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PURPOSE: Cancer survivors frequently report significant forgetfulness, but standard neuropsychological tests often fail to detect primary memory deficits. Past research has suggested survivors may misattribute forgetfulness to memory decay rather than impairments in initial encoding, but no studies have tested whether this pattern is evident in older survivors, who are more vulnerable to age-related memory difficulties. We examined whether long-term breast cancer survivors treated in older adulthood demonstrate deficits in initial encoding, as opposed to increased rates of memory decay, relative to non-cancer controls. METHODS: Three hundred twenty-eight breast cancer survivors age 60 and above, 5–15 years post-treatment, and 162 age-matched non-cancer controls completed list learning and narrative memory assessments at four time-points over 2 years. Performance on learning trials and delayed recall was analyzed at each time-point to assess group differences in memory encoding, and memory decay was assessed by analyzing changes in performance across delays. RESULTS: Univariate ANCOVAs correcting for age and education showed that survivors had worse initial encoding performance across multiple time-points, which were compensated for with multiple learning trials to produce recall performance comparable to controls. There were no significant group differences in memory decay. CONCLUSIONS: Older long-term breast cancer survivors exhibit a consistent pattern of initial encoding deficits, but memory retention was comparable to controls. Future research should consider the role of encoding deficits and age-related factors when evaluating cognitive function in older survivors. IMPLICATIONS FOR CANCER SURVIVORS: Commonly reported memory problems may stem from encoding deficits in older long-term cancer survivors.

Invasive species can have profound impacts in non-native environments, the mechanisms behind which are often unclear. Learning and memory are notably two traits that may facilitate their impact. Behavioural traits can subsequently mediate learning ability in invasive species, the interaction between which may provide means by which to both better understand and manage invaders. We evaluated this relationship in lionfish (Pterois volitans), a species introduced to and invasive in the western Atlantic Ocean. We trained lionfish in a food reward task and assessed the degree to which behavioural traits and navigation strategy influenced their performance. We then evaluated memory retention by subjecting fish to training breaks of 5 to 42 days. Lionfish exhibited high inter-individual variability in learning. Half of the lionfish tested learned to navigate the maze, whose performance was strongly mediated by behaviour. Learning ability was positively correlated with boldness, exploratory tendency, and speed of task completion, but irrespective of spatial navigation strategy. However, fast exploratory fish trained in the complex navigation strategy had difficulty adapting to changing environmental conditions, indicative of a speed-accuracy trade-off. Lionfish were able to remember the location of the food reward for up to 6 weeks. Behavioural-mediated learning may help explain and understand the high impact of lionfish and other non-indigenous species in their invaded range and may elucidate spatiotemporal context-dependencies in their ecological impact.

Visual working memory retains visual information for controlling behavior. We studied how information in visual working memory is prioritized for being used. In two experiments, participants memorized the stimuli of a memory display for a brief interval, followed by a retro-cue. The retro-cue was either valid, indicating which stimulus from the memory display was relevant (i.e., had priority) in the upcoming comparison with a probe, or was neutral (uninformative). Next, the probe was presented, terminated by a mask, and participants reported whether it matched a stimulus from the memory display. The presentation duration of the probe was varied. Assessing performance as a function of presentation duration allowed to disentangle two components of working memory: memory retention and the speed of processing the probe for the memory-based comparison. Compared with neutral retro-cues, valid retro-cues improved retention and at the same time accelerated processing of the probe. These findings show for the first time that prioritization in working memory impacts on distinct mechanisms: retrospectively, it supports memory retention, and prospectively, it enhances perceptual processing in upcoming comparison tasks.

Memory consolidation requires astrocytic microdomains for protein recycling; but whether this lays a mechanistic foundation for long-term information storage remains enigmatic. Here we demonstrate that persistent synaptic strengthening invited astrocytic microdomains to convert initially internalized (pro)-brain-derived neurotrophic factor (proBDNF) into active prodomain (BDNFpro) and mature BDNF (mBDNF) for synaptic re-use. While mBDNF activates TrkB, we uncovered a previously unsuspected function for the cleaved BDNFpro, which increases TrkB/SorCS2 receptor complex at post-synaptic sites. Astrocytic BDNFpro release reinforced TrkB phosphorylation to sustain long-term synaptic potentiation and to retain memory in the novel object recognition behavioral test. Thus, the switch from one inactive state to a multi-functional one of the proBDNF provides post-synaptic changes that survive the initial activation. This molecular asset confines local information storage in astrocytic microdomains to selectively support memory circuits., Beatrice Vignoli et al. examine potential molecular mechanisms of long-term storage information in mice. Their results suggest that astrocytes may help convert neuronal BDNF precursor into active prodomain and mature forms to enhance post-synaptic signaling and memory, providing further insight into the development of memory circuits.

