Encoding specific associative memory: Evidence from behavioral and neural manipulations.

Within-subjects procedures with rats assessed the associative structures acquired during conditioning trials in which the interval between the stimuli and food was either short or long (i.e., A–10 s→food and B–40 s→food). In Experiments 1 and 2, after these conditioning trials, A and B served as second-order reinforcers for 2 further stimuli (i.e., X→A and Y→B); whereas Experiment 3 used a sensory preconditioning procedure in which X→A and Y→B trials occurred before the conditioning trials, and rats were finally tested with X and Y. In each experiment, Y elicited greater responding at test than did X. This finding supports the contention that the long-lived trace of B (associated with food on B–40 s→food trials) is more similar to the memory of B that was associatively provoked by Y, than is the short-lived trace of A (associated with food on A–10 s→food trials) to the memory of A that was associatively provoked by X. These conclusions were reinforced by the effects of a neural manipulation that disrupted discrimination learning involving the short traces of stimuli but not the long traces of the same stimuli. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The control of instrumental action following outcome devaluation in young children aged between 1 and 4 years.

To determine the role of action-outcome learning in the control of young children's instrumental behavior, the authors trained 18- to 48-month-olds to manipulate visual icons on a touch-sensitive display to obtain different types of video clips as outcomes. Subsequently, one of the outcomes was devalued by repeated exposure, and children's propensity to perform the trained actions was tested in extinction. On test, children with a mean age greater than 2.5 years performed the action trained with the devalued outcome less than those trained with the still-valued outcome, thereby demonstrating that their actions were mediated by action-outcome learning. By contrast, the instrumental responses of younger children (mean age     

Stimulus competition between a discrete cue and a training context: Cue competition does not result from the division of a limited resource.

Several associative learning theories explain cue competition as resulting from the division of a limited resource among competing cues. This leads to an assumption that behavioral control by 2 cues competing with each other should always reflect a tradeoff, resulting in apparent conservation of total reinforcer value across all competing cues. This assumption was tested in 3 conditioned lick suppression experiments with rats, investigating the effects of changing the conditioned stimulus (CS) duration (Experiment 1), administering pretraining exposures to the CS (Experiment 2), and presenting nonreinforced CSs during the intertrial interval (Experiment 3) on Pavlovian conditioned responding to both the CS and the conditioning context. Fear conditioned to the context and to the CS decreased when the CS was of longer duration, massively preexposed before being paired with the reinforcer, or presented alone during the intertrial interval. These observations are problematic for the theories that explain cue competition as the division of a limited resource and suggest that the total reinforcer value across competing cues is not always fixed for a given reinforcer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of diagnostic category and reinforcer on learning without awareness.

Learning without awareness was tested by asking Ss to construct sentences using pronouns (I, we, he, they) and verbs presented to them. 3 groups were employed—normals, neurotics, and schizophrenics, under 4 experimental conditions: (a) E "rewarded" (said "good" to) 2 of the pronouns (I, we); (b) the use of he or they was "punished" ("not so good"); (c) differential reinforcement as was appropriate re: "punishment" and "reward" when employing the pronouns; (d) control. Results: normals profited well from all conditions of reinforcement; neurotics, only from reward or reward and punishment; schizophrenics, from punishment alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Preexposure and extinction effects of lithium chloride induced taste-potentiated aversions for spatially contiguous auditory food cues in rats": Correction to Ellins and von Kluge (1987).

