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Neuroscience and Biobehavioral Reviews 2008Previous research suggests that early performance of amnesic individuals in a probabilistic category learning task is relatively unimpaired. When combined with impaired... (Review)
Review
Previous research suggests that early performance of amnesic individuals in a probabilistic category learning task is relatively unimpaired. When combined with impaired declarative knowledge, this is taken as evidence for the existence of separate implicit and explicit memory systems. The present study contains a more fine-grained analysis of learning than earlier studies. Using a dynamic lens model approach with plausible learning models, we found that the learning process is indeed indistinguishable between an amnesic and control group. However, in contrast to earlier findings, we found that explicit knowledge of the task structure is also good in both the amnesic and the control group. This is inconsistent with a crucial prediction from the multiple-systems account. The results can be explained from a single system account and previously found differences in later categorization performance can be accounted for by a difference in learning rate.
Topics: Adaptation, Psychological; Algorithms; Amnesia; Association Learning; Case-Control Studies; Female; Humans; Male; Middle Aged; Models, Neurological; Models, Psychological; Probability Learning; Reference Values
PubMed: 17854893
DOI: 10.1016/j.neubiorev.2007.07.005 -
BMJ (Clinical Research Ed.) Jan 1991
Topics: Aged; Amnesia; Automobile Driving; Humans; Ischemic Attack, Transient; Middle Aged; Migraine Disorders; Recurrence; Time Factors
PubMed: 1995116
DOI: 10.1136/bmj.302.6768.62 -
The Journal of Neuroscience : the... Dec 2022Associative binding is key to normal memory function and is transiently disrupted during periods of post-traumatic amnesia (PTA) following traumatic brain injury (TBI)....
Associative binding is key to normal memory function and is transiently disrupted during periods of post-traumatic amnesia (PTA) following traumatic brain injury (TBI). Electrophysiological abnormalities, including low-frequency activity, are common following TBI. Here, we investigate associative memory binding during PTA and test the hypothesis that misbinding is caused by pathological slowing of brain activity disrupting cortical communication. Thirty acute moderate to severe TBI patients (25 males; 5 females) and 26 healthy controls (20 males; 6 females) were tested with a precision working memory paradigm requiring the association of object and location information. Electrophysiological effects of TBI were assessed using resting-state EEG in a subsample of 17 patients and 21 controls. PTA patients showed abnormalities in working memory function and made significantly more misbinding errors than patients who were not in PTA and controls. The distribution of localization responses was abnormally biased by the locations of nontarget items for patients in PTA, suggesting a specific impairment of object and location binding. Slow-wave activity was increased following TBI. Increases in the δ-α ratio indicative of an increase in low-frequency power specifically correlated with binding impairment in working memory. Connectivity changes in TBI did not correlate with binding impairment. Working memory and electrophysiological abnormalities normalized at 6 month follow-up. These results show that patients in PTA show high rates of misbinding that are associated with a pathological shift toward lower-frequency oscillations. How do we remember what was where? The mechanism by which information (e.g., object and location) is integrated in working memory is a central question for cognitive neuroscience. Following significant head injury, many patients will experience a period of post-traumatic amnesia (PTA) during which this associative binding is disrupted. This may be because of electrophysiological changes in the brain. Using a precision working memory test and resting-state EEG, we show that PTA patients demonstrate impaired binding ability, and this is associated with a shift toward slower-frequency activity on EEG. Abnormal EEG connectivity was observed but was not specific to PTA or binding ability. These findings contribute to both our mechanistic understanding of working memory binding and PTA pathophysiology.
Topics: Male; Female; Humans; Amnesia; Memory, Short-Term; Amnesia, Retrograde; Brain Injuries, Traumatic; Psychotic Disorders
PubMed: 36316155
DOI: 10.1523/JNEUROSCI.0564-22.2022 -
Cortex; a Journal Devoted To the Study... Dec 1984A case of post traumatic retrograde amnesia is described. The patient presented after an initial coma a global amnesia, but the fixation deficit rapidly disappeared, and...
A case of post traumatic retrograde amnesia is described. The patient presented after an initial coma a global amnesia, but the fixation deficit rapidly disappeared, and a severe retrograde amnesia dating back to childhood experience and learning remained the main symptom. Amnesia for remote events was associated with didactic memory deficit and, at a lesser degree, with a verbal memory deficit. Recovery of fixation allowed a progressive relearning. This pattern of impairment was recently related to mesencephalic lesions, but we think that the role of temporal lobe involvement cannot be neglected.
