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PubMed2004

Shrinkage of the entorhinal cortex over five years predicts memory performance in healthy adults.

Lesions in the hippocampus (HC), the entorhinal cortex (EC), and the prefrontal cortex (PFC) are associated with impairment of episodic memory; reduced HC volume is linked to memory declines in dementia; and decline in EC volume predicts progression from mild cognitive impairment to dementia. However, in healthy adults, the relationship between memory and regional volumes is unclear, and no data are available on the relationship of longitudinal regional shrinkage to memory performance in a cognitively intact population. The objective of this study was to examine whether shrinkage of the EC, HC, and PFC over a 5 year period can predict declarative memory performance in healthy adults. The volumes of three brain regions were measured on magnetic resonance images that were acquired twice, 5 years apart. Multiple measures of episodic memory were administered at follow-up. Results indicated that the volume of HC and PFC (but not EC) correlated with age at baseline and follow-up. However, after age differences in memory were taken into account, none of the regional volumes was associated with memory performance at follow-up. In contrast, greater annual rate of shrinkage in EC (but not HC or PFC) predicted poorer memory performance. Thus, in a healthy and educated population, even mild age-related shrinkage of the EC may be a sensitive predictor of memory decline.

Age Distribution↗

PubMed2000

Memory failure has different mechanisms in subcortical stroke and Alzheimer's disease.

Patients with extensive subcortical cerebrovascular disease may have impaired memory, often despite the absence of medial temporal or diencephalic strokes. In this group, episodic memory failure may arise from frontal lobe dysfunction based on disruption of frontosubcortical loops caused by lacunae. We tested this idea by studying cognitively impaired subcortical stroke (CIS) patients and Alzheimer's disease (AD) patients with [18F]-fluorodeoxyglucose positron emission tomography using a continuous verbal memory task during the period of tracer uptake. Patients were matched on severity of cognitive impairment and overall memory task performance. As hypothesized, we found a double dissociation in the relations between metabolism and memory in these groups, such that memory in CIS (but not in AD) correlates with prefrontal lobe metabolism, whereas in AD (but not in CIS), memory correlates with left hippocampal and temporal lobe metabolism. Analysis of memory subscores showed that CIS patients made more errors on short-delay trials, which is consistent with working memory failure. It seems that different pathogenic mechanisms underlie episodic memory failure in subcortical cerebrovascular disease and AD.

Aged↗

PubMed1989

Memory complaints in the elderly: a study of 367 community-dwelling individuals from 50 to 80 years old.

State of memory was evaluated by a Memory Clinic in 367 community-dwelling patients aged from 50 to 80. They performed an exhaustive subjective evaluation including: severity of memory complaint, social status, activity scale, subjective Memory score, Zung's anxiety and depression scales and Well Being Questionnaire. Objective memory performance was evaluated by a complete memory scanning leading to a Global Objective Memory Score. No relationship was found between severity of memory complaints and age, sex, educational level, marital status, living alone or in family, and memory tests performance. More severe complaints were reported in people with poor social network, negative stereotypes on aging, and poor affective status. A strong correlation was found between severity of memory complaints and scores in self-reporting depression questionnaire, even in people with low depression scores.

Aged↗

PubMed1994

Remote memory and lexical retrieval in a case of frontal Pick's disease.

OBJECTIVE: To examine the status of remote memory and lexical retrieval processes in a patient with frontal lobe-type dementia studied serially during an 18-month period. DESIGN: Longitudinal single-case study. SETTING: University hospital. PATIENT: A 67-year-old man presented to the hospital with progressive frontal lobe dysfunction confirmed by neuropsychological testing and single photon emission-computed tomographic scan. Postmortem brain examination demonstrated focal atrophy of the orbitofrontal region of the frontal lobe and medial temporal structures with abundant Pick's bodies and Pick's cells. MAIN OUTCOME MEASURES: Anterograde memory was assessed on a range of free recall and recognition tests using verbal and nonverbal material. Remote memory was assessed by Famous Faces and Famous Events tests and the Crovitz test of remote personal memory. Lexical retrieval was examined using initial-letter and semantic category-based fluency tasks. RESULTS: Initially there was a dissociation between anterograde memory, which was severely impaired, and relatively spared remote memory. Within retrograde memory there was evidence of selective difficulty in retrieving contextually rich and time-specific personal memories and in dating personal and public memories. In contrast, retrieval of names of famous persons and recognition of famous events was relatively normal. As the disease progressed, performance on all remote memory tests worsened, but without a temporally graded pattern. Lexical retrieval was markedly impaired and affected to an equivalent degree performance on initial-letter and category fluency tasks. CONCLUSION: These findings are interpreted in the context of a general retrieval deficit resulting from the interruption of frontostriatal circuits.

