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PubMedDate not supplied

Metamorphosis of the mushroom bodies; large-scale rearrangements of the neural substrates for associative learning and memory in Drosophila.

Paired brain centers known as mushroom bodies are key features of the circuitry for insect associative learning, especially when evoked by olfactory cues. Mushroom bodies have an embryonic origin, and unlike most other brain structures they exhibit developmental continuity, being prominent components of both the larval and the adult CNS. Here, we use cell-type-specific markers, provided by the P[GAL4] enhancer trap system, to follow specific subsets of mushroom body intrinsic and extrinsic neurons from the larval to the adult stage. We find marked structural differences between the larval and adult mushroom bodies, arising as the consequence of large-scale reorganization during metamorphosis. Extensive, though incomplete, degradation of the larval structure is followed by establishment of adult specific alpha and beta lobes. Kenyon cells of embryonic origin, by contrast, were found to project selectively to the adult gamma lobe. We propose that the gamma lobe stores information of relevance to both developmental stages, whereas the alpha and beta lobes have uniquely adult roles.

Animals↗
PubMed1989

A reexamination of the role of imagery in learning and memory.

Five experiments were conducted to examine whether the superior recall of concrete over abstract words might be better accounted for in terms of relative differences in the processing of relational and distinctive information rather than redundant verbal and imaginal memory codes. Concrete and abstract word pairs were presented in the standard paired-associated learning task or under conditions intended to affect the nature and extent of relational processing between pair members. Concreteness effects were attenuated or eliminated when relational processing was prevented at encoding (Experiments 3, 4, and 5) or when the use of encoded relations within pairs was prevented at recall (Experiments 1, 2, and 3). The results indicated the viability of an account of concreteness effects in paired-associate learning based on the joint functions of distinctive and relational information. They also remove theoretical constraints imposed on imagery theories by the incorrect assumption of a uniform presence of concreteness effects in memory for word lists.

Adult↗
PubMed1983

[Significance of the time of administering substance P on learning and memory in rats].

We studied the influence of time and period of application of substance P (SP) on type and size of the effects on learning in Wistar rats. Treatment with SP before acquisition training had a fascillitating effect on learning. If SP was applied from the 1st or 3rd d of acquisition training there was no effect; if given from the 2nd d an inhibition was found; if given from the 4th d the consolidation of memory became finished. We found during the inhibition of exploration if SP was given acquisition training only (and no longer during the retention test). Some possible explanations of these differing effects of SP are discussed.

Animals↗
PubMed1994

The effect of electroconvulsive shock and nifedipine on spatial learning and memory in rats.

Several traumatic events including brain contusion, electroconvulsive shock therapy, epileptic seizures and others, may cause short-term retrograde amnesia. In spite of much recent attention, pharmacological treatment of memory impairment has not been fully successful. In the present paper we report on the possible antiamnesic action of the L-type calcium channel blocker, nifedipine. Rats trained in the spatial memory task showed gradual improvement in the escape latency to find the submerged platform. After completion of the learning, they also showed a strong spatial bias toward the place that previously contained the target platform. Prolonged post-trial electroconvulsive shock induced memory impairment. The calcium channel blocker, previously reported as a "cognitive enhancer," given either before or after the learning trial revealed no antiamnesic effect. Nifedipine also does not exert any action when given alone. These results suggest that the drug may not have antiamnesic action on human memory disturbed by electroconvulsive therapy.

Animals↗
PubMed1980

The role of opioid peptides in memory and learning.

Evidence is discussed which points to the existence of a physiologic amnesic mechanism mediated by beta-endorphin and perhaps by other opioid peptides as well. This mechanism is triggered by various forms of training and by either painful or painless stimulation. It may operate through the inhibition of central dopaminergic and beta-adrenergic systems that modulate the memory consolidation process. This amnesic mechanism in unrelated to the regulation of pain perception, and operates at opioid peptide levels several orders of magnitude below those that are needed to cause analgesia or other effects. In addition, shuttle avoidance and habituation learning seem to be dependent on a state induced by the release of beta-endorphin. It is possible that this may be related to the amnesic properties of this substance. Therefore, it appears that the endogenous opioid peptides may exert their primary function in the modulation of memory processes.

Amnesia↗
PubMed1987

Participation of angiotensin II in learning and memory. III. Interactions of angiotensin II with GABAergic drugs.

The experiments were carried out on male albino rats trained and tested for retention (24 hr later) in a shuttle-box. Angiotensin II (AT II) 0.10 micrograms intracerebroventricularly (i.c.v.), gamma-aminobutyric acid (GABA) 100 micrograms i.c.v., bicuculline 0.5 and 1.0 mg/kg intraperitoneally (i.p.), and picrotoxin 0.5 and 1.0 mg/kg i.p. administered independently or in combinations immediately after training. AT II was found to improve retention. GABA also facilitated retention. Combination of AT II + GABA potentiated the memory-improving effect of AT II. Bicuculline and picrotoxin at a dose of 0.5 mg/kg did not affect retention, while at a dose of 1.0 mg/kg they improved it. Combinations of AT II + bicuculline (0.5 mg/kg) and AT II + picrotoxin (0.5 mg/kg) abolished the retention-improving effect of AT II. Bicuculline (0.5 mg/kg) or picrotoxin (0.5 mg/kg) abolished the retention-facilitating effect of the combination of AT II + GABA as well as the potentiating action of GABA on the memory effect of AT II. These results suggest the participation of GABAergic transmission in the CNS in the mechanisms of the long-term memory-improving effect of AT II.

