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PubMed1975

Neurohypophyseal hormones, analogs, and fragments: their effect on puromycin-induced amnesia.

Neurohypophyseal hormones and several of their analogs, as well as N-terminal and C-terminal fragments, have been studied for their ability to attenuate puromycin-induced amnesia in mice. [8-Lysine]vasopressin, [8-arginine]vasopressin, and the analogs des-9-glycinamide-[8-lysine]vasopressin, [1-beta-mercaptopropionic acid, 8-lysine]vasopressin, [1,6-aminosuberic acid, 8-lysine]vasopressin, [4-leucine, 8-lysine]vasopressin, glycyl-glycyl-glycyl-[8-lysine]vasopressin, [1-beta-mercaptopropionic acid, 8-D-arginine]vasopressin, and [1,6-aminosuberic acid, 8-arginine]vasopressin are active. [8-Arginine]oxytocin as well as oxytocin and all of its other analogs tested are inactive with the striking exception of glycyl-glycyl-glycyl-oxytocin. The structural aspects of the neurohypophyseal hormones which appear to be important for significant activity in memory consolidation include the combination of a cyclic moiety containing the Tyr and Phe residues along with a basic residue in position 8. Another series of active compounds comprises C-terminal neurohypophyseal peptides and analogs thereof, including the naturally occurring Pro-Leu-Gly-NH2 and, most surprisingly, Leu-Gly-NH2, as well as its derivatives D-Leu-Gly-NH2 and the diketopiperazine, cyclo(-Leu-Gly-).

Amnesia↗
PubMed1992

Basolateral amygdala lesions block diazepam-induced anterograde amnesia in an inhibitory avoidance task.

This experiment examined the effects of diazepam (DZP) on acquisition and retention of an inhibitory avoidance response by rats with excitotoxic-induced lesions of central (CE), lateral (LAT), or basolateral (BL) amygdala nuclei. Sham-operated and lesioned rats received i.p. injections of DZP (2.0 mg per kg of body weight) 30 min before training in a continuous multiple-trial inhibitory avoidance task. Retention was tested 48 h later. Acquisition was not impaired by the lesions or the DZP. Retention was impaired in animals with CE and LAT lesions in comparison with sham-operated controls. DZP impaired retention in the sham-operated controls as well as CE- and LAT-lesioned animals but did not affect retention in animals with BL lesions. These findings indicate that the DZP-induced anterograde amnesia for inhibitory avoidance training is mediated through influences involving the BL amygdala nucleus.

Amnesia↗
PubMed1994

The animal model of human amnesia: long-term memory impaired and short-term memory intact.

Normal monkeys and monkeys with lesions of the hippocampal formation and adjacent cortex (the H+ lesion) were trained on the delayed nonmatching to sample (DNMS) task with a delay of 0.5 s between the sample and the choice. The animals with H+ lesions learned the task normally at this short delay and also exhibited the same pattern of response latencies as normal monkeys. This finding contrasts with previous observations that initial learning of the DNMS task with delays of 8-10 s is impaired after H+ lesions. The absence of an impairment at a delay of 0.5 s indicates that the H+ lesion does not affect short-term memory. In contrast, when monkeys with H+ lesions were tested at longer delays (> 30 s), an impairment was observed. This selective impairment occurred when the delays were presented sequentially (from 0.5 s to 10 min) and also when delays were presented in a mixed order (1 s, 1 min, and 10 min). The data indicate that the H+ lesion produces a selective impairment in long-term memory, in the absence of a detectable deficit in short-term memory or perception. Accordingly, the findings confirm the long-standing idea, based primarily on studies of humans, that short-term memory is independent of medial temporal lobe function. The findings thereby establish an important parallel between memory impairment in monkeys and humans and provide additional support for the validity of the animal model of human amnesia in the monkey.

Amnesia↗
PubMed2001

Post-Traumatic amnesia: consistency-of-recovery and duration-to-recovery following traumatic brain impairment.

The aim of this research was to examine the nature and order of recovery of orientation and memory functioning during Post-Traumatic Amnesia (PTA) in relation to injury severity and PTA duration. The Westmead PTA Scale was used across consecutive testing days to assess the recovery of orientation and memory during PTA in 113 patients. Two new indices were examined: a Consistency-of-Recovery and a Duration-to-Recovery index. A predictable order of recovery was observed during PTA: orientation-to-person recovered sooner and more consistently than the following cluster; orientation-to-time, orientation-to-place, and the ability to remember a face and name. However, the type of memory functioning required for the recall face and name task recovered more consistently than that required for memorizing three pictures. An important overall finding was that the "order-of-recovery" of orientation and memory functioning was dependent upon both the elapsed days since injury, and the consistency of recovery. The newly developed indices were shown to be a valuable means of accounting for differences between groups in the elapsed days to recovery of orientation and memory. These indices also clearly increase the clinical utility of the Westmead PTA Scale and supply an objective means of charting (and potentially predicting) patients' recovery on the different components of orientation and memory throughout their period of hospitalization.

