Long-term memory modulation by posttraining epinephrine in rats: Differential effects depending on the basic learning capacity.

Effects of posttraining epinephrine on retention of a massed (1 session, 30 trials) 2-way active avoidance task were studied in rats. Immediately after the training session rats received an injection of 0.05 or 0.01 mg/kg intraperitoneal/ly (ip) epinephrine, or distilled water. Retention was tested 11, 20 or 45 days after training, in independent groups of rats. The 20- and 45-day retention was improved in poor-learning rats and disrupted in good-learning rats. It was concluded that the effect (facilitatory or disruptive) of posttraining epinephrine on memory consolidation depends on the basic learning capacity of rats for this task and needs a long time to be expressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shuttle-box memory facilitation by posttraining intracranial self-stimulation: Differential effects in rats with high and low basic conditioning levels.

The effects of intracranial self-stimulation (ICSS) on retention (after 24 hr, 7, 15, or 60 days) of a massed 2-way active avoidance task were studied in independent groups of rats. All groups showed a higher performance on the retention session than on the acquisition one. In the control subjects. the higher retention performances were observed in the 7- and 15-day groups. However, the ICSS treatment facilitated the 24-hr retention compared with its control group, allowing the treated subjects to achieve the same level of performance on the 24-hr retention session than that achieved by the control rats at the 7-day retention test. In the 24-hr groups, the facilitatory ICSS effect was stronger in the subjects with a low level of conditioning and weaker in those with a high level. Results suggest that posttraining ICSS accelerates memory consolidation and equalizes the performance of poor and good learners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Norepinephrine and posttraining memory consolidation in neonatal rats.

Wistar rat pups, aged Postnatal Day 5, were trained in an olfactory associative learning task with citral odor as the conditioned stimulus (CS) and intraoral infusions of milk as the unconditioned stimulus (US). Following a 30-min training session, pups were injected with either the norephinephrine 13-receptor antagonist propranolol or the β-receptor agonist isoproterenol. Pups were tested 24 hr later for an acquired relative odor preference for the CS. Propranolol injected immediately following training impaired memory for the CS in a dose-dependent manner. This posttraining effect lasted less than 4 hr. Isoproterenol injected immediately after training also impaired memory performance, even at very low doses. These results suggest that posttraining levels of norepinephrine play a critical role in memory consolidation in the newborn, with elevations or decrements in noradrenergic activity resulting in impaired memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory facilitation by posttraining and pretest ACTH, epinephrine, and vasopressin administration: Two separate effects.

Rats were trained in a step-down inhibitory avoidance task using a 0.3-mA, 2-s, 60 Hz footshock and tested 24 hr later. The animals received, 1 min after training and/or 5 min before testing, an ip injection of saline, ACTH1–24 (0.2 μg/kg), lysine-vasopressin (10 μg/kg), epinephrine (5 μg/kg), naloxone (0.4 mg/kg), or a combination of naloxone with one of the hormones. Both the posttraining and the pretest injection of the hormones enhanced retention test performance; the enhancement was larger in animals that received the two treatments. Posttraining, but not pretest, naloxone administration also caused an enhancement. However, posttraining naloxone potentiated, and pretest naloxone antagonized, the effect of the concomitantly injected hormones. These data show that the posttraining and the pretest effect of the hormones are independent, are due to different mechanisms, and can be additive. In addition, it does not seem possible to explain posttraining memory facilitation by the hormones as owing to an addition to the reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endogenous opioid facilitation of maternal memory in rats.

In rats, contact with pups at parturition establishes a form of maternal memory that enables female rats to respond rapidly to pups in the future. Treatment of pregnant female rats with the long-lasting μ opioid receptor antagonist, β-funaltrexamine (β-FNA), prior to parturition interfered with the establishment of maternal memory. Similar treatment 3 hr postpartum resulted in disrupted retention of maternal memory that appeared nonspecific, with both drug- and vehicle-treated rats displaying a deficit. However, infusion of the opioid antagonist 24 hr postpartum had no effect on the retention of maternal memory tested 7 days later. These findings indicate that the establishment of maternal memory is mediated by endogenous opioid activity around the time of parturition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention impairment by posttraining epinephrine: Role of state dependency and of endogenous opioid mechanisms.

Mice were trained in a step-through inhibitory avoidance task with a 0.6-mA, 60-Hz, 2-s footshock and were tested for retention 3 or 6 hr later. Posttraining intraperitioneal administration of a high dose (25.0 μg per mouse) of epinephrine (Epi) impaired retention; this effect was counteracted by another injection of the same dose of Epi given before retention testing either 3 or 6 hr after training. When administered before the 6-hr test but not the 3-hr test, however, Epi enhanced retention (i.e., above that of controls). The retention enhancement, but not the reversal of impairing effects of posttraining Epi, was antagonized by naltrexone (20.0 μg per mouse). Naltrexone, when administered alone, had no effect on retention when given before testing. However, posttraining administration of naltrexone produced an enhancement of retention detectable 6 but not 3 hr after training. Furthermore, posttraining naltrexone also blocked the impairing effect of posttraining Epi otherwise seen 6 hr after training. Results suggest that the impairment of retention caused by posttraining Epi is attributable to the induction of state dependency based on an Epi state. When the animals are tested 3 hr after training, this effect appears alone. But, when tested 6 hr after training, the Epi effect appears together with an opioid presumably β-endorphin-mediated, state dependency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory enhancement with posttraining intraventricular glucose injections in rats.

