Posttrial d-amphetamine sulfate and one-trial learning in mice.

Conducted 3 experiments with a total of 216 male albino LACA mice to investigate the effect of dextroamphetamine sulfate on memory in such a way that (a) state-dependency learning effects were excluded, (b) the time of learning was known rather precisely, (c) the drug might be introduced rapidly after the learning trial if recovered, and (d) no previous learning experience or drug effects would be present to confound the interpretation of results. Results show that amphetamine (2 mg/Kg, iv) immediately after footshock on a 1-trial passive avoidance learning task impaired performance in retention tests 24 and 96 hrs later. When the injection was delayed by as little as 90 sec, no such impairment was seen. A similar injection immediately after the learning trial of a water-rewarded 1-trial appetitive task had no discernible effect on performance in retention trials 24 hrs and 6 wks later. It is argued that the effects of the amphetamines on learning behavior depend on whether reward or punishment is involved and, further, that all such effects could be accounted for in terms of the drugs' influence on memory mechanisms. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cue-dependent amnesia in rats.

Gave 78 male Sprague-Dawley rats extensive training in a complicated appetitive maze. Following a retention interval of 7 days, Ss were given a single ECS. Ss for which memory cues had been reinstated just prior to ECS were more amnesic upon retest than Ss whose memories had not been reinstated. Thus, amnesia can be produced for well-established memories if the memory cues are present at the time the amnesic agent occurs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preserved learning and memory in amnesia: Intact adaptation-level effects and learning of stereoscopic depth.

Amnesic patients and control Ss performed similarly on 2 memory tests. In experiments 1A and 1B, amnesic patients exhibited intact adaptation-level effects: An experience lifting and judging a group of weights influenced their judgments of a 2nd group of weights 20–25 min later. The effect did not depend on peripheral accommodation, because Ss used 1 hand during their 1st encounter with the weights and the opposite hand during their 2nd encounter. In Experiment 2, amnesic patients acquired at a normal rate the ability to perceive binocular depth using random-dot stereograms. In both experiments, amnesic patients benefited from recent experience, despite the fact that they could not remember their prior experience accurately. The preserved memory abilities demonstrated here appear to be examples of implicit, or nondeclarative, memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Autonomic and behavioral correlates of appetitive conditioning in rats.

The cardiac responses accompanying conditioned stimulus (CS)-generated (orienting) and unconditioned stimulus (US)-generated appetitively motivated behaviors (P. C. Holland, 1977) were investigated. On the basis of contemporary psychophysiological research, CS-generated responses were predicted to produce bradycardia, and US-generated responses to produce tachycardia. Pairing a 10-s visual CS with food delivery produced conditioned behavioral orienting (rearing) during the initial portion of the CS, followed by magazine approach (US-generated) responses as the CS progressed. CS onset produced a decrease in heart rate, mediated by an increase in parasympathetic stimulation of the heart, which persisted throughout the 10-s CS; no support for a biphasic cardiac response was observed. These data are discussed with respect to other conditioned autonomic responses and their relevance to foraging and food ingestion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Paired-associate learning and priming effects in amnesia: A neuropsychological study.

Conducted 4 experiments investigating the role of priming effects in paired-associate learning. Ss for all 4 experiments were 5 male and 3 female alcoholics (mean age 53.8 yrs; WAIS—R IQs 85–203) with Korsakoff syndrome. Control Ss were 26 male alcoholics (mean age 47.6 yrs). Exp I illustrated the distinction between the memory impairment of amnesic (Korsakoff) Ss and their intact priming ability. In Exp II, amnesic Ss showed good paired-associate learning for related word pairs but controls performed significantly better. Exp II also showed that the forgetting of related word pairs by amnesic Ss followed the same time course as the decay of word priming. Exp III showed that amnesic Ss were as good as controls at learning related word pairs when word-association tests were used. Exp IV showed that amnesic Ss exhibited normal priming when they were asked to free associate to words that were semantically related to previously presented words. Results indicate that both priming effects and paired-associate learning of related words depended on activation, a process that is preserved in amnesia. Activation is a transient phenomenon presumed to operate on and facilitate access to preexisting representations. (67 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observation learning in day-old chicks using a one-trial passive avoidance learning paradigm

