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PubMed1987

The effects of exifone, a new agent for senile memory disorder, on two models of memory in the mouse.

The effects of exifone (ADLONE), hexahydro-2,3,4,3',4',5'-benzophenone, were tested in two models of memory in the mouse: habituation of exploratory activity and antagonism of amnesia induced by scopolamine in a passive avoidance task. In the first model, mice which had received exifone (128 and 256 mg/kg IP) 30 minutes before a 3 minute exposure to a staircase exploratory test showed a more marked decrease in exploratory activity in the same apparatus 24 hours later (habituation) than a control group indicating improved memory. Similar results were obtained with piracetam (512 mg/kg, IP). In the second model exifone (512 mg/kg PO), administered 60 minutes before both the learning and retention trials of a standard step-through passive avoidance, task partially antagonized the amnesia induced by 10 mg/kg scopolamine IP administered immediately after the learning trial. Similar results were obtained with piracetam (800 mg/kg PO). Taken together these results suggest that exifone facilitates memory function in simple rodent models in a manner consistent with its supposed therapeutic effects in man.

Amnesia↗

PubMed1983

Studies on the immune response in chickens. IV. Generation of hapten-specific memory and absence of increase in carrier-specific helper memory in antibody response to sheep red blood cell antigen and its hapten-conjugate.

The role of carrier recognition in the hapten-specific antibody response of chickens to hapten (TNP) conjugate of sheep red blood cells (SRBC) was studied. The anti-TNP antibody response to the challenge with either TNP-SRBC or DNP conjugate of Salmonella enteritidis (DNP-Sal) of chickens previously primed with TNP-SRBC was definitely higher than that of unprimed chickens. Injection of TNP-chicken red blood cells, which did not provoke any significant primary anti-TNP response, also induced the memory for secondary anti-TNP response to the challenge with TNP-SRBC or DNP-Sal. The TNP-specific memory generated by stimulation with TNP-SRBC was adoptively transferable by spleen cells into cyclophosphamide (CY)-treated X-irradiated syngeneic recipients. On the other hand, the SRBC-specific memory for augmentation of anti-TNP response to the challenge with TNP-SRBC was never detected in chickens previously primed with either any of a wide range of doses (10(4)-10(8)) of SRBC, solubilized SRBC or SRBC fixed with formaldehyde, nor in CY-treated X-irradiated chickens receiving SRBC-primed spleen cells. The anti-TNP response of chickens to the challenge with TNP-SRBC was rather suppressed by the SRBC preimmunization. The passively administered anti-SRBC chicken serum also suppressed the response to TNP-SRBC. The carrier-specific suppressor activity generated by SRBC stimulation was not adoptively transferable by spleen cells. It is suggested from these results that the mechanism of amplification of the anti-hapten antibody response of chickens to hapten-SRBC conjugate is primarily mediated by the hapten-recognition, and carrier-recognition is more important for suppression rather than for amplification of the anti-hapten response, although the inductive mechanism for anti-hapten response itself should somehow involve the carrier recognition.

Animals↗

PubMed1986

Tranquillising memories: a review of the effects of benzodiazepines on human memory.

Studies from 1973 to 1985 of the effects of benzodiazepines on memory are summarised and reviewed. Anterograde amnesia appears a common effect of all benzodiazepines although its onset and duration vary with the particular benzodiazepine, its dose and route of administration. Memory impairments increase with task difficulty. There is some evidence that partial tolerance to amnesic effects develops with repeated doses of diazepam, but research with other benzodiazepines is inconclusive. Amnesia is in part a by-product of the sedative action of benzodiazepines, although these drugs may also have a specific effect of disrupting the consolidation of information in long-term memory. State-dependent effects are partial and relatively small. Methodological problems are discussed and attention is drawn to the lack of repeated dose studies, of studies with patient populations and with anxious volunteers.

Amnesia↗

PubMed2006

Declarative memory: sleep protects new memories from interference.

Interference is one of the most fundamental phenomena in memory research: acquiring new memories causes forgetting of other, related memories. A new study shows that sleep, interposed between learning episodes, can mitigate the extent to which new (post-sleep) learning interferes with recall of previously acquired knowledge.