Aged↗

PubMed2006

Perceived loss of memory ability and cerebral metabolic decline in persons with the apolipoprotein E-IV genetic risk for Alzheimer disease.

CONTEXT: Concerns about age-related memory loss are greater in persons who have the apolipoprotein E-IV (APOE4) genetic risk for Alzheimer disease, but the correlation between the degree of concerns and future cerebral metabolic decline is unknown. OBJECTIVE: To investigate whether the degree of self-perceived memory loss is associated with regional cerebral metabolic decline. DESIGN: Longitudinal study. SETTING: Aging and Memory Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles. PARTICIPANTS: Thirty right-handed, cognitively intact, middle-aged and older adults (age range, 50-82 years) with age-associated memory complaints, 14 of whom were carriers of the apolipoprotein E-IV allele, were recruited for longitudinal study. MAIN OUTCOME MEASURES: At baseline, we administered a standardized neuropsychological battery and assessed self-appraisal of memory functioning using the Memory Functioning Questionnaire, which yields 4 factor scores indicating frequency of forgetting, seriousness of forgetting, retrospective functioning, and mnemonics use. Regional cerebral glucose metabolism was determined using fluorodeoxyglucose F18-positron emission tomography at baseline and after 2 years. RESULTS: At baseline, APOE4 carriers and noncarriers did not differ significantly on objective memory measures or on Memory Functioning Questionnaire factor scores. However, the factor score for frequency of forgetting significantly correlated with global cerebral metabolic decline in all subjects regardless of APOE4 genetic risk (P = .01). By contrast, the factor score for mnemonics use significantly correlated with metabolic decline in the temporal regions in APOE4 carriers but not in noncarriers (P = .03). CONCLUSIONS: The degree of perceived memory loss correlates with subsequent global cerebral metabolic decline for APOE4 carriers and noncarriers; hence, memory complaints may reflect underlying cerebral metabolic changes. Compensatory strategies, as reflected by more frequent mnemonics use in APOE4 carriers, may reflect underlying metabolic changes in the brain regions associated with prodromal Alzheimer disease. Self-reported mnemonics use may be helpful in identifying persons for clinical monitoring.

Aged↗

PubMed1975

Immunological memory function of the T and B cell types: distribution over mouse spleen and lymph nodes.

Spleens from LAF1 mice injected intravenously with sheep erythrocytes (SE) are relatively rich in memory T cells early in the immune response (1 to 3 days) and rich in memory B cells as the response progresses (2 weeks or more). Marked cooperation for the secondary immune response in vitro was obtained by combining 10(6) spleen cells from LAF1 mice, taken 2 days after intravenous priming with SE, with 10(7) spleen cells from day 14 primed mice. The results indicate relative deficiencies in the spleen for B memory cells on days 1 to 2 and for T memory cells on day 14 after priming. Day -14, but not day -2, immune lymph node (LN) cells could replace the day -2 spleen cells (anti-Thy 1.2 sensitive) in the in vitro cooperation with day -14 immune spleen cells. Immune spleen cells taken 4 to 7 days after priming contain more equivalent numbers of B and T memory cells, but 10 to 7 days after transfer of such immune spleen cells without SE into irradiated recipients the T memory cells were again more prominent in lymph node and the B memory cells in spleen as shown by in vitro cooperation studies. These results suggest that during the second week after intravenous injection of SE relatively more T than B memory cells migrate from spleen to lymph node, resulting in an imbalance in the splenic memory cell population favoring B memory cell function.

Animals↗

PubMed1984

Immune response against the T-independent antigen alpha (1----3) dextran. II. Occurrence of B gamma memory cells in the course of immunization with the native polysaccharide is T cell dependent.

