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PubMed1990

Relations between source amnesia and frontal lobe functioning in older adults.

A study is reported in which the relations among normal aging, source amnesia, and frontal lobe functioning were explored. Twenty-four older adults (aged 60-84 years) were tested on their ability to remember where they had acquired new factual information; they were also given the Wisconsin Card Sorting Test (WCST), a test of verbal fluency, and other psychometric tests. The degree of source amnesia in this normal sample correlated with age, verbal fluency, and some measures from the WCST. Source amnesia was not related to Performance IQ, however, or to a measure of fact recall. The implications for the relations among aging, memory, and frontal lobe functions are discussed.

Age Factors↗

PubMed2005

New semantic learning and generalization in a patient with amnesia.

New learning of semantic information is impaired in amnesia. Several reports have demonstrated that "errorless" learning techniques have allowed patients with amnesia to acquire at least some form of new semantic information, although this information appears to be relatively inflexible. Using insights and principles from connectionist modeling of cortical and medial temporal lobe memory systems, the authors describe why errorless learning procedures act as a poor proxy for the medial temporal lobe, suggesting that they artificially eliminate the variability that defines semantic information. The authors trained a patient with severe amnesia on new semantic sentences both with and without variance and then tested him on both repeated and related novel sentences to assess generalization. He successfully learned new semantic information in both conditions but demonstrated better generalization of semantic concepts following training with variance.

Aged↗

PubMed1975

Effect of age of habit on susceptibility to cycloheximide-induced amnesia in mice.

The amnesic effects of cycloheximide (CYC) on habits of different ages were investigated in a food-motivated, discrimination-reversal task. Groups of C57BL/6J mice were injected 30 min before training or immediately, 3 days, 6 days, or 9 days after training. Retention was tested 24 hr after CYC treatment. The usual amnesic effect of CYC occurred in animals injected before training. No amnesia was apparent in groups injected immediately, 3 days, or 9 days after training. However, a reliable and reproducible amnesia occurred in the group injected 6 days after training. This amnesia could be reversed by pretest treatment with a monoamine oxidase inhibitor, pheniprazine. Pheniprazine, given 7 days after training, also enhanced retrieval of memory in saline-injected mice.

Amnesia↗

PubMed1992

Metabolic impairment in human amnesia: a PET study of memory networks.

Human amnesia is a clinical syndrome exhibiting the failure to recall past events and to learn new information. Its "pure" form, characterized by a selective impairment of long-term memory without any disorder of general intelligence or other cognitive functions, has been associated with lesions localized within Papez's circuit and some connected areas. Thus, amnesia could be due to a functional disconnection between components of this or other neural structures involved in long-term learning and retention. To test this hypothesis, we measured regional cerebral metabolism with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET) in 11 patients with "pure" amnesia. A significant bilateral reduction in metabolism in a number of interconnected cerebral regions (hippocampal formation, thalamus, cingulate gyrus, and frontal basal cortex) was found in the amnesic patients in comparison with normal controls. The metabolic impairment did not correspond to alterations in structural anatomy as assessed by magnetic resonance imaging (MRI). These results are the first in vivo evidence for the role of a functional network as a basis of human memory.

Adult↗

PubMed2001

Differential prevention of morphine amnesia by antisense oligodeoxynucleotides directed against various Gi-protein alpha subunits.

The effect of the i.c.v. administration of pertussis toxin (PTX) and antisense oligodeoxynucleotide directed against the alpha subunit of different Gi-proteins (anti-Gialpha1, anti-Gialpha2, anti-Gialpha3) on amnesia induced by morphine was evaluated in the mouse passive avoidance test. The administration of morphine (6 - 10 mg kg(-1) i.p.) immediately after the training session produced amnesia that was prevented by PTX (0.25 microg per mouse i.c.v.) administered 7 days before the passive avoidance test. Anti-Gialpha1 (6.25 microg per mouse i.c.v.) and anti-Gialpha3 (12.5 microg per mouse i.c.v.), administered 18 and 24 h before the training session, prevented the morphine amnesia. By contrast, pretreatment with anti-Gialpha2 (3.12 - 25 microg per mouse i.c.v.) never modified the impairment of memory processes induced by morphine. At the highest effective doses, none of the compounds used impaired motor coordination, as revealed by the rota rod test, nor modified spontaneous motility and inspection activity, as revealed by the hole board test. These results suggest the important role played by Gi1 and Gi3 protein subtypes in the transduction mechanism involved in the impairment of memory processes produced by morphine.

Amnesia↗

PubMed1999

Trauma-induced dissociative amnesia in World War I combat soldiers. II. Treatment dimensions.