Adolescent↗
PubMed2001

Executive amnesia in a patient with pre-frontal damage due to a gunshot wound.

This paper reports the case of a young patient with extensive pre-frontal damage in whom we tested the hypothesis that intensive training improves executive performance as assessed by the Wisconsin Card Sorting Test (WCST). As long as her declarative memory, complex perceptual abilities and global cognitive status were spared, we surmised that any deficit in executive learning would have occurred in relative isolation. We showed that her abnormal performance on the WCST, both on the standard as well as on the post-instruction condition, was due to an impairment of shifting attention across perceptual dimensions (extra-dimensional). In contrast, her ability to shift attention within perceptual categories (intra-dimensional) was spared, as were her declarative memory, object and visuospatial perception, oral language comprehension and praxis (ideomotor, tool use and constructional). This case supports the hypothesis that executive amnesia is a type of amnesic disorder distinct from the classic amnesic syndrome due to mamillo-temporomedial damage. As such, it is probably closely related to procedural learning and may depend on the same fronto-subcortical loops that mediate the actual execution of behaviour.

Adolescent↗
PubMed2001

Posthypnotic amnesia for material learned before or during hypnosis: explicit and implicit memory effects.

This article focuses on dissociations between explicit and implicit expressions of memory during posthypnotic amnesia (PHA). Despite evidence of such dissociations, experimental design in this area has not always been consistent with contemporary memory research. Within a paradigm that aimed for conceptual and methodological clarity, we presented 40 high and 38 low hypnotizable individuals with a word list either before or during hypnosis, gave them a PHA suggestion for the word list, and tested them on explicit and implicit memory tasks. In the absence of conscious recollection, highs showed equivalent levels of priming (perceptual and semantic) to lows. However, when analysis focused only on those highs who remained amnesic after the implicit memory tasks, we confirmed perceptual, but not semantic, priming. These findings highlight the impact of methodological choices on theoretical interpretations of memory performance following a suggestion for PHA.

Adolescent↗
PubMed1990

Transient global amnesia.

Transient global amnesia is often attributed to a seizure, vascular cause, or migraine, but the outcome is usually benign. The presence of migraine and important risk factors for stroke necessitates close patient monitoring. Anti-platelet therapy should be considered.

Amnesia↗
PubMed2005

Non-declarative memory in the rehabilitation of amnesia.

The ability of amnesic patients to learn and retain non-declarative information has been consistently demonstrated in the literature. This knowledge provided by basic cognitive neuroscience studies has been widely neglected in neuropsychological rehabilitation of memory impaired patients. This study reports the case of a 43 year old man with severe amnesia following an anterior communicating artery (ACoA) aneurysm rupture. The patient integrated a comprehensive (holistic) day treatment programme for rehabilitation of brain injury. The programme explored the advantages of using preserved non-declarative memory capacities, in the context of commonly used rehabilitation approaches (i.e. compensation for lost function and domain-specific learning). The patient's ability to learn and retain new cognitive and perceptual-motor skills was found to be critical for the patient's improved independence and successful return to work.

Adult↗
PubMed1982

Selective effects of cholinergic treatment on verbal memory in posttraumatic amnesia.

The combined effects or orally administered physostigmine and lecithin were assessed in a double-blind study of a single patient with posttraumatic amnesia. Treatment improved verbal recall but not verbal recognition, visual memory, or conceptual reasoning. Both storage and retrieval of words in verbal memory were facilitated. Greater improvement in learning of longer or semantically homogeneous word lists than shorter or semantically mixed lists may indicate that treatment reduced the effects of interstimulus interference. Greater divergence of recognition response biases for semantically homogeneous vs. mixed lists was observed under treatment, reflecting some enhancement of semantic appreciation. Absence of a treatment effect on visual nonverbal memory may be due in part to lateralization of the mesencephalic lesion to the left in this patient. Lack of improvement of encoding capacity, d', or conceptual reasoning may reflect a greater dependence of basal forebrain structures on catecholaminergic than cholinergic mechanisms.

Adult↗
PubMed1984

The clinical aspects of memory disorders: contributions from experimental studies of amnesia and dementia.