The immune response of BALB/c mice against the bacterial antigen dextran B1355S [alpha (1----3)dextran] (Dex), a class 2 T cell-independent antigen, is largely restricted to IgM class antibody production. However, despite the fact that Dex fails to give rise to enhanced IgG responses upon repeated immunization, the development of Dex-specific B gamma memory cells, i.e. resting B cells committed to the production of specific IgG antibodies, is observed upon immunization with Dex. These B gamma memory cells, albeit not activated to IgG production in situ, can be activated upon adoptive transfer into irradiated congenic BALB Ighb mice. This mouse strain is a nonresponder strain to Dex. The expression of adoptively transferred Dex-specific B gamma memory cells is T cell-independent as T cell depletion of spleen prior to cell transfer into BALB.Ighb recipients does not abolish the IgG response. Dex-primed athymic BALB/c nude mice, in contrast to euthymic mice, give a pronounced primary IgG response but do not develop Dex-specific B gamma memory cells. Yet, they do so when reconstituted with syngenic T cells prior to immunization. This indicates that the formation of Dex-specific B gamma memory cells requires the presence of functional T cells. The pronounced primary IgG anti-Dex response of nude mice is greatly impaired by T cell reconstitution. Thus, with regard to T cell dependence, there is an inverse relationship between the formation of B gamma memory cells and the capacity to produce IgG anti-Dex. Dex-specific B gamma memory cells from BALB/c mice are expressed in congenic BALB.Ighb recipients (nonresponder to Dex) but not when transferred into identically treated syngenic hosts. This also applies to memory cells from Dex-primed female (CBA/N X BALB/c)F1 [NBF1] or from (BALB/c X CBA/N)F1 hybrids. Dex-specific B gamma memory cells from these donors are demonstrable upon adoptive transfer into BALB.Ighb mice, but they are not expressed when transferred into syngenic recipients, including male NBF1 hybrids. NBF1 males, albeit possessing the VH-Dex+ allele, do not mount humoral responses to Dex, a deficiency which is ascribed to an X chromosome-linked B cell defect. The apparent absence of Dex-specific antibodies in NBF1 males provides an opportunity to examine whether B gamma memory cell expression is inhibited in syngenic recipients by anti-Dex or autologous anti-idiotype antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2004

CD4 T cells guarantee optimal competitive fitness of CD8 memory T cells.

We studied the contribution of CD4 T cell help to survival and competitive fitness of CD8 memory T cells specific for influenza virus nucleoprotein. In agreement with recent studies, the optimal generation of functional memory CD8 T cells required CD4 help, although long-term maintenance of resting CD8 memory T cells did not absolutely depend on the presence of CD4 T cells. Nonetheless, CD4 T cells were essential during differentiation of CD8 memory T cells to imprint on them the capacity to compete effectively with other memory T cells. CD8 memory cells generated with help survived better in secondary polyclonal hosts, and co-transfer into lymphopenic hosts together with "un-helped" CD8 memory cells showed improved homeostatic expansion of CD8 memory cells that had been generated with CD4 help. Therefore, the requirement for CD4 help in CD8 T cell memory extends to homeostatic parameters that ensure the maintenance and competitive fitness of memory clones.

Animals↗

PubMed2001

Memory self-appraisal and depressive symptoms in people at genetic risk for Alzheimer's disease.

OBJECTIVES: A previous study found that subjective memory loss in middle-aged and older persons is associated with the major genetic risk for Alzheimer's disease, the apolipoprotein E-4 (APOE-4) allele. No previous study has focused on subjective memory complaints and depressive symptoms in the same subject population at genetic risk for Alzheimer's disease. METHOD: Sixty-six persons (mean age = 64 years, range = 43 to 82 years) without major depression or dementia but with mild age-related memory complaints were rated for severity of depressive symptoms, using the Hamilton Depression Rating Scale, and assessed for the presence of the APOE-4 allele. Severity of subjective memory loss was assessed using the Memory Functioning Questionnaire, which measures four memory domains: frequency of forgetting, seriousness of forgetting, retrospective functioning, and mnemonics usage. RESULTS: Depressive symptoms were significantly associated with subjective memory loss in subjects without the APOE-4 allele, for retrospective functioning (perceived change in memory) and mnemonics usage, but not in APOE-4 carriers. The same significant associations were found when the analysis was limited to the 44 subjects in the mid-age range (55-74 years), wherein APOE-4 confers its greatest effects on risk for Alzheimer's disease. CONCLUSION: These results confirm that mild depressive symptoms are related to subjective memory loss, but for some forms of memory complaint, the relationship holds true only for people without the major known genetic risk for Alzheimer's disease.

Adult↗

PubMed2002

Human declarative memory formation: segregating rhinal and hippocampal contributions.