The ATP-binding cassette (ABC) transporters belong to a large superfamily of proteins which share a common function and a common nucleotide-binding domain. The CvaB protein from Escherichia coli is a member of the bacterial ABC exporter subfamily and is essential for the export of the peptide antibiotic colicin V. Here we report that, surprisingly, the CvaB carboxyl-terminal nucleotide-binding domain (BCTD) can be preferentially cross-linked to GTP but not to ATP at low temperatures. The cross-linking is Mg2+ and Mn2+ dependent. However, BCTD possesses similar GTPase and ATPase activities at 37 degrees C, with the same kinetic parameters and with similar responses to inhibitors. Moreover, a point mutation (D654H) in CvaB that completely abolishes colicin V secretion severely impairs both GTPase and ATPase activities in the corresponding BCTD, indicating that the two activities are from the same enzyme. Interestingly, hydrolysis activity of ATP is much more cold sensitive than that of GTP: BCTD possesses mainly GTP hydrolysis activity at 10 degrees C, consistent with the cross-linking results. These findings suggest a novel mechanism for an ABC protein-mediated transport with specificity for GTP hydrolysis.     

Retention of classroom and television learning.

Comparison of retention three years after instruction was made for four conditions of learning introductory psychology: An off-campus television group (n = 40), a traditional classroom group (n = 22), a TV-in-studio class (n = 11), and a kinescope class (n = 10). The original-test-retention-test differences were not significant, nor was the test x group interaction. "The results… indicate that… long-term retention of… material learned by television… is as good as that learned by traditional means… ." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using signaled barpressing tasks to study the neural substrates of appetitive and aversive learning in rats: Behavioral manipulations and cerebellar lesions.

Describes the development of standard within-S conditioning tasks for studying similarities and differences in the neural substrates of appetitive and aversive learning. Rats learned to press a bar during a brief tone presentation to receive a food pellet reward (the appetitive task). Using the same tone signal, conditioning chamber, and trial timing parameters, the same rats were then trained to press the bar during the tone presentation to avoid a mild footshock (the aversive task). As an initial study of the neural substrates of these forms of learning, the involvement of the cerebellum was assessed. Bilateral lesions of the deep cerebellar nuclei prevented the learning of the aversive task but had no effect on the learning of the appetitive task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

State-dependent models of ECS-induced amnesia in rats.

Conducted 3 experiments with a total of 220 male albino Sprague-Dawley rats, to investigate 2 state-dependent hypotheses which state that ECS-induced amnesia occurs when (a) the physiological state during testing is dissimilar from that during training (regardless of when consolidation occurs), or (b) the state at testing differs from that during consolidation (consolidation is assumed to occur after ECS). Data were gathered in a 1-trial passive-avoidance apparatus, and amnesia as a function of states during acquisition, consolidation, and testing was examined. Exp. I failed to support the train-test, state-dependent position. Exp. II produced data consistent with the consolidate-test, state-dependent position, but Exp. III found that the consolidate-test, state-dependent data were confounded by an induced recovery effect independent of S's physiological state at the time of testing. Although inconsistent with either of the state-dependent hypotheses, data support a retrieval-failure view of experimental amnesia. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anterograde amnesia induced by hyperthermia in rats.

Anterograde amnesia (AA), forgetting of events that occur following a traumatic episode, has recently been demonstrated by using hypothermia as the amnestic agent. However, no data currently exist to indicate if hyperthermia might affect memory processing in a similar manner. Experiments 1 and 2 demonstrated that increasing the colonic body temperature of the rat to 3–4°C or more above normal during avoidance training, produced a significant retention loss when the test occurred 24 hr after training. In Experiment 3, AA resulting from an elevation in temperature was reversed by reheating "amnestic" subjects just prior to the 24-hr test. By rapidly reversing hyperthermia immediately after the training trial with a cooling procedure, Experiment 4 demonstrated that hyperthermia-induced AA was not the result of retrograde influences of the heating treatment. Results are discussed in terms of possible retention deficits which could conceivably follow environmental heat stress or fever hyperthermia resulting from bacterial infection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of D-cycloserine on the extinction of appetitive operant learning.

