105 resultados para amnesia


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Head trauma leading to concussion and electroconvulsive shock (ECS) in humans causes amnesia for events that occurred shortly before the injury (retrograde amnesia). The present experiment investigated the amnesic effect of lidocaine and ECS in 25 rats trained on a working memory version of the Morris water task. Each day, the escape platform was moved to a new location; learning was evidenced by a decrease in the latency to find the platform from the first to the second trial. "Consolidation" of this newly encoded spatial engram was disrupted by bilateral inactivation of the dorsal hippocampus with 1 microliter of 4% lidocaine applied as soon as possible after the first trial. When trial 2 was given after recovery from the lidocaine (30 min after the injection), a normal decrease in latency indicated that the new engram was not disrupted. When trial 2 was given under the influence of lidocaine (5 min after injection), absence of latency decrease demonstrated both the success of the inactivation and the importance of hippocampus for the task. To examine the role of events immediately after learning, ECS (30 or 100 mA, 50 Hz, 1.2 sec) was applied 0 sec to 45 sec after a single escape to the new platform location. A 2-h delay between ECS and trial 2 allowed the effects of ECS to dissipate. ECS applied 45 sec or 30 sec after trial 1 caused no retrograde amnesia: escape latencies on trial 2 were the same as in control rats. However, ECS applied 0 sec or 15 sec after trial 1 induced clear retrograde amnesia: escape latencies on trial 2 were no shorter than on trial 1. It is concluded that the consolidation of a newly formed memory for spatial location can only be disrupted by ECS within 30 sec after learning.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We tested amnesic patients, patients with frontal lobe lesions, and control subjects with the deferred imitation task, a nonverbal test used to demonstrate memory abilities in human infants. On day 1, subjects were given sets of objects to obtain a baseline measure of their spontaneous performance of target actions. Then different event sequences were modeled with the object sets. On day 2, the objects were given to the subjects again, first without any instructions to imitate the sequences, and then with explicit instructions to imitate the actions exactly as they had been modeled. Control subjects and frontal lobe patients reproduced the events under both uninstructed and instructed conditions. In contrast, performance by the amnesic patients did not significantly differ from that of a second control group who had the same opportunities to handle the objects but were not shown the modeled actions. These findings suggest that deferred imitation is dependent on the brain structures essential for declarative memory that are damaged in amnesia, and they support the view that infants who imitate actions after long delays have an early capacity for long-term declarative memory.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

El conjunto arquitectónico de la Feria Internacional del Calzado de Elda (Alicante), obra del arquitecto Miguel López González, fue demolido en el año 2000 y, con él, han desaparecido sus documentos gráficos. Se trataba de un recinto ocupado por dos prismas: uno horizontal, más comercial, para la Feria, y otro vertical, más representativo, para oficinas. Un pabellón y un rascacielos: dos aportaciones del Movimiento Moderno. En este artículo, a partir de los escasos documentos gráficos y fotografías de la maqueta recuperados, así como de las huellas de su derribo, se intenta reconstruir el proceso de los proyectos que se sucedieron y sirvieron de base a la construcción del edificio. Con su desaparición, éste se ha convertido en representante, no solo de una corriente arquitectónica, sino de toda una sociedad, que se ha sometido a un proceso de amnesia, al perder parte de su patrimonio tanto construido como dibujado. Se procede, pues, a la recuperación de la memoria gráfica de este edificio emblemático.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Thesis (Ph.D.)--University of Washington, 2016-06

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background: Alcohol-induced blackouts (ie, periods of anterograde amnesia) have received limited recent research attention. Objective: To examine the genetic epidemiology of lifetime blackouts and having had 3 or more blackouts in a year, including analyses controlling for the frequency of intoxication. Design, Setting, and Participants: Members of the young adult Australian Twin Register, a volunteer twin panel born between January 1, 1964, and December 3 1, 1971, were initially registered with the panel as children by their parents between 1980 and 1982. They underwent structured psychiatric telephone inter-views from February 1996 through September 2000. The current sample contains 2324 monozygotic and dizygotic twin pairs (mean [SDI