Hippocampus↗

PubMed2005

Relations between vocabulary development and verbal short-term memory: The relative importance of short-term memory for serial order and item information.

Although many studies have shown an association between verbal short-term memory (STM) and vocabulary development, the precise nature of this association is not yet clear. The current study reexamined this relation in 4- to 6-year-olds by designing verbal STM tasks that maximized memory for either item or serial order information. Although empirical data suggest that distinct STM processes determine item and serial order recall, these were generally confounded in previous developmental studies. We observed that item and order memory tasks were independently related to vocabulary development. Furthermore, vocabulary development was more strongly associated with STM for order information in 4- and 6-year-olds and with STM for item information in 5-year-olds. These data highlight the specificity of verbal STM for serial order and item information and suggest a causal association between order STM processes and vocabulary development, at least in 4- and 6-year-olds.

Child↗

PubMed2004

Posttraining administration of pentylenetetrazol dissociates gabapentin effects on memory consolidation from that on memory retrieval process in mice.

Gabapentin (GBP), an anticonvulsant drug, 10 mg/kg, i.p., but not 100 mg/kg, i.p., enhanced retention of an inhibitory avoidance task when given 20 min after training, as indicated by retention performance 48 h later. The immediate post-training administration of pentylenetetrazol (PTZ, 45 mg/kg, i.p.) impaired retention performance. The amnesic effects of the convulsant drug PTZ were not influenced by GBP at any level of doses. However, GBP 100 mg/kg, but not 10 mg/kg, delayed the latency to first clonic body seizures and decreased the duration of convulsion induced by PTZ. The enhancing effect of GBP on retention was not prevented by the opiate receptor antagonist, naltrexone (0.01 mg/kg, i.p.), which completely prevented the impairment of retention caused by PTZ. Further, naltrexone did not modify the convulsions induced by PTZ. In mice pretreated with naltrexone and that received PTZ, the administration of GBP again, enhanced retention performance during the retention test. Since previous results indicate that the amnesic action of PTZ are due to an effect on memory retrieval, the present results provide additional pharmacological evidence suggesting that GBP influenced memory consolidation and not memory retrieval of an inhibitory avoidance task in mice.

Amines↗

PubMed2006

Patterns of impairment in autobiographical memory in the degenerative dementias constrain models of memory.

Detailed study of the autobiographical memory (ABM) impairments seen in different forms of degenerative dementia, in particular Alzheimer's disease (AD) and semantic dementia (SD) can inform neuropsychological models of memory. A modified ABM questionnaire which allowed more detailed analysis of episodic and semantic ABM was used to study the pattern of deficits in patients with minimal to mild Alzheimer's disease (AD) and in two patients with mild and moderate semantic dementia (SD). The questionnaire tested both cued and free recall. A group of healthy elderly was also tested. AD patients differed from controls in all measures. There was no clear temporal gradient for episodic ABM, but a modest gradient was observed for semantic ABM. The mild SD patient performed at control level for episodic ABM but showed a deficit within the range of the AD patients for semantic ABM except for the most recent life period. In contrast the moderate SD patient was impaired within the range of the AD patients for both episodic and semantic ABM. The evidence for differential impairment of episodic and semantic ABM retrieval in AD and SD is interpreted as supporting the multiple trace model of memory.

Aged↗

PubMed2005

Self-initiated encoding facilitates object working memory in schizophrenia: implications for the etiology of working memory deficit.

BACKGROUND: Working memory (WM) deficit is present in a majority of patients with schizophrenia but it is unclear which components of WM are impaired. Past studies suggest that encoding may be compromised. One important determinant of encoding is the deployment of selective attention to the target stimulus. In addition, attention and encoding are modulated by motivational factors. In this study, we investigated the effects of self-initiated encoding (i.e., voluntary attention) on WM. METHODS: 19 patients with schizophrenia and 19 matched control subjects participated in visual WM and control tasks. Encoding was manipulated by asking subjects to select from two face targets and memorize 1) one of the two identical faces (Non-preference condition), 2) one that is marked (Non-choice condition), and 3) one they prefer (Preference condition). WM accuracy for both location (spatial) and identity (object) was measured. RESULTS: Overall, patients with schizophrenia were less accurate and slower than the control subjects but the deficit was greater for object WM. However, patients were more accurate in object WM when they selected a preferred face as their target during encoding (preference condition) compared with the other two conditions. This effect was not significant for spatial WM. CONCLUSIONS: These results suggest that voluntary, self-initiated attention may facilitate object encoding especially if the selection of the target involves affective choice, and that attention may play different roles in encoding 'what' versus 'where' in WM. Since encoding affects all forms of memory, these results may have a more general implication for memory.