Four experiments with rat subjects examined whether D-cycloserine (DCS), a partial NMDA agonist, facilitates the extinction of operant lever-pressing reinforced by food. Previous research has demonstrated that DCS facilitates extinction learning with methods that involve Pavlovian extinction. In the current experiments, operant conditioning occurred in Context A, extinction in Context B, and then testing occurred in both the extinction and conditioning contexts. Experiments 1A and 1B tested the effects of three doses of DCS (5, 15, and 30 mg/kg) on the extinction of lever pressing trained as a free operant. Experiment 2 examined their effects when extinction of the free operant was conducted in the presence of nonresponse-contingent deliveries of the reinforcer (that theoretically reduced the role of generalization decrement in suppressing responding). Experiment 3 examined their effects on extinction of a discriminated operant, that is, one that had been reinforced in the presence of a discriminative stimulus, but not in its absence. A strong ABA renewal effect was observed in all four experiments during testing. However, despite the use of DCS doses and a drug administration procedure that facilitates the extinction of Pavlovian learning, there was no evidence in any experiment that DCS facilitated operant extinction learning assessed in either the extinction or the conditioning context. DCS may primarily facilitate learning processes that underlie Pavlovian, rather than purely operant, extinction. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Source of cues for cue-dependent amnesia in rats.

In 2 experiments 54 Sprague-Dawley male albino rats were given extensive training in a complicated appetitive maze and then handled extensively for 7 days. On the 7th day of the retention interval some Ss were exposed to the "cognitive" learning cues of the maze and some were not. Immediately afterward Ss were given ECS or sham ECS. To the extent that cognitive learning cues are assumed to activate memory, the ECS impaired retrieval of memory only for those Ss which had the cues reinstated prior to ECS administration. It appears that memory must be active at the time of ECS in order to obtain retrieval deficits. In a 3rd experiment with 36 Ss the intensity of hunger drive, manipulated by the amount of prefeeding, was not a cue for memory activation and subsequent cue-dependent amnesia. Arousal is therefore not believed to be crucial for the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loss and recovery of long-term memories after ECS in rats: Evidence for state-dependent recall.

Trained 24 male albino Sprague-Dawley rats on 3 2-choice discriminations. The 1st and 3rd problems were learned to avoid shock (S1 and S3), and the 2nd problem to obtain food (F2). Immediately after reaching criterion on S3, Ss were given ECS, and retention of S1 and F2 was assessed. Under normal conditions, retention of F2 was good but retention of S1 was poor, replicating earlier findings of M. Robbins and D. Meyer (see record 1970-11961-001). However, retention of S1 was significantly improved, and retention of F2 disrupted, if a 2nd ECS was administered 15 min. before testing. A state-dependent hypothesis proposed to explain these data also accounts for a number of other ECS phenomena. A novel aspect of the hypothesis is that ECS produces retrograde dissociative effects, and that administration of a 2nd ECS creates conditions favorable to the recall of dissociated information. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Additional evidence for intact appetitive trace conditioning in hippocampal-lesioned rats.

Hippocampal lesions impair aversive trace conditioning but do not interfere with appetitive Pavlovian trace conditioning of the licking response (LR). This experiment examined whether learning to discriminate the events occurring in the home cage and in the training chamber could account for the differential effects of hippocampal lesions on aversive and appetitive trace conditioning. Performance of rats with excitotoxic lesions of the hippocampus was compared to that of sham-operated rats in LR trace conditioning. The unconditional stimulus (US) “cola soft drink” was delivered only in the training chamber. Thus, as in aversive conditioning procedures, the hedonic properties of the US and the resulting behaviors and motivational states occurred only in that environment. The results failed to reveal learning differences between lesioned rats and controls. Our findings and those of other reports concur that trace conditioning with an appetitive US is independent of the hippocampal system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention of response persistence in weanling and adolescent rats.