Reports an error in "Preexposure and extinction effects of lithium chloride induced taste-potentiated aversions for spatially contiguous auditory food cues in rats" by Stuart R. Ellins and Silvia von Kluge (Behavioral Neuroscience, 1987[Apr], Vol 101[2], 164-169). The aforementioned article contains errors in the last paragraph of the Results section, none of which change the results of the experiment. The corrected paragraph sections are provided in the erratum. (The following abstract of the original article appeared in record 1987-24095-001.) Taste potentiated illness-induced aversions for noisy food were studied in Sprague-Dawley rats. The rats ate from receptacles containing salty food and a contiguous tone produced by speakers under the food followed by lithium chloride injections. In preference tests, the rats then avoided noisy food in favor of quiet food followed by extinction and spontaneous recovery of the auditory aversion over repeated nonreinforced trials. Other rats were given either 4 or 10 days of exposure to the noisy food prior to taste-toxicosis treatment. None of these rats subsequently avoided noisy food. The importance of spatial contiguity and methodological variation in associating nongustatory food cues with illness is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pigeons learn stimulus identity and stimulus relations when both serve as redundant, relevant cues during same-different discrimination training.

The authors taught pigeons to discriminate displays of 16 identical items from displays of 16 nonidentical items. Unlike most same-different discrimination studies-where only stimulus relations could serve a discriminative function-both the identity of the items and the relations among the items were discriminative features of the displays. The pigeons learned about both stimulus identity and stimulus relations when these 2 sources of information served as redundant, relevant cues. In tests of associative competition, identity cues exerted greater stimulus control than relational cues. These results suggest that the pigeon can respond to both specific stimuli and general relations in the environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhancement of responding to A after A+/AX+ training: Challenges for a comparator theory of learning.

Two appetitive Pavlovian conditioning experiments with rats investigated the associative changes that A undergoes in an A+/AX+ blocking procedure. Conditioned responding to A was enhanced relative to stimulus B, which had been conditioned in isolation (B+). This result was interpreted in terms of the formation of a within-compound association between A and X. The results of Experiment 2 supported this conclusion by demonstrating that X had associative strength of its own and, furthermore, that extinguishing X resulted in a similar level of responding to A and B. These results are considered in terms of retrospective revaluation theories of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Military training and principles of learning.

"If I were faced with the problem of improving training, I should not look for much help from the well-known learning principles like reinforcement, distribution of practice, response familiarity, and so on. I should look instead at the technique of task analysis and at the principles of component task achievement, intratask transfer, and the sequencing of subtask learning to find those ideas of greatest usefulness in the design of effective training." Major sections are: Some Representative Military Tasks, Learning, Principles, Using These Assumptions and Principles in Training Design, What Is Applicable to the Design of Training? and Summary. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulation of the Effective Salience of a Stimulus by Direct and Associative Activation of Its Representation.

In 2 experiments, rats received exposure to presentations of a footshock preceded by a given cue. In the PRf (partial reinforcement) condition, this cue also occurred in the absence of the shock; in the CRf (continuous reinforcement) condition, it did not. Subsequent testing in which a new stimulus was used to signal the shock (Experiment 1) showed that the shock was more effective as a reinforcer for the PRf than for the CRf group. In Experiment 2, the shock was used as a conditioned stimulus signaling food delivery, and it was found that conditioning occurred more readily in the PRf than in the CRf group. These results accord with the hypothesis that preexposure to the shock results in a decline in its effective salience but that experience of a cue that signals shock in the absence of the shock itself attenuates this effect and helps maintain stimulus salience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deficits in Attentional Orienting Following Damage to the Perirhinal or Postrhinal Cortices.

The authors used an associative learning paradigm to assess the effects of perirhinal or postrhinal damage on attentional orienting. Control rats and rats with lesions of either the perirhinal or postrhinal cortex initially displayed high levels of orienting behavior (rearing) to presentations of a light cue. Continued nonreinforced presentations resulted in normal habituation of the response. In addition, orienting reemerged in control rats, indicating increased attentional processing of the cue. This conditioned orienting did not reemerge in rats with either perirhinal or postrhinal lesions, providing direct evidence that the rat perirhinal and postrhinal cortices each play a role in attention. These results are consistent with an emerging view that some structures within the medial temporal lobe have nonmnemonic functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of acquisition training schedule on extinction and reinstatement of cocaine self-administration in male rats.