Many studies have shown that practicing retrieval produces better memory retention compared to restudy. Though previous literature has provided valuable insights about the retrieval practice effect, it is still unclear how emotion arousal influences the retrieval practice effect, and whether the effect would be manifested in recollection or familiarity processes. To answer these questions, in the current study, negative and neutral words were used as stimuli and participants were asked to perform a recognition test or restudy the words after initial study. At the end of the experiment, a final recognition test with involving the remember-know paradigm was shown. Behavioral data were collected with EEG recorded throughout the experiment. The behavioral retrieval practice effect was only found for the neutral but not the negative words. Consistently, significant ERP differences between the restudy and retrieval practice conditions were only found for neutral, but not negative items, which was a component from 700 to 900 ms at left-posterior electrode cluster. Moreover, we found that the effects of emotion arousal on the retrieval practice effect were mainly reflected in the recollection process. These findings provide behavioral and neural evidence that emotion arousal can influence the retrieval practice effect.

It remains unknown whether transcranial alternating current stimulation (tACS) affects episodic memory and the effect of gamma oscillations delivered to the left prefrontal cortex (PFC) on long-term memory retention has not been fully investigated. We examined whether tACS over the left PFC enhances recognition of episodic memory. The study enrolled 36 healthy young adult volunteers. The participants were randomly assigned to either a tACS group [n = 18; 14 females; mean age ± standard deviation (SD): 21.2 ± 0.4 years] or a sham-control group [n = 18; 14 females; mean age ± SD: 21.2 ± 0.4 years]. Participants received either tACS or sham stimulation both during the learning task that was conducted on day 1 and during a recognition task on day 2. The recognition task was also conducted on days 1 and 7, and response accuracy was measured at all three time points (days 1, 2, and 7). Patients in the tACS group were better able to retain long-term memory than those in the sham-control group. These findings suggest that tACS over the left PFC enhances recognition of episodic memory in healthy young adults.

When listening, familiarity with an attended talker’s voice improves speech comprehension. Here, we instead investigated the effect of familiarity with a distracting talker. In an irrelevant-speech task, we assessed listeners’ working memory for the serial order of spoken digits when a task-irrelevant, distracting sentence was produced by either a familiar or an unfamiliar talker (with rare omissions of the task-irrelevant sentence). We tested two groups of listeners using the same experimental procedure. The first group were undergraduate psychology students (N=66) who had attended an introductory statistics course. Critically, each student had been taught by one of two course instructors, whose voices served as familiar and unfamiliar task-irrelevant talkers. The second group of listeners were family members and friends (N=20) who had known either one of the two talkers for more than ten years. Students, but not family members and friends, made more errors when the task-irrelevant talker was familiar versus unfamiliar. Interestingly, the effect of talker familiarity was not modulated by the presence of task-irrelevant speech: students experienced stronger working-memory disruption by a familiar talker irrespective of whether they heard a task-irrelevant sentence during memory retention or merely expected it. While previous work has shown that familiarity with an attended talker benefits speech comprehension, our findings indicate that familiarity with an ignored talker deteriorates working memory for target speech. The absence of this effect in family members and friends suggests that the degree of familiarity modulates memory disruption.

The orbitofrontal cortex (OFC) is thought to link stimuli and actions with anticipated outcomes in order to sustain flexible behavior in an ever-changing environment. How it retains these associations to guide future behavior is less well-defined. Here we focused on one subregion of this heterogeneous structure, the ventrolateral OFC (VLO). CaMKII-driven inhibitory Gi-coupled designer receptors exclusively activated by designer drugs (DREADDs) were infused and subsequently activated by their ligand Clozapine-N-oxide (CNO) in conjunction with fear extinction training (a form of aversive conditioning) and response-outcome conditioning (a form of appetitive conditioning). Gi-DREADD-mediated inactivation of the VLO during extinction conditioning interfered with fear extinction memory, resulting in sustained freezing when mice were later tested drug-free. Similarly, Gi-DREADD-mediated inactivation in conjunction with response-outcome conditioning caused a later decay in goal-directed responding-that is, mice were unable to select actions based on the likelihood that they would be rewarded in a sustainable manner. By contrast, inhibitory Gi-DREADDs in the basolateral amygdala (BLA) impaired the acquisition of both conditioned fear extinction and response-outcome conditioning, as expected based on prior studies using other inactivation techniques. Meanwhile, DREADD-mediated inhibition of the dorsolateral striatum enhanced response-outcome conditioning, also in line with prior reports. Together, our findings suggest that learning-related neuroplasticity in the VLO may be necessary for memory retention in both appetitive and aversive domains.

