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Hippocampus 2001In humans, the phenomenon of temporally graded retrograde amnesia has been described in the clinic and the laboratory for more than 100 years. In the 1990s, retrograde... (Review)
Review
In humans, the phenomenon of temporally graded retrograde amnesia has been described in the clinic and the laboratory for more than 100 years. In the 1990s, retrograde amnesia began to be studied prospectively in experimental animals. We identified 13 published studies in which animals were given equivalent training at two or more separate times before damage to the fornix or hippocampal formation. Eleven of these studies found temporally graded retrograde amnesia, with the extent of amnesia ranging from several days to a month or two. We consider these studies and also suggest why temporally graded retrograde amnesia has sometimes not been observed. Although the evidence in favor of temporally graded retrograde amnesia is substantial, the inference from this work, that memory is reorganized as time passes, is rather vague and depends on mechanisms yet to be identified. It is therefore encouraging that many opportunities exist for moving beyond purely descriptive studies to studies that involve treatments or manipulations directed toward yielding information about mechanisms.
Topics: Amnesia, Retrograde; Animals; Entorhinal Cortex; Fornix, Brain; Hippocampus; Humans
PubMed: 11261772
DOI: 10.1002/1098-1063(2001)11:1<50::AID-HIPO1019>3.0.CO;2-G -
Current Opinion in Neurology Dec 2009Malingered anterograde amnesia is a phenomenon that has been exhaustively studied, whereas research on retrograde amnesia has tended to focus upon functional and organic... (Review)
Review
PURPOSE OF REVIEW
Malingered anterograde amnesia is a phenomenon that has been exhaustively studied, whereas research on retrograde amnesia has tended to focus upon functional and organic accounts of impairment. The present review explores studies relevant to extending the malingering paradigm to retrograde amnesia.
RECENT FINDINGS
In the period reviewed, very little work has directly addressed the area of malingered retrograde amnesia. Researchers have tended to explain apparent 'anomalies' in memory performance or individual presentation, as manifestations of unconscious or psychological distress-mediated behaviour. In contrast, research with offenders claiming amnesia for their crimes has emphasized that malingered retrograde amnesia can be identified with relevant assessment methods. Brain imaging work too has begun to clearly describe the associated neural processes that underlie deception. It appears that the necessary coalescence of insights from clinical neuropsychology, brain imaging and neurology has reached a critical moment.
SUMMARY
Current and previous studies are reviewed that addresses the assessment of malingered retrograde amnesia and evidences that a critical moment has been reached.
Topics: Amnesia, Retrograde; Brain; Diagnostic Imaging; Humans; Malingering; Neuropsychological Tests
PubMed: 19745730
DOI: 10.1097/WCO.0b013e32833299bb -
Handbook of Clinical Neurology 2016Retrograde amnesia is described as condition which can occur after direct brain damage, but which occurs more frequently as a result of a psychiatric illness. In order... (Review)
Review
Retrograde amnesia is described as condition which can occur after direct brain damage, but which occurs more frequently as a result of a psychiatric illness. In order to understand the amnesic condition, content-based divisions of memory are defined. The measurement of retrograde memory is discussed and the dichotomy between "organic" and "psychogenic" retrograde amnesia is questioned. Briefly, brain damage-related etiologies of retrograde amnesia are mentioned. The major portion of the review is devoted to dissociative amnesia (also named psychogenic or functional amnesia) and to the discussion of an overlap between psychogenic and "brain organic" forms of amnesia. The "inability of access hypothesis" is proposed to account for most of both the organic and psychogenic (dissociative) patients with primarily retrograde amnesia. Questions such as why recovery from retrograde amnesia can occur in retrograde (dissociative) amnesia, and why long-term new learning of episodic-autobiographic episodes is possible, are addressed. It is concluded that research on retrograde amnesia research is still in its infancy, as the neural correlates of memory storage are still unknown. It is argued that the recollection of episodic-autobiographic episodes most likely involves frontotemporal regions of the right hemisphere, a region which appears to be hypometabolic in patients with dissociative amnesia.
Topics: Amnesia, Retrograde; Humans; Psychophysiologic Disorders
PubMed: 27719861
DOI: 10.1016/B978-0-12-801772-2.00036-9 -
Revue Neurologique 2017Dissociative amnesias have been reported in neurological episodes mild enough to not cause any visible lesions on morphological examination. Disproportionate retrograde... (Review)
Review
Dissociative amnesias have been reported in neurological episodes mild enough to not cause any visible lesions on morphological examination. Disproportionate retrograde amnesia with or without identity loss happens in the context of psychological trauma (known or not). In metabolic imaging studies, some authors have reported functional alterations, particularly in the bilateral hippocampus, right temporal regions and inferolateral prefrontal cortex, despite normal morphological imaging. To avoid the presumption of an organic, psychogenic or mixed origin for such changes, De Renzi et al. suggested the term 'functional amnesia' to describe the condition. Patients have sometimes recovered during events similar to those preceding the amnesia in either a spectacular fashion or never. Also, in some cases, distraction or sedation may trigger the start of recovery. During psychotherapy, one patient remembered seeing a car on fire when he was a boy, and his amnesia started when his house was on fire. This suggests control by the frontal cortex, with repression blocking amnesic traces in the new emotional and biological context.