Partial reinforcement is known to increase resistance to extinction (Rn) relative to training with continuous reinforcement. This phenomenon, referred to as the partial reinforcement extinction effect, is one of the most robust in learning and conditioning studies. Experiment 1 investigated manipulations known to affect the partial reinforcement extinction effect and determined their possible relevance for drug use patterns. Male rats received intravenous cocaine self-administration training under partial reinforcement (FR-10) training or continuous reinforcement (FR-1) conditions with either a low (0.25 mg/kg infusion) or a high cocaine dose (1.00 mg/kg infusion). Animals were placed on an extinction (recurrent nonreward) schedule for 10 days (1-hr sessions) prior to being tested for cue-induced reinstatement (single 2-hr session). Experiment 2 involved acquisition of cocaine self-administration under FR-1 conditions of short training (15 days) or extended training (30 days) with a low dose (0.25 mg/kg infusion) or a medium dose (0.50 mg/kg infusion) of cocaine reward prior to extinction or reinstatement. Experiment 1 showed that rats trained with FR-10-high dose outcomes exhibited greater Rn than the remaining groups. Additionally, FR-10-high dose and FR-10-low dose rats were more likely to return to active drug seeking during the reinstatement test. In Experiment 2, rats trained under FR-1-medium dose conditions were more persistent during extinction following short acquisition training than comparable rats experiencing extended acquisition training. The reinstatement test was conducted following extinction, in which it was observed that overtraining under FR-1-medium dose reward schedules resulted in a decrease in the tendency to return to active drug seeking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Within-subject effects of number of trials in rat conditioning procedures.

D. A. Gottlieb (2008) reported finding no effects of number of conditioning trials in a series of between-subjects magazine approach experiments, when number of sessions and total training time were held constant. This article reports 7 comparable within-subject experiments that looked for effects of number of trials in a variety of conditioning preparations. Experiments 1–3 detected effects of multiplying the number of trials by factors of 4 and 8 in a conditioned magazine approach procedure in which visual and auditory stimuli were paired with food. Experiments 4A and 4B detected effects of a factor of 4 trials in a conditioned flavor preference procedure in which flavors were paired with polycose. Experiments 5 and 6 detected an effect of a factor of 3 trials in a conditioned taste aversion procedure and in a fear conditioning procedure, respectively. Results suggest that variables other than number of trials might play important roles in determining the acquisition of conditioned responding, but effects of number of trials can be detected with sensitive enough procedures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ethanol-induced preferences or aversions as a function of age in preweanling rats.

The reinforcing value of a relatively high ethanol dose (3 g/kg) administered intragastrically was investigated in preweanling rats. Ethanol intoxication on Postnatal Days 7-8 increased ethanol intake and enhanced the drug's palatability when tested 3 days later. In contrast, intoxication on Days 10-11 decreased ethanol intake and increased aversive responses to the drug. When reducing the delay between intoxication and test to 24 hr, the taste aversion was enhanced, whereas the preference was unaffected. Results suggest an ontogenetic change in pups' perception of the reinforcing value of ethanol that coincides with the end of a sensitive period for learning preferences in rats younger than 9 days old (T. L. Roth & R. M. Sullivan, 2003; R. M. Sullivan, M. Landers, B. Yeaman, & D. A. Wilson, 2000). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of the medial prefrontal cortex in acquired distinctiveness and equivalence of cues.

In the present study, the authors examined the role of the medial prefrontal cortex in acquired equivalence and distinctiveness of cues. Rats were placed in 4 experimental contexts (A, B, C, and D) where they received presentations of 2 auditory stimuli (X and Y). In Contexts A and B, X was paired with food and Y was not, whereas in Contexts C and D, Y was paired with food and X was not. Rats that received sham lesions and those with lesions of the medial prefrontal cortex acquired this configural discrimination equally readily. Rats then received many pellets in A but not in C. After this training, sham-lesion rats exhibited more magazine activity in B than in D (an acquired distinctiveness/acquired equivalence effect), whereas those with medial prefrontal cortex lesions did not. These results indicate that the medial prefrontal cortex is involved in the process by which experience with stimuli influences the degree of generalization between them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple Systems for Spatial Learning: Dead Reckoning and Beacon Homing in Rats.

