Effects of morphine and its withdrawal on Y-maze spatial recognition memory in mice

Effects of morphine on acquisition and retrieval of memory have been proven in the avoidance paradigms. In present study, we used a two-trial recognition Y-maze to test the effects of acute morphine and morphine withdrawal on spatial recognition memory. T

Both stress experience and age determine the impairment or enhancement effect of stress on spatial memory retrieval

It has been documented that stress or glucocorticoids have conflicting effects on memory under different conditions. However, it is not fully understood why stress can either impair or enhance memory. Here, we have examined the performance of six age groups of Wistar rats in a water maze spatial task to evaluate the effects of stress under different conditions. We found that the impairment or enhancement effect of an 'elevated platform' (EP) stress on memory was dependent on previous stress experience and on age. EP stress impaired memory retrieval in water maze naive animals. but enhanced rather than impaired memory retrieval in young water maze stress-experienced animals. Furthermore, exogenously applied corticosterone or foot shock stress before water maze training prevented the impairment of memory retrieval that should be induced by treatment with corticosterone or foot shock before the 'probe trial'. Again, memory retrieval was enhanced in young animals under these conditions, and this enhancement can be prevented by the glucocorticoid receptor antagonist RU 38486. Thus, glucocorticoid receptor activation not only induced impairment of memory but also increased the capacity of young animals to overcome a later stress. The present findings suggest that the effect of stress on memory can be switched from impairment to enhancement dependent on both stress experience and age.

Impact of astaxanthin-enriched algal powder of Haematococcus pluvialis on memory improvement in BALB/c mice

The impact of astaxanthin-enriched algal powder on auxiliary memory improvement was assessed in BALB/c mice pre-supplemented with different dosages of cracked green algal (Haematococcus pluvialis) powder daily for 30 days. The supplemented mice were first tested over 8 days to find a hidden platform by swimming in a Morris water maze. Then, for 5 days, the mice were used to search for a visible platform in a Morris water maze. After that, the mice practised finding a safe place-an insulated platform in a chamber-for 2 days. During these animal experimental periods, similar algal meals containing astaxanthin at 0, 0.26, 1.3 and 6.4 mg/kg body weight were continuously fed to each group of tested mice. Profiles of latency, distance, speed and the direction angle to the platforms as well as the diving frequency in each group were measured and analyzed. The process of mice jumping up onto the insulated platform and diving down to the copper-shuttered bottom with a 36 V electrical charge were also monitored by automatic video recording. The results of the Morris maze experiment showed that middle dosage of H. pluvialis meals (1.3 mg astaxanthin/kg body weight) significantly shortened the latency and distance required for mice to find a hidden platform. However, there was no obvious change in swim velocity in any of the supplemented groups. In contrast, the visible platform test showed a significant increase in latency and swim distance, and a significant decrease in swim speed for all groups of mice orally supplemented with H. pluvialis powder compared to the placebo group (P < 0.05 or P < 0.01). Mice supplemented with the algal meal hesitantly turned around the original hidden platform, in contract to mice supplemented with placebo, who easily forgot the original location and accepted the visible platform as a new safe place. These results illustrate that astaxanthin-enriched H. pluvialis powder has the auxiliary property of memory improvement. The results from the platform diving test showed that the low and middle dosage of H. pluvialis powder, rather that the high dosage, increased the latency and reduced the frequency of diving from the safe insulated platform to the electrically stimulated copper shutter, especially in the low treatment group (P < 0.05). These results indicate that H. pluvialis powder is associated with dose-dependent memory improvement and that a low dosage of algal powder (<= middle treatment group) is really good for improving the memory.

The computer simulation of primate (Macaca mulatta) spatial visual delayed response and cerebral prefrontal control function

Cerebral prefrontal function is one of the important aspects in neurobiology. Based on the experimental results of neuroanatomy, neurophysiology, behavioral sciences, and the principles of cybernetics and information theory after constructed a simple model simulating prefrontal control function, this paper simulated the behavior of Macaca mulatta completing delayed tasks both before and after its cerebral prefrontal cortex being damaged. The results indicated that there is an obvious difference in the capacity of completing delayed response tasks for the normal monkeys and those of prefrontal cortex cut away. The results are agreement with experiments. The authors suggest that the factors of affecting complete delayed response tasks might be in information keeping and extracting of memory including information storing, keeping and extracting procedures rather than in information storing process.