The effectiveness of retrieval practice for aiding long-term memory, referred to as the testing effect, has been widely demonstrated. However, the specific neurocognitive mechanisms underlying this phenomenon remain unclear. In the present study, we sought to explore the role of pre-retrieval processes at initial testing on later recognition performance by using event-related potentials (ERPs). Subjects studied two lists of words (Chinese characters) and then performed a recognition task or a source memory task, or restudied the word lists. At the end of the experiment, subjects received a final recognition test based on the remember-know paradigm. Behaviorally, initial testing (active retrieval) enhanced memory retention relative to restudying (passive retrieval). The retrieval mode at initial testing was indexed by more positive-going ERPs for unstudied items in the active-retrieval tasks than in passive retrieval from 300 to 900 ms. Follow-up analyses showed that the magnitude of the early ERP retrieval mode effect (300-500 ms) was predictive of the behavioral testing effect later on. In addition, the ERPs for correctly rejected new items during initial testing differed between the two active-retrieval tasks from 500 to 900 ms, and this ERP retrieval orientation effect predicted differential behavioral testing gains between the two active-retrieval conditions. Our findings confirm that initial testing promotes later retrieval relative to restudying, and they further suggest that adopting pre-retrieval processing in the forms of retrieval mode and retrieval orientation might contribute to these memory enhancements.

Using rat model of experimental anxiety-depressive disorder caused by postnatal administration of methionyl-2(S)-cyanopyrrolidine, an inhibitor of dipeptidyl peptidase IV, we compared conditioned active avoidance response and memory retention in males and females. In experimental males and females, conditioning was impaired in comparison with the control. In experimental groups, females were worse learners than males, while in control groups, females were better learners than males. Memory retention in experimental animals did not differ from that in controls 24 h after learning. Two months after learning, control females demonstrated better retention than control males.

Humans and rats poisoned with sarin develop chronic neurological disabilities that are not prevented with standardized antidotal therapy. We hypothesized that rats poisoned with the sarin analogue diisopropylfluorophosphate (DFP) and resuscitated with atropine and pralidoxime would have long-term memory deficits that were preventable with naltrexone treatment. Long Evans rats (250–275 g) were randomized to: DFP (N = 8): single subcutaneous (SC) injection of DFP (5 mg/kg). Treatment (N = 9): DFP (5 mg/kg) followed by chronic naltrexone (5 mg/kg/day × 12 weeks). Control (N = 12): single SC injection of isopropyl alcohol, (DFP vehicle) followed by chronic naltrexone (5 mg/kg/day). If toxicity developed after injection, antidotal therapy was initiated with atropine (2 mg/kg) and pralidoxime (25 mg/kg) and repeated as needed. After 12 weeks, rats underwent testing for place learning (acquisition) across 5 days of training using the Morris Water Maze. On day 6 a memory retention test was performed. Statistical analysis was performed using IBM SPSS Statistics. Rats receiving DFP rapidly developed toxicity requiring antidotal rescue. No differences in acquisition were seen between the DFP vs. DFP + naltrexone rats. During memory testing, DFP-poisoned rats spent significantly less time (29.4 ± 2.11 versus 38.5 ± 2.5 s, p 0.05) on the test for memory retention. Poisoning with DFP induced impaired memory retention. Deficits were not prevented by acute rescue with atropine and pralidoxime. Chronic naltrexone treatment led to preserved memory after DFP poisoning.

In the present study, we examined how the function relating continued retrieval practice (e.g., one, three, or five tests) and long-term memory retention is modulated by desirable difficulty (R. A. Bjork, 1994). Of particular interest was how retrieval difficulty differed across young and older adults and across manipulations of lag (Exp. 1) and spacing (Exp. 2). To extend on previous studies, the acquisition phase response latency was used as a proxy for retrieval difficulty, and our analysis of final-test performance was conditionalized on acquisition phase retrieval success, to more directly examine the influence of desirable difficulty on retention. The results from Experiment 1 revealed that continued testing in the short-lag condition led to consistent increases in retention, whereas continued testing in the long-lag condition led to increasingly smaller benefits in retention for both age groups. The results from Experiment 2 revealed that repeated spaced testing enhanced retention relative to taking one spaced test, for both age groups; however, repeated massed testing only enhanced retention over taking one test for young adults. Across both experiments, the response latency results were overall consistent with an influence of desirable difficulty on retention. The discussion focuses on the role of desirable difficulty during encoding in producing the benefits of lag, spacing, and testing.