Recent findings suggest that peripheral epinephrine enhancement of memory storage may be mediated in part by an increase in circulating glucose levels subsequent to epinephrine release or injection. Because glucose, unlike epinephrine, has ready access to the central nervous system (CNS), it is possible that glucose acts directly on central processes to enhance memory. To test this possibility, rats were trained on a one-trial inhibitory avoidance task and received immediate or delayed injections of glucose in artificial cerebrospinal fluid. On retention tests 24 hr after training, animals that received 3 or 5 μg glucose (in 1 μl cerebrospinal fluid over 3 min) had significantly enhanced performance of the learned response. Findings are consistent with the view that glucose can regulate the storage of new information by acting on central processes. Whether there are additional peripheral contributions to glucose effects on memory remains to be determined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of posttraining epinephrine injections on retention of avoidance training in mice

Sixty depressed nonschizophrenic patients were admitted to a research unit. Following one drug-free week and one week of placebo, patients received 3.5 mg/kg of imipramine hydrochloride for 28 days. Plasma levels of imipramine and its metabolite desipramine hydrochloride (desmethylimipramine) were measured three times weekly and the relationship between plasma steady-state levels and clinical outcome was examined. Steady-state levels ranged from 50 to 1,050 ng/ml. There was a statistically and clinically significant relationship between plasma levels and response. The relationship existed across the entire sample, and was accentuated when the bipolar and unipolar nondelusional populations were examined. Because a strong relationship between sex and outcome was observed, the unipolar nondelusional patients were stratified by sex and a significant relationship still persisted. Only the unipolar delusional patients failed to demonstrate an association between blood level and clinical response.     

Reversible lesions of the nucleus of the solitary tract attenuate the memory-modulating effects of posttraining epinephrine.

Male rats implanted with cannula tips placed above the nucleus of the solitary tract (NTS) were trained to obtain food pellets placed in 2 arms of a Y-maze and then given a footshock in 1 arm of the maze. Ss then received bilateral injections of lidocaine or buffer into the NTS and peripheral injections of saline or epinephrine (0.01 or 0.05 mg/kg, intraperitoneally [ip]). Two tests were given 24 and 48 hrs after training to assess retention in the presence and absence of contextual cues (the stainless steel floor) associated with the footshock training trial. Epinephrine (0.05 mg/kg) produced a significant enhancement in retention, which was attenuated by injections of lidocaine into the NTS. These findings indicate that the NTS is involved in mediating the memory-modulating effects of peripheral epinephrine and that such effects are initiated at least in part by activation of vagal afferents projecting to the NTS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term working memory.

To account for the large demands on working memory during text comprehension and expert performance, the traditional models of working memory involving temporary storage must be extended to include working memory based on storage in long-term memory. In the proposed theoretical framework cognitive processes are viewed as a sequence of stable states representing end products of processing. In skilled activities, acquired memory skills allow these end products to be stored in long-term memory and kept directly accessible by means of retrieval cues in short-term memory, as proposed by skilled memory theory. These theoretical claims are supported by a review of evidence on memory in text comprehension and expert performance in such domains as mental calculation, medical diagnosis, and chess. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social facilitation and inhibition to hunger-induced killing by rats.

Gave 162 male Long-Evans rats different types of experiences to alter their mouse- and rat-pup-killing behavior. First, hungry Ss given considerable experience in mouse killing did kill rat pups, whereas inexperienced Ss were unlikely to kill pups. Second, nonkilling experiences subsequently inhibited hunger-induced mouse killing. Nonkilling experience was given by presenting rat pups and mice to food-satiated Ss and by presenting rat pups to hungry Ss. Inhibition was greater when pups were presented to satiated Ss rather than to hungry, and when pups, rather than mice, were used as inhibitory stimuli. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term study of chronic oral aluminum exposure and spatial working memory in rats.

The authors report an effort to advance animal models that mimic the cognitive decline of Alzheimer's disease. Rats were trained and repeatedly tested in a spatial delayed matching-to-position paradigm in the water maze, with the location of the submerged platform changing between, but not within, days. After Trial 1 (random search) and intertrial intervals of 30 s or 1 hr, memory was tested in Trial 2. Young rats quickly acquired this task and were repeatedly tested after different intervals over 7 months, with a slight increase in performance toward the end of testing, but no difference in latencies between delays. Oral long-term treatment of 1 group with 0.1 % aluminum caused no delay-dependent working memory deficit. This testing protocol may enable between- and within-subject long-term assessment of spatial working memory before and after drug treatment and may prove useful in animal models of progressive cognitive decline. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Double dissociation of hippocampal and dorsal-striatal memory systems by posttraining intracerebral injections of 2-amino-5-phosphonopentanoic acid.

