Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AMNESIA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources
PubMed2000

Developmental amnesia associated with early hypoxic-ischaemic injury.

We recently reported on three young patients with severe impairments of episodic memory resulting from brain injury sustained early in life. These findings have led us to hypothesize that such impairments might be a previously unrecognized consequence of perinatal hypoxic-ischaemic injury. Neuropsychological and quantitative magnetic resonance investigations were carried out on five young patients, all of whom had suffered hypoxic-ischaemic episodes at or shortly after birth. All five patients showed severe impairments of episodic memory (memory for events), with relative preservation of semantic memory (memory for facts). However, none had any of the major neurological deficits that are typically associated with hypoxic-ischaemic injury, and all attended mainstream schools. Quantitative magnetic resonance investigations revealed severe bilateral hippocampal atrophy in all cases. As a group, the patients also showed bilateral reductions in grey matter in the regions of the putamen and the ventral part of the thalamus. On the basis of their clinical histories and the pattern of magnetic resonance findings, we attribute the patients' pathology and associated memory impairments primarily to hypoxic-ischaemic episodes sustained very early in life. We suggest that the degree of hypoxia-ischaemia was sufficient to produce selective damage to particularly vulnerable regions of the brain, notably the hippocampi, but was not sufficient to result in the more severe neurological and cognitive deficits that can follow hypoxic-ischaemic injury. The impairments in episodic memory may be difficult to recognize, particularly in early childhood, but this developmental amnesia can have debilitating consequences, both at home and at school, and may preclude independent life in adulthood.

Adolescent↗
PubMed2000

Word repetition in amnesia. Electrophysiological measures of impaired and spared memory.

Amnesic patients often show improved performance when stimuli are repeated, even in the absence of conscious memory for those stimuli. Although these performance changes are typically attributed to perceptual or motor systems, in some cases they may be related to basic language processing. We examined two neurophysiological measures that vary with word repetition in 12 amnesic patients and 12 control subjects: (i) a late positive component of the event-related potential (ERP) linked to conscious memory and (ii) the N400 component that varies with language comprehension. In each trial, the subject heard a category name, then viewed a word, and then decided whether the word was semantically congruous or incongruous (e.g. 'yes' for 'baby animal: cub'; 'no' for 'water sport: kitchen'). Recall and recognition testing at the end of the experiment showed that control subjects had better memory for congruous than for incongruous words, as did the amnesic patients, who performed less well overall. In contrast, amnesic patients were unimpaired on the category decisions required in each trial and, like the control subjects, showed a large N400 for incongruous relative to congruous words. Similarly, when incongruous trials were repeated after 0-13 intervening trials, N400s were reduced in both groups. When congruous trials were repeated, a late positive repetition effect was observed, but only in the control group. Furthermore, the amplitude of the late positive repetition effect was highly correlated with later word recall in both patients and controls. In the patients, the correlation was also observed with memory scores from standardized neuropsychological tests. These data are consistent with a proposed link between the late positive repetition effect and conscious memory. On the other hand, the N400 repetition effect was not correlated with episodic memory abilities, but instead indexed an aspect of memory that was intact in the amnesic patients. The preserved N400 repetition effect is an example of preserved memory in amnesia that does not easily fit into the categories of low-level perceptual processing or of motor learning. Instead, the sensitivity of the N400 to both semantic context and repetition may reflect a short-term memory process that serves language comprehension in realtime.

Adult↗
PubMed2003

Working memory and executive functions in transient global amnesia.

Transient global amnesia (TGA) is usually considered to produce a profound impairment of long-term episodic memory, while at the same time sparing working memory. However, this neuropsychological dissociation has rarely been examined in detail. While a few studies have assessed some components of working memory in TGA, the results that have been obtained are far from conclusive. To clarify this issue, we carried out a comprehensive investigation of working memory in 10 patients during a TGA attack. In the first study, we report the results from three patients examined with a battery of neuropsychological tests designed to assess each of the three subcomponents of Baddeley's model of working memory. In a second study, seven different patients underwent neuropsychological investigations that focused specifically on the central executive system, using a protocol derived from a study by Miyake and colleagues. Our findings showed that subcomponents of working memory, such as the phonological loop and visuo-spatial sketch pad, were spared in TGA patients. Specific executive functions that entailed inhibitory control, dual task performance, updating and shifting mechanisms were also found to be normal. However, we found significantly impaired performance for the Brown-Peterson test, and that TGA patients were significantly impaired in the recollection of their episodic memories. They also made reduced numbers of 'remember' compared with 'know' judgments in the episodic memory test several days after TGA. On the basis of our findings, it would appear that the episodic memory deficit during TGA is not related to elementary aspects of executive functioning. Our data also highlight the nature of the cognitive mechanisms involved in the Brown-Peterson task, which may well depend on long-term memory (such as the process of semantic encoding). Lastly, the selective deficit in recollective episodic memories observed in TGA may be principally related to medial temporal lobe abnormalities that have been reported in this syndrome.