Two experiments (192 Sprague-Dawley rats) examined parameters affecting retention of continuously reinforced (CRF) and partially reinforced (PRF) runway training in weanling and adolescent Ss. In Exp I, weanling Ss were given CRF or PRF training and 12 hrs, 3 days, or 10 days later were given 8 CRF reacquisition trials followed by extinction. In Exp II, weanling and adolescent Ss were given CRF or PRF runway training and extinguished 10 days later following 0, 8, or 24 CRF reacquisition trials. Results suggest that (a) weanlings characteristically display a partial reinforcement extinction effect (PREE) of unusually large magnitude if extinguished within 12 hrs of training, (b) this large-magnitude PREE dissipates within 3 days of training regardless of the number of CRF reacquisition trials preceding extinction, (c) no PREE of any magnitude is seen in weanlings or adolescents following a 10-day interval unless CRF reacquisition trials precede extinction, and (d) retention of the PREE is poor or nonexistent in Ss trained as adolescents and extinguished 10 days later, even with CRF reacquisition preceding extinction. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preventing and alleviating hypothermia-induced amnesia in weanling and young adult rats.

Reminder (Experiment 1) and familiarization (Experiment 2) treatments were found to have similiar effects on the 24-hr retention performance of 24- to 26- and 90- to 100-day-old rats that either did or did not undergo an amnesic treatment (hypothermia) immediately after training. Similar degrees of retrograde amnesia and normal forgetting were evident in both trained age groups that were not subjected to familiarization or reminder treatments. These results suggest that memory processes in weanling and adult rats are similar in susceptibility to disruption by an established amnesic treatment (hypothermia) and in the ease of prevention of and recovery from amnesia by recognized preventive (familiarization) and alleviation (reminder) measures. The similarity of the effects of these preventive and alleviation treatments on normal forgetting and induced amnesia suggests that experimentally induced amnesia may be a fruitful approach to studying the ontogeny of memory processes and, more specifically, to studying factors that influence infantile amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual evoked potentials during appetitive behavior after septal lesions in rats.

Analyzed averaged visual evoked responses (VERs) at the cortex to flashes used as probe stimuli during different phases of fixed-ratio barpressing for sucrose, using 5 lesioned and 7 nonlesioned male Holtzman rats. Results reveal changes in late components (including after-discharge responses) of VERs of septal preparations that would suggest enhanced electrophysiological arousal to appetitive conditions. The brain-damaged Ss also displayed heightened electrophysiological reactivity to conditions of frustration instituted by intermittent withholding of reinforcement. These dysfunctions were related to the reduced distractibility to trains of extraneous stimuli shown by septal preparations during appetitive behavior. It is suggested that impairment in inhibitory modulation of arousal mechanisms is related to augmentation in behavioral response tendencies often displayed by septal preparations. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of CS-US interval on several different indices of learning in appetitive conditioning.

Four experiments examined the effects of varying the conditioned stimulus-unconditioned stimulus (CS-US) interval (and US density) on learning in an appetitive magazine approach task with rats. Learning was assessed with conditioned response (CR) measures, as well as measures of sensory-specific stimulus-outcome associations (Pavlovian-instrumental transfer, potentiated feeding, and US devaluation). The results from these studies indicate that there exists an inverse relation between CS-US interval and magazine approach CRs, but that sensory-specific stimulus-outcome associations are established over a wide range of relatively long, but not short, CS-US intervals. These data suggest that simple CR measures provide different information about what is learned than measures of the specific stimulus-outcome association, and that time is a more critical variable for the former than latter component of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Element pretraining influences the content of appetitive serial compound conditioning in rats.

Examined the effects of prior pairings of conditioned stimulus/stimuli (CS)2 with the unconditioned stimulus/stimuli (UCS) on the nature of the associations formed in CS1?→?CS2?→?UCS serial compound conditioning, in 4 experiments with 72 male and 32 female albino rats. In Exps I and II, prior training of CS2 prevented the acquisition of stimulus–stimulus (S–S) associations between CS1 and stimulus features of CS2 but enhanced the acquisition of stimulus–response (S–R) associations between CS1 and the emotional conditioned response (CR) evoked by CS2. In Exps III and IV, the effects of CS2 pretraining were not due to CS2 training itself, but rather to its endowing CS2 with the ability to evoked a strong CR during the early stages of serial compound conditioning. In Exp III, suppression of the CR to a pretrained CS2 during serial compound conditioning permitted the establishment of S–S associations. In Exp IV, the induction of a CR in the presence of an untrained CS2 during serial compound conditioning prevented the acquisition of S–S associations. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)