Topics: Amnesia; Amnesia, Retrograde; Brain; Humans; Life Change Events; Stress, Psychological
PubMed: 28860028
DOI: 10.1016/j.neurol.2017.07.007 -
Journal of Neurosurgical Anesthesiology Oct 2021
Topics: Amnesia, Retrograde; Humans; Monitoring, Intraoperative; Neurosurgical Procedures
PubMed: 32028375
DOI: 10.1097/ANA.0000000000000681 -
Neurocase 2001
Review
Topics: Amnesia, Retrograde; Brain Injuries; Head Injuries, Closed; Humans; Stress, Psychological
PubMed: 11557823
DOI: 10.1093/neucas/7.4.269 -
Progress in Neurobiology May 2021Seizures cause retrograde amnesia, but underlying mechanisms are poorly understood. We tested whether seizure activated neuronal circuits overlap with spatial memory...
Seizures cause retrograde amnesia, but underlying mechanisms are poorly understood. We tested whether seizure activated neuronal circuits overlap with spatial memory engram and whether seizures saturate LTP in engram cells. A seizure caused retrograde amnesia for spatial memory task. Spatial learning and a seizure caused cFos expression and synaptic plasticity overlapping set of neurons in the CA1 of the hippocampus. Recordings from learning-labeled CA1 pyramidal neurons showed potentiated synapses. Seizure-tagged neurons were also more excitable with larger rectifying excitatory postsynaptic currents than surrounding unlabeled neurons. These neurons had enlarged dendritic spines and saturated LTP. A seizure immediately after learning, reset the memory engram. Seizures cause retrograde amnesia through shared ensembles and mechanisms.
Topics: Amnesia, Retrograde; CA1 Region, Hippocampal; Excitatory Postsynaptic Potentials; Hippocampus; Humans; Neuronal Plasticity; Pyramidal Cells; Seizures; Synapses
PubMed: 33388373
DOI: 10.1016/j.pneurobio.2020.101984 -
Experimental Brain Research Aug 2023Is retrograde amnesia associated with an ability to know who we are and imagine what we will be like in the future? To answer this question, we had S.G., a patient with...
Is retrograde amnesia associated with an ability to know who we are and imagine what we will be like in the future? To answer this question, we had S.G., a patient with focal retrograde amnesia following hypoxia, two brain-damaged (control) patients with no retrograde memory deficits, and healthy controls judge whether each of a series of trait adjectives was descriptive of their present self, future self, another person, and that person in the future, and later recognize studied traits among distractors. Healthy controls and control patients were more accurate in recognizing self-related compared to other-related traits, a phenomenon known as the self-reference effect (SRE). This held for both present and future self-views. By contrast, no evidence of (present or future) SRE was observed in SG, who concomitantly showed reduced certainty about his personality traits. These findings indicate that retrograde amnesia can weaken the self-schema and preclude its instantiation during self-related processing.
Topics: Humans; Amnesia, Retrograde; Memory Disorders; Brain Injuries; Language; Neuropsychological Tests
PubMed: 37450003
DOI: 10.1007/s00221-023-06661-2 -
Current Opinion in Neurobiology Apr 1995The fact that information acquired before the onset of amnesia can be lost (retrograde amnesia) has fascinated psychologists, biologists, and clinicians for over 100... (Review)
Review
The fact that information acquired before the onset of amnesia can be lost (retrograde amnesia) has fascinated psychologists, biologists, and clinicians for over 100 years. Studies of retrograde amnesia have led to the concept of memory consolidation, whereby medial temporal lobe structures direct the gradual establishment of memory representations in neocortex. Recent theoretical accounts have inspired a simple neural network model that produces behavior consistent with experimental data and makes these ideas about memory consolidation more concrete. Recent physiological and anatomical findings provide important information about how memory consolidation might actually occur.
Topics: Amnesia, Retrograde; Animals; Humans; Memory; Nervous System Physiological Phenomena
PubMed: 7620304
DOI: 10.1016/0959-4388(95)80023-9 -
International Journal of Clinical... Nov 2021Midazolam, a short-acting benzodiazepine, has sedative, anxiolytic, amnestic and anticonvulsant effects. Given its advantages of rapid onset, short duration and low...
BACKGROUND
Midazolam, a short-acting benzodiazepine, has sedative, anxiolytic, amnestic and anticonvulsant effects. Given its advantages of rapid onset, short duration and low toxicity, midazolam is optimal for any procedural sedation. Midazolam is known to cause anterograde amnesia; however, the possibility of retrograde amnesia has also been raised. This prospective cohort, non-randomised study evaluated the presence and extent of retrograde amnesia induced by midazolam during caesarean delivery.
METHODS
One hundred parturients scheduled for elective caesarean delivery under spinal anaesthesia were enrolled. As soon as giving birth, six picture cards were shown to the patients in 1-min intervals, and then midazolam (0.1 mg/kg) was given or not according to the patients' preference. This overall retrograde recall rate of six cards was the primary outcome of our study, which was asked by a blinded investigator.
RESULTS
The overall retrograde card recall rate was lower in the midazolam group compared with the control group (77.0 ± 13.4 vs. 87.7 ± 3.9%, P < .001), especially at 1 minute before midazolam administration (58% vs. 88%, P < .001). Decreased memory trend was observed as time progressed towards midazolam administration in the midazolam group (P = .035). More patients answered 'yes' to the factitious event in the midazolam group than in the control group (26% vs. 4%, P = .004).
CONCLUSION
Intravenous midazolam could cause a brief-period retrograde amnesia in visual and event memory. Moreover, there were more spurious reports of intraoperative factitious events in the midazolam group, implying that episodic memories were also affected by midazolam.
Topics: Amnesia, Retrograde; Cohort Studies; Female; Humans; Hypnotics and Sedatives; Midazolam; Pregnancy; Prospective Studies
PubMed: 34037290
DOI: 10.1111/ijcp.14402