Aged↗
PubMed2006

What does transient global amnesia really mean? Review of the literature and thorough study of 142 cases.

Since the first reports of transient global amnesia (TGA) were published in 1956, several neuropsychological and functional imaging studies have shed light on different aspects of this neurological syndrome. By establishing diagnostic criteria, Hodges and Warlow (1990b) have made it far easier to identify clinical TGA-related features. However, no comprehensive survey has been yet carried out in order to validate their criteria/findings or provide information about previously unknown features. In the present paper, (i) we review the literature published since Hodges and Warlow's study and seek to characterize the demographic and clinical features of TGA more accurately, (ii) we report 142 personal TGA cases, with supplementary information regarding both episodes and patients, such as precipitating events, associated symptoms and personality, and (iii) we suggest the existence of different groups of TGA patients, on the basis of a hierarchical cluster analysis. This revealed that in women, episodes are mainly associated with an emotional precipitating event, a history of anxiety and a pathological personality. In men, they occur more frequently after a physical precipitating event. In younger patients, a history of headaches may constitute an important risk factor. No link was found with vascular risk factors. The relevance of each of the above-mentioned variables is discussed in the light of our classification. An extensive description of cases from both the literature and our patient population allows us to refine the characterization of clinical TGA features.

Adult↗
PubMed2006

Selective affection of hippocampal CA-1 neurons in patients with transient global amnesia without long-term sequelae.

The aetiology, pathomechanisms and anatomical correlates of transient global amnesia (TGA) still remain obscure. Recently, focal MR-signal diffusion-weighted imaging (DWI) changes in the hippocampus have been described in patients with TGA, but the exact localization, long term outcome and pathophysiological nature of these lesions still remain unknown. The topography and time course of hippocampal DWI lesions in 41 TGA patients was studied using serial 3 T high-resolution MR-imaging and correlated to clinical and neuropsychometric results. Of these, 29 patients showed 36 DWI lesions with corresponding T(2) lesions in the hippocampus within a time window of 48 h after onset. Almost all lesions (94%; 34/36) were selectively found in the CA-1 sector (Sommer sector) of the hippocampal cornu ammonis. Most DWI lesions (8/10) were already detectable in the peri-acute phase <6 h after onset of symptoms. A follow-up study 4-6 months after the episode did not show evidence for residual structural sequelae of these lesions (n = 20/20). A venous MR angiography of the intracranial dural sinus showed an asymmetric venous drainage in 21/24 (88%) patients. In 11/16 (69%) patients with unilateral lesions, the asymmetry corresponded to the side of the DWI lesion. Significant episodic verbal memory deficits in the acute phase (n = 14/18) were associated with lesions of the dominant hemisphere while impairment of visuospatial memory was associated with lesions of the non-dominant hemisphere. Persistent neuropsychological sequelae were not detected 4-6 months after the episode (n = 16). This is the first prospective study combining high-resolution imaging and neuropsychometry analysing the detailed functional anatomy and outcome of hippocampal DWI/T(2) lesions in TGA supporting the view the TGA being a benign transient disorder. The TGA can be considered a model for a focal transient perturbation of memory circuits in the temporo-mesial region.

Adult↗
PubMedDate not supplied

Distinctive forms of partial retrograde amnesia after asymmetric temporal lobe lesions: possible role of the occipitotemporal gyri in memory.