Many of the standardized memory tests employed by clinical neuropsychologists fail to demonstrate important differences in the memory disorders of amnesic and demented patients. To exemplify this heterogeneity of amnesic symptoms, the anterograde and retrograde amnesias of patients with Huntington's Disease (HD) and of patients with alcoholic Korsakoff's syndrome are compared. While both patient groups have similar MQs, they differ dramatically in their recall and recognition memory and in their ability to acquire procedural (rule-based) information. The Korsakoff patients are impaired in both recall and recognition memory but are able to acquire and retain mirror reading skills. In contrast, the patients with HD are impaired in their acquisition of procedural knowledge and in verbal recall although their recognition memory approaches normality. The importance of such information for the assessment of the patients' memory disorders is discussed.

Alcohol Amnestic Disorder↗
PubMed1990

Persistent memory impairment following transient global amnesia.

A controlled neuropsychological study of 41 patients tested at 6 months after attacks of transient global amnesia (TGA) revealed no evidence of general intellectual, immediate (short-term) memory or nonverbal memory impairment. The patient group's performance was, however, significantly worse than that of the control's on measures of verbal memory notably immediate, 30-minute and 24-hour delayed paragraph recall. In addition, tests of public and personal remote memory revealed significant impairment of naming and recognition of famous faces, and of dating famous events without evidence of a temporal gradient, and impairment of cued recall of autobiographical memories on the Modified Crovitz Test. These findings suggest that following TGA there is persistent, albeit mild, hippocampal-diencephalic dysfunction which appears to involve left-sided structures preferentially. This impairment probably results from the attack, although a pre-existent deficit cannot be excluded.

Aged↗
PubMed1993

Proactive interference in patients with amnesia resulting from anterior communicating artery aneurysm.

Diencephalic and temporal amnesics display an excessive sensitivity to proactive interference (PI) in memory tasks of the AB/AC kind. There exists considerable controversy about the nature of this sensitivity to PI. Moreover, it is an open question whether such sensitivity to PI is an obligatory feature of amnesia, or rather an incidental result of frontal damage often reported in amnesics. This question was reexamined by enrolling patients with an operated aneurysm of the anterior communicating artery (ACoA) and matched controls for an AB/AC learning task of two lists of 12 paired-associate words. It appeared that ACoA patients, like diencephalic and temporal amnesics, did indeed display a marked sensitivity to PI when compared to normals (Exp. I), even when performance of both groups in the learning of the first list was equated (Exp. II). The distribution of errors made in learning the second list, as well as the correlations between performance in learning the second list and a Stroop test, suggest that sensitivity to PI in ACoA amnesics could be the consequence of an inability to suppress irrelevant information at retrieval due to defective inhibitory attentional mechanisms. Complementary data collected in a small sample of Korsakoff's amnesic subjects are also described.

Adult↗
PubMed2000

Post-traumatic amnesia after closed head injury: a review of the literature and some suggestions for further research.

Post-traumatic amnesia (PTA) is a transient sequela of closed head injury (CHI). The term PTA has been in clinical use for over half a century, and generally refers to the subacute phase of recovery immediately after unconsciousness following CHI. The duration of PTA predicts functional outcome after CHI, but its pathophysiological mechanism is not known. This paper compares current methods of determining the duration of PTA, summarizes reports on neuropsychological deficits in PTA, reviews available data that allow inferences about its mechanism, and suggests methods for further exploration of its pathophysiology.

Amnesia↗
PubMed2001

Transient crossed aphasia and persistent amnesia after right thalamic haemorrhage.

A 45-year-old right-handed woman suffered transient aphasia and persistent amnesia after a right thalamic haemorrhage. This patient appeared to have crossed aphasia, although it disappeared within 8 weeks. It is noteworthy that the patient had a unilateral right thalamic lesion but exhibited both verbal and non-verbal memory impairment. Computed tomography and magnetic resonance imaging revealed cerebral haemorrhage in the right thalamus involving the ventral anterior nucleus, medioventral nucleus, mamillothalamic tract, internal medullary lamina, and mediodorsal nucleus. An amytal test was performed and suggested that the right hemisphere was dominant for language functions and the left hemisphere was dominant for visuospatial functions. Single photon emission CT revealed a low perfusion area only in the right thalamus. These findings suggest that the right hemisphere might be dominant for both verbal and non-verbal memory function in this patient, although visuospatial function was lateralized in the left hemisphere.

Amnesia↗
PubMed2001

Amnesia, neuroendocrine levels and PTSD in motor vehicle accident victims.