Effects of Prenatal Exposure to a 50-Hz Magnetic Field on One-Trial Passive Avoidance Learning in 1-Day-Old Chicks

We investigated memory impairment in newly hatched chicks following in ovo exposure to a 50-Hz magnetic field (MF) of 2 mT (60 min/day) on embryonic days 12-18. Isolated and paired chicks were used to test the effect of stress during training, and memory retention was tested at 10, 30, and 120 min, following exposure to a bitter-tasting bead (100% methylanthranilate). Results showed that memory was intact at 10 min in both isolated and paired chicks with or without MF exposure. However, while isolated chicks had good memory retention levels at 30 and 120 min, those exposed to MF did not. The results suggest a potential disruption of memory formation following in ovo exposure to MF, with this effect only evident in the more stressed, isolated chicks. Bioelectromagnetics 31:150-155, 2010. (C) 2009 Wiley-Liss. Inc.

Spatial exploration induces a persistent reversal of long-term potentiation in rat hippocampus

Experience-dependent long-lasting increases in excitatory synaptic transmission in the hippocampus are believed to underlie certain types of memory(1-3). Whereas stimulation of hippocampal pathways in freely moving rats can readily elicit a long-term potentiation (LTP) of transmission that may last for weeks, previous studies have failed to detect persistent increases in synaptic efficacy after hippocampus-mediated learning(4-6). As changes in synaptic efficacy are contingent on the history of plasticity at the synapses(7), we have examined the effect of experience-dependent hippocampal activation on transmission after the induction of LTP, We show that exploration of a new, non-stressful environment rapidly induces a complete and persistent reversal of the expression of high-frequency stimulation-induced early-phase LTP in the CA1 area of the hippocampus, without affecting baseline transmission in a control pathway. LTP expression is not affected by exploration of familiar environments. We found that spatial exploration affected LTP within a defined time window because neither the induction of LTP nor the maintenance of long-established LTP was blocked. The discovery of a novelty-induced reversal of LTP expression provides strong evidence that extensive long-lasting decreases in synaptic efficacy may act in tandem with enhancements at selected synapses to allow the detection and storage of new information by the hippocampus.

Lead exposure through gestation-only caused long-term learning/memory deficits in young adult offspring

Numerous observations in clinical and preclinical studies indicate that the developing brain is particular sensitive to lead (Pb)'s pernicious effects. However, the effect of gestation-only Pb exposure on cognitive functions at maturation has not been studied. We investigated the potential effects of three levels of Pb exposure (low, middle, and high Pb: 0.03%, 0.09%, and 0.27% of lead acetate-containing diets) at the gestational period on the spatial memory of young adult offspring by Morris water maze spatial learning and fixed location/visible platform tasks. Our results revealed that three levels of Pb exposure significantly impaired memory retrieval in male offspring, but only female offspring at low levels of Pb exposure showed impairment of memory retrieval. These impairments were not due to the gross disturbances in motor performance and in vision because these animals performed the fixed location/visible platform task as well as controls, indicating that the specific aspects of spatial learning/memory were impaired. These results suggest that exposure to Pb during the gestational period is sufficient to cause long-term learning/memory deficits in young adult offspring. (C) 2003 Elsevier Inc. All rights reserved.

Opioid Withdrawal for 4 Days Prevents Synaptic Depression Induced by Low Dose of Morphine or Naloxone in Rat Hippocampal CA1 Area In Vivo