To promote consistent thinking about nutrition, we gave the students thought-provoking, one-a-day nutrition questions throughout a 4-week gastroenterology course. The interactive and detailed feedback for each question also served as an education tool. The questions helped to increase competency in nutrition by enhancing learning and memory retention of concepts.

How can we improve memory retention? A large body of research has suggested that difficulty encountered during learning, such as when practice sessions are distributed rather than massed, can enhance later memory performance (see R. A. Bjork & E. L. Bjork, 1992). Here, we investigated whether divided attention during retrieval practice can also constitute a desirable difficulty. Following two initial study phases and one test phase with Swahili–English word pairs (e.g., vuvi–snake), we manipulated whether items were tested again under full or divided attention. Two days later, participants were brought back for a final cued-recall test (e.g., vuvi–?). Across three experiments (combined N = 122), we found no evidence that dividing attention while practicing retrieval enhances memory retention. This finding raises the question of why many types of difficulty during practice do improve long-term retention, but dividing attention does not.

Aged dogs spontaneously develop progressive decline in both cognitive and behavioral function, in addition to neuropathological changes, that collectively parallel several aspects of human aging and Alzheimer's disease progression and likely contribute to the development of canine cognitive dysfunction syndrome. In the current study, ethologically relevant spatial learning, retention, and reversal learning tasks were conducted, with the goal of expanding canine neuropsychological testing to pet dogs. Initially, dogs (N = 44, aged 7.8 ± 2.8 years, mean ± SD) had to learn which of two alternative routes successfully led out of a T-maze. Two weeks later, long-term memory retention was assessed, immediately followed by a reversal learning task in which the previously correct route out of the maze was reversed compared with the initial learning and memory retention tasks. No effects of age were evident on the learning or retention tasks. However, older (≥ 8 years) dogs were significantly impaired on the reversal learning task compared with younger ones (8 years). Moreover, trial response latency was significantly increased in aged dogs across both the initial and reversal learning tasks but not on the retention task, which suggests that processing speed was impaired by increasing age during the acquisition of novel spatial information but not during performance of previously learned responses. Overall, the current study provides a framework for assessing cognitive function in pet dogs, which should improve understanding of the effects of aging on cognition in the dog population.

Time-dependent effects of ethanolic extract of Boswellia papyrifera, administered systemically, on spatial memory retention in the Morris water maze were investigated in male rats. A total extract of Boswellia papyrifera (300 mg/kg) was administered every eight hours to three groups of rats by gavage for 1, 2 and 4 weeks. In a separate set of experiments, three doses of a fraction of the extract, called the boswellic acids (100, 200 and 300 mg/kg) were administered by gavage to three groups of rats three times a day for 2 weeks. Following these applications, animals were trained for 4 days. Behavioral testing for evaluation of spatial memory retention was performed 48 h after completion of training. Boswellia papyrifera extracts and boswellic acids caused a significant reduction in escape latency and distance traveled but had no influence on swimming speed. These findings provide evidence that Boswellia papyrifera extracts affect spatial memory retention irrespective of the treatment period. In addition our data show that systemic administration of the boswellic acids fraction enhanced spatial memory retention in a dose-dependent manner. These improving effects may be due to some extent to the interactions of these products with inflammatory mediators, neurotransmitter signaling cascades or protein kinase pathways in the brain.

When mining software repositories, two distinct sources of information are usually explored: the history log and snapshots of the system. Results of analyses derived from these two sources are biased by the frequency with which developers commit their changes. We argue that the usage of mainstream SCM (software configuration management) systems influences the way that developers work. For example, since it is tedious to resolve conflicts due to parallel commits, developers tend to minimize conflicts by not contemporarily modifying the same file. This however defeats one of the purposes of such systems. We mine repositories created by our tool Syde, which records changes in a central repository whenever a file is compiled locally in the IDE (integrated development environment) by any developer in a multi-developer project. This new source of information can augment the accuracy of analyses and breaks new ground in terms of how such information can assist developers. We illustrate how the information we mine provides a refined notion of code ownership with respect to the one inferred by SCM system data. We demonstrate our approach on three case studies, including an industrial one. Ownership models suffer from the assumption that developers have a perfect memory. To account for their imperfect memory, we integrate into our ownership measurement a model of memory retention, to simulate the effect of memory loss over time. We evaluate the characteristics of this model for several strengths of memory.