Adult↗

PubMed2003

Prefrontal activity associated with working memory and episodic long-term memory.

Many recent neuroimaging studies have highlighted the role of prefrontal regions in the sustained maintenance and manipulation of information over short delays, or working memory (WM). In addition, neuroimaging findings have highlighted the role of prefrontal regions in the formation and retrieval of memories for events, or episodic long-term memory (LTM), but it remains unclear whether these regions are distinct from those that support WM. We used event-related functional magnetic resonance imaging (fMRI) to identify patterns of prefrontal activity associated with encoding and recognition during WM and LTM tasks performed by the same subjects. Results showed that the same bilateral ventrolateral prefrontal regions (at or near Brodmann's Areas [BA] 6, 44, 45, and 47) and dorsolateral prefrontal regions (BA 9/46) were engaged during encoding and recognition within the context of WM and LTM tasks. In addition, a region situated in the left anterior middle frontal gyrus (BA 10/46) was engaged during the recognition phases of the WM and LTM tasks. These results support the view that the same prefrontal regions implement reflective processes that support both WM and LTM.

Adult↗

PubMedDate not supplied

Age-related cognitive impairments as assessed with an automated repeated measures memory task: implications for the possible role of acetylcholine and norepinephrine in memory dysfunction.

Although there exists a general agreement that certain aspects of learning and memory, and certain associated neuronal systems may be impaired with aging, systematic parametric studies are needed to characterize the nature and limits of these age-related impairments and to identify the underlying neuronal mechanisms. We review a series of experiments that examined the effects of aging and experimental treatments on rats' performance of a continuous nonmatching-to-sample, working memory task. In these studies, disruption of cholinergic transmission produced robust impairments that increased with retention interval duration, but could be observed even at the shortest intervals tested. In contrast, age-related impairments were less robust. With tone and light discriminative stimuli age-related impairments were not observed under conditions that were sensitive to disruption of cholinergic transmission, but were observed with increased retention interval duration. Finally, disruption of noradrenergic transmission produced a marginal disruption of memory performance, at worst. The generality of these results, and possible implication for future studies and animal models of dementia are discussed.

Acetylcholine↗

PubMed2001

Long-term memory traces facilitate short-term memory trace formation in audition in humans.

Long-term memory traces of one's native language have an effect on the short-term memory traces formed by phonemes, Nature 385 (1997) 432. We investigated whether they also affect the number of stimulus repetitions needed to form an adequate memory trace used in the elicitation of the mismatch negativity (MMN), an event-related response to a change in an ongoing sound stream. We recorded MMNs to infrequent stimuli occurring in trains of prototype and non-prototype phonemes, matched in their physical distances, and in trains of sinusoidal tones. We found that the number of standards needed to produce a prominent MMN was smaller for native-language prototype phonemes than to non-prototype phonemes, suggesting a faster trace development.

Adult↗

PubMed1999

Mushroom body ablation impairs short-term memory and long-term memory of courtship conditioning in Drosophila melanogaster.

We have evaluated the role of the Drosophila mushroom bodies (MBs) in courtship conditioning, in which experience with mated females causes males to reduce their courtship toward virgins (Siegel and Hall, 1979). Whereas previous studies indicated that MB ablation abolished learning in an olfactory conditioning paradigm (deBelle and Heisenberg, 1994), MB-ablated males were able to learn in the courtship paradigm. They resumed courting at naive levels within 30 min after training, however, while the courtship of control males remained depressed 1 hr after training. We also describe a novel courtship conditioning paradigm that established long-term memory, lasting 9 days. In MB-ablated males, memory dissipated completely within 1 day. Our results indicate that the MBs are not required for learning and immediate recall of courtship conditioning but are required for consolidation of short-term and long-term associative memories.

