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PubMed2006

Recovery of components of memory in post-traumatic amnesia.

PRIMARY OBJECTIVE: Post-traumatic amnesia by definition indicates significant impairment of new learning ability, however very few studies have, examined the natural history and resolution of memory and new learning during PTA. Those studies which have, tended to examine orientation separately from the memory processes required to achieve orientation. Analysis of the order of recovery of the items of the Westmead PTA scale was used to examine recovery of memory and new learning capacity. METHODS: The results of daily assessment of 34 patients with traumatic brain injury (TBI) on the Westmead PTA scale were analysed for order of recovery. RESULTS: The pattern of rank order of item recovery indicated that Date of Birth recovered consistently first. There was variability in the remaining items, however items reflecting long-term memory tended to recover second and items reflecting simple new learning followed. Recall of all three pictures reflecting complex new learning recovered last. CONCLUSION: The pattern of recovery of memory and new learning during PTA reflects a number of complex, inter-related variables including; the familiarity with the information, amount of rehearsal both before and since the accident and the number of cues available in the environment.

Adolescent↗
PubMed2006

Treating dysarthria following traumatic brain injury: investigating the benefits of commencing treatment during post-traumatic amnesia in two participants.

PRIMARY OBJECTIVE: The aims of this preliminary study were to explore the suitability for and benefits of commencing dysarthria treatment for people with traumatic brain injury (TBI) while in post-traumatic amnesia (PTA). It was hypothesized that behaviours in PTA don't preclude participation and dysarthria characteristics would improve post-treatment. RESEARCH DESIGN: A series of comprehensive case analyses. METHODS AND PROCEDURES: Two participants with severe TBI received dysarthria treatment focused on motor speech deficits until emergence from PTA. A checklist of neurobehavioural sequelae of TBI was rated during therapy and perceptual and motor speech assessments were administered before and after therapy. MAIN OUTCOMES AND RESULTS: Results revealed that certain behaviours affected the quality of therapy but didn't preclude the provision of therapy. Treatment resulted in physiological improvements in some speech sub-systems for both participants, with varying functional speech outcomes. CONCLUSIONS: These findings suggest that dysarthria treatment can begin and provide short-term benefits to speech production during the late stages of PTA post-TBI.

Adult↗
PubMed1998

Transient global amnesia triggered by mild head injury.

An episode of transient global memory loss was observed in a 27-year-old woman following a mild head injury in a car accident. Her clinical and neuropsychological profiles were indistinguishable from those of transient global amnesia (TGA). This paper argues that a cause-effect relationship may be postulated between head trauma and transient memory loss, perhaps as the result of a very stressful situation such as a car crash.

Acute Disease↗
PubMed1999

Measuring recovery from post traumatic amnesia.

Three groups of participants were assessed. Each participant was tested on 20 occasions. The groups comprised people (i) in post traumatic amnesia (PTA) following severe head injury (n=9), (it) with severe head injury but not in PTA (n=10), and (iii) with no history of head injury or other neurological condition (n=13). Subjects were given several tests of memory, attention and learning in order to determine which tests were good at (a) distinguishing people in PTA from those not in PTA, and (b) monitoring recovery over time. The results indicate that people in PTA have a wide range of deficits and their cognitive recovery is a gradual process rather than an all-or-none phenomenon. In terms of measurement, the study suggests that a good test of PTA should include orientation questions, together with a reaction time measure, a visual recognition test and a speed of information processing measure. Most of the tests administered were good at distinguishing between brain-injured and nonbrain-injured people, although only two tests distinguished between the two brain-injured groups, i.e. those in PTA and those out of PTA. Almost all tests were good at monitoring recovery from PTA.

Adult↗
PubMed2005

Childhood amnesia in children and adolescents: their earliest memories.

Investigations of childhood amnesia have almost exclusively focused on the earliest memories of adults. Here we investigate the earliest memories of children of 6--19 years old. Parents confirmed the memory events and dated the memories. There were surprisingly few developmental differences between the earliest memories of children. Although 6--9-year-olds recalled earlier events than did older children, there were no differences between older age groups. Memories from all age groups were similar in structure, social orientation, and the nature of the recalled event. However, memories of older children were more likely to involve negative affect. There were also few gender differences, although girls were more likely to recall traumatic or transitional events while boys were more likely to recall play events. Overall, results deepen the paradox of early memory: 6--9-year-olds have verbally accessible memories from very early childhood that then seem to disappear as they get older.

Adolescent↗
PubMedDate not supplied

Functional neuroimaging correlates of functional amnesia.