Rats homed with food in a large lighted arena. Without visual cues, they used dead reckoning. When a beacon indicated the home, rats could also use the beacon. Homing did not differ in 2 groups of rats, 1 provided with the beacon and 1 without it; tests without the beacon gave no evidence that beacon learning overshadowed dead reckoning (Experiment 1). When the beacon was at the home for 1 group and in random locations for another, there was again no evidence of cue competition (Experiment 2). Dead reckoning experience did not block acquisition of beacon homing (Experiment 3). Beacon learning and dead reckoning do not compete for predictive value but acquire information in parallel and are used hierarchically. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of passive-avoidance training on sleep-wake state-specific activity in the basolateral and central nuclei of the amygdala.

This study examined the effects of intense emotional learning on the sleep-wake state-specific electroencephalographic (EEG) activities of the basolateral (BLA) and central (CeA) nuclei of the amygdala. Rats were trained on a passive-avoidance learning (PAL) protocol that was followed by 6 hrs of undisturbed polygraphic recording and a PAL test. After PAL training, the total amount of REM sleep decreased; high-frequency EEG power decreased in the CeA during REM sleep and increased in the BLA during all sleep-wake stages. These results suggest that there is no homeostatic demand for REM sleep after intense emotional learning. However, the PAL-specific changes in the local EEG suggest that some form of memory processing may occur within the amygdala during REM sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

高钾电解质体系下阳极品质和锂钾含量对炭渣量的影响

长期跟踪了某电解铝企业电解槽的运行过热度、不同炭阳极运行期间的炭渣量和电解质中含碳量,开展了电解质组分调整试验,跟踪分析了炭渣量和运行过热度随锂钾含量变化的过程。结果表明,高品质阳极能够明显降低炭渣量和电解质中的含碳量。电解运行过热度偏低,炭渣量偏高可能是高钾低锂电解质体系的特征,降低电解质中钾含量、适当提高锂含量,能够提高电解运行过热度,降低炭渣量。阳极质量、电解质中锂钾含量、运行过热度、阳极覆盖料中的含碳量都是影响电解过程中炭渣产生量的重要因素。     

Choice and contingency in the development of behavioral autonomy during instrumental conditioning.

In two experiments hungry rats received extensive training to lever press for food outcomes before one outcome was devalued by aversion conditioning and responding tested in extinction. If the rats were trained on a concurrent schedule in which two responses yielded different outcomes, performance during the extinction test was reduced by devaluation of the associated outcome. By contrast, if a single response was trained concurrently with the noncontingent presentations of the other outcome, test performance was insensitive to devaluation of the contingent outcome. This finding demonstrates that training on a schedule that offers a choice between responses that yield different outcomes prevents the onset of behavioral autonomy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When training with a partner is inferior to training alone: The importance of dyad type and interaction quality.

Dyad training, where trainees learn in pairs but ultimately perform individually, has been shown to be an effective method for training some skills. The effectiveness of this approach, however, may be tied to the type of task to be trained and the quality of the interaction in the dyad. We report two studies on the effectiveness of dyad training and the role of metacognitive activity for learning a software program. In Study 1, participants completed training alone or with a partner. Performance was assessed individually immediately after training and again after a 1-week nonuse interval. Results of Study 1 suggested that learning retention is superior when people are trained individually. Study 2 examined performance for individuals, task-switching dyads, and interdependent dyads. Results also showed that performance for individuals was superior to dyads and that the type of dyad collaboration did not affect performance. However, partner-prompted metacognitive activity was helpful for interdependent dyads and harmful for task-switching dyads, suggesting that the quality of collaboration varies by dyad type. Our findings suggest that dyad training may not be effective for all types of tasks. Possible boundary conditions for effective dyad training are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)