OBJECTIVE: This is the second part of a study of posttraumatic amnesia in World War I (WW I) soldiers. It moves beyond diagnostic validation of posttraumatic amnesia (PTA), to examine treatment findings, and relates these to contemporary treatment of dissociative amnesia, including treatment of victims of civilian trauma (e.g. childhood sexual abuse). METHOD: Key WW I studies are surveyed which focus on the treatment of PTA and traumatic memories. The dissociation-integration and repression-abreaction models are contrasted. RESULTS: Descriptive evidence is cited in support of preferring Myers' and McDougalls' dissociation-integration treatment approach over Brown's repression-abreaction model. CONCLUSION: Therapeutic findings in this paper complement diagnostic data from the first report. Although effective treatment includes elements of both the dissociative-integrative and abreactive treatment approaches, cognitive integration of dissociated traumatic memories and personality functions is primary, while emotional release is secondary.

Abreaction↗

PubMedDate not supplied

Dissociative symptoms and amnesia in Dutch concentration camp survivors.

We examined to what extent dissociative phenomena in concentration camp survivors are related to post-traumatic stress symptoms. Self-reports of amnesia for traumatic war events and other dissociative experiences were studied in a sample of 31 Dutch survivors of World War II (WWII) Japanese concentration camps. Seventeen survivors treated for war-related psychiatric symptoms were compared to 14 concentration camp survivors who had no psychiatric diagnosis. Although survivors who received treatment scored significantly higher on the Impact of Event Scale and the Post-Traumatic Symptom Scale than control survivors, the two groups did not differ in terms of accessibility of war memories or dissociative experiences. Levels of post-traumatic stress symptoms were not significantly correlated with dissociative experiences. In both groups, reports of psychogenic amnesia for traumatic events were rare. Our results support previous studies demonstrating that post-traumatic stress symptoms are not necessarily accompanied by dissociative experiences. They also contradict the suggestion that amnesia is a common phenomenon in people who have been exposed to war atrocities.

Adolescent↗

PubMed2002

Transient aphasia and persistent amnesia after surgery for internal carotid artery--posterior communicating artery aneurysm.

We report a case of transient aphasia and persistent amnesia after clipping of a ruptured cerebral aneurysm to treat a subarachnoid hemorrhage. Postoperatively, aphasia was identified and magnetic resonance imaging (MRI) showed an abnormal intensity area in the left anterior thalamus. Single photon emission computed tomography (SPECT) revealed a wider area of low perfusion surrounding the left thalamus and left frontotemporal lobe than that shown by the MRI. His aphasia resolved over the subsequent 12-week period. He was left with an isolated disturbance of memory; in the absence of any dementia, aphasia or disturbance of consciousness, his condition was classified as one of amnesia. SPECT 14 weeks after admission revealed an area of low perfusion limited to the left thalamus. These findings suggest that the persistence of amnesia in this case was caused by the infarction of the mammillothalamic tract, and the recovery from aphasia may have resulted from the disappearance of surrounding edema.

Amnesia↗

PubMed2006

Functional ("psychogenic") amnesia.

Patients who present with severely impaired memory functioning without a discernable neurological cause typically have experienced one or more severely stressful life events. These patients, who are described as having "psychogenic" or "dissociative" amnesia, typically differ from patients with the neurologic amnestic syndrome in that memory for their personal life histories is much more severely affected than is their ability to learn and retain new information; that is, they have isolated retrograde amnesia. Recent cognitive and brain imaging research has begun to reveal some of the cerebral mechanisms underlying functional amnesia, but this disorder remains best conceptualized as a relatively rare form of illness-simulating behavior rather than a disease. Neuropsychological assessment is often useful in revealing the circumscribed nature of the patient's performance deficits, the spared functions that can be brought to bear in rehabilitation, and the emotional disorders requiring psychiatric treatment. Controlled treatment trials are nonexistent, but case reports suggest that supportive psychotherapy, systematic relaxation training, hypnosis, and sedative/anxiolytic medications are useful in facilitating recovery. These treatments are often combined with a psychoeducational approach that essentially reteaches the patient his or her life story.

Adult↗

PubMed2004

The effect of midazolam on visual search: Implications for understanding amnesia.

The notion of multiple memory systems based on conscious accessibility has been supported largely by neuropsychological patient studies. Specifically, it was widely held that amnesic patients have impaired explicit memory performance but spared implicit memory performance. However, recent patient studies have called the implicit/explicit memory distinction into question. In this study, normal participants were tested on a visual search task, once after an injection of midazolam, an anesthetic that induces temporary amnesia, and once after an injection of saline. Under the influence of midazolam, participants did not show facilitation in search times for repeated configurations (contextual cuing), although there was a general speed-up in performance across blocks in both the midazolam and saline conditions. Neither the contextual-cuing effect nor the procedural-learning effect was available to subjective experience, yet only one of these was affected by midazolam-induced amnesia. These data call into question the notion that memory systems divide on the basis of subjective experience of consciousness or reportability. Rather, the findings support the contention that anterograde amnesia affects learning that depends on building novel associations in memory and that this deficit does not hinge upon accessibility to consciousness.