We tested the hypothesis that partial forms of retrograde amnesia were associated with highly asymmetric lesions to the inferior and anterior-medial temporal lobe. Postencephalitic subjects EK and DR were both impaired on standardized retrograde memory tests, but showed strikingly different profiles in cognitive tasks of name stem completion, name:face matching, temporal ordering, forced choice recognition, and occupational judgments of famous names and faces from the past 3 decades. EK sustained left inferior and anterior-medial temporal lobe lesion with a small right temporal polar lesion, and showed near-complete loss of retrieval, knowledge, and familiarity associated with famous names but minimal deficiencies with famous faces. DR sustained right inferior and anterior-medial temporal lobe lesion and showed a milder retrograde loss limited to utilizing famous face prompts in name stem completion, name:face matching, occupational judgments, and forced choice recognition. These impairments were also different from the memory retrieval deficit, but intact recognition shown by a case of ruptured anterior communicating artery aneurysm with presumed basal forebrain damage. We hypothesize that EK's extensive loss of famous name knowledge was related to left inferior temporal lobe damage, particularly in the lateral and medial occipitotemporal gyri. This region in the left temporal lobe may serve as a critical processing area for retrograde memory that permits activation of established semantic, temporal, and visual (i.e., facial) associations biographically dependent on the category of proper names. On the basis of connectional anatomy patterns in the nonhuman primate, this region receives extensive hippocampal output and is interconnected with the temporal polar region and cortical association areas, which have been implicated in retrieval and storage aspects of retrograde memory. In the right hemisphere, the occipitotemporal gyri may serve an important role in famous face processing as part of a bilateral neural network.

Adult↗
PubMed2001

The effects of live, taped, and no music on people experiencing posttraumatic amnesia.

This study compared the effects of live, taped, and no music, on agitation and orientation levels of people experiencing posttraumatic amnesia (PTA). Participants (N = 22) were exposed to all 3 conditions, twice over 6 consecutive days. Songs used in the live and taped music conditions were identical and were selected based on participants' own preferred music. Pre and posttesting was conducted for each condition using the Agitated Behavior Scale (Corrigan, 1989) and the Westmead PTA Scale (Shores, Marosszeky, Sandanam, Batchelor, 1986). Participants' memory for the music used was also tested and compared with their memory for pictorial material presented in the Westmead PTA Scale. Results indicate that music significantly reduced agitation (p <.0001) and enhanced orientation (p <.001) however, the difference between live and taped music was not significant (p =.7). The mean number of pictures in the Westmead PTA scale recalled was 0.84 and the mean number of music selections recalled was 1.22 but this difference was not significant (p =.7). However, the trend suggests that music selections are more easily encoded in memory and then retrieved on request, than that of pictures. Analysis of responses in a follow-up assessment questionnaire showed that 77% of participants recalled the music program while in PTA, indicating that it reached the memory threshold. Sixty-four percent recalled the live music and 55% recalled the taped music condition however this difference was not significant (p =.7). Results suggest that music therapy programs have an important role to play in the management of people in PTA.

Adult↗
PubMed2001

'I know your name but not your face': explaining modality-based differences in access to biographical knowledge in a patient with retrograde amnesia.

In current functional models of person recognition it is proposed that there exists a single common body of semantic information concerning people accessible from all modalities (e.g. names, faces). In this paper, we present evidence that challenges this view. Two experiments are discussed investigating residual autobiographical and public knowledge in a patient suffering from retrograde amnesia. Knowledge about people was investigated in each case by asking a series of questions, ranging from the very general to the very specific. Experiment 1 examined knowledge about famous people. The results showed that the patient accessed more information about famous people when cued with names than when cued with faces. Experiment 2 examined knowledge about people known personally to the patient. Again, the same pattern of results emerged. While the patient responded accurately to all questions posed with name cues, her ability to recall the same information when prompted with face cues was clearly inferior. This modality-based difference in accessing biographical knowledge is discussed in relation to models of person recognition.

Adolescent↗
PubMed2000

Oral sedation allows for comfort and amnesia during office surgery.

Surgical procedures commonly associated with parenteral sedation or general anesthesia were completed in an office operating room with local anesthesia and oral medication. Diazepam and alprazolam were used in combination to produce a relaxed state, allowing local anesthesia to be instilled. Surgery was completed successfully in all patients, and no untoward effects were seen in the patients. Amnesia was associated with the drug combination, and a protective action of the long-lived drugs against lidocaine toxicity is theorized.