The formation of memory is believed to depend on experience- or activity-dependent synaptic plasticity, which is exquisitely sensitive to psychological stress since inescapable stress impairs long-term potentiation (LTP) but facilitates long-term depression (LTD). Our recent studies demonstrated that 4 days of opioid withdrawal enables maximal extents of both hippocampal LTP and drug-reinforced behavior; while elevated-platform stress enables these phenomena at 18 h of opioid withdrawal. Here, we examined the effects of low dose of morphine (0.5 mg kg(-1), i.p.) or the opioid receptor antagonist naloxone (1 mg kg(-1), i.p.) on synaptic efficacy in the hippocampal CA1 region of anesthetized rats. A form of synaptic depression was induced by low dose of morphine or naloxone in rats after 18 h but not 4 days of opioid withdrawal. This synaptic depression was dependent on both N-methyl-D-aspartate receptor and synaptic activity, similar to the hippocampal long-term depression induced by low frequency stimulation. Elevated-platform stress given 2 h before experiment prevented the synaptic depression at 18 h of opioid withdrawal; in contrast, the glucocorticoid receptor (GR) antagonist RU38486 treatment (20 mg kg(-1), s.c., twice per day for first 3 days of withdrawal), or a high dose of morphine reexposure (15 mg kg(-1), s.c., 12 h before experiment), enabled the synaptic depression on 4 days of opioid withdrawal. This temporal shift of synaptic depression by stress or GR blockade supplements our previous findings of potentially correlated temporal shifts of LTP induction and drug-reinforced behavior during opioid withdrawal. Our results therefore support the idea that stress experience during opioid withdrawal may modify hippocampal synaptic plasticity and play important roles in drug-associated memory. (C) 2009 Wiley-Liss, Inc.

A time-varying controllable fault-tolerant field associative memory model and its simulation

A time-varying controllable fault-tolerant field associative memory model and the realization algorithms are proposed. On the one hand, this model simulates the time-dependent changeability character of the fault-tolerant field of human brain's associative memory. On the other hand, fault-tolerant fields of the memory samples of the model can be controlled, and we can design proper fault-tolerant fields for memory samples at different time according to the essentiality of memory samples. Moreover, the model has realized the nonlinear association of infinite value pattern from n dimension space to m dimension space. And the fault-tolerant fields of the memory samples are full of the whole real space R-n. The simulation shows that the model has the above characters and the speed of associative memory about the model is faster.

加工深度、记忆材料类型对FOK和FOnK判断的影响

Predecessors’ research found that feeling-of-knowing and feeling-of-not-knowing was two different cognitional processes. Processing depth had more good effects on FOK judgment, but it had little effects on FOnK judgment, furthermore, it perhaps decreased the accuracy of FOnK judgment. On the base of predecessors’ research the experiment discussed the different effects on FOK judgment and FOnK judgment by processing depth and memory materials of different kinds. The first purpose was to find that the effects of processing depth on FOK judgment and FOnK judgment were different or not. The second purpose was to reveal the two different memory materials of the Paired-Chinese-words and the Paired- Chinese-phonetic-alphabet would cause difference on the grade and accuracy of FOK judgment or not, and if the two different kinds of memory materials took different effects on FOK judgment and FOnK judgment. The third purpose was to search if there was interaction on processing depth and different kinds of memory materials. The experiment used the Paired-Chinese-words and the Paired- Chinese-phonetic-alphabet as the materials, and regarded processing depth in the time of encoding stage and different kinds of memory materials as the independent variable. The experiment regarded validity of memory; the grade of FOK judgment; the accuracy of FOK judgment; the accuracy of FOnK judgment as the dependent variable. The experiment adopted the “RJR” normal researching form of FOK judgment projected by Hart. The result of the researching proved that in the condition of deep processing in the time of encoding stage, the validity of memory; the grade of FOK judgment; the accuracy of FOK judgment were higher than in the condition of superficial processing, but processing depth had little effect on accuracy of FOnK judgment. FOK judgment and FOnK judgment were two different cognitional processes. Memory materials of different kinds led clear difference on the dependent variable of the validity of memory; the grade of FOK judgment; the accuracy of FOK judgment, and also had little effect on accuracy of FOnK judgment. Processing depth and different kinds of memory materials had interaction on their effects on FOK judgment. Regard the accuracy of recall, the percentage of “feeling of knowing”, the percentage of “feeling of not knowing”, and the grade of FOK judgment as the dependent variables, memory materials of different kinds make little effect in the condition of superficial processing in the time of encoding stage, but in the condition of deep processing in the time of encoding stage, Chinese characters was higher than Chinese phonetic alphabet.