age 29.9 [2.5] years) for whom both twins' responses were coded for blackout questions and for frequency of intoxication. Main Outcome Measure: Data on lifetime blackouts and having had 3 or more blackouts in a year were collected within an examination of the genetic epidemiology of alcoholism. Results: A lifetime history of blackouts was reported by 39.3% of women and 52.4% of men; 11.4% of women and 20.9% of men reported having had 3 or more blackouts in a year. The heritability of lifetime blackouts was 52.5% and that of having had 3 or more blackouts in a year was 57.8%. Models that controlled for frequency of intoxication found evidence of substantial genetic contribution unique to risk for the blackouts and a significant component of genetic risk shared with frequency of intoxication. Conclusions: The finding of a substantial genetic contribution to liability for alcohol-induced blackouts including a component of genetic loading shared with frequency of intoxication may offer important additional avenues to investigate susceptibility to alcohol-related problems.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study aimed to replicate and cross-validate the Rapid Screen of Concussion (RSC) for diagnosing mild TBI (mTBI). One hundred (81 male, 19 female) cases of mTBI and 35 (23 male and 12 female) cases of orthopaedic injuries were tested within 24 hr of injury. Double cross-validation was used to examine whether total RSC scores obtained in the cur-rent sample, generalised to one previously reported. In the new sample, mTBI patients answered fewer orientation questions, recalled fewer words on the learning trial and after a delay, judged fewer sentences in 2 min, and completed fewer symbols in the Digit Symbol Substitution Test than orthopaedic controls. The formulae and cut-offs developed on the original and new samples produced similar sensitivity and overall correct classification rates. Inclusion of the Digit Symbol Substitution Test performance of the new sample improved the sensitivity (80.2%) and specificity (82.6%) in males. It did not improve the correct classification rate in females, which was 89.5% sensitivity and 91.7% specificity before the inclusion of the Digit Symbol Substitution Test. Taken together, these results indicate that a combined score on this 12-min screen yields a measure of level of brain impairment up to 24 hr after mTBI.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

J.L., then a 25-year-old physiotherapist, became densely amnesic following herpes simplex encephalitis. She displayed severe retrograde amnesia, category-specific semantic memory loss, and a profound anterograde amnesia affecting both verbal and visual memory. Her working memory systems were relatively spared as were most of her cognitive problem-solving abilities, but her social functioning was grossly impaired. She was able to demonstrate several previously learned physiotherapy skills, but was unable to modify her application of these procedures in accordance with patient response. She showed no memory of theoretical or propositional knowledge, and could neither plan treatment or reason clinically. Three years later, J.L. had profound impairment of anterograde and retrograde declarative memory, with relative sparing of working memory for problem solving and long-term memory of procedural skills. The theoretical and practical implications of her amnesic syndrome are discussed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Three-, 4- and 5-year-old children were asked to report something that they did do yesterday and something that they were going to do tomorrow. They were also asked to recall events that had not occurred yesterday, and predict events that would not occur tomorrow. In two studies these simple questions revealed striking age differences in the ability to report personal events from the past and the future. Only a minority of 3-year-olds but a majority of the older children were able to appropriately answer these questions. These findings substantiate the proposal that the ability to recall past events and the ability to predict future events (i.e., mental time travel), emerge in tandem between the ages of 3 and 5 years. (c) 2005 Elsevier Inc. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Cognitive systems research involves the synthesis of ideas from natural and artificial systems in the analysis, understanding, and design of all intelligent systems. This chapter discusses the cognitive systems associated with the hippocampus (HC) of the human brain and their possible role in behaviour and neurodegenerative disease. The hippocampus (HC) is concerned with the analysis of highly abstract data derived from all sensory systems but its specific role remains controversial. Hence, there have been three major theories concerning its function, viz., the memory theory, the spatial theory, and the behavioral inhibition theory. The memory theory has its origin in the surgical destruction of the HC, which results