Acetaminophen↗
PubMed1991

Stages of recovery during post-traumatic amnesia and subsequent everyday memory deficits.

Post-traumatic amnesia (PTA) is the period following brain trauma when patients are unable to acquire and retain information. Nineteen patients with brain injury were assessed for PTA, with a new scale, after they regained consciousness, every 24 h. Patients recovered orientation and their capacity to recognise new information, and finally their ability to recall this information. The longer the duration of PTA, the poorer was performance on an everyday memory test given one month after recovery from PTA. Patients with orthopaedic injuries and without brain injury showed minimal impairment on the PTA scale. The predictive value of the scale (multiple R = 0.88) with respect to subsequent everyday memory performance indicates its usefulness as an index of severity of brain injury.

Amnesia↗
PubMed1993

Interleukin-2 enhances scopolamine-induced amnesia and hyperactivity in the mouse.

We studied the effects of human recombinant interleukin-2 (IL-2) on scopolamine-induced amnesia for a passive avoidance response and on scopolamine-induced hyperactivity, in the mouse. The pre-training intraperitoneal administration of the cytokine significantly enhanced the amnesic effect of scopolamine (1.0 mg kg-1 i.p.). Similar effects were observed after repeated administration (2,500 IU/mouse i.p. for 10 days) of the cytokine. In this condition, the treatment with the pro-cholinergic drug acetylcarnitine completely blocked the pro-amnesic effect of IL-2. The cytokine did not affect plasma glucose concentrations, nor induced any change in footshock sensitivity. Intraperitoneal injection of IL-2 significantly enhanced the scopolamine-induced hyperactivity, whereas the cytokine alone was ineffective in modifying locomotor activity. Our results suggest an involvement of the cholinergic system in the neuromodulatory action of IL-2.

Amnesia↗
PubMed1995

Inhibitors of PLA2 and NO synthase cooperate in producing amnesia of a spatial task.

Both nitric oxide and arachidonic acid have been suggested to play a role as a retrograde messenger in synaptic plastic changes which underlie memory formation. However, inhibitors of nitric oxide (NO) synthesis or of arachidonic acid release have produced contradictory results. We suggest a model which involves simultaneous release of both messenger types which can compensate for the loss of one type. To test this theory, rats were injected either with a drug that inhibits release of arachidonic acid, or a drug that inhibits synthesis of NO, or with both drugs. Acquisition of a water maze task was not different between groups. In the test sessions, however, animals injected with both drugs showed marked amnesic symptoms, while the groups injected with a low dose of nordihydroguaiaretic acid (NDGA) or with nitro-L-arginine (L-NARG) showed a trend towards amnesia. The effect of both drugs appears to be additive. The results support the proposed theory.

Amino Acid Oxidoreductases↗
PubMed1995

Pregnenolone sulfate antagonizes dizocilpine amnesia: role for allopregnanolone.

Pregnenolone (PREG) is metabolized in brain to progesterone (PROG), 5 alpha-dihydroprogesterone (5 alpha-DHP) and allopregnanolone (ALLO). Infusion of adrenalectomized/castrated rats with PREG sulfate prevented the cognition deficit elicited by the ionotropic glutamate receptor antagonists, dizocilpine and CPPene. Using a new gas chromatographic/mass-spectrometric method, we demonstrated that PREG sulfate infusion markedly increased the PREG, PROG, 5 alpha-DHP and ALLO brain content. The increase in 5 alpha-DHP and ALLO, but not PREG or PROG content and the antagonism of dizocilpine amnesia observed by injecting rats with PREG sulfate was reversed by inhibiting the conversion of PROG to 5 alpha-DHP with the 5 alpha-reductase blocker SKF 105111. We and others have shown that ALLO potently modulate GABAA receptor function whereas 5 alpha-DHP fails to induce rapid changes in neurotransmitter receptor function. Thus it is possible to suggest that the increase in the brain content of ALLO, rather than 5 alpha-DHP, mediates the effect of PREG sulfate on dizocilpine- or CPPene-induced cognition deficit.

Amnesia↗
PubMed1997

Interleukin-6 affects scopolamine-induced amnesia, but not brain amino acid levels in mice.