Background Spaced-repetition and test-enhanced learning are two methodologies that boost knowledge retention. ALERT STUDENT is a platform that allows creation and distribution of Learning Objects named flashcards, and provides insight into student judgments-of-learning through a metric called ‘recall accuracy‘. This study aims to understand how the spaced-repetition and test-enhanced learning features provided by the platform affect recall accuracy, and to characterize the effect that students, flashcards and repetitions exert on this measurement. Methods Three spaced laboratory sessions (s0, s1 and s2), were conducted with n=96 medical students. The intervention employed a study task, and a quiz task that consisted in mentally answering open-ended questions about each flashcard and grading recall accuracy. Students were randomized into study-quiz and quiz groups. On s0 both groups performed the quiz task. On s1 and s2, the study-quiz group performed the study task followed by the quiz task, whereas the quiz group only performed the quiz task. We measured differences in recall accuracy between groups/sessions, its variance components, and the G-coefficients for the flashcard component. Results At s0 there were no differences in recall accuracy between groups. The experiment group achieved a significant increase in recall accuracy that was superior to the quiz group in s1 and s2. In the study-quiz group, increases in recall accuracy were mainly due to the session, followed by flashcard factors and student factors. In the quiz group, increases in recall accuracy were mainly accounted by flashcard factors, followed by student and session factors. The flashcard G-coefficient indicated an agreement on recall accuracy of 91% in the quiz group, and of 47% in the study-quiz group. Conclusions Recall accuracy is an easily collectible measurement that increases the educational value of Learning Objects and open-ended questions. This metric seems to vary in a way consistent with knowledge retention, but further investigation is necessary to ascertain the nature of such relationship. Recall accuracy has educational implications to students and educators, and may contribute to deliver tailored learning experiences, assess the effectiveness of instruction, and facilitate research comparing blended-learning interventions. Electronic supplementary material The online version of this article (doi:10.1186/s12909-014-0275-0) contains supplementary material, which is available to authorized users.

Background The increasing complexity of medical curricula would benefit from adaptive computer supported collaborative learning systems that support study management using instructional design and learning object principles. However, to our knowledge, there are scarce reports regarding applications developed to meet this goal and encompass the complete medical curriculum. The aim of ths study was to develop and assess the usability of an adaptive computer supported collaborative learning system for medical students to manage study sessions. Results A study platform named ALERT STUDENT was built as a free web application. Content chunks are represented as Flashcards that hold knowledge and open ended questions. These can be created in a collaborative fashion. Multiple Flashcards can be combined into custom stacks called Notebooks that can be accessed in study Groups that belong to the user institution. The system provides a Study Mode that features text markers, text notes, timers and color-coded content prioritization based on self-assessment of open ended questions presented in a Quiz Mode. Time spent studying and Perception of knowledge are displayed for each student and peers using charts. Computer supported collaborative learning is achieved by allowing for simultaneous creation of Notebooks and self-assessment questions by many users in a pre-defined Group. Past personal performance data is retrieved when studying new Notebooks containing previously studied Flashcards. Self-report surveys showed that students highly agreed that the system was useful and were willing to use it as a reference tool. Conclusions The platform employs various instructional design and learning object principles in a computer supported collaborative learning platform for medical students that allows for study management. The application broadens student insight over learning results and supports informed decisions based on past learning performance. It serves as a potential educational model for the medical education setting that has gathered strong positive feedback from students at our school. This platform provides a case study on how effective blending of instructional design and learning object principles can be brought together to manage study, and takes an important step towards bringing information management tools to support study decisions and improving learning outcomes.

It has been reported that selective GABA(B) receptor antagonists can enhance cognitive performance in a variety of learning paradigms. This prompted us to examine the effects of some more potent and newly synthesised GABAB antagonists CGP 71982, CGP 62349 and CGP 55845A in an active avoidance test in rats. A two-way active avoidance test with negative reinforcement was performed for the first 5 of 12 days of antagonist administration. CGP 71982 and CGP 55845A at all doses applied (0.01-1.0 mg/kg) had an improving effect on learning, and memory retention on day 12; the rats made more avoidances in both sessions compared to controls. CGP 62349 was only active at the lowest dose tested (0.01 mg/kg). The present study confirms that GABA(B) receptor antagonists can enhance cognitive performance but provides no insight into the mechanism of action of these novel antagonists.