Topics: Adult; Amnesia; Amnesia, Retrograde; Brain Injuries; Humans; Male; Psychological Tests; Wechsler Scales
PubMed: 6518798
DOI: 10.1016/s0010-9452(84)80060-x -
Psychologie & Neuropsychiatrie Du... Mar 2006The two main aetiologies of transient amnesia in the elderly are idiopathic transient global amnesia (TGA) and iatrogenic or toxic amnesia. Vascular and epileptic... (Review)
Review
The two main aetiologies of transient amnesia in the elderly are idiopathic transient global amnesia (TGA) and iatrogenic or toxic amnesia. Vascular and epileptic amnesia are less common. According to the literature, transient psychogenic amnesia, which is a frequent cause of amnesia at age 30 to 50, is very rare in the elderly. TGA is the prototypical picture of transient amnesia. It occurs more often after age 50, with no identified cause, even if some authors accept emotional stress or minor head trauma as occasional precipitants. The mechanism of TGA remains a matter of discussion. It may be the consequence of a spreading depression similar to that described in migraine with aura, but other arguments support an ischemic mechanism. Iatrogenic amnesias are mainly caused by benzodiazepines (BZs) or anticholinergics. The former may occur in a non-anxious subject, who is not a usual consumer of BZ and takes a single dose. The latter are more often due to a hypersensitivity to anticholinergic drugs, in particular in patients presenting with a covert, incipient Alzheimer's disease. A vascular origin must be considered when amnesia is accompanied by other neurological symptoms, and when the regression of the amnesic disorder is slow, lasting several days. It results from lesions involving various mechanisms and locations, mainly subcortical. Partial seizures, most often mesio-temporal, more rarely frontal, may be the cause of transient amnesia in the elderly, in the absence of a past history of epilepsy. The red flag supportive of an epileptic origin is the repetition of stereotyped amnesic episodes. EEG demonstration of seizures may be difficult and the response to antiepileptic drugs effective on partial seizures is usually good.
Topics: Aged; Aging; Amnesia, Transient Global; Benzodiazepines; Cholinergic Antagonists; Craniocerebral Trauma; Depression; Emotions; Epilepsies, Partial; Humans; Iatrogenic Disease; Migraine Disorders; Stroke
PubMed: 16556516
DOI: No ID Found -
Hippocampus Feb 2016Aging has been associated with a decline in relational memory, which is critically supported by the hippocampus. By adapting the transitivity paradigm (Bunsey and...
Aging has been associated with a decline in relational memory, which is critically supported by the hippocampus. By adapting the transitivity paradigm (Bunsey and Eichenbaum (1996) Nature 379:255-257), which traditionally has been used in nonhuman animal research, this work examined the extent to which aging is accompanied by deficits in relational learning and flexible expression of relational information. Older adults' performance was additionally contrasted with that of amnesic case DA to understand the critical contributions of the medial temporal lobe, and specifically, the hippocampus, which endures structural and functional changes in healthy aging. Participants were required to select the correct choice item (B versus Y) based on the presented sample item (e.g., A). Pairwise relations must be learned (A->B, B->C, C->D) so that ultimately, the correct relations can be inferred when presented with a novel probe item (A->C?Z?). Participants completed four conditions of transitivity that varied in terms of the degree to which the stimuli and the relations among them were known pre-experimentally. Younger adults, older adults, and DA performed similarly when the condition employed all pre-experimentally known, semantic, relations. Older adults and DA were less accurate than younger adults when all to-be-learned relations were arbitrary. However, accuracy improved for older adults when they could use pre-experimentally known pairwise relations to express understanding of arbitrary relations as indexed through inference judgments. DA could not learn arbitrary relations nor use existing knowledge to support novel inferences. These results suggest that while aging has often been associated with an emerging decline in hippocampal function, prior knowledge can be used to support novel inferences. However, in case DA, significant damage to the hippocampus likely impaired his ability to learn novel relations, while additional damage to ventromedial prefrontal and anterior temporal regions may have resulted in an inability to use prior knowledge to flexibly express indirect relational knowledge.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aging; Amnesia; Female; Follow-Up Studies; Hippocampus; Humans; Learning; Male; Middle Aged; Photic Stimulation; Young Adult
PubMed: 26234960
DOI: 10.1002/hipo.22501 -
Postgraduate Medical Journal Apr 2007Transient global amnesia usually affects patients between the ages of 40 and 80. Patients with this condition are often described--wrongly--as being confused. It... (Review)
Review
Transient global amnesia usually affects patients between the ages of 40 and 80. Patients with this condition are often described--wrongly--as being confused. It presents classically with an abrupt onset of severe anterograde amnesia. It is usually accompanied by repetitive questioning. The patient does not have any focal neurological symptoms. Patients remain alert, attentive, and cognition is not impaired. However, they are disoriented to time and place. Attacks usually last for 1-8 h but should be less than 24 h. It is possible that it may result from different mechanisms such as venous congestion with valsalva-like activities before symptom onset, arterial thromboembolic ischaemia and vasoconstriction due to hyperventilation. Diagnosis may be made safely in the presence of a characteristic collateral history. No specific treatment is indicated for a typical episode.