in severe anterograde and partial retrograde amnesia. The spatial theory has its origin in the observation that neurons in the HC of animals show activity related to their location within the environment. By contrast, the behavioral inhibition theory suggests that the HC acts as a ‘comparator’, i.e., it compares current sensory events with expected or predicted events. If a set of expectations continues to be verified then no alteration of behavior occurs. If, however, a ‘mismatch’ is detected then the HC intervenes by initiating appropriate action by active inhibition of current motor programs and initiation of new data gathering. Understanding the cognitive systems of the hippocampus in humans may aid in the design of intelligent systems involved in spatial mapping, memory, and decision making. In addition, this information may lead to a greater understanding of the course of clinical dementia in the various neurodegenerative diseases in which there is significant damage to the HC.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This article discusses the structure, anatomical connections, and functions of the hippocampus (HC) of the human brain and its significance in neuropsychology and disease. The HC is concerned with the analysis of highly abstract data derived from all sensory systems but its specific role remains controversial. Hence, there have been three major theories concerning its function, viz., the memory theory, the spatial theory, and the behavioral inhibition system (BIS) theory. The memory theory has its origin in the surgical destruction of the HC, which results in severe anterograde and partial retrograde amnesia. The spatial theory has its origin in the observation that neurons in the HC of animals show activity related to their location within the environment. By contrast, the behavioral inhibition theory suggests that the HC acts as a ‘comparator’, i.e., it compares current sensory events with expected or predicted events. If a set of expectations continues to be verified then no alteration of behavior occurs. If, however, a ‘mismatch’ is detected then the HC intervenes by initiating appropriate action by active inhibition of current motor programs and initiation of new data gathering. Understanding the anatomical connections of the hippocampus may lead to a greater understanding of memory, spatial orientation, and states of anxiety in humans. In addition, HC damage is a feature of neurodegenerative diseases such as Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), Pick’s disease (PiD), and Creutzfeldt-Jakob disease (CJD) and understanding HC function may help to explain the development of clinical dementia in these disorders.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This article discusses the structure, anatomical connections, and functions of the hippocampus (HC) of the human brain and its significance in neuropsychology and disease. The HC is concerned with the analysis of highly abstract data derived from all sensory systems but its specific role remains controversial. Hence, there have been three major theories concerning its function, viz., the memory theory, the spatial theory, and the behavioral inhibition system (BIS) theory. The memory theory has its origin in the surgical destruction of the HC, which results in severe anterograde and partial retrograde amnesia. The spatial theory has its origin in the observation that neurons in the HC of animals show activity related to their location within the environment. By contrast, the behavioral inhibition theory suggests that the HC acts as a 'comparator', i.e., it compares current sensory events with expected or predicted events. If a set of expectations continues to be verified then no alteration of behavior occurs. If, however, a 'mismatch' is detected then the HC intervenes by initiating appropriate action by active inhibition of current motor programs and initiation of new data gathering. Understanding the anatomical connections of the hippocampus may lead to a greater understanding of memory, spatial orientation, and states of anxiety in humans. In addition, HC damage is a feature of neurodegenerative diseases such as Alzheimer's disease (AD), dementia with Lewy bodies (DLB), Pick's disease (PiD), and Creutzfeldt-Jakob disease (CJD) and understanding HC function may help to explain the development of clinical dementia in these disorders.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This dissertation analyzes six twenty-first century novels that reflect Spain's current intellectual trends on the Spanish Civil War, Francoism and the transition to a democratic system. These novels deal with the complex correlation between memory and amnesia caused by the traumatic events of the Civil War. Despite the abundance of literature on this topic, these writers insist on the need for the recovery of historical and collective memory in order to halt the negative historical revisionism of recent years. Beginning with the death of Francisco Franco, this work focuses on the historical-theoretical framework that leads to the development of this mnemonic narrative and outlines the politics of memory effectuated during the transitional period, a lieu de mémoire frequently revisited and examined by new generations of writers. The novels analyzed also call for the retelling of history from the perspective of everyday people and address the need to pay overdue homage to victims of the post-war era.