基于可复制性的独立成分分析——应用于功能磁共振成像数据

This dissertation systematically depicted and improved the application of Independent Component Analysis (ICA) to Functional Magnetic Resonance Imaging (fMRI), following the logic of verification, improvement, extension, and application. The concept of “reproducibility” was the philosophy throughout its four concluded studies. In the “verification” study, ICA was applied to the resting-state fMRI data, verified the resultant components with reproducibility, and examined the consistency of the results from ICA and traditional “seed voxel” method. At the meantime, the limitation of ICA application on fMRI data analysis was presented. In the “improvement” study, an improved ICA algorithm based on reproducibility, RAICAR, was developed to aid some of the limitations of ICA application. RAICAR was able to rank ICA components by reproducibility, determine the number of reliable components, and obtain more stable results. RAICAR provided useful tools for validation and interpretation of ICA results. In the “extension” study, RAICAR as well as the concept of “reproducibility” was extended to multi-subject ICA analysis, and gRAICAR algorithm was developed. gRAICAR allows some variation across subjects, examining common components among subjects. gRAICAR is also capable to detect potential subject grouping on some components. It is a new way for exploratory group analysis on fMRI. In the “application” study, two newly developed methods, RAICAR and gRAICAR, were used to investigate the effect of early music training on the brain mechanism of memory and learning. The results showed brain mechanism difference in memory retrieval and learning process between two groups of subjects. This study also verified the usefulness and importance of the new methods.

PLCß介导的钙调腺苷酸环化酶在突触可塑性相关基因转录中的作用和FE65对海马依赖学习及LTP的调节

Gene regulation is required for activity-dependent changes in synaptic plasticity and remodeling. The metabotropic glutamate receptors (mGluRs) contribute to different brain functions, including learning/memory, mental disorders, drug addiction, and persistent pain in the CNS. We found that Gp I mGluRs activate PLCß through Gq and then lead to activation of several calcium-dependent signaling pathways, including ERK, which play an important role in gene transcription. These findings support a calcium-dependent role for Gq in release of Calcium and activation of calcium-stimulated adenylyl cyclases I in activity-dependent transcription in response to application of group I metabotropic glutamate receptors agonist and may provide insights into group I mGluRs-dependent synaptic plasticity through MAP kinases signaling. Moreover, the present study investigated the transcription-dependent changes of Arc in response to the activation of group I mGluRs and suggested the central role of ERK1/2 in group I mGluR-mediated Arc transcription. Further, we selected APP-interaction protein FE65 to investigate the mechanism of transcription-related process in synaptic plasticity. FE65 is expressed predominantly in the brain, and interacts with the C-terminal domain of β-amyloid precursor protein (APP). We examined hippocampus-dependent memory and in vivo long-term potentiation (LTP) at the CA1 synapses with the isoform-specific FE65 knock-out (p97FE65-/-) mice. p97FE65 knock-out mice showed impaired short-term memory for both TDPA and CFC when tested 10min after training, which is transcription-independent. Consistently, at the Schaffer collateral-CA1 synapses, p97FE65 knock-out mice showed defective early phase LTP. These results demonstrate novel roles of FE65 in synaptic plasticity, acquisition, and retention for certain forms of memory formation.

长时记忆中图形不同特征的加工与提取

Information can be represented both conceptually and imaginarily in long-term memory. However, it seems that only conceptual representation appears, neglecting imaginary information, in most of the long-term memory (LTM) models. In the matter of fact, picture can be stored in LTM directly and conceptually. There is no evidence for what specific type of information, conceptual or imaginary, for the color, shape, or texture to be represented. However, it is evident that the shape and color can be represented separately in LMT. Further research is needed on whether features are represented separately or not, such as color and texture, texture and shape etc. Rehearsal plays important role in picture memory besides the types of storage and representation. Memory of picture is indeed enhanced by rehearsal. There are two types of rehearsal. One is for creating image, another is articulatory loop. Which one will be taken during picture memory process depends on the characteristics of stimuli, subjects' encoding preferences and/or task requirements. Nevertheless, the relation between two types of rehearsal is not very clear yet up to now. Different features could be activated at different time course or possibilities since they can be represented separately. Six experiments were conducted dealing with the characteristics of representation, rehearsal and retrieval of picture in LTM. From these experiments, further understanding of picture information processing was expected. It would add more evidence to the LTM models, and make practical sense to the computer visual identification. The first two experiments were based on the paradigm from Hanna et al.(1996) to investigate separable representation of texture and shape, texture and color. The results indicated that texture could be represented separately with color and shape respectively. It suggested that different features might be processed in different way during remembering. Another interest finding is that recognition performance for shape, color and texture are quite different. What for shape is highest, for color is lowest, and for texture is between of them. Three features of picture can be represented separately. How about the roles of rehearsal when they enter the LTM from short-term memory(STM)? The second three experiments assigned three different types of rehearsal, i. e. visual, verbal, and subject-run(might be both of visual and verbal). The findings are that performances of picture memory were affected significantly by different types of rehearsal. Both visual and verbal rehearsal played important role during remembering process. It seems that verbal rehearsal, which might enhance the relative strength of memory trace, was much more effective than visual one. In addition, subjects tended to choose those difficult-to-name, features to rehearse, to improve the memory performance. Only two features were changed in each of the first two experiments. They might interact (facilitate or disturb) each other when they were retrieved. So it was difficult to identify the retrieval difference between them. In the last experiment, easy-to-name pictures were studied, and only one feature could be recognized. The results indicated that the retrieval performances of three features(shape, color, and texture) were quite different. They were different on the relative strength of memory trace, with the shape was strongest, color was lightest, and texture was in between. No difference was found on the absolute strength of them.