Especially in the field of memory encoding and retrieval, the results of functional neuroimaging have provided new insights in anatomico-functional interactions. In particular this holds true for the role of the prefrontal cortex in mnestic information processing, for the contribution and participation of the two hemispheres in various processes of information transmission, and for views on disturbed information processing after organically obvious and so-called psychogenic forms of memory impairments. This report particularly stresses the insights obtained by functional neuroimaging for probably environmentally triggered deficiencies in memory processing and discusses possible subtle neuroanatomical correlates of functional amnesias. It is especially emphasised that stress conditions and depressive states may modify the release of steroids (glucocorticoids) and transmitter agonists at the brain level with the consequence of selective memory disturbances which may manifest as a "mnestic block syndrome".

Amnesia↗
PubMedDate not supplied

FDG-PET analysis and findings in amnesia resulting from hypoxia.

The assumptions underlying neuroimaging, and problems in its analysis and interpretation, are commonly underestimated in neuropsychology. The ways in which fluoro-deoxy-glucose (FDG) positron emission tomography (PET) data can be analysed are discussed. PET findings from four patients who had suffered severe amnesia, following episodes of acute hypoxia, are presented. These patients had shown evidence of medial temporal (hippocampal and parahippocampal) atrophy on MRI brain scans. The PET data were analysed in several different ways. The converging findings were that the patients showed bilateral thalamic hypometabolism, and there was also evidence of retrosplenial hypometabolism bilaterally. Cognitively, these patients performed most like other patients with medial temporal lesions, but the results indicate that structural lesions can have distal metabolic effects on structures elsewhere. These findings are interpreted in the light of neuroanatomical observations concerning parallel projections between medial temporal lobe structures and the thalamus, some of which pass via the retrosplenium.

Adult↗
PubMed2005

Years of severe and isolated amnesia can precede the development of dementia in early-onset Alzheimer's disease.

A young patient with a severe and isolated memory disorder, meeting the criteria for MCI, was followed for a period of 8 years. His overall functional level remained stable with a CDR-score at 0.5 until the last year when it dropped to 1.0. Neuropsychological testing showed severe memory deficits but otherwise normal cognitive functions. Only minimal progression was measured; however, the last testing showed impaired abstraction and executive functioning as well as discrete problems generating names of objects and people. Neuroimaging, with MRI and SPECT, was consistent with a progressive degenerative disorder, and cerebrospinal fluid levels of beta-amyloid 1-42, tau protein, and phosphorylated tau protein were characteristic of Alzheimer's disease (AD). We argue that this is a case of prodromal AD, which illustrates an extreme version of the normal course with respect to slow progression of the disease and severity of amnesia early in the course.

Alzheimer Disease↗
PubMed2007

Amnesia and driving.

Two experienced drivers who developed severe amnesia due to bilateral hippocampal lesions participated in a series of standardized challenges of driving performance and knowledge of driving rules. During drives in a high fidelity simulator and on the road in an instrumented vehicle, they demonstrated vehicle control similar to that of normal drivers on measures of steering, speed control, safety errors, and driving with distraction. Their knowledge of driving rules, safety procedures, and road sign meaning also was normal. However, both participants were impaired at following route directions, and both had unsafe responses in a difficult crash avoidance scenario on the simulator. These findings suggest that memory impairment acquired by experienced drivers does not impair most aspects of driving performance, but may increase safety risk under some challenging circumstances.

Amnesia↗
PubMedDate not supplied

Predicting syndromes of amnesia from a composite holographic associative recall/recognition model (CHARM).

The composite holographic associative recall/recognition model (CHARM) is used to predict the amnesia syndromes that are expected under conditions of discrete lesions to different components of the model. The components that are needed to allow recognition, recall, and rehearsal are: (1) perceptual/lexical processing and pattern identification, (2) consciousness or working memory, (3) association formation, (4) composite storage, (5) novelty monitoring and control, and (6) retrieval. Deficits in each of these components will have specific effects on memory, generating characteristic profiles of performance. Comparison of the profiles exhibited by patients to the component-based profiles predicted by the model identify the component impaired in a given patient, and connect the memory impairments to the underlying infarcted brain structures. The model, thus, relates the memory tasks to the particular memory components that allow enactment of those tasks, and shows how the dysfunction of particular components produces specific impairments.

Amnesia↗
PubMedDate not supplied

A positive approach to viewing processing deficit theories of amnesia.

This reply is admittedly a defence of the encoding-deficits theory of amnesia. However, it attempts to go further by proposing that this deficit, which was originally designed just to explain amnesics' explicit episodic memory disorder, might be viewed as being but one instance of a more general disorder characteristic of all aspects of amnesic patients' information processing. It is proposed that amnesic patients' inability to perform more consciously controlled conceptual analyses results not only in explicit recall deficits, but sometimes also in instances of below normal implicit memory and recognition ability. Their ability to perform automatic, perceptual-level processing produces normal performance on some implicit and some recognition tasks, but it is not sufficient for all tasks.