Adult↗

PubMed1992

Self-ratings of memory dysfunction: different findings in depression and amnesia.

An 18-item self-rating test of memory functions was administered to two patient groups: seven patients with amnesia resulting from Korsakoff's syndrome and six other amnesic patients. These results were compared to results obtained previously for depressed psychiatric inpatients (n = 19) and depressed inpatients prescribed electroconvulsive therapy (ECT) (n = 35). The latter group was tested both before and 1 week after completion of the course of ECT. One pattern of memory self-ratings was reported by the two groups of depressed patients. These two groups reported an approximately equivalent level of impairment across all test items. A different pattern of memory self-ratings was reported by the two groups of amnesic patients and by the group tested after ECT. These patients reported considerably more impairment on some items than others, such that performance was not equivalent across test items. Finally, the patients with Korsakoff's syndrome underestimated their memory problems, reporting a less severe impairment than the other amnesic patients. The results show that the memory problems experienced in depression and in amnesia are distinguishable with self-assessment techniques. In addition, the similarity between memory self-ratings reported by patients after ECT and by amnesic patients supports the idea that memory complaints after ECT reflect primarily the experience of amnesia. Self-rating forms like the one described here may have useful application to many diagnostic groups where questions arise about the nature of reported memory problems.

Adult↗

PubMed1993

Searching for the anatomical basis of retrograde amnesia.

The case of a patient with profound retrograde and minor anterograde amnesia is described and used to discuss the kind of brain damage which will most likely result in persistent retrograde amnesia as the principal symptom. The patient was an industrial manager who had fallen off a horse four years prior to the present neuropsychological and neuroradiological investigation. MRI examination revealed an injury to both temporal poles and to the latero-ventral portion of the right prefrontal cortex. The prefrontal and temporal cortical damage on the right side deeply invaded the white matter while the temporal cortical damage on the left side was much smaller; here, however, portions of the temporo-parietal transition zone were affected as well. The patient was of average intelligence. His attention, short-term memory, and learning ability were average or somewhat below average. His old memories were severely affected in the personal-episodic domain, and much less so in that of semantic remote memory. We conclude from this case that the necessary anatomical substrate for the retrieval of old episodic memories lies within the anterior temporal regions (including deeper situated fiber projections) and possibly involves an interaction with the prefrontal cortex, and that this damage is dissociable from the medial temporal-lobe damage leading to anterograde amnesia.

Amnesia, Retrograde↗

PubMed1994

Two tests for assessing remote public knowledge: a tool for assessing retrograde amnesia.

Guidelines for the construction and development of tests of remote memory are provided. These guidelines follow from methodological considerations and from certain theoretical issues we believe that remote memory tests should address if they are to further our understanding of amnesia. These include: the pattern of temporal gradient; memory for different broad classes of information such as famous names and famous events; and recall and recognition of different types of detail such as contextual and non-contextual information associated with remote memory. With respect to the first of these, we argue that it is impossible to fully evaluate competing hypotheses about temporally graded retrograde amnesia unless items are selected from at least two difficulty levels, and from at least two time periods. The construction of two equivalent tests of remote memory, one for famous people, the other for famous events, is described, and the theoretical issues listed earlier were addressed using these tests in a study comparing the remote memory of 13 organic amnesics and 13 age- and IQ-matched controls. The principal findings were as follows. There was only weak evidence that amnesics' remote memory for famous people and events was temporally graded over a 20 year period, and recognition memory and memory for non-contextual detail were equally impaired. Mayes, Meudell, and Pickering's (1985) context memory deficit hypothesis was supported, however, because amnesics were more impaired in their ability to date recognised items. In addition, although there was little support for a temporally graded retrograde impairment on the recognition question, there was much clearer evidence for the temporal dating question. Also, one patient, SR, showed a selective deficit in dating recognised names and events from the 1980s. Finally, the correlations between measures of anterograde and retrograde amnesia were all non-significant. Suitable items for the construction of remote memory tests probing the four decades 1950s to 1980s are presented. A subset of these, from the 1970s and 1980s, were shown to have satisfactory psychometric qualities, and can therefore be recommended for more widespread clinical use, although more extensive normative data than that provided here will be necessary.