Animals↗

PubMed1999

Attrition of T cell memory: selective loss of LCMV epitope-specific memory CD8 T cells following infections with heterologous viruses.

Using a variety of techniques, including limiting dilution assays (LDA), intracellular IFNgamma assays, and Db-IgG1 MHC dimer staining to measure viral peptide-specific T cell number and function, we show here that heterologous virus infections quantitatively delete and qualitatively alter the memory pool of T cells specific to a previously encountered virus. We also show that a prior history of a virus infection can alter the hierarchy of the immunodominant peptide response to a second virus and that virus infections selectively reactivate memory T cells with distinct specificities to earlier viruses. These results are consistent with a model for the immune system that accommodates memory T cell populations for multiple pathogens over the course of a lifetime.

Animals↗

PubMed2003

Regulation of the generation and maintenance of T-cell memory: a direct, default pathway from effectors to memory cells.

Memory T cells are derived directly from effector cells without need for additional antigen, TcR triggering or induced cytokines. A large fraction of effectors can become memory cells without division, supporting a default pathway with little further differentiation. This suggests that the same signals during infection/vaccination determine the extent and nature of both effector and memory cell development.

Animals↗

PubMed1997

Memories are made of this: the genetic basis of memory.

Total amnesia is rare, but we face an 'epidemic' of memory loss. At present there are around 18 million people worldwide with Alzheimer's disease, and this figure is predicted to double in the next 25 years. While traditional clinical and experimental studies have elucidated much about the basic processes of memory and learning, modern genetic techniques. Only time will tell whether this knowledge will yield preventive or curative therapy for memory loss.

Alzheimer Disease↗

PubMed1999

Effects of guided imagery on memory distortion in women reporting recovered memories of childhood sexual abuse.

We tested whether having participants imagine unusual childhood events inflates their confidence that these events happened to them, and tested whether this effect is greater in women who report recovered memories of childhood sexual abuse than in women who do not. Participants were pretested on how confident they were that certain childhood events had happened to them before being asked to imagine some of these events in the laboratory. New confidence measures were readministered. Although guided imagery did not significantly inflate confidence that early childhood events had occurred in either group, the effect size of inflated confidence was more than twice as large in the control group as in the group with recovered memory. These data suggest that individuals can counteract memory distortions potentially associated with guided imagery, at least under some conditions.

Adolescent↗

PubMed1998

Memorial consequences of forced confabulation: age differences in susceptibility to false memories.

Numerous studies have demonstrated that exposure to misinformation about a witnessed event can lead to false memories in both children and adults. The present study extends this finding by identifying forced confabulation as another potent suggestive influence. Participants from 3 age groups (1st grade, 3rd/4th grade, and college age) viewed a clip from a movie and were "forced" to answer questions about events that clearly never happened in the video they had seen. Despite evidence that participants would not have answered these questions had they not been coerced into doing so, 1 week later participants in all age groups came to have false memories for the details they had knowingly fabricated earlier. The results also showed that children were more prone to this memory error than were adults.

Age Factors↗

PubMed1989

Conversation memory: the effects of speaker status on memory for the assertiveness of conversation remarks.

We conducted three experiments to examine the effects of information about a speaker's status on memory for the assertiveness of his or her remarks. Subjects either read (Experiments 1 and 2) or listened to a conversation (Experiment 3) and were later tested for their memory of the target speaker's remarks with either a recognition (Experiment 1) or a recall procedure (Experiments 2 and 3). In all experiments the target speaker's ostensible status was manipulated. In Experiment 1, subjects who believed the speaker was high in status were less able later to distinguish between remarks from the conversation and assertive paraphrases of those remarks. This result was replicated in Experiment 2, but only when the status information was provided before subjects read the conversation and not when the information was provided after the conversation had been read. Experiment 2's results eliminate a reconstructive memory interpretation and suggest that information about a speaker's status affects the encoding of remarks. Experiment 3 examined this effect in a more ecologically representative context.

Assertiveness↗