PRIMARY OBJECTIVE: To examine the initial neuroendocrine responses and subsequent PTSD symptomatology among amnesic and non-amnesic victims of motor vehicle accidents. It was hypothesized that amnesic patients would be less likely to meet PTSD criteria at 1 month follow-up and would display lower catechalomine levels and higher basal cortisol than non-amnesics. METHODS AND PROCEDURE: Fifteen-hour urinary hormone samples were collected from 70 MVA victims upon hospital admission. Participants were assessed for PTSD symptomatology 1 month later. MAIN OUTCOMES AND RESULTS: Amnesic patients displayed lower NE/cortisol ratios than non-amnesics, were less likely than non-amnesics to develop PTSD, and displayed fewer PTSD symptoms than non-amnesics. CONCLUSIONS: Amnesics may physiologically experience a motor vehicle accident differently from non-amnesics and have lower subsequent PTSD incidence. These results provide partial support for the hypothesis that amnesia for a traumatic event can serve as a buffering function in the development of subsequent PTSD among MVA victims.

Accidents, Traffic↗
PubMed2004

Evaluating computer-assisted memory retraining programmes for people with post-head injury amnesia.

OBJECTIVE: The present study was designed to perform theory-driven empirical work that might contribute to a better understanding of computer-assisted training effects adopting theoretically different memory retraining strategies for people who had amnesia as a result of a brain injury. RESEARCH DESIGN: A pre-test and post-test control group quasi-experimental design was adopted to test the differences in effectiveness of four different computer-assisted memory training strategies, which were hypothesized to improve different memory skills of persons with brain injury. METHOD AND PROCEDURES: Twenty-six persons with brain injury were randomly assigned to four age- and gender-matched memory training groups (self-paced, feedback, personalized, visual presentation) and they were trained using the related computer software, evaluated by the Rivermead Behavioural Memory Test (RBMT), self-efficacy scale and built-up computer performance records. MAIN OUTCOMES AND RESULTS: All the four memory training methods showed positive among the persons with brain injury as compared with a control group, although there was no statistically significant difference among the four training methods. However, clinical improvement was found in all four methods and the Feedback group showed significant improvement in self efficacy, in comparison with the other groups. CONCLUSION: This attempt to develop and evaluate different computer applications for memory retraining was made and the effectiveness of applying customized computer technology in memory rehabilitation was critically evaluated. Results of the present study showed that the unique customized therapeutic characteristics of computer-assisted memory retraining (e.g. self-paced practice, performance feedback, salient visual presentation and personalized training contents) are positive attributes of memory skill retraining outcomes.

Adolescent↗
PubMed2005

Effect of an integrated reality orientation programme in acute care on post-traumatic amnesia in patients with traumatic brain injury.

PRIMARY OBJECTIVE: To assess the effect of an integrated reality orientation programme (North Star Project) in acute care on the duration of post-traumatic amnesia (PTA) of patients suffering from traumatic brain injury (TBI). It was hypothesized that those patients having participated in this programme would show a shorter PTA than those patients that did not. METHOD: Duration of PTA for 12 patients with TBI who were part of the North Star Project was compared with that of 26 patients matched for initial GCS and age for whom this approach was not available (control group). RESULTS: Length of PTA was shorter by 5 days for the North Star patients. This result was not statistically significant (p = 0.19) but is clinically relevant. No between-group difference was found for Glasgow Coma Scale. CONCLUSIONS: Consequences of shorter PTA would include increased and more appropriate patient interaction and earlier transfer to rehabilitation. The North Star project also allows the family to become more actively involved in the treatment of their loved one. Further study is required to evaluate this intervention strategy to improve orientation for the patient with TBI.

Adolescent↗
PubMed2006

Post-traumatic amnesia predicts long-term cerebral atrophy in traumatic brain injury.

PRIMARY OBJECTIVE: To examine post-traumatic amnesia (PTA) and its relation to long-term cerebral atrophy in persons with traumatic brain injury (TBI) using objective indicators of PTA duration and Quantitative Magnetic Resonance Imaging (QMRI). It was hypothesized that longer PTA would predict later generalized atrophy (increased ventricle-to-brain ratio (VBR)). As a guide in assessing patients with TBI, this study determined the probability of developing chronic cerebral atrophy based on PTA duration. RESEARCH DESIGN: Probability model using 60 adult patients with mild-to-severe TBI. MAIN OUTCOMES AND RESULTS: A logistic regression model with a cut-off determined by normative QMRI data confirmed that longer PTA duration predicts increased VBR. A probability model demonstrated a 6% increase in the odds of developing later atrophy on neuroimaging with each additional day of PTA. CONCLUSIONS: PTA has previously proven to be a good indicator of later cognitive recovery and functional outcome and also predicts long-term parenchymal change.

Adolescent↗