Topics: Amnesia, Transient Global; Automobile Driving; Diagnosis, Differential; Humans; Prognosis
PubMed: 17403949
DOI: 10.1136/pgmj.2006.052472 -
Revue Scientifique Et Technique... Aug 1997Paralytic shellfish poisoning (PSP) has been documented for two centuries and control programmes have been operated for fifty years. Although some illnesses are reported... (Review)
Review
Paralytic shellfish poisoning (PSP) has been documented for two centuries and control programmes have been operated for fifty years. Although some illnesses are reported almost every year, the last known death from PSP occurred in 1981. In more recent years, amnesic shellfish poisoning, ciguatera poisoning, diarrhoetic shellfish poisoning, scombroid (histamine) poisoning and tetramine poisoning have been documented. The most frequently observed of these diseases is scombroid poisoning from improperly stored fish, but PSP and ciguatera poisoning have the most serious consequences. Vibrio infections arising from naturally-contaminated shellfish are virtually unknown, and viral illnesses from polluted harvested waters are rare. Control is achieved through monitoring of waters for indicators of human pathogens. Inspection systems based on the hazard analysis and critical control point principles are being introduced into all areas of fish and shellfish harvesting. The Inspection Directorate of the Department of Fisheries and Oceans joined the new Canadian Food Inspection Agency in 1997, which co-ordinates all Federal control measures for food in Canada.
Topics: Amnesia; Animals; Bridged-Ring Compounds; Canada; Ciguatera Poisoning; Diarrhea; Foodborne Diseases; Histamine; Humans; Marine Toxins; Seafood
PubMed: 9501380
DOI: 10.20506/rst.16.2.1058 -
Alcohol-Induced Amnesia and Personalized Drinking Feedback: Blackouts Predict Intervention Response.Behavior Therapy Jan 2019Alcohol-induced amnesia ("blackout") is a reliable predictor of alcohol-related harm. Given its association with other negative consequences, experience of... (Randomized Controlled Trial)
Randomized Controlled Trial
Alcohol-induced amnesia ("blackout") is a reliable predictor of alcohol-related harm. Given its association with other negative consequences, experience of alcohol-induced amnesia may serve as a teachable moment, after which individuals are more likely to respond to intervention. To test this hypothesis, alcohol-induced amnesia was evaluated as a moderator of brief intervention effect on (a) alcohol-related consequences and (b) the proposed intervention mediators, protective behavioral strategies and peak blood alcohol concentration (BAC). Baseline alcohol risk measured using the Alcohol Use Disorders Identification Test (AUDIT) was also evaluated as a moderator to rule out the possibility that amnesia is simply an indicator of more general alcohol risk. College students (N = 198) reporting alcohol use in a typical week completed assessments at baseline and 1-month follow-up as part of a larger intervention trial. Participants were randomized to assessment only (AO; n = 58) or personalized feedback intervention (PFI; n = 140). Hierarchical regression was used to examine direct and indirect intervention effects. A significant group-by-amnesia interaction revealed that only PFI participants who had experienced alcohol-induced amnesia in the past month reported decreases in alcohol consequences at 1-month follow-up. The PFI reduced alcohol-related consequences indirectly through changes in peak BAC, but only among those who had experienced amnesia at baseline. In contrast, baseline alcohol risk (AUDIT) did not moderate intervention effects, and use of protective behavioral strategies did not statistically mediate intervention effects. Findings suggest that loss of memory for drinking events is a unique determinant of young adult response to brief alcohol intervention. Normative feedback interventions may be particularly effective for individuals who have experienced alcohol-induced amnesia in the past 30 days.
Topics: Adolescent; Alcohol Drinking; Amnesia; Blood Alcohol Content; Counseling; Early Medical Intervention; Feedback, Psychological; Female; Follow-Up Studies; Forecasting; Humans; Male; Students; Young Adult
PubMed: 30661564
DOI: 10.1016/j.beth.2018.03.008 -
Dementia and Geriatric Cognitive... 2010Subjects with mild cognitive impairment (MCI) constitute a risk population of developing dementia and thus a population of clinical interest. This study reviews recent... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND/AIMS
Subjects with mild cognitive impairment (MCI) constitute a risk population of developing dementia and thus a population of clinical interest. This study reviews recent work on the incidence of MCI in the elderly.
METHODS
Incidence papers were identified by a systematic literature search. Studies on the incidence of MCI were considered if they identified 'cognitively mildly impaired' subjects by application of the MCI criteria, used the 'person-years-at-risk' method, and were based on population- or community-based samples.
RESULTS
Nine studies were identified. The incidence of amnestic MCI subtypes ranged between 9.9 and 40.6 per 1,000 person-years, and the incidence of non-amnestic MCI subtypes was 28 and 36.3 per 1,000 person-years. Regarding any MCI, incidence rates of 51 and 76.8 per 1,000 person-years were found. A higher risk of incident MCI mainly resulted for higher age, lower education and hypertension.
DISCUSSION
The incidence rates of MCI varied widely, and possible risk factors for incident MCI were analysed only to a limited extent. The findings call for an agreement concerning the criteria used for MCI and the operationalisation of these criteria.
Topics: Aged; Amnesia; Brazil; Cognition Disorders; Epidemiologic Methods; Europe; Humans; Population; Risk Factors; Socioeconomic Factors; United States
PubMed: 20150735
DOI: 10.1159/000272424