Adult↗

PubMed1994

The Autobiographical Memory Interview (AMI) in organic and psychogenic amnesia.

The Autobiographical Memory Interview (AMI) is a semi-structured interview, sampling a subject's recollections across three broad time-periods. In patients with organic amnesia or dementia, there is an impairment in recalling both autobiographical facts and incidents, and there is a temporal gradient such that early memories are relatively spared. Correlations with measures of anterograde memory are relatively low, and lesions affecting the frontal lobes, anterior temporal poles, the posterior-medial temporal lobes, or even projections from the occipital lobes, can impair retrieval of autobiographical memories. In schizophrenia, an impairment in retrieving autobiographical incidents, comparable with organic amnesia, has been reported in some patients. However a patient with delusional memories secondary to schizophrenia is cited, in whom AMI performance was normal. Finally, patients with psychogenic amnesia show a variable pattern of performance, but, in general, there is a disproportionate impairment of autobiographical memory, and often an anomalous temporal gradient, which can recover subsequently.

Alcohol Amnestic Disorder↗

PubMed2003

Infantile amnesia reconsidered: a cross-cultural analysis.

A number of theories have been offered over the past hundred years to explain the phenomenon of infantile amnesia, the common inability to remember autobiographical experiences from the first years of life. Recent comparative studies that examine autobiographical memories in different populations, particularly populations in North America and East Asia, have yielded intriguing findings that provide a unique opportunity to revisit some of the major theoretical views and to propose new accounts. In light of these findings, this article discusses five theoretical explanations for infantile amnesia, including cognitive and social discontinuity, the emergence of the self, early parent-child memory sharing, functions of autobiographical memory, and the complexity of life experience. The reconsideration of infantile amnesia from a cross-cultural perspective suggests that while the basic mechanisms and contributing factors may be universal, the specific ways in which these mechanisms and factors are manifested differ qualitatively across cultures. A theoretical approach that takes the larger cultural context into account can help us understand this long-standing puzzle.

Adult↗

PubMedDate not supplied

Extending models of hippocampal function in animal conditioning to human amnesia.

Although most analyses of amnesia have focused on the loss of explicit declarative and episodic memories following hippocampal-region damage, considerable insights into amnesia can also be realised by studying hippocampal function in simple procedural, or habit-based, associative learning tasks. Although many simple forms of associative learning are unimpaired by hippocampal damage, more complex tasks which require sensitivity to unreinforced stimuli, configurations of multiple stimuli, or contextual information are impaired by hippocampal damage. In several recent papers we have developed a computational theory of hippocampal function which argues that this brain region plays a critical role in the formation of new stimulus representations during learning (Gluck & Myers, 1993, 1995; Myers & Gluck, 1996; Myers, Gluck, & Granger, 1995). We have applied this theory to a broad range of empirical data from studies of classical conditioning in both intact and hippocampal-lesioned animals, and the model correctly accounts for these data. The classical conditioning paradigm can be adapted for use in humans, and similar results for acquisition are obtained in both normal and hippocampal-damaged humans. More recently, we have begun to address an important set of category learning studies in both normals and hippocampal-damaged amnesics. This work integrates experimental studies of amnesic category learning (Knowlton, Squire, & Gluck, 1994) with theoretical accounts of associative learning, and builds on previously established behavioural correspondences between animal conditioning and human category learning (Gluck & Bower, 1988a). Our work to date illustrates some initial progress towards a more integrative understanding of hippocampal function in both animal and human learning, which may be useful in guiding further empirical and theoretical research in human memory and amnesia.

Amnesia↗

PubMedDate not supplied

The relationships between temporal lobe and diencephalic structures implicated in anterograde amnesia.

The relationship between the anterograde amnesic syndromes associated with diencephalic and temporal lobe pathology is examined in the light of recent findings. It is proposed that a common feature of anterograde amnesia is damage to part of an "extended hippocampal system" comprising the hippocampus, the fornix, the mammillary bodies, and the anterior thalamic nuclei. Damage to this system results in deficits in the recall of episodic information, the core symptom of anterograde amnesia. In contrast, lesions in this system need not disrupt tests of recognition memory when they primarily tax familiarity judgements. It is assumed that familiarity judgements depend on other regions (e.g. the rhinal cortex in the case of temporal lobe amnesia) and that the extended hippocampal system is principally involved in those aspects of recognition that are retrieval-based rather than familiarity-based. These proposals arise from new evidence on the performance of delayed nonmatching-to-sample by animals, from a meta-analysis of the performance of amnesic subjects on a test of recognition memory, and from new research into the pattern of connections between the medial temporal lobe and the medial diencephalon in primates.

Amnesia↗