The medial temporal lobe (MTL) is the core structure of the declarative memory system, but which specific operation is performed by anatomically defined MTL substructures? One hypothesis proposes that the hippocampus carries out an exclusively mnemonic operation during declarative memory formation that is insensitive to content, whereas the rhinal cortex carries out an operation supporting memory formation indirectly. To explore the interaction between a salient item feature and memory formation, we contrasted neural correlates of memory formation of high- and low-frequency words. Event-related potentials (ERPs) were recorded via depth electrodes from within the MTL in nine epilepsy patients while they memorized single words. To assess memory formation, ERPs to words subsequently recalled in a free recall test were contrasted with ERPs to forgotten words. More high- than low-frequency words were remembered. High-frequency words led to distinct ERP subsequent memory effects in rhinal cortex and hippocampus. Low-frequency words, however, were only associated with the hippocampal ERP effect. The anatomically restricted interaction between word frequency and memory formation might indicate a semantically affected operation in the parahippocampal region supporting memory formation indirectly. By contrast, the missing interaction in hippocampal recordings might suggest a direct correlate of declarative memory formation that is insensitive to item properties.

Adult↗

PubMed2004

Stress generates emotional memories and retrograde amnesia by inducing an endogenous form of hippocampal LTP.

Models of the neurobiology of memory have been based on the idea that information is stored as distributed patterns of altered synaptic weights in neuronal networks. Accordingly, studies have shown that post-training treatments that alter synaptic weights, such as the induction of long-term potentiation (LTP), can interfere with retrieval. In these studies, LTP induction has been relegated to the status of a methodological procedure that serves the sole purpose of disturbing synaptic activity in order to impair memory. This perspective has been expressed, for example, by Martin and Morris (2002: Hippocampus 12:609-636), who noted that post-training LTP impairs memory by adding "behaviorally meaningless" noise to hippocampal neural networks. However, if LTP truly is a memory storage mechanism, its induction should represent more than just a means with which to disrupt memory. Since LTP induction produces retrograde amnesia, the formation of a new memory should also produce retrograde amnesia. In the present report, we suggest that one type of learning experience, the storage of fear-related (i.e., stressful) memories, is consistent with this prediction. Studies have shown that stress produces potent effects on hippocampal physiology, generates long-lasting memories, and induces retrograde amnesia, all through mechanisms in common with LTP. Based on these findings, we have developed the hypothesis that a stressful experience generates an endogenous form of hippocampal LTP that substitutes a new memory representation for preexisting representations. In summary, our hypothesis implicates the induction of endogenous synaptic plasticity by stress in the formation of emotional memories and in retrograde amnesia.

Amnesia, Retrograde↗

PubMed2006

Influence of predator stress on the consolidation versus retrieval of long-term spatial memory and hippocampal spinogenesis.

We have studied the influence of predator stress (30 min of cat exposure) on long-term (24 h) spatial memory and the density of spines in basilar dendrites of CA1 neurons. Predator stress occurred either immediately before water maze training (Stress Pre-Training) or before the 24 h memory test (Stress Pre-Retrieval). The Control (nonstress) group exhibited excellent long-term spatial memory and a robust increase in the density of stubby, but not mushroom, shaped spines. The Stress Pre-Training group had impaired long-term memory and did not exhibit any changes in spine density. The Stress Pre-Retrieval group was also impaired in long-term memory performance, but this group exhibited an increase in the density of stubby, but not mushroom, shaped spines, which was indistinguishable from the control group. These findings indicate that: (1) A single day of water maze training under control conditions produced intact long-term memory and an increase in the density of stubby spines in CA1; (2) Stress before training interfered with the consolidation of information into long-term memory and suppressed the training-induced increase in spine density; and (3) Stress immediately before the 24 h memory test trial impaired the retrieval of the stored memory, but did not reverse the training-induced increase in CA1 spine density. Overall, this work provides evidence of structural plasticity in dendrites of CA1 neurons which may be involved in the consolidation process, and how spinogenesis and memory are modulated by stress.

Amnesia↗

PubMed2006

Hippocampal place cells, context, and episodic memory.

