spatial information may decline as working-memory load is increased. In Experiment 3, cue-manipulation tests confirmed that pigeons’ choice behavior in the open-field task is controlled by memory for previously visitad room locations. 相似文献
13.
In four experiments, each using a single conditioning trial, rats avoided a light more than a saccharin solution after these stimuli had been paired with footshock, whereas saccharin was avoided more than the light after these stimuli had been paired with lithium injection. The use of a single conditioning trial precludes possible US-induced differential orientations from influencing which stimuli will be associated on the conditioning trial. This cue-consequence specificity effect was obtained even when subjects conditioned with lithium received a non-contingent footshock prior to the test session, and when subjects conditioned with footshock received a noncontingent lithium injection before testing (Experiments 2–4). Weak aversions to the light in rats given a light-lithium pairing and noncontingent footshock and to the saccharin in subjects that received a saccharin-footshock pairing and noncontingent lithium administration were obtained in Experiment 2. However, these weak aversions were not obtained when subjects were given three nonreinforced exposures to the test chamber before the test session (Experiments 3 and 4). These results indicate that US-induced differential orientations do not mediate the cue-consequence effect in aversion learning. 相似文献
14.
In two experiments, the influence of exposure to a CS? on the acquisition and retention of a conditioned odor aversion was examined. Preweanling rats were given exposure to the CS? either prior to (CS?/CS+) or following (CS + /CS?) the pairing of a second odor (the CS+) with footshock. The results of Experiment 1 indicated that subjects in both of the treatment conditions acquired aversions of comparable strength to the odor paired with footshock and that retention of the odor aversion was not affected by order of stimulus presentation during conditioning. Experiment 2 indicated, however, that the effectiveness of pretest exposure to various elements of the conditioning episode in reactivation of the memory for conditioningwas dependent on the order of stimulus presentation during conditioning. This differential effectiveness of the various reactivation treatments is discussed in terms of their relationship to the associative “status” of the stimuli present during conditioning and in terms of the information provided to the animal by the reactivation treatment. 相似文献
15.
Retention of a brightness discrimination avoidance task by rats is impaired (Kamin effect) following a 1-h training-to-test interval (TTI), is enhanced after a 3-day TTI (reminiscence, or long-term spontaneous improvement), and is disrupted following a 21-day TTI (long-term forgetting). An exposure to the conditioned stimulus (CS), delivered 5 mm before a 1-h delayed retention test, not only compensated for the performance deficit that corresponds to the Kamin effect, but induced a large improvement in performance similar to that normally obtained after a 3-day TTI. It can be proposed that such cuing may act either by accelerating a natural memory-trace maturation process or by improving the retrievability of the memory trace. Since these possibilities lead to opposite predictions concerning the length of the facilitation induced by cuing, the effect of a pretest exposure to the CS on performance obtained during a 1-h delayed retention test was studied after several cuing-to-test intervals (0, 5, 10, or 20 min). The results, which indicate that cuing transiently enhanced subsequent retention performance, more convincingly support the retrieval hypothesis. The effects of pretest exposure to the CS (which occurred 5 min before testing) were also examined 10 min, 1 h, or 24 h after initial training. The results indicate that the facilitative effect of cuing obtained when retention performance was disrupted shortly after training (1-h TTI) was also obtained after a 24-h retention interval, in the absence of performance disruption. An interpretation of the facilitative effect of a pretest exposure to the CS is proposed, and implications concerning the memory trace are further discussed in relation to the multidimensional hypothesis. 相似文献
16.
The present experiment employed an appetitive spatial discrimination response to examine alleviation of forgetting induced by retroactive interference. For separate groups of rats, a footshock that had occurred during acquisition contingent upon a correct response was tested for its effectiveness as a reactivation treatment. The results indicated that the footshock effectively alleviated forgetting, but only for rats experiencing the shock stimulus during original learning. These results suggest that a reactivation treatment may arouse affective or stimulus properties in common with the target memory to elicit retrieval of that memory. 相似文献
17.
In five conditioned taste aversion experiments with rats, summation, retardation, and preference tests were used to assess the effects of extinguishing a conditioned saccharin aversion for three or nine trials. In Experiment 1, a summation test showed that saccharin aversion extinguished over nine trials reduced the aversion to a merely conditioned flavor (vinegar), whereas three saccharin extinction trials did not subsequently influence the vinegar aversion. Experiment 2 clarified that result, with unpaired controls equated on flavor exposure prior to testing; the results with those controls suggested that the flavor extinguished for nine trials produced generalization decrement during testing. In Experiment 3, the saccharin aversion reconditioned slowly after nine extinction trials, but not after three. Those results suggested the development of latent inhibition after more than three extinction trials. Preference tests comparing saccharin consumption with a concurrently available fluid (water in Experiment 4, saline in Experiment 5) showed that the preference for saccharin was greater after nine extinction trials than after three. However, saccharin preference after nine extinction trials was not greater, as compared with that for either latent inhibition controls (Experiments 4 and 5) or a control given equated exposures to saccharin and trained to drink saline at a high rate prior to testing (Experiment 5). Concerns about whether conditioned inhibition has been demonstrated in any flavor aversion procedure are discussed. Our findings help explain both successes and failures in demonstrating postextinction conditioned response recovery effects reported in the conditioned taste aversion literature, and they can be explained using a memory interference account. 相似文献
18.
Three experiments evaluated the effects of a single electroconvulsive shock in alleviating the learned helplessness effect in rats. The experiments differed primarily in terms of the location of the ECS treatment in the experimental sequence of events. In Experiment 1, ECS was given following helplessness training and testing and was evaluated during a retesting phase; in Experiment 2, ECS was given either immediately after helplessness training or immediately before helplessness testing; and, in Experiment 3, ECS was given prior to helplessness training. In all three experiments, significant helplessness effects occurred for subjects not receiving ECS but were absent in subjects receiving ECS. The data were compared with expectations arising from both amnesia-inducing and biochemical-change interpretations of the effects of ECS. 相似文献
19.
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
20.
Normally, retention of an avoidance response by a rat is impaired when the test context is novel or does not correspond to the training context. Experiment 1 demonstrates that such an impairment of test performance can be alleviated if a rat receives a cuing treatment or reminder of training in the novel test context prior to testing. Experiment 2 indicates that when rats receive avoidance training in one context and then receive a reminder of training in a novel context, they perform more poorly when tested in the training context than do animals that receive no reminder. This finding is discussed in relation to current theories of contextual influence over retention performance. 相似文献