A new finding suggests that memory removal may be an active process, as blocking NMDA receptors after induction of long-term potentiation prolongs LTP and memory retention.

Result Post-training subcutaneous (s.c.) injection of morphine dose-dependently induced impairment of memory retention, indicating morphine-induced amnesia. Intra-CA1 microinjections of different doses of nicotine, immediately before post-training administration of morphine dose-dependently inhibited morphine-induced amnesia. While, post-training bilateral microinjections of the same doses of nicotine into the CA1 regions alone did not affect memory retention.

SrBi2Ta2O9(SBT) films have been prepared by the sol-gel technique on n-Si(100) substrates and nonvolatile memory operation of a metal-ferroelectric-semiconductor field effect transistor (MFSFET) using the SBT/Si structure has been demonstrated. Ploy-crystalline SBT films can be obtained on Si substrates and it is shown by the secondary ion mass spectrometry (SIMS) that the inter-diffusion between SBT and Si is suppressed even though high annealing temperature is required for the SBT film growth. Then the SBT/Si MFSFETs have been fabricated. Drain current - gate voltage characteristics clearly show hysteresis loops due to the ferroelectric nature of the SBT film. It is demonstrated that the drain current can be controlled by the “write” pulse, which was applied before the measurements, even at the same “read” gate voltage. Memory retention characteristics of SBT/Si MFSFETs are also presented.

Hippocampal insulin-like growth factor 2 (IGF2) has a crucial role in memory consolidation and can improve memory retention.

Three experiments describe retroactive memory enhancement in chicks by chlorpromazine (CPZ), a potent membrane stabilizer at anesthetic doses. First, chicks trained on a one-trial peck suppression task under moderate aversant conditions and given 60--144 mg CPZ/kg, intraperitoneally, displayed increased memory retention 24 h later when compared with chicks given saline or 15--36 mg CPZ/kg. The second experiment confirmed the memory enhancement using a different moderate aversant on a different peck target and extended the effect to 48 h. The third experiment demonstrated the CPZ effect to be retrograde because the enhancement observed when CPZ was injected 1 min or 3 min after training did not occur when injection was delayed 4 h. One speculative interpretation of retrograde enhancement with CPZ includes the stabilization of swollen dendritic spines, which may facilitate neuronal pathways.

During the postnatal period, male Wistar rats were treated with orotate, either from the 6th to 15th, 16th to 25th, or 26th to 35th day of life. Learning and memory were tested in adulthood. Rats that received orotate from the 6th to 15th day showed a better retention of a learned brightness discrimination (Y-maze) than controls. An active avoidance (pole jumping) was learned more quickly by the rats orotate-treated from the 6th to 15th day than by controls. The spontaneous locomotor activity of previously orotate-treated rats was the same as in controls. Body weight measurements revealed no differences between orotate rats and control rats. The results suggest that memory retention in adulthood can be improved by postnatal orotate treatment.

The effect of methylglucamine orotate (MGO) on learning and memory was investigated in 24-month-old rats using brightness discrimination in a Y-chamber and active avoidance in a shuttle box. In both learning procedures, an improvement of memory retention following 5-day MGO treatment (225 mg/kg per day) was observed. The retention of untreated old animals was significantly lower compared to 8-week-old rats. MGO treatment resulted in a significant improvement of retention in old rats, which nearly compensated for their memory deficit.

Effect of ECS on memory retention was studied in Octopus vulgaris. Two methods of training were used. 1. Animals trained in a shuttle-box to swim from a dark to a light compartment and to remain there during 25 sec to avoid electroshock, were given 20 learning trials on Day 1 and 10 retention trials 3 days later. No improvement in the performance occurred concerning anticipatory runs to the light compartment but a significant decrease in the number of returns to the dark compartment (incorrect crossings) during Day 1 was recorded. ECS within 1 min after trial 20 caused significant deficits in retention. 2. Animals that previously had been learnt to attack a vertical rectangle moved up and down, were given 30 trials during which if octopuses attacked the shape they would now receive a shock. 15 retention trials were run 2 days later. ECS within 1 min after trial 30 caused significant deficit in retention.