Rats received an 8-trial training session on a spatial or cued task in a water maze, followed by a posttraining intracerebral injection of AP5 or saline. On a retention test 24 hr later, latency to mount the escape platform was used as a measure of memory. Intrahippocampal (10 μg), but not intra-dorsal striatal (2, 5, or 10 μg), injection of AP5 impaired memory in the spatial task. In contrast, intra dorsal striatal (2 μg), but not intrahippocampal (2, 5, or 10 μg) injection of AP5 impaired memory in the cued task. Intracerebral injections of AP5 delayed 2 hr posttraining were ineffective. The findings indicate a double dissociation of the roles of the hippocampus and dorsal striatum in memory, a role for N -methyl-{d}-aspartate receptor function in posttraining memory processes, and a glutamatergic modulation of both hippocampal and dorsal striatal memory processes, suggesting that different forms of memory may share a similar neurochemical basis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term epinephrine therapy of ocular hypertension

Nineteen patients with symmetrical ocular hypertension and symmetrical cupping of the optic nerves were made asymmetric with respect to intraocular pressure for one to five years by unilateral topical treatment with epinephrine hydrochloride. Development of glaucomatous visual field defects was observed in 32% of the untreated eyes and in none of the treated eyes (P less than .05). Progressive cupping of the optic nerve was noted in 53% of the untreated eyes and in 11% of the treated eyes (P less than .025). Evidence of glaucomatous damage was observed more frequently in subjects maintained on this regimen for longer periods and in subjects with initial horizontal cup/disc ratios greater than 0.4 (P less than .05). None of the eyes, either treated or untreated, with mean intraocular pressures less than 24 mm Hg developed glaucomatous damage during the period of this study.     

Long-term semantic memory versus contextual memory in unconscious number processing.

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the "larger" response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social facilitation of operant behavior in satiated rats.

Tested 24 male, Long-Evans hooded rats in 2 motivational states (hungry and satiated) and 2 social conditions (single and paired) in adjacent and communicating Skinner boxes for the effect of a social stimulus on operant behavior. The social stimulus interfered in all conditions except 1: satiated Ss paired with hungry Ss pressed the bar significantly more often than in any other condition. It is concluded that the social facilitation effect is produced by progressive changes in the motivational state of the S as well as by a set of stimuli triggering the operant behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term memory loss in senescent rats: Neuropsychological analysis of interference and context effects.

Four experiments were reported in which normal, senescent (25–27 months) and young adult (6 months) rats were tested for recall of a passive avoidance response 1 hr or several weeks after conditioning. There were no age differences at the 1-hr test, but a decrement was observed in old rats tested under standard conditions after long delays. The age-related impairment was exaggerated when additional approach training was administered in an identical apparatus between avoidance conditioning and testing. When the approach training was administered in an apparatus that contrasted markedly from the original, no age differences were observed. It was concluded that increased susceptibility to interference and contextual factors contributed to rapid forgetting in old rats, a pattern very similar to that observed previously in young adult rats with selective lesions to the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term memory and mental rotation.

Performance of 45 undergraduates on a long-term memory mental rotation paradigm was investigated in 5 experiments and compared with performance in a standard (simultaneous presentation) short-term paradigm. Two related findings emerged: (a) a substantial reduction in RT slope in a "memory" version of the "mental rotation" paradigm and (b) evidence from "fold point" analyses to suggest individualized strategies by Ss in the memory condition. Both of these findings have theoretical and methodological relevance to questions about the interplay of theory and methodology in this research area. (French abstract) (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The facilitation of long-term memory improvement and operative development.

J. Piaget and B. Inhelder (1973) have reported that children's memories for pictures or events improve between early (1-wk) and late (several-month) recall sessions in conjunction with operative growth. Using the concept of verticality, the present study investigated (a) if an intervening operative training task would increase memory improvements, and (b) if exposure to the memory stimulus per se would enhance later operative performance. 97 3rd graders were randomly assigned to 1 of 4 groups—with or without operative training and with or without a memory task. At the end of the school year, all Ss were tested for operative level. The trained group showed significantly more memory progressions and fewer regressions than the untrained group on 1 of 2 memory stimuli. On the 2nd stimulus, performance was consistently high across children and recall sessions, and thus no differences were found as a function of training. Participation in the memory task enhanced later operative performance. Implications for Piagetian memory research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term memory for knowledge learned in school.

Three experiments examined students' long-term retention of knowledge learned in college courses. In Exp 1 retention was measured 4 and 11 mo after the term ended. Students retained a great deal of what they originally learned, and there were no differential forgetting effects as a function of level of original learning. Exp 2 compared retention for recall test items and 3 types of multiple-choice test items: recognition, comprehension, and mental skills. Students performed poorer on recall items, but there were no differences among the multiple-choice items measuring the other types of tasks. Exp 3 analyzed retention for student tutors. Tutors retained more after 4 mo than the students they tutored. This suggests that tutoring, a type of overlearning, has positive effects that are maintained over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)