Although most observers agree that the hippocampus has a critical role in learning and memory, there remains considerable debate about the precise functional contribution of the hippocampus to these processes. Two of the most influential accounts hold that the primary function of the hippocampus is to generate cognitive maps and to mediate episodic memory processes. The well-documented spatial firing patterns (place fields) of hippocampal neurons in rodents, along with the spatial learning impairments observed with hippocampal damage support the cognitive mapping hypothesis. The amnesia for personally experienced events seen in humans with hippocampal damage and the data of animal models, which show severe memory deficits associated with hippocampal lesions, support the episodic memory account. Although an extensive literature supports each of these hypotheses, a specific contribution of place cells to episodic memory has not been clearly demonstrated. Recent data from our laboratory, together with previous findings, indicate that hippocampal place fields and neuronal responses to task-relevant stimuli are highly sensitive to the context, even when the contexts are defined by abstract task demands rather than the spatial geometry of the environment. On the basis of these findings, it is proposed that place fields reflect a more general context processing function of the hippocampus. Hippocampal context representations could serve to differentiate contexts and prime the relevant memories and behaviors. Since episodic memories, by definition, include information about the time and place where the episode occurred, contextual information is a necessary prerequisite for any episodic memory. Thus, place fields contribute importantly to episodic memory as part of the needed context representations. Additionally, recent findings indicate that hippocampal neurons differentiate contexts at progressively finer levels of detail, suggesting a hierarchical coding scheme which, if combined with temporal information, could provide a means of differentiating memory episodes.

Action Potentials↗

PubMedDate not supplied

Predictors of the use of memory improvement strategies by older adults.

This study examined the ability of depression, health, and memory self-efficacy scores to predict the use of internal and external memory strategies by cognitively impaired and cognitively intact older adults. There were no differences between the groups on memory self-efficacy scores and on the extent of their use of the external memory strategy of place. The cognitively intact group used strategies to aid memory more often than did the cognitively impaired group and used more external than internal memory strategies. The cognitively intact group used the internal strategies of elaboration and rehearsal more often than the other group and were less likely to expend effort than the other group. Memory self-efficacy scores were the sole predictor of use of external memory aids by the cognitively intact group, and age was the sole predictor of use of external memory aids by the cognitively impaired group. No variable was able to predict the use of internal memory strategies by either group.

Adaptation, Psychological↗

PubMed2007

Memory deficits in long-term survivors of childhood brain tumors may primarily reflect general cognitive dysfunctions.

BACKGROUND: To analyze the impact of potential predictors on memory performance in survivors of childhood brain tumors and to examine whether deficits in memory after radiotherapy (RT) should be considered part of a more global mental dysfunction. PROCEDURE: We studied 126 patients with brain tumors diagnosed before the age of 15 years and treated January 1970 through February 1997 in Eastern Denmark. Sixty-nine of the 126 patients had received RT. In addition to working memory and long-term memory (LTM), general intelligence (IQ) was assessed. RESULTS: The mean test scores in nearly all memory tests were lower than expected from available norms. In multiple linear regression, treatment with RT, hemisphere tumor location, and hydrocephalus treated with a shunt at the time of diagnosis were found to be significant risk factors for memory deficits. When IQ was included as a covariate, RT did not significantly predict memory performance, while shunt and tumor location remained significant for several but not all tests. CONCLUSION: These results suggest that in patients treated with RT, memory deficits primarily reflect a general cognitive dysfunction, and it is likely that these intelligence deficits may compromise the chances of success of special memory training. In contrast, memory deficits in non-irradiated patients may to some degree reflect specific cognitive dysfunctions being most pronounced for patients treated with a shunt and for patients with hemispheric tumors.

Adolescent↗

PubMed2000

The role of the human thalamus in language and memory: evidence from electrophysiological studies.

The data reviewed here indicate that electrical stimulation of the dominant ventrolateral thalamus can produce deficits in language processing that are not seen after similar stimulation of the nondominant ventrolateral thalamus. The nature of the language deficit produced varies, depending upon the rostrocaudal location of the stimulation site. Stimulation of the anterior left ventrolateral thalamus in right-handed patients resulted in production of a repeated erroneous word, stimulation of the medial ventrolateral thalamus evoked perseveration, and stimulation of the posterior ventrolateral thalamus and anterior pulvinar resulted in misnaming and omissions. Additional studies have examined the effect of electrical thalamic stimulation on verbal and nonverbal short-term memory. Left (but not right) ventrolateral thalamic stimulation during verbal memory input greatly decreased subsequent recall errors, while stimulation during verbal memory retrieval increased recall errors. This finding contrasted with those obtained from studies on nonverbal memory, in which right ventrolateral stimulation during memory input decreased recall errors, while left thalamic stimulation at the same stage increased recall errors. Left pulvinar stimulation disrupted verbal memory processing, while right pulvinar stimulation disrupted nonverbal memory processing. Limited evidence suggests that the effects of thalamic electrical stimulation on verbal memory may persist for several days after the stimulation has ended. The lateralization of thalamic functions also affects the motoric aspects of speech production. Left (but not right) ventrolateral thalamic stimulation disrupted speech articulation and increased the expiratory phase of respiration. The fact that these motor effects were evoked from the same general area of the thalamus that produced the language deficits discussed above raises the possibility that the thalamus is involved in coordinating the cognitive and motoric aspects of language production. A model of thalamic function is discussed in which defined regions of the thalamus operate as a "specific alerting response," increasing the input to memory of category-specific material while simultaneously inhibiting retrieval from memory.