^ This work concludes that, while the texts may be considered settings for posthumous tributes, they could likewise advocate for a national reconciliation. Thus, as this narrative reveals, by focusing more on the need for a work on memory than on political and ideological polarizations, the memory of restitution does not interfere with the memory of reconciliation. The writers in question are nonetheless aware that reconciliation cannot be based on a spurious amnesia. The first step, therefore, towards reconciliation is to achieve a legitimate dialogue with regard to the traumatic past, and literary works may offer a tenable path. ^

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The neoliberal period was accompanied by a momentous transformation within the US health care system.  As the result of a number of political and historical dynamics, the healthcare law signed by President Barack Obama in 2010 ‑the Affordable Care Act (ACA)‑ drew less on universal models from abroad than it did on earlier conservative healthcare reform proposals. This was in part the result of the influence of powerful corporate healthcare interests. While the ACA expands healthcare coverage, it does so incompletely and unevenly, with persistent uninsurance and disparities in access based on insurance status. Additionally, the law accommodates an overall shift towards a consumerist model of care characterized by high cost sharing at time of use. Finally, the law encourages the further consolidation of the healthcare sector, for instance into units named “Accountable Care Organizations” that closely resemble the health maintenance organizations favored by managed care advocates. The overall effect has been to maintain a fragmented system that is neither equitable nor efficient. A single payer universal system would, in contrast, help transform healthcare into a social right.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Purpose: To investigate the cognition-enhancing effects of aqueous extract of Indigofera tinctoria Linn (ITE, Fabaceae) in experimental amnesic mice. Methods: Scopolamine (2 mg/kg, i.p.) was used to induce amnesia in mice. The cognitive-enhancing activity of the ITE (5, 10 and 20 μg/mL) was studied by passive avoidance response, elevated plus maze and Y-maze behavioral paradigm in normal and scopolamine-induced amnesic mice. Antioxidant activities were also determined based on the ability of ITE to inhibit lipid peroxide, superoxide and hydroxyl radicals. Results: Scopolamine-induced cognitive deficits were significantly reversed by ITE (p < 0.001 at 20 mg/kg) in a dose-dependent fashion in all the behavioral paradigms tested. Furthermore, ITE dosedependently scavenged lipid peroxide, superoxide and hydroxyl free radicals with 50 % inhibition concentration (IC50) of 7.28 ± 0.37, 5.25 ± 0.28 and 7.62 ± 0.43 μg/mL, respectively. Conclusion: ITE possesses cognitive-enhancing properties in amnesic mice due to its potent antioxidant action.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Ribot’s law refers to the better preservation of remote memories compared with recent ones that presumably characterizes retrograde amnesia. Even if Ribot-type temporal gradient has been extensively studied in retrograde amnesia, particularly in Alzheimer’s disease (AD), this pattern has not been consistently found. One explanation for these results may be that rehearsal frequency rather than remoteness accounts for the better preservation of these memories. Thus, the aim of present study was to address this question by studying retrograde semantic memory in subjects with amnestic mild cognitive impairment (aMCI) (n = 20), mild AD (n = 20) and in healthy older controls (HC; n = 19). In order to evaluate the impact of repetition as well as the impact of remoteness, we used a test assessing memory for enduring and transient public events that occurred in the recent and remote past. Results show no clear temporal gradient across time periods (1960–1975; 1976–1990; 1991–2005; 2006–2011), but a better performance was observed in all three groups for enduring compared with transient events. Moreover, although deficits were globally found in both patients groups compared with HC, more specific analyses revealed that aMCI patients were only impaired on transient events while AD patients were impaired on both transient and enduring events. Exploratory analyses also revealed a tendency suggesting preservation of remote transient events in aMCI. These findings are discussed with regards to memory consolidation models.