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Results for “AMNESIA”

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At least 1,621 records · Page 90Linked to original sources
PubMed1993

Dopamine agonist treatment of antegrade amnesia from a mediobasal forebrain injury.

We studied the persistent antegrade memory impairment in a woman whose brain had been surgically impaled, leaving a 1-cm-wide mediobasal tract of encephalomalacia that extended just anterior to the septal nuclei and medial to the nucleus accumbens. In a blinded, controlled, alternating repeated-measures protocol, bromocriptine significantly improved her verbal learning, functional memory, and daily recall, perhaps by acting on neurons that had been disconnected from the ventral tegmental tract's dopaminergic inputs.

Adult↗
PubMed2006

Working memory and long-term memory for faces: Evidence from fMRI and global amnesia for involvement of the medial temporal lobes.

Behavioral studies with amnesic patients and imaging studies with healthy adults have suggested that medial temporal lobe (MTL) structures known to be essential for long-term declarative memory (LTM) may also be involved in the maintenance of information in working memory (WM). To examine whether MTL structures are involved in WM maintenance for faces, and the nature of that involvement, WM and LTM for faces were examined in normal participants via functional magnetic resonance imaging (fMRI) and in amnesic patients behaviorally. In Experiment 1, participants were scanned while performing a WM task in which they determined if two novel faces, presented 7 s apart, were the same or different. Later, participants' LTM for the faces they saw during the WM task was measured in an unexpected recognition test. During WM maintenance, the hippocampus was activated bilaterally, and there was greater activation during maintenance for faces that were later remembered than faces later forgotten. A conjunction analysis revealed overlap in hippocampal activations across WM maintenance and LTM contrasts, which suggested that the same regions were recruited for WM maintenance and LTM encoding. In Experiment 2, amnesic and control participants were tested on similar WM and LTM tasks. Amnesic patients, as a group, had intact performance with a 1-s maintenance period, but were impaired after a 7-s WM maintenance period and on the LTM task. Thus, parallel neuroimaging and lesion designs suggest that the same hippocampal processes support WM maintenance, for intervals as short as 7 s, and LTM for faces.

Adolescent↗
PubMed2007

Effect of unitization on associative recognition in amnesia.

We examined how associative recognition performance in amnesic patients is mediated by use of a unitized (i.e., holistic) encoding strategy, and the degree to which the unitization effect is related to sparing of familiarity-based recognition. Participants studied word pairs as either separate lexical units in sentences (i.e., nonunitized) or as compounds (unitized). Under standard recognition instructions, normal controls and patients with left-temporal lobe damage (previously determined to have impairments in both recollection and familiarity) showed no difference for unitized and nonunitized pairs, whereas hypoxics (previously determined to have impaired recollection but relatively preserved familiarity) showed an advantage of unitized over nonunitized pairs. This effect was reproduced in normal healthy participants under instructions to restrict responses to judgments of familiarity. The results indicate that unitization may mediate the degree of associative recognition impairment exhibited by some amnesic patients, and that the effect is related to preserved familiarity capacity. The relevance of the results to the debate over the importance of the hippocampus in memory for associations is discussed.

Adult↗
PubMed1995

Encoding specificity and intrusion in Alzheimer's disease and amnesia.

This study was designed to examine how the pattern of memory deficits and the interaction between episodic and semantic encoding/retrieval conditions influenced intrusions in a population of Alzheimer and amnesic patients. We used as a model for an encoding/retrieval experiment a 2 x 2 experimental design in which two encoding conditions are crossed with two retrieval conditions. It was found that encoding specificity affected intrusions only if patients, regardless of their clinical diagnosis, were grouped according to the type of memory impairment.

Aged↗