Electrophysiology↗

PubMed1988

Measuring memory.

Three broad approaches to the measurement of memory functioning will be described. The first of these involves using memory as a general indicator of any dysfunction in the central nervous system. This approach will be illustrated using Sternberg's short-term memory scanning paradigm. Its strengths are that such tests are often very sensitive, but they are often very difficult to interpret both theoretically and in practical terms. A second approach is to use a range of tasks selected so as to tap different aspects of human memory. Such an approach is of considerably more theoretical interest, and is discussed in more detail by Eysenck (this volume). Its weaknesses are that theories of memory are still changing relatively quickly, and that mapping such results onto memory outside the laboratory is often complex. A third approach is to attempt a more direct measure of everyday memory. The use of questionnaires for this purpose will be critically discussed, and a new test of everyday memory will be described. This test, the Rivermead Behavioural Memory Test, correlates well with observations of memory lapses in patients, and appears to offer a promising new line of development.

Humans↗

PubMed1995

Brief wakeful response to command indicates wakefulness with suppression of memory formation during surgical anesthesia.

OBJECTIVE: In a previous study of patients emerging from anesthesia following surgery, we found that a brief wakeful response to command of an eye opening or single hand squeeze or count was not associated with memory formation, while the response of four hand squeezes or counts was associated with memory. We wanted to determine the anesthetic requirements for obtaining this brief wakeful response endpoint during surgery and to determine if memory occurred at this endpoint during surgical anesthesia. METHODS: Six different combinations of isoflurane, 70% N2O, and fentanyl were administered to 326 patients undergoing pelvic laparoscopy. After insertion of the trocar, anesthesia was reduced while patients were given verbal commands, and they were observed for movement responses to surgery and to command. Patients were classified as either not arousing, arousing with a movement response to surgery, or arousing with a wakeful response to command. For the patients who aroused, we calculated the percentage of arousal responses that were wakeful responses to command. The effect of fentanyl dosage upon the percentage of arousal responses that were wakeful responses to command was determined by using a Mann-Whitney test to compare a group of patients receiving fentanyl 2 micrograms/kg or less, with a group receiving fentanyl 4 micrograms/kg. In a subset of 39 patients, the potential for memory formation was evaluated by presenting a target sound to 29 patients during a period of either no arousal, movement response to surgery, or wakeful response to command; for a control group of 10 patients, no target sound was presented. All 39 patients were tested for memory of the target sound; the results from each group receiving a target sound were compared with the results of the control group, using a Mann-Whitney test. MAIN RESULTS: A total of 68 patients aroused with either a movement response or a wakeful response to command. Wakeful responses occurred with only 1 of 39 patients (3%) receiving fentanyl 2 micrograms/kg or less; but, wakeful responses occurred with 17 of 29 patients (59%) receiving fentanyl 4 micrograms/kg. The difference between the groups was significant at p = 0.01. None of the 68 patients had recall of intraoperative events or unpleasant dreams. None of these patients who were in the multiple-choice memory subset recalled the target sound. There were no statistically significant differences on the multiple-choice memory test between the groups presented with the target sound and the control group. Patient anecdotes suggested that some patients may have had memory of the target sound; but, memory was no more likely in patients with a brief wakeful response to command than in those who responded with a movement to surgical stimulation or those who did not have an arousal response. CONCLUSIONS: A brief wakeful response to a command of opening the eyes or squeezing the hand was not associated with increased memory formation during surgery. A brief wakeful response to command was found during surgery when patients received fentanyl 4 micrograms/kg; but it was rarely found at fentanyl dosages of 2 micrograms/kg or less.

Adolescent↗