Angiotensin II↗
PubMed2006

Deception strategies in children: examination of forced choice recognition and verbal learning and memory techniques.

Thirty-five children ages 6-12 years were asked to complete two alternate forms of the Hopkins Verbal Learning Test-Revised (HVLT-R), once with the instruction to feign cognitive impairment and once instructed to do their best. They were also asked to complete the Test of Memory Malingering (TOMM). Regardless of condition, children performed comparably to adult norms on the TOMM, obtaining a score of 45 or above on Trial 2. Regarding the HVLT-R, differences emerged only when children were initially told to "do their best," followed by a subsequent trial in which they were told feign impairment. Within this group of participants, children demonstrated significantly lower levels of learning across trials and fewer words recalled in comparison to when they were instructed to do their best. In contrast, no reliable differences on the HVLT-R were observed among children who were initially told to feign impairment and subsequently told to do their best. These results suggest that the elicitation of "feigned" impairment within this age group on the HVLT-R requires the initial provision of an opportunity for optimal performance.

Age Factors↗
PubMed2002

A combined pharmacological and genetic approach to investigate the role of orphanin FQ in learning and memory.

Using a combination of the selective opioid receptor-like1 (ORL1) receptor agonist, Ro 64-6198, and orphanin FQ/nociceptin (OFQ/N) peptide knockout (KO) mice, the influence of OFQ/N on cognition has been studied in the rodent. In wild type, C57BL/6J mice, Ro 64-6198 (0.3-1 mg/kg i.p.) impaired the acquisition of spatial learning in the Morris water maze, although a mild neurological impairment was evident which complicated precise interpretation. In Lister hooded rats, Ro 64-6198 (6 mg/kg i.p.) produced delay dependent impairments in rats performing either a delayed matching or a delayed nonmatching to position task with only a modest (< 20%) effect on omissions - an effect consistent with a short-term memory impairment. Electrophysiological studies demonstrated an inhibitory effect of OFQ/N on LTP recorded from the CA1 region of wild type mice, but not in ORL1 receptor knockout mice. In contrast to the ORL1 agonist, mice deficient in the OFQ/N peptide showed some evidence of improved spatial learning, fear conditioning and passive avoidance retention. However, CA1 LTP was similar between OFQ/N peptide KO mice and wild type controls. Subsequent receptor radioautography studies demonstrated the presence of ORL1 receptors within various regions of the medial temporal lobe system: i.e. CA1, dentate gyrus molecular layer, subiculum, perirhinal cortex. Taken together, these results suggest a bi-directional effect of OFQ/N containing systems on aspects of cognitive behaviour, particularly those elements associated with hippocampal function. This is consistent with a likely modulatory role of OFQ/N on hippocampal and associated cortical circuitry.

Animals↗
PubMed2003

An investigation of errorless learning in memory-impaired patients: improving the technique and clarifying theory.

In rehabilitating individuals who demonstrate severe memory impairment, errorless learning techniques have proven particularly effective. Prevention of errors during acquisition of information leads to better memory than does learning under errorful conditions. This paper presents results of a study investigating errorless learning in three patient groups: those demonstrating mild, moderate, and severe memory impairments. The first goal of the study was to trial a new version of errorless learning, one encouraging more active participation in learning by patients via the use of elaboration and self-generation. This technique led to significantly better memory performance than seen under standard errorless conditions. This finding highlights the value of encouraging active and meaningful involvement by patients in errorless learning, to build upon the benefits flowing from error prevention. A second goal of the study was to clarify the mechanisms underlying errorless learning. Memory performance under errorless and errorful conditions was compared within and across each group of patients, to facilitate theoretical insight into the memory processes underlying performance. The pattern of results observed was equivocal. The data most strongly supported the hypothesis that the benefits seen under errorless learning reflect the operation of residual explicit memory processes, however a concurrent role for implicit memory processes was not ruled out.

Adult↗
PubMed1981

Recovery of visual-spatial learning and memory in chronic alcoholics.

Administered the Memory-for-Designs Test and a verbal and visuospatial paired associate learning test to separate groups of alcoholics (N = 32) 3 and 11 weeks abstinent from alcohol and to a matched control group (N = 16). Alcoholics were not impaired in verbal learning. Alcoholics 3 weeks abstinent performed significantly less well than controls on all nonverbal tasks and less well than 11-weeks alcoholics on one nonverbal measure. No significant differences were found between 11-week alcoholics and controls. The results suggest that some recovery of function may occur in alcoholics after 10 weeks of abstinence. The data also support the hypothesis of impaired right hemisphere in alcoholics.

Alcoholism↗