We have previously shown that, after peripheral administration, different cytokines affect cognitive functions in mice. In this study, we evaluated the effects of mouse interleukin-6 (IL-6) on the classical behavioural test of scopolamine-induced amnesia for a passive avoidance response in the mouse. Pretraining i.p. administration of this cytokine (0.125 and 0.5 microgram/mouse) significantly reduced the amnesic action of the muscarinic receptor antagonist. As it is well known that brain amino acids are deeply involved in the modulation of cognitive processes we measured the levels of glutamine, aspartic acid, glutamic acid and GABA in the hippocampus and hypothalamus of mice treated with IL-6. At both doses which affected the cognitive functions, this cytokine had no effect on brain levels of measured amino acids. Neither nociceptive thresholds to a thermal stimulus, nor spontaneous locomotor activity were modified by the acute administration of IL-6 (0.5 microgram/mouse). Our data confirm previous observations indicating that peripheral administration of cytokines affects some, but not other brain functions and suggest the involvement of IL-6 in the central modifications induced by the immune activation.

Amino Acids↗
PubMed2000

Dynorphin A-(1-13) and (2-13) improve beta-amyloid peptide-induced amnesia in mice.

The anti-amnesic effects of dynorphins on beta-amyloid peptide-(25-35)-induced impairment of learning and/or memory in mice were investigated using a Y-maze task and a passive avoidance test. Administration of beta-amyloid peptide-(25-35) (betaAP(25-35); 8.2 nmol, i.c.v.) 7 and 14 days before behavioral tests induced a decrease in both alternation behavior and latency in passive avoidance tests. Dynorphin A-(1-13) and A-(2-13) (0.5 and/or 1.5 nmol, i.c.v.) 30 min before behavioral tests improved the beta-amyloid peptide-(25-35)-induced impairment of alternation performance and shortened the step-down latency. Nor-binaltorphimine (4.9 nmol, i.c.v.) partially blocked the effects of dynorphin A-(1-13), but not A-(2-13). These results indicate that dynorphin A-(1-13) and A-(2-13) improve amnesia induced by betaAP-(25-35) via not only kappa opioid receptors, but also by non-opioid mechanisms.

Amnesia↗
PubMed2000

Time course of focal slow wave activity in transient ischemic attacks and transient global amnesia as measured by magnetoencephalography.

In this longitudinal study multichannel MEG was used to localize and to quantify focal pathological spontaneous neuromagnetic activity in six patients with transient ischemic attacks (TIA) and two patients with transient global amnesia (TGA). Slow (2-6 Hz) and beta (14-30 Hz) activity were monitored up to 10 weeks. Results were compared with normative data, and changes over time were statistically analyzed. MEG detected pathological activity that persisted clinical symptoms. Focal slow activity originating from sensorimotor (TIA) and mesiotemporal (TGA) cortices exceeded normal values up to 14 times during the first hours after the attack and recovered to normal within 11 days. Focal beta activity was not useful to monitor the time course of TIA or TGA.

Aged↗
PubMed2004

Amnesia produced by pre-training infusion of serotonin into the substantia nigra.

Interference with dopaminergic, GABAergic or cholinergic activity of the substantia nigra is sufficient to disrupt cognitive functions. In spite of the known interactions between these neurotransmitters and serotonin, there is a notable scarcity of data germane to the participation of nigral serotonin in learning and memory. It was important, therefore, to investigate the possible involvement of serotonin in cognition. Pre-training injections of serotonin into the nigra of rats produced strong amnesia of an aversively-motivated task (inhibitory avoidance) compared to similar injections into the cerebral cortex and zona incerta. The present findings support the hypothesis that nigral serotonergic activity is involved in memory functions.

Amnesia↗
PubMed1981

A psychosocial study of chronic, circumscribed amnesia.

N. A. has been amnesic since 1960 when he sustained a penetrating stab wound to the region of the left dorsomedial thalamus. The amnesia occurs as a strikingly circumscribed disorder in an intelligent (IQ = 124) individual without other cognitive dysfunction. Here, we attempt to characterize the nature of this amnesic disorder as revealed in daily activities, conversations, and personality. These observations are considered in the context of current views about the nature of normal memory and its neurological foundations.

Adult↗