Amnesia↗
PubMedDate not supplied

Consolidating dispersed neocortical memories: the missing link in amnesia.

Consolidation is often conceptualised as a general process by which memory traces can be strengthened in the brain. An alternative idea, developed here, is that a particular sort of consolidation is required for establishing memories belonging to a neurobiologically defined category-memories dispersed across multiple distinct neocortical zones. These memories are consolidated via the formation of a neocortical cell assembly that confers coherence to the set of scattered neocortical memory traces. A set of memory traces linked in this manner can subsequently serve as the basis for conscious recollection. A disruption of this neocortical consolidation process is held to be responsible for the patterns of preserved and impaired memory observed in amnesic patients. A suitable strategy for empirically testing this sort of theory requires an examination of evidence from neuropsychological studies of amnesia and from studies of the neural substrates of memory functions in normal subjects.

Amnesia↗
PubMed1978

Effect of age on amnesia and sedation induced by flunitrazepam during local anaesthesia for bronchoscopy.

Bronchoscopy was undertaken in 79 outpatients using local anaesthesia plus an i.v. injection of flunitrazepam 0.01 mg kg-1. The co-operation of the patients and the ease of bronchoscopy were good regardless of the age of the patient. There was an increase in amnesia for the bronchoscopy with increasing age, but the most distinct difference between different age groups was that the amnesic action of flunitrazepam was evident earlier and persisted longer in patients of more than 60 yr. Eye co-ordination and ability to stand steadily and walk on a line returned to normal more slowly in patients more than 60 than in those less than 60 yr, but no differences in recovery were noted between patients less than 40 and those of 40--59 yr, or between those 60--69 and those more than 70 yr.

Adult↗
PubMed1990

The aetiology of transient global amnesia. A case-control study of 114 cases with prospective follow-up.

A case-control comparison of 114 transient global amnesia (TGA) patients using both normal community-based controls (n = 109) and transient ischaemic attack (TIA) controls (n = 212) showed no evidence of an increased risk of TGA associated with any of the conventional risk factors for cerebrovascular disease. However, migraine was significantly more common in the TGA patients than in either control group. A prospective longitudinal study using actuarial (life table) analysis confirmed that the prognosis of the TGA patients was strikingly better than that of the TIA controls. An important minority (7%) of TGA cases developed epilepsy, usually within one year of presentation. On the basis of this evidence, a thromboembolic aetiology for TGA can be confidently rejected, at least for the vast majority of cases. There are good theoretical reasons to link migraine and TGA casually, and occasionally epilepsy may masquerade as TGA. In the remaining cases the cause remains unknown.

Adult↗
PubMed1991

Amnesia in man following transection of the fornix. A review.

Published accounts of the effects of fornix damage on memory in man are critically evaluated. Most weight is given to cases of surgical transection of the fornix, though other causes of fornix damage are briefly discussed. It is concluded that fornix transection causes amnesia.

Amnesia↗
PubMed1992

Transient global amnesia. A case control study.

A case control study of transient global amnesia (TGA), transient ischaemic attacks (TIA) and normal controls is described. Each of the 51 TGA patients, selected between January 1985 and March 1990, was compared with four controls (two TIAs and two normals) for the presence of vascular risk factors (hypertension, diabetes, smoking habits, cholesterol, triglycerides and haematocrit levels, heart disease, previous stroke), previous TGA, migraine, psychiatric illness and recent head trauma. Patients with TGA had less diabetes, hypercholesterolaemia and hypertriglyceridaemia than TIA. TGA subjects had significantly more hypertension (odds ratio = 3.31) and migraine (odds ratio = 8.67) than normal controls. During a mean of 17.4 mths of follow-up (range 1-96 mths), three subjects had recurrent TGA, one sustained a TIA and a minor stroke, but none had seizures. Thrombo-embolism and epilepsy are unlikely to be the cause of this benign disorder. The role is stressed of appropriate precipitants, including haemodynamic changes, and of individual susceptibility (of which migraine is probably a marker) in the genesis of TGA.

Adult↗
PubMed1994

Agnosia, alexia and a remarkable form of amnesia in an adolescent boy.

Childhood cases of global anterograde amnesia, visual agnosia or alexia without agraphia, either alone or in any combination, are extremely rare. Here we report the case of a male adolescent, Neil (a pseudonym), who consequent to a pineal tumour began to exhibit all three disorders in the presence of normal verbal intelligence. The most surprising aspect of Neil's case, however, is his ability to retrieve postmorbid memories through the act of writing without being able to provide any oral account of the content of his written reports. His memory retrieval thus has some of the character of 'automatic writing'. This evidence pointing to Neil's possession of a dissociated form of episodic memory presents a new challenge to our understanding of the organization of memory and of the cerebral systems underlying it.

Adolescent↗