记忆年老化与焦虑

It is well established that memory functioning deteriorates with advancing age. However, research indicates that the magnitude of age-related memory deficits varies across different types of memory, and broad individual differences can be observed in the rate and timing of memory aging. The general aim of this study was to investigate the selectivity and variability of memory functioning in relation to anxiety. Firstly, memory effectiveness was assessed in episodic memory tasks with reality monitoring and external source monitoring paradigms, semantic memory tasks referred to general knowledge and word fluency, and perceptual priming task reflected in word completion. According to the scores on trait version of STAI, the high-trait and low-trait anxious subjects were screened respectively from young and old participants matched for educational level. Secondly, based on the results of the first part, concurrent primary and secondary tasks with probe technique assessing spare processing capacity were used to explore the relation between memory efficiency and anxiety. The first main findings were that: (a) there were no age-related differences in semantic memory assessed by general knowledge and PRS, whereas age effects were observed in episodic memory and semantic memory assessed by word fluency with stringent time restraints. (b) Furthermore, comparison of age-related deficits in source and item was not related to the presentation ways and encoding effort for source, but was affected by types of source. Specifically, memory was more sensitive to aging than item memory in external source monitoring processes involved in discriminating two external sources (i.e., female vs. male voices), but not in reality monitoring processes in discriminating between internal and external sources (i.e., acting vs. listening). The second main findings were that: (a) Anxiety had no effects on the effectiveness and efficiency of semantic memory in recall of general knowledge and PRS, but impaired those of semantic memory in word fluency. (b) The effects of anxiety on episodic memory were different between the old and the young. Both the effectiveness and the efficiency of episodic memory of the old were affected adversely by anxiety. More importantly, source recall in external source monitoring processes was observed to be more vulnerable to anxiety than item memory. The effectiveness of episodic memory of the young was relatively unrelated to anxiety, while anxiety might have adverse effect on their memory efficiency. These results indicated that: First, the selectivity of age-related memory deficits existed not only between memory systems, but also within episodic memory system. The tendency to forget the source even when the fact was retained in external source monitoring was suggested to be a specific feature of cognitive aging. Second, anxiety had adverse impact on the individual differences in memory aging, and mediated partial age-related differences in episodic memory performance.

樟柳碱和石杉碱甲对学习和记忆的影响及其有关机制的研究

Two experiments were designed to examine the role of the cholinergic agents, anisodine and huperzine A, and related mechanisms. In experiment 1, the effects of anisodine and huperzine A on rat performance in Morris water maze were observed. It was found that the drugs injected before daily training had significant effect on performance of place navigation task and transfer test, while the drugs injected after daily training, before retest and overtraining had no such effect. the results indicated that the drugs, which only have effects on reference memory related to cognitive mapping strategy, may mediate the acquisition process of memory. In experiment 2, the spontaneous hippocampol neuronal activities and the effects of the drugs on them in awake rabbits were observed. The results showed that anisodine had significant inhibitory effect on the activities, the opposite effect was found in huperzine A. Furthermore, sensory stimulation and administration of huperzine A have similar effects. It was sujested that hipppocampus be directly relavent to transmission of information to memory storage